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Question 1
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A 67-year-old man arrives at the emergency department with abrupt onset left-sided foot and leg weakness and sensory loss. According to his wife, he stumbled and fell while they were out for dinner. Imaging results indicate an infarct in the anterior cerebral artery (ACA).
Which lobes of the brain are expected to be impacted the most?Your Answer: Frontal and parietal lobes
Explanation:The anterior cerebral artery is responsible for supplying blood to a portion of the frontal and parietal lobes. While this type of stroke is uncommon and may be challenging to diagnose through clinical means, imaging techniques can reveal affected vessels or brain regions. Damage to the frontal and parietal lobes can result in significant mood, personality, and movement disorders.
It’s important to note that the occipital lobe and cerebellum receive their blood supply from the posterior cerebral artery and cerebellar arteries (which originate from the basilar and vertebral arteries), respectively. Therefore, they would not be impacted by an ACA stroke. Similarly, the middle cerebral artery is responsible for supplying blood to the temporal lobe, so damage to the ACA would not affect this area.
The Circle of Willis is an anastomosis formed by the internal carotid arteries and vertebral arteries on the bottom surface of the brain. It is divided into two halves and is made up of various arteries, including the anterior communicating artery, anterior cerebral artery, internal carotid artery, posterior communicating artery, and posterior cerebral arteries. The circle and its branches supply blood to important areas of the brain, such as the corpus striatum, internal capsule, diencephalon, and midbrain.
The vertebral arteries enter the cranial cavity through the foramen magnum and lie in the subarachnoid space. They then ascend on the anterior surface of the medulla oblongata and unite to form the basilar artery at the base of the pons. The basilar artery has several branches, including the anterior inferior cerebellar artery, labyrinthine artery, pontine arteries, superior cerebellar artery, and posterior cerebral artery.
The internal carotid arteries also have several branches, such as the posterior communicating artery, anterior cerebral artery, middle cerebral artery, and anterior choroid artery. These arteries supply blood to different parts of the brain, including the frontal, temporal, and parietal lobes. Overall, the Circle of Willis and its branches play a crucial role in providing oxygen and nutrients to the brain.
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This question is part of the following fields:
- Cardiovascular System
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Question 2
Correct
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As a medical student on placement with a surgical team, you come across a patient who has developed foot drop in their right leg after surgery. You notice that the patient is dragging their right foot and experiencing weakness in dorsiflexion and eversion of their foot, as well as an inability to extend their toes. Which nerve is most likely to have been affected during the operation?
Your Answer: Common fibular nerve
Explanation:The common fibular nerve starts at the top of the popliteal fossa, passing medial to the biceps femoris and then crossing over the head of the gastrocnemius. It provides an articular branch to the knee before winding around the neck and passing under the Fibularis longus. At this point, it divides into superficial and deep branches. In the popliteal fossa, it also divides to give the lateral sural cutaneous nerve, which joins with a branch from the tibial nerve to form the sural nerve. If the nerve is damaged, it can result in foot drop, which can occur due to prolonged pressure on the nerve during an operation or other causes. Motor loss of other nerves, such as the tibial, sciatic, inferior gluteal, or femoral nerves, can result in weakness in other muscles.
Lower limb anatomy is an important topic that often appears in examinations. One aspect of this topic is the nerves that control motor and sensory functions in the lower limb. The femoral nerve controls knee extension and thigh flexion, and provides sensation to the anterior and medial aspect of the thigh and lower leg. It is commonly injured in cases of hip and pelvic fractures, as well as stab or gunshot wounds. The obturator nerve controls thigh adduction and provides sensation to the medial thigh. It can be injured in cases of anterior hip dislocation. The lateral cutaneous nerve of the thigh provides sensory function to the lateral and posterior surfaces of the thigh, and can be compressed near the ASIS, resulting in a condition called meralgia paraesthetica. The tibial nerve controls foot plantarflexion and inversion, and provides sensation to the sole of the foot. It is not commonly injured as it is deep and well protected, but can be affected by popliteral lacerations or posterior knee dislocation. The common peroneal nerve controls foot dorsiflexion and eversion, and can be injured at the neck of the fibula, resulting in foot drop. The superior gluteal nerve controls hip abduction and can be injured in cases of misplaced intramuscular injection, hip surgery, pelvic fracture, or posterior hip dislocation. Injury to this nerve can result in a positive Trendelenburg sign. The inferior gluteal nerve controls hip extension and lateral rotation, and is generally injured in association with the sciatic nerve. Injury to this nerve can result in difficulty rising from a seated position, as well as difficulty jumping or climbing stairs.
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This question is part of the following fields:
- Musculoskeletal System And Skin
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Question 3
Correct
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A middle-aged woman presents with complaints of profound sadness, marked difficulty with focus, and an inability to make choices. During the appointment, her speech is notably sluggish and she struggles to articulate her emotions. How would you characterize the alterations in her cognitive functioning and thought processes?
Your Answer: Psychomotor retardation
Explanation:Psychomotor Retardation in Severe Depression
Psychomotor retardation is a cognitive symptom commonly observed in individuals with severe depression. It is characterized by a significant slowing down of both thinking and behavior. This symptom can manifest in various ways, such as slowed speech, reduced movement, and delayed responses.
In contrast, other disorders such as mania and schizophrenia are associated with different forms of thought disorders. Mania is characterized by racing thoughts and impulsivity, while schizophrenia is associated with disorganized thinking and delusions.
It is important to recognize the presence of psychomotor retardation in individuals with severe depression as it can significantly impact their daily functioning and quality of life. Treatment options for this symptom may include medication, psychotherapy, and lifestyle changes. By addressing this symptom, individuals with severe depression can improve their overall well-being and ability to function in their daily lives.
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This question is part of the following fields:
- Psychiatry
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Question 4
Correct
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A 27-year-old female patient complains of lower abdominal pain and dysuria for the past 5 days. Upon examination, her GP orders cultures which reveal visible organism growth on Thayer-Martin agar plate. What is the probable pathogen responsible for her symptoms?
Your Answer: Neisseria gonorrhoeae
Explanation:Neisseria gonorrhoeae is the correct answer. The growth of this organism on Thayer-Martin agar, a heated blood agar plate that inhibits the growth of contaminating bacteria and fungi, is indicative of a possible infection. Escherichia coli, Proteus mirabilis, and Pseudomonas aeruginosa are all potential causes of urinary symptoms, but they are not cultured using Thayer-Martin agar. Escherichia coli is cultured using MacConkey’s agar, while Proteus mirabilis and Pseudomonas aeruginosa are cultured using other types of agar.
Culture Requirements for Common Organisms
Different microorganisms require specific culture conditions to grow and thrive. The table above lists some of the culture requirements for the more common organisms. For instance, Neisseria gonorrhoeae requires Thayer-Martin agar, which is a variant of chocolate agar, and the addition of Vancomycin, Polymyxin, and Nystatin to inhibit Gram-positive, Gram-negative, and fungal growth, respectively. Haemophilus influenzae, on the other hand, grows on chocolate agar with factors V (NAD+) and X (hematin).
To remember the culture requirements for some of these organisms, some mnemonics can be used. For example, Nice Homes have chocolate can help recall that Neisseria and Haemophilus grow on chocolate agar. If I Tell-U the Corny joke Right, you’ll Laugh can be used to remember that Corynebacterium diphtheriae grows on tellurite agar or Loeffler’s media. Lactating pink monkeys can help recall that lactose fermenting bacteria, such as Escherichia coli, grow on MacConkey agar resulting in pink colonies. Finally, BORDETella pertussis can be used to remember that Bordetella pertussis grows on Bordet-Gengou (potato) agar.
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This question is part of the following fields:
- General Principles
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Question 5
Correct
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A 28-year-old male patient is diagnosed with an inguinal hernia and is scheduled for open surgical repair. During the procedure, the surgeons opt to use a mesh to reinforce the posterior wall of the inguinal canal. What structures will be located behind the mesh?
Your Answer: Transversalis fascia
Explanation:The posterior wall of the inguinal canal is formed by the transversalis fascia, the conjoint tendon, and the deep inguinal ring located laterally. The superior wall (roof) is made up of the internal oblique and transversus abdominis muscles, while the anterior wall consists of the aponeurosis of the external oblique and internal oblique muscles. The lower wall (floor) is formed by the inguinal ligament and lacunar ligament.
The inguinal canal is located above the inguinal ligament and measures 4 cm in length. Its superficial ring is situated in front of the pubic tubercle, while the deep ring is found about 1.5-2 cm above the halfway point between the anterior superior iliac spine and the pubic tubercle. The canal is bounded by the external oblique aponeurosis, inguinal ligament, lacunar ligament, internal oblique, transversus abdominis, external ring, and conjoint tendon. In males, the canal contains the spermatic cord and ilioinguinal nerve, while in females, it houses the round ligament of the uterus and ilioinguinal nerve.
The boundaries of Hesselbach’s triangle, which are frequently tested, are located in the inguinal region. Additionally, the inguinal canal is closely related to the vessels of the lower limb, which should be taken into account when repairing hernial defects in this area.
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This question is part of the following fields:
- Gastrointestinal System
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Question 6
Correct
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A 50-year-old patient has discovered a lump in her neck and another one in her groin. She has been experiencing feverish symptoms for several months and has had to change her bedclothes twice in the last week. Upon examination, smooth, firm, enlarged lymph nodes are noted at both sites. The patient's GP is concerned about the possibility of an underlying lymphoma and has referred her to secondary care for further investigations. A CT scan has not revealed any other lymph nodes. What is the most appropriate diagnosis and staging for this patient?
Your Answer: On biopsy the malignant lymphoid cells would be likely to have many of the characteristics of their parent cells
Explanation:Lymphomas and their Staging
Malignancies that arise from lymphocytes can spread to different lymph node groups due to their ability to retain adhesion and signalling receptors. Lymphomas can present at various sites, including bone marrow, gut, and spleen, as normal trafficking of lymphoid cells occurs through these places. Interestingly, higher-grade lymphomas are easier to cure than lower grade lymphomas, despite initially being associated with a higher mortality rate. On the other hand, low-grade lymphomas may not require immediate treatment, but the disease progresses over time, leading to a poorer prognosis.
To diagnose lymphoma, a biopsy of the affected area, such as a lymph node or bone marrow, is necessary. The Ann Arbor staging system is used to stage lymphomas, with Stage I indicating disease in a single lymph node group and Stage IV indicating extra-nodal involvement other than the spleen. The addition of a ‘B’ signifies the presence of ‘B’ symptoms, which are associated with a poorer prognosis for each disease stage.
From the examination findings, it is evident that the disease is present on both sides of the diaphragm, indicating at least Stage III lymphoma. the staging of lymphomas is crucial in determining the appropriate treatment plan and predicting the patient’s prognosis.
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This question is part of the following fields:
- Haematology And Oncology
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Question 7
Correct
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A 28-year-old woman comes in for her first ultrasound after discovering she is pregnant. The scan reveals that the placenta is properly implanted. What modifications take place in the endometrium during days 5-13 in response to fetal tissue implantation?
Your Answer: Decidualization
Explanation:The blastocyst typically implants in the endometrium around day 6-7 and finishes by day 10, which is during the secretory phase when progesterone from the corpus luteum is present. A woman will only test positive for pregnancy after implantation has occurred. During implantation, the blastodisc is formed.
Apposition is the process of the blastocyst aligning with the endometrium, which is influenced by signals from both the endometrium and the blastocyst. The endometrium releases COX-2, growth factors, cytokines, and hormones like estrogen and progesterone, while the blastocyst releases EGF, LIF signaling, growth factors, and cytokines. NSAIDs should be avoided during the peri-implantation stage due to the importance of COX-2 in apposition.
Attachment is the next stage, which occurs when the blastocyst attaches to the endometrium through pinopods and microvilli. The endometrium is only receptive to implantation during a narrow window of the menstrual cycle, but sperm can survive for up to 7 days, leading to unexpected pregnancies.
Penetration is the final stage, where the blastocyst becomes embedded in the endometrium, and the development of the placenta begins. Haemochorial placentation is characterized by changes in the uterus, including the differentiation of the endometrium into the decidua, enlarged stromal cells, and NK cells, as well as the transformation of the uterine spiral arteries.
Embryology is the study of the development of an organism from the moment of fertilization to birth. During the first week of embryonic development, the fertilized egg implants itself into the uterine wall. By the second week, the bilaminar disk is formed, consisting of two layers of cells. The primitive streak appears in the third week, marking the beginning of gastrulation and the formation of the notochord.
As the embryo enters its fourth week, limb buds begin to form, and the neural tube closes. The heart also begins to beat during this time. By week 10, the genitals are differentiated, and the embryo exhibits intermittent breathing movements. These early events in embryonic development are crucial for the formation of the body’s major organs and structures. Understanding the timeline of these events can provide insight into the complex process of human development.
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This question is part of the following fields:
- General Principles
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Question 8
Correct
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What occurs during metaphase II of meiosis?
Your Answer: The cell's chromosomes attach to the meiotic spindle to divide into chromatids
Explanation:The Process of Meiosis
Meiosis is a complex process that involves two major cycles. The first cycle, meiosis I, condenses the reproductive cell’s DNA into chromosomes that are then replicated, creating two pairs of each original chromosome. These pairs are then separated, and the cell divides with one chromosome in each daughter cell. The second cycle, meiosis II, splits the chromosomes into individual chromatids, which are then separated as in meiosis I. This separation is facilitated by a spindle, a set of parallel fibers that attach to the center of each chromosome and split into two, making the chromatids travel on the polar opposite sides of the cell. The cell then divides again, giving rise to four haploid daughter cells.
During meiosis II, the chromosomes align on the spindle in metaphase II. Tetrads separate during anaphase I and line up during metaphase I. Sister chromatids separate on the meiotic spindle during anaphase II. Finally, chromosomes uncoil and lengthen at the end of meiosis, in telophase II. This process is essential for the production of gametes and the continuation of sexual reproduction in many organisms.
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This question is part of the following fields:
- Basic Sciences
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Question 9
Correct
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A 67-year-old widower is brought to the acute psychiatric ward due to treatment-resistant severe depression. Upon physical examination, the patient displays slow movements and rigid limbs. Their body is bent, and they have a sad expression on their face with slow speech. All tests show no evidence of organic disorder, and the patient is not taking any psychotropic medication. What term best describes this presentation?
Your Answer: Psychomotor retardation
Explanation:Psychomotor Retardation in Depression
Psychomotor retardation is a common manifestation of depression, characterized by slow movement, speech, and rigidity in limbs. Patients may also exhibit a bent body posture and feelings of emptiness and hopelessness. It is crucial to rule out other potential causes, such as medication side effects or neurological disorders like Parkinson’s disease.
In severe cases, psychomotor retardation can progress to catatonia, where the patient is unresponsive to external stimuli despite being awake. It is essential to recognize and address these symptoms promptly to ensure proper diagnosis and treatment. By the signs and symptoms of psychomotor retardation, healthcare professionals can provide appropriate care and support to individuals experiencing depression.
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This question is part of the following fields:
- Psychiatry
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Question 10
Correct
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A 32-year-old man comes to your clinic seeking help to quit his long-term heroin use. He appears alert and behaves appropriately. During the examination, you observe track marks on his arm, but his pupils are normal in size, equal, and reactive.
Which medication would be the most suitable for initiating detoxification in this patient?Your Answer: Buprenorphine
Explanation:Buprenorphine is the preferred first-line treatment for opioid detoxification, followed by methadone if necessary. Chlordiazepoxide is used for alcohol detoxification by replacing the GABA-enhancing effects of alcohol. Disulfiram is a maintenance medication used to reduce alcohol cravings after detoxification by causing unpleasant symptoms when alcohol is consumed. N-acetyl-cysteine (NAC) is used to treat paracetamol overdose by increasing glutathione concentration, which is necessary for the conjugation of NAPQI, a hepatotoxic substance responsible for liver damage.
Understanding Opioid Misuse and its Management
Opioid misuse is a serious problem that can lead to various complications and health risks. Opioids are substances that bind to opioid receptors, including natural opiates like morphine and synthetic opioids like buprenorphine and methadone. Signs of opioid misuse include rhinorrhoea, needle track marks, pinpoint pupils, drowsiness, watering eyes, and yawning.
Complications of opioid misuse can range from viral and bacterial infections to venous thromboembolism and overdose, which can lead to respiratory depression and death. Psychological and social problems such as craving, crime, prostitution, and homelessness can also arise.
In case of an opioid overdose, emergency management involves administering IV or IM naloxone, which has a rapid onset and relatively short duration of action. Harm reduction interventions such as needle exchange and testing for HIV, hepatitis B & C may also be offered.
Patients with opioid dependence are usually managed by specialist drug dependence clinics or GPs with a specialist interest. Treatment options may include maintenance therapy or detoxification, with methadone or buprenorphine recommended as the first-line treatment by NICE. Compliance is monitored using urinalysis, and detoxification can last up to 4 weeks in an inpatient/residential setting and up to 12 weeks in the community. Understanding opioid misuse and its management is crucial in addressing this growing public health concern.
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This question is part of the following fields:
- General Principles
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Question 11
Correct
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A 55-year-old man comes to his physician complaining of severe morning headaches. The doctor conducts a neurological evaluation to detect any neurological impairments. During the assessment, the patient exhibits normal responses for all tests except for the absence of corneal reflex.
Which cranial nerve is impacted?Your Answer: Trigeminal nerve
Explanation:The loss of corneal reflex is associated with the trigeminal nerve, specifically the ophthalmic branch. This reflex tests the sensation of the eyeball when cotton wool is used to touch it, causing the eye to blink in response. The glossopharyngeal nerve is not associated with the eye but is involved in the gag reflex. The optic nerve is responsible for vision and does not provide physical sensation to the eyeball. The oculomotor nerve is primarily a motor nerve and only provides sensory information in response to bright light. The trochlear nerve is purely motor and has no sensory innervations.
Cranial nerves are a set of 12 nerves that emerge from the brain and control various functions of the head and neck. Each nerve has a specific function, such as smell, sight, eye movement, facial sensation, and tongue movement. Some nerves are sensory, some are motor, and some are both. A useful mnemonic to remember the order of the nerves is Some Say Marry Money But My Brother Says Big Brains Matter Most, with S representing sensory, M representing motor, and B representing both.
In addition to their specific functions, cranial nerves also play a role in various reflexes. These reflexes involve an afferent limb, which carries sensory information to the brain, and an efferent limb, which carries motor information from the brain to the muscles. Examples of cranial nerve reflexes include the corneal reflex, jaw jerk, gag reflex, carotid sinus reflex, pupillary light reflex, and lacrimation reflex. Understanding the functions and reflexes of the cranial nerves is important in diagnosing and treating neurological disorders.
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This question is part of the following fields:
- Neurological System
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Question 12
Correct
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A 68-year-old woman arrives at the emergency department with complaints of shortness of breath and palpitations. During the examination, you observe an irregularly irregular pulse. To check for signs of atrial fibrillation, you opt to conduct an ECG. In a healthy individual, where is the SA node located in the heart?
Your Answer: Right atrium
Explanation:The SA node is situated at the junction of the superior vena cava and the right atrium, and is responsible for initiating cardiac impulses in a healthy heart. The AV node, located in the atrioventricular septum, regulates the spread of excitation from the atria to the ventricles. The patient’s symptoms of palpitations and shortness of breath, along with an irregularly irregular pulse, strongly indicate atrial fibrillation. ECG findings consistent with atrial fibrillation include an irregularly irregular rhythm and the absence of P waves.
The heart has four chambers and generates pressures of 0-25 mmHg on the right side and 0-120 mmHg on the left. The cardiac output is the product of heart rate and stroke volume, typically 5-6L per minute. The cardiac impulse is generated in the sino atrial node and conveyed to the ventricles via the atrioventricular node. Parasympathetic and sympathetic fibers project to the heart via the vagus and release acetylcholine and noradrenaline, respectively. The cardiac cycle includes mid diastole, late diastole, early systole, late systole, and early diastole. Preload is the end diastolic volume and afterload is the aortic pressure. Laplace’s law explains the rise in ventricular pressure during the ejection phase and why a dilated diseased heart will have impaired systolic function. Starling’s law states that an increase in end-diastolic volume will produce a larger stroke volume up to a point beyond which stroke volume will fall. Baroreceptor reflexes and atrial stretch receptors are involved in regulating cardiac output.
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This question is part of the following fields:
- Cardiovascular System
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Question 13
Correct
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A preteen girl presents with vaginal discharge and itching. She is subsequently diagnosed with preadolescent atrophic vaginitis which her doctor explains is because she has not yet entered adolescence. What is the underlying pathophysiology of preadolescent atrophic vaginitis?
Your Answer: Lack of vaginal oestrogen causing infection-prone alkaline environment
Explanation:The cause of prepubertal atrophic vaginitis is a deficiency of vaginal estrogen, making any response suggesting otherwise incorrect. This leads to an environment that is prone to infection due to its alkalinity, as estrogen boosts lactobacilli levels, which aid in the conversion of glucose to lactic acid. It is critical to consider this diagnosis when a prepubertal female patient complains of vaginal itching and discharge.
Understanding Atrophic Vaginitis
Atrophic vaginitis is a condition that commonly affects women who have gone through menopause. Its symptoms include vaginal dryness, painful intercourse, and occasional spotting. Upon examination, the vagina may appear dry and pale. The condition can be treated with vaginal lubricants and moisturizers. However, if these remedies do not provide relief, a topical estrogen cream may be prescribed.
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This question is part of the following fields:
- Reproductive System
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Question 14
Correct
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A new diagnostic test is being developed and this is now being trialed on 10,000 patients, 500 of which are known to be over the age of 60.
Each patient receives one test, producing 1,200 positive results. 400 of those with a positive test are later confirmed to be over the age of 60.
Calculate the positive predictive value (PPV) of the test.Your Answer: 40%
Explanation:Precision refers to the consistency of a test in producing the same results when repeated multiple times. It is an important aspect of test reliability and can impact the accuracy of the results. In order to assess precision, multiple tests are performed on the same sample and the results are compared. A test with high precision will produce similar results each time it is performed, while a test with low precision will produce inconsistent results. It is important to consider precision when interpreting test results and making clinical decisions.
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This question is part of the following fields:
- General Principles
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Question 15
Correct
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A 24-year-old man with asthma is brought to the emergency department due to shortness of breath. He has been experiencing a worsening cough with thick yellow phlegm for the past three days. He regularly uses a beclomethasone inhaler and salbutamol inhaler as needed.
Upon assessment, the patient's heart rate is 166 bpm, blood pressure is 113/65 mmHg, oxygen saturation is 91%, and respiratory rate is 29. He is only able to speak in broken sentences.
Which of the following therapies is most likely to exacerbate his asthma?Your Answer: Bisoprolol
Explanation:Treatment for Acute Asthma Attack
When a person experiences an acute asthma attack, the first and most important treatment is to administer oxygen. This is followed by nebulised salbutamol to dilate the airways, oral steroids, and appropriate antibiotics if the productive cough is due to a chest infection. However, the use of the beta blocker bisoprolol to reduce the heart rate would be inappropriate.
Salbutamol works by targeting beta-2 adrenoceptors, which causes the bronchi to dilate. However, cardiac muscle also has beta adrenoceptors, which can cause an increased heart rate. In this case, the patient is likely tachycardic due to increased work of breathing and salbutamol administered on the way to the hospital. Bisoprolol, on the other hand, is a beta antagonist that counteracts these effects by causing a reduction in heart rate and smooth muscle constriction, which would constrict the bronchi. This is the opposite of the desired effect and can worsen the patient’s condition. Therefore, it is important to avoid using bisoprolol in the treatment of acute asthma attacks.
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This question is part of the following fields:
- Pharmacology
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Question 16
Correct
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A 28-year-old primigravida arrives at the emergency department with concerns about persistent fatigue and muscle pains, despite being 15 weeks pregnant. She initially assumed the symptoms would resolve on their own, but has now developed a high fever. After undergoing several tests, serology reveals the presence of toxoplasmosis antibodies. Subsequent PCR testing confirms intrauterine toxoplasmosis.
What is the increased risk for the baby in this scenario?Your Answer: Cataracts
Explanation:TORCH infections are one of the causes of neonatal cataracts, along with genetic syndromes like Down’s and Marfan’s. If not detected during pregnancy, neonatal cataracts can be identified by an absent red reflex in the newborn. Toxoplasmosis, if left untreated, can lead to visual defects such as cataracts and retinitis, as well as calcifications and hydrocephalus.
Macrosomia, a condition where the baby is born with a higher than average birth weight, is associated with risk factors such as maternal obesity, previous diabetes diagnosis, and maternal age over 35. In contrast, TORCH infections are linked to intrauterine growth restriction.
Neonatal lupus can develop if the mother has systemic lupus erythematosus, but it is not related to TORCH infections. Erythema toxicum neonatorum, a common and harmless rash that can appear in the days following birth, is not associated with TORCH infections.
Understanding Cataracts
A cataract is a common eye condition that occurs when the lens of the eye becomes cloudy, making it difficult for light to reach the retina and causing reduced or blurred vision. Cataracts are more common in women and increase in incidence with age, affecting 30% of individuals aged 65 and over. The most common cause of cataracts is the normal ageing process, but other possible causes include smoking, alcohol consumption, trauma, diabetes mellitus, long-term corticosteroids, radiation exposure, myotonic dystrophy, and metabolic disorders such as hypocalcaemia.
Patients with cataracts typically experience a gradual onset of reduced vision, faded colour vision, glare, and halos around lights. Signs of cataracts include a defect in the red reflex, which is the reddish-orange reflection seen through an ophthalmoscope when a light is shone on the retina. Diagnosis is made through ophthalmoscopy and slit-lamp examination, which reveal a visible cataract.
In the early stages, age-related cataracts can be managed conservatively with stronger glasses or contact lenses and brighter lighting. However, surgery is the only effective treatment for cataracts, involving the removal of the cloudy lens and replacement with an artificial one. Referral for surgery should be based on the presence of visual impairment, impact on quality of life, patient choice, and the risks and benefits of surgery. Complications following surgery may include posterior capsule opacification, retinal detachment, posterior capsule rupture, and endophthalmitis. Despite these risks, cataract surgery has a high success rate, with 85-90% of patients achieving corrected vision of 6/12 or better on a Snellen chart postoperatively.
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This question is part of the following fields:
- Neurological System
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Question 17
Correct
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Which of the following is the least probable cause of an extended prothrombin time?
Your Answer: Acquired factor 12 deficiency
Explanation:Cholestatic jaundice and prolonged antibiotic therapy can lead to a deficiency in vitamin K.
Abnormal coagulation can be caused by various factors such as heparin, warfarin, disseminated intravascular coagulation (DIC), and liver disease. Heparin prevents the activation of factors 2, 9, 10, and 11, while warfarin affects the synthesis of factors 2, 7, 9, and 10. DIC affects factors 1, 2, 5, 8, and 11, and liver disease affects factors 1, 2, 5, 7, 9, 10, and 11.
When interpreting blood clotting test results, different disorders can be identified based on the levels of activated partial thromboplastin time (APTT), prothrombin time (PT), and bleeding time. Haemophilia is characterized by increased APTT levels, normal PT levels, and normal bleeding time. On the other hand, von Willebrand’s disease is characterized by increased APTT levels, normal PT levels, and increased bleeding time. Lastly, vitamin K deficiency is characterized by increased APTT and PT levels, and normal bleeding time. Proper interpretation of these results is crucial in diagnosing and treating coagulation disorders.
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This question is part of the following fields:
- Haematology And Oncology
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Question 18
Correct
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A 56-year-old teacher presents to her GP with increasing fatigue, weakness, and weight loss. She has a medical history of type II diabetes mellitus and osteoarthritis in her right knee. Her father passed away from dilated cardiomyopathy at age 47. During examination, she has multiple spider naevi on her chest and appears tanned. She does not smoke and only drinks during Christmas. Abdominal examination reveals hepatomegaly, but no other signs. Recent genetic testing at home has shown that she is HLA-A3 positive. Blood tests indicate an elevated ferritin and increased transferrin saturation. What is the most probable diagnosis?
Your Answer: Haemochromatosis
Explanation:The most likely diagnosis for the patient with liver cirrhosis, based on blood and genetic testing, is haemochromatosis. This condition is linked to HLA-A3, which is strongly associated with the mutated HFE gene responsible for the disease. While other options may cause liver disease, they do not explain the blood results or have a connection to HLA-A3. Wilson’s disease may also have neurological symptoms, and Goodpasture’s disease affects the kidneys and lungs, not the liver.
HLA Associations: Diseases and Antigens
HLA antigens are proteins encoded by genes on chromosome 6. There are two classes of HLA antigens: class I (HLA A, B, and C) and class II (HLA DP, DQ, and DR). Diseases can be strongly associated with certain HLA antigens. For example, HLA-A3 is associated with haemochromatosis, HLA-B51 with Behcet’s disease, and HLA-B27 with ankylosing spondylitis, reactive arthritis, and acute anterior uveitis. Coeliac disease is associated with HLA-DQ2/DQ8, while narcolepsy and Goodpasture’s are associated with HLA-DR2. Dermatitis herpetiformis, Sjogren’s syndrome, and primary biliary cirrhosis are associated with HLA-DR3. Finally, type 1 diabetes mellitus is associated with HLA-DR3 but more strongly associated with HLA-DR4, specifically the DRB1 gene (DRB1*04:01 and DRB1*04:04).
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This question is part of the following fields:
- General Principles
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Question 19
Correct
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A 30-year-old patient comes to you with symptoms of fever, thrush, malaise, and generalised lymphadenopathy. Your supervisor requests that you conduct an HIV blood test. What steps should you take?
Your Answer: Explain the implications for testing for HIV to the patient, seek permission and take the bloods yourself
Explanation:According to the GMC’s guidance on HIV & AIDS ethical considerations from October 1995 to October 1997, consent must be obtained for HIV testing due to the potential negative impact a diagnosis may have on an individual’s social and financial situation. Additionally, healthcare professionals are prohibited from refusing treatment to patients based on their medical condition, even if it poses a risk to the healthcare provider.
HIV seroconversion is a process where the body develops antibodies against the virus. This process is symptomatic in 60-80% of patients and usually presents as a glandular fever type illness. The severity of symptoms is associated with a poorer long-term prognosis. The symptoms typically occur 3-12 weeks after infection and include a sore throat, lymphadenopathy, malaise, myalgia, arthralgia, diarrhea, maculopapular rash, mouth ulcers, and rarely meningoencephalitis.
Diagnosing HIV involves testing for HIV antibodies, which may not be present in early infection. However, most people develop antibodies to HIV at 4-6 weeks, and 99% do so by 3 months. The diagnosis usually involves both a screening ELISA test and a confirmatory Western Blot Assay. Additionally, a p24 antigen test can be used to detect a viral core protein that appears early in the blood as the viral RNA levels rise. Combination tests that test for both HIV p24 antigen and HIV antibody are now standard for the diagnosis and screening of HIV. If the combined test is positive, it should be repeated to confirm the diagnosis. Some centers may also test the viral load (HIV RNA levels) if HIV is suspected at the same time. Testing for HIV in asymptomatic patients should be done at 4 weeks after possible exposure, and after an initial negative result, a repeat test should be offered at 12 weeks.
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This question is part of the following fields:
- General Principles
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Question 20
Correct
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Which of the following hepatobiliary conditions is commonly linked with ulcerative colitis, typically seen in adult patients?
Your Answer: Primary sclerosing cholangitis
Explanation:The risk of developing liver cancer is higher in patients with primary sclerosing cholangitis (PSC) and ulcerative colitis. However, the risk of malignant transformation is not increased in patients with Crohn’s disease. Impaired entero-hepatic circulation in Crohn’s disease is linked to the development of gallstones. Unlike PSC, ulcerative colitis does not elevate the risk of other liver lesions.
Understanding Ulcerative Colitis
Ulcerative colitis is a type of inflammatory bowel disease that causes inflammation in the rectum and spreads continuously without going beyond the ileocaecal valve. It is most commonly seen in people aged 15-25 years and 55-65 years. The symptoms of ulcerative colitis are insidious and intermittent, including bloody diarrhea, urgency, tenesmus, abdominal pain, and extra-intestinal features. Diagnosis is done through colonoscopy and biopsy, but in severe cases, a flexible sigmoidoscopy is preferred to avoid the risk of perforation. The typical findings include red, raw mucosa that bleeds easily, widespread ulceration with preservation of adjacent mucosa, and inflammatory cell infiltrate in lamina propria. Extra-intestinal features of inflammatory bowel disease include arthritis, erythema nodosum, episcleritis, osteoporosis, uveitis, pyoderma gangrenosum, clubbing, and primary sclerosing cholangitis. Ulcerative colitis is linked with sacroiliitis, and a barium enema can show the whole colon affected by an irregular mucosa with loss of normal haustral markings.
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This question is part of the following fields:
- Gastrointestinal System
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Question 21
Correct
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A 43-year-old man is brought to the emergency department via ambulance after being found collapsed on the street. He is barely responsive and has a heart rate of 120 beats per minute, blood pressure of 80/40 mmHg, oxygen saturations of 92%, and a temperature of 39 ºC. During a full secondary survey, gas gangrene is discovered on his lower limbs. Biopsy results later confirm that the causative organism is Clostridium perfringens. What is the responsible toxin for this presentation?
Your Answer: Alpha toxin
Explanation:Gas gangrene is a severe infection caused by Clostridium perfringens, which produces alpha-toxin, a lecithinase. This toxin causes local haemolysis, leading to areas of hypoperfusion and subsequent hypoxia, creating an anaerobic environment that allows the bacteria to thrive and cause further damage.
Cereulide, Exfoliatin, and Exotoxin A are incorrect as they are produced by Bacillus cereus, Staphylococcus aureus, and Pseudomonas aeruginosa, respectively, and cause different illnesses or symptoms such as vomiting and diarrhoea, blistering of the skin, and inhibition of protein synthesis.
Exotoxins vs Endotoxins: Understanding the Differences
Exotoxins and endotoxins are two types of toxins produced by bacteria. Exotoxins are secreted by bacteria, while endotoxins are only released when the bacterial cell is lysed. Exotoxins are typically produced by Gram-positive bacteria, with some exceptions like Vibrio cholerae and certain strains of E. coli.
Exotoxins can be classified based on their primary effects, which include pyrogenic toxins, enterotoxins, neurotoxins, tissue invasive toxins, and miscellaneous toxins. Pyrogenic toxins stimulate the release of cytokines, resulting in fever and rash. Enterotoxins act on the gastrointestinal tract, causing either diarrheal or vomiting illness. Neurotoxins act on the nerves or neuromuscular junction, causing paralysis. Tissue invasive toxins cause damage to tissues, while miscellaneous toxins have various effects.
On the other hand, endotoxins are lipopolysaccharides that are released from Gram-negative bacteria like Neisseria meningitidis. These toxins can cause fever, sepsis, and shock. Unlike exotoxins, endotoxins are not actively secreted by bacteria but are instead released when the bacterial cell is lysed.
Understanding the differences between exotoxins and endotoxins is important in diagnosing and treating bacterial infections. While exotoxins can be targeted with specific treatments like antitoxins, endotoxins are more difficult to treat and often require supportive care.
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This question is part of the following fields:
- General Principles
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Question 22
Correct
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A 29-year-old rugby player comes to your clinic with a painful shoulder. The discomfort began three weeks ago after a rugby match. Although he has experienced aches and pains after rugby before, this has been more persistent and limiting. He has been painting a room in his house and finds that the pain worsens when he reaches upward. He has been unable to participate in rugby or go to the gym. During the examination, there is tenderness on the tip of the shoulder. Both the empty can test is positive. You suspect that the patient may have a partial articular supraspinatus tendon avulsion (PASTA) lesion. Where does the supraspinatus tendon insert on the humerus?
Your Answer: Greater tubercle of the humerus
Explanation:The greater tubercle of the humerus is the correct answer. It is the insertion site for the supraspinatus muscle, which is one of three rotator cuff muscles that insert onto the greater tubercle. The infraspinatus muscle inserts onto the middle facet of the greater tubercle, while the teres minor muscle inserts onto the inferior facet.
The lesser tubercle of the humerus is located on the anteromedial aspect of the bone and is the insertion site for the subscapularis muscle, which is the remaining rotator cuff muscle.
The deltoid tuberosity is found on the lateral surface of the humeral shaft and is the insertion site for the deltoid muscle.
The intertubercular sulcus is a groove in the humerus that houses the tendon of the long head of biceps brachii. The floor of the intertubercular sulcus is the insertion site for the latissimus dorsi muscle.
The capitulum of the humerus is located at the distal end of the bone and articulates with the head of the radius.
PASTA lesions are partial tears of the supraspinatus tendon where it inserts into the humerus. They typically occur in athletes after a pulling or twisting injury.
The empty can test, also known as Jobe’s test, is used to test the supraspinatus tendon. It involves slight abduction of the arm, rotating the arm so the thumbs point downwards (as though holding two empty cans), and resisting downward pressure from the examiner. A positive test result indicates a PASTA lesion.
Understanding the Rotator Cuff Muscles
The rotator cuff muscles are a group of four muscles that are responsible for the movement and stability of the shoulder joint. These muscles are known as the SItS muscles, which stands for Supraspinatus, Infraspinatus, teres minor, and Subscapularis. Each of these muscles has a specific function in the movement of the shoulder joint.
The Supraspinatus muscle is responsible for abducting the arm before the deltoid muscle. It is the most commonly injured muscle in the rotator cuff. The Infraspinatus muscle rotates the arm laterally, while the teres minor muscle adducts and rotates the arm laterally. Lastly, the Subscapularis muscle adducts and rotates the arm medially.
Understanding the functions of each of these muscles is important in diagnosing and treating rotator cuff injuries. By identifying which muscle is injured, healthcare professionals can develop a treatment plan that targets the specific muscle and promotes healing. Overall, the rotator cuff muscles play a crucial role in the movement and stability of the shoulder joint.
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This question is part of the following fields:
- Musculoskeletal System And Skin
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Question 23
Correct
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A woman falls onto her neck and examination elicits signs of lateral medullary syndrome. Which description provides the correct findings?
Your Answer: Ipsilateral loss of pain and temperature in the face with dysphagia and ataxia and contra lateral loss in the body
Explanation:The lateral medullary syndrome is characterized by damage to the structures in the lateral medulla, which is supplied by the posterior inferior cerebellar artery. This can result in various examination findings, including ataxia from damage to the inferior cerebellar peduncle, dysphagia from damage to the nucleus ambiguus, and ipsilateral loss of pain and temperature from the face due to damage to the spinal trigeminal nucleus. Additionally, there may be contralateral loss of pain and temperature in the body from damage to the lateral spinothalamic tract.
In contrast, Brown-Sequard syndrome, which results from cord hemisection, is characterized by ipsilateral loss of light touch proprioception and contralateral loss of pain and temperature. Pontine stroke may present with hypertonia and contralateral neglect, while the triad of gait disturbance, urinary incontinence, and dementia is seen in normal pressure hydrocephalus. Medial medullary syndrome may present with ipsilateral tongue deviation, contralateral limb weakness, and contralateral loss of proprioception.
Understanding Lateral Medullary Syndrome
Lateral medullary syndrome, also referred to as Wallenberg’s syndrome, is a condition that arises when the posterior inferior cerebellar artery becomes blocked. This condition is characterized by a range of symptoms that affect both the cerebellum and brainstem. Cerebellar features of the syndrome include ataxia and nystagmus, while brainstem features include dysphagia, facial numbness, and cranial nerve palsy such as Horner’s. Additionally, patients may experience contralateral limb sensory loss. Understanding the symptoms of lateral medullary syndrome is crucial for prompt diagnosis and treatment.
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This question is part of the following fields:
- Neurological System
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Question 24
Correct
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At a routine check-up, a teenage girl is being educated by her physician about the ovarian cycle. The physician informs her that the primordial follicles undergo modifications until they develop into mature follicles. What specific alteration indicates the conversion of the primordial follicle into a primary follicle?
Your Answer: Development of the zona pellucida
Explanation:The formation of the zona pellucida is a significant milestone in the growth of the ovarian follicle, indicating the transition from a primordial follicle to a primary follicle. As the follicle continues to develop, it undergoes several changes, each marking a different stage of growth.
The stages of ovarian follicle development are as follows:
1. Primordial follicles: These contain an oocyte and granulosa cells.
2. Primary follicles: At this stage, the zona pellucida begins to form, and the granulosa cells start to proliferate.
3. Pre-antral follicles: The theca develops during this stage.
4. Mature/Graafian follicles: The antrum forms, marking the final stage of follicular growth.
5. Corpus luteum: The oocyte is released due to the enzymatic breakdown of the follicular wall, and the corpus luteum forms.
Anatomy of the Ovarian Follicle
The ovarian follicle is a complex structure that plays a crucial role in female reproductive function. It consists of several components, including granulosa cells, the zona pellucida, the theca, the antrum, and the cumulus oophorus.
Granulosa cells are responsible for producing oestradiol, which is essential for follicular development. Once the follicle becomes the corpus luteum, granulosa lutein cells produce progesterone, which is necessary for embryo implantation. The zona pellucida is a membrane that surrounds the oocyte and contains the protein ZP3, which is responsible for sperm binding.
The theca produces androstenedione, which is converted into oestradiol by granulosa cells. The antrum is a fluid-filled portion of the follicle that marks the transition of a primary oocyte into a secondary oocyte. Finally, the cumulus oophorus is a cluster of cells surrounding the oocyte that must be penetrated by spermatozoa for fertilisation to occur.
Understanding the anatomy of the ovarian follicle is essential for understanding female reproductive function and fertility. Each component plays a unique role in the development and maturation of the oocyte, as well as in the processes of fertilisation and implantation.
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This question is part of the following fields:
- Reproductive System
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Question 25
Correct
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A 60-year-old carpenter comes to your clinic complaining of back pain. He reports that this started a few weeks ago after lifting heavy wood. He experiences a sharp pain that travels from his lower back down the lateral aspect of his left thigh. Despite resting his leg, the pain persists. You suspect that he may have a herniated disc that is compressing his sciatic nerve and want to perform an examination to confirm the presence of sciatic nerve lesion features.
What is the most probable feature that you will discover during the examination?Your Answer: Right sided foot drop
Explanation:Foot drop is a possible consequence of sciatic nerve damage. The patient in question may have a herniated disc caused by heavy lifting, which is compressing their sciatic nerve and leading to weakness in the foot dorsiflexors.
If a person experiences pain when they abduct their hip, it could be due to damage to the superior gluteal nerve.
Damage to the femoral nerve can cause pain when extending the knee, as well as pain when flexing the thigh.
Femoral nerve damage can also result in loss of sensation over the medial aspect of the thigh, as well as the anterior aspect of the thigh and lower leg.
Damage to the lateral cutaneous nerve of the thigh can cause loss of sensation over the posterior surface of the thigh, as well as the lateral surface of the thigh.
Understanding Foot Drop: Causes and Examination
Foot drop is a condition that occurs when the foot dorsiflexors become weak. This can be caused by various factors, including a common peroneal nerve lesion, L5 radiculopathy, sciatic nerve lesion, superficial or deep peroneal nerve lesion, or central nerve lesions. However, the most common cause is a common peroneal nerve lesion, which is often due to compression at the neck of the fibula. This can be triggered by certain positions, prolonged confinement, recent weight loss, Baker’s cysts, or plaster casts to the lower leg.
To diagnose foot drop, a thorough examination is necessary. If the patient has an isolated peroneal neuropathy, there will be weakness of foot dorsiflexion and eversion, and reflexes will be normal. Weakness of hip abduction is suggestive of an L5 radiculopathy. Bilateral symptoms, fasciculations, or other abnormal neurological findings are indications for specialist referral.
If foot drop is diagnosed, conservative management is appropriate. Patients should avoid leg crossing, squatting, and kneeling. Symptoms typically improve over 2-3 months.
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This question is part of the following fields:
- Neurological System
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Question 26
Correct
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A 75-year-old man presents to the clinic with a chief complaint of dyspnea while in a supine position. Despite having a normal ejection fraction, what could be a potential cause for his symptoms?
Your Answer: He has diastolic dysfunction
Explanation:When there is systolic dysfunction, the ejection fraction decreases as the stroke volume decreases. However, in cases of diastolic dysfunction, ejection fraction is not a reliable indicator as both stroke volume and end-diastolic volume may be reduced. Diastolic dysfunction occurs when the heart’s compliance is reduced.
Cardiovascular physiology involves the study of the functions and processes of the heart and blood vessels. One important measure of heart function is the left ventricular ejection fraction, which is calculated by dividing the stroke volume (the amount of blood pumped out of the left ventricle with each heartbeat) by the end diastolic LV volume (the amount of blood in the left ventricle at the end of diastole) and multiplying by 100%. Another key measure is cardiac output, which is the amount of blood pumped by the heart per minute and is calculated by multiplying stroke volume by heart rate.
Pulse pressure is another important measure of cardiovascular function, which is the difference between systolic pressure (the highest pressure in the arteries during a heartbeat) and diastolic pressure (the lowest pressure in the arteries between heartbeats). Factors that can increase pulse pressure include a less compliant aorta (which can occur with age) and increased stroke volume.
Finally, systemic vascular resistance is a measure of the resistance to blood flow in the systemic circulation and is calculated by dividing mean arterial pressure (the average pressure in the arteries during a heartbeat) by cardiac output. Understanding these measures of cardiovascular function is important for diagnosing and treating cardiovascular diseases.
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This question is part of the following fields:
- Cardiovascular System
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Question 27
Correct
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In which location do most intracerebral hemorrhages take place?
Your Answer: Basal ganglia
Explanation:Types and Locations of Intracranial Bleeds
Intracranial bleeds refer to any type of bleeding that occurs within the cranium. There are four main types of intracranial bleeds: extradural, subdural, subarachnoid, and intracerebral. Extradural bleeds occur outside the periosteal dura mater, while subdural bleeds occur between the meningeal dura mater and arachnoid mater. Subarachnoid bleeds occur between the arachnoid mater and pia mater, where cerebrospinal fluid circulates. Intracerebral bleeds, on the other hand, occur within the cerebral tissue itself.
Of all the types of intracranial bleeds, intracerebral bleeds are the most common. They typically occur deep within the cerebral hemispheres, affecting the basal ganglia, such as the caudate nucleus and putamen. These types of bleeds are usually caused by hypertension, rather than trauma or atherosclerosis. While it is possible for bleeds to occur in any area of the brain, those that occur in the brainstem are particularly debilitating.
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This question is part of the following fields:
- Clinical Sciences
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Question 28
Correct
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A 25-year-old, biology student, with a history of insomnia, has approached their college doctor with inquiries about a newly advertised medication for insomnia treatment. The medication boosts the synthesis of gamma-aminobutyric acid (GABA) from glutamate, resulting in a calming effect.
What is the enzyme that the drug is mimicking?Your Answer: Glutamate decarboxylase
Explanation:The conversion of glutamate to GABA is catalyzed by glutamate decarboxylase. Other enzymes involved in this process include glutamate synthase, which converts glutamine to glutamate, glutamine synthetase, which converts glutamate to glutamine and vice versa, and 4-aminobutyrate transaminase, which converts GABA to succinate semialdehyde.
Understanding GABA as the Principal Inhibitory Neurotransmitter of the Cortex
GABA, or gamma-aminobutyric acid, is a crucial neurotransmitter that plays a significant role in regulating brain activity. It is considered the principal inhibitory neurotransmitter of the cortex, which means that it helps to reduce the activity of neurons in this region of the brain. This is important because excessive neuronal activity can lead to seizures, anxiety, and other neurological disorders.
GABA is produced in a region of the brain called the substantia nigra pars reticulata. This area is responsible for regulating movement and is also involved in the production of dopamine, another important neurotransmitter. GABA is released by neurons in the cortex and binds to specific receptors on other neurons, which helps to reduce their activity.
The importance of GABA in the brain cannot be overstated. It is involved in a wide range of functions, including sleep, anxiety, and mood regulation. It is also a target for many drugs used to treat neurological disorders, such as epilepsy and anxiety. Understanding the role of GABA in the brain is crucial for developing new treatments for these conditions and improving our overall understanding of brain function.
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This question is part of the following fields:
- General Principles
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Question 29
Correct
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Sophie is a 55-year-old woman who was brought to the hospital by her daughter, who noticed that Sophie looked a bit yellow. On examination, you confirm that she is indeed jaundiced. However, she is not in any pain. When pressed, she mentions that her stools have become pale and are hard to flush down, while her urine has become quite dark. She has also unintentionally lost 4kg of her weight in the past 1 month, but is not worried by this as she was initially overweight. There is a palpable mass on her right upper quadrant, below the right costal margin. Your colleague says that this her condition is most likely due to gallstone obstruction. However, you remember a certain law that you learnt in medical school which negates your colleague's opinion.
What is the law that you have remembered?Your Answer: Courvoisier's law
Explanation:The Modified Glasgow criteria is utilized for evaluating the gravity of acute pancreatitis.
Additionally, it should be noted that there are no medical laws named after Murphy, Gallbladder, or Charcot, although there is a Murphy’s sign and a Charcot’s triad. However, the Courvoisier’s law is applicable in cases of painless obstructive jaundice, indicating that a palpable gallbladder is unlikely to be caused by gallstones.
Pancreatic cancer is a type of cancer that is often diagnosed late due to its non-specific symptoms. The majority of pancreatic tumors are adenocarcinomas and are typically found in the head of the pancreas. Risk factors for pancreatic cancer include increasing age, smoking, diabetes, chronic pancreatitis, hereditary non-polyposis colorectal carcinoma, and mutations in the BRCA2 and KRAS genes.
Symptoms of pancreatic cancer can include painless jaundice, pale stools, dark urine, and pruritus. Courvoisier’s law states that a palpable gallbladder is unlikely to be due to gallstones in the presence of painless obstructive jaundice. However, patients often present with non-specific symptoms such as anorexia, weight loss, and epigastric pain. Loss of exocrine and endocrine function can also occur, leading to steatorrhea and diabetes mellitus. Atypical back pain and migratory thrombophlebitis (Trousseau sign) are also common.
Ultrasound has a sensitivity of around 60-90% for detecting pancreatic cancer, but high-resolution CT scanning is the preferred diagnostic tool. The ‘double duct’ sign, which is the simultaneous dilatation of the common bile and pancreatic ducts, may be seen on imaging.
Less than 20% of patients with pancreatic cancer are suitable for surgery at the time of diagnosis. A Whipple’s resection (pancreaticoduodenectomy) may be performed for resectable lesions in the head of the pancreas, but side-effects such as dumping syndrome and peptic ulcer disease can occur. Adjuvant chemotherapy is typically given following surgery, and ERCP with stenting may be used for palliation.
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This question is part of the following fields:
- Gastrointestinal System
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Question 30
Correct
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A 30-year-old man comes in with an anterior dislocation of his shoulder that occurred during a football game. He reports numbness in the 'regimental badge' area of the shoulder, suggesting axillary nerve injury. During which stage of the cell cycle is a mature neuron cell most likely to be found?
Your Answer: Quiescent stage
Explanation:Mature neuron cells are in a state of cell cycle arrest and do not undergo division, remaining in the G0 phase.
The Cell Cycle and its Regulation
The cell cycle is a process that regulates the growth and division of cells. It is controlled by proteins called cyclins, which in turn regulate cyclin-dependent kinase (CDK) enzymes. The cycle is divided into four phases: G0, G1, S, G2, and M. During the G0 phase, cells are in a resting state, while in G1, cells increase in size and determine the length of the cell cycle. Cyclin D/CDK4, Cyclin D/CDK6, and Cyclin E/CDK2 regulate the transition from G1 to S phase. In the S phase, DNA, RNA, and histones are synthesized, and centrosome duplication occurs. Cyclin A/CDK2 is active during this phase. In G2, cells continue to increase in size, and Cyclin B/CDK1 regulates the transition from G2 to M phase. Finally, in the M phase, mitosis occurs, which is the shortest phase of the cell cycle. The cell cycle is regulated by various proteins, including p53, which plays a crucial role in the G1 phase. Understanding the regulation of the cell cycle is essential for the development of new treatments for diseases such as cancer.
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This question is part of the following fields:
- General Principles
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Question 31
Correct
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A researcher is developing a new test for Alzheimer's disease that uses gel electrophoresis to separate native proteins by 3-D structure. This is an example of:
Your Answer: Western blotting
Explanation:PCR (Polymerase Chain Reaction)
GEL (Gel Electrophoresis)
BLAST (Basic Local Alignment Search Tool)Overview of Molecular Biology Techniques
Molecular biology techniques are essential tools used in the study of biological molecules such as DNA, RNA, and proteins. These techniques are used to detect and analyze these molecules in various biological samples. The most commonly used techniques include Southern blotting, Northern blotting, Western blotting, and enzyme-linked immunosorbent assay (ELISA).
Southern blotting is a technique used to detect DNA, while Northern blotting is used to detect RNA. Western blotting, on the other hand, is used to detect proteins. This technique involves the use of gel electrophoresis to separate native proteins based on their 3-D structure. It is commonly used in the confirmatory HIV test.
ELISA is a biochemical assay used to detect antigens and antibodies. This technique involves attaching a colour-changing enzyme to the antibody or antigen being detected. If the antigen or antibody is present in the sample, the sample changes colour, indicating a positive result. ELISA is commonly used in the initial HIV test.
In summary, molecular biology techniques are essential tools used in the study of biological molecules. These techniques include Southern blotting, Northern blotting, Western blotting, and ELISA. Each technique is used to detect specific molecules in biological samples and is commonly used in various diagnostic tests.
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This question is part of the following fields:
- General Principles
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Question 32
Correct
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A 48-year-old man is brought into the emergency department after attempting to take his own life. He was found at home with empty packets of paracetamol by his side. He is still conscious. A history is taken from him to evaluate his risk of future attempts.
What is the most significant risk factor for a successful suicide?Your Answer: Addiction to opiates
Explanation:Individuals with a history of alcohol or drug abuse and deliberate self harm, particularly males, should be considered at high risk for suicide.
The risk of suicide in psychiatric patients is often stratified into high, medium, or low risk categories, but there is limited evidence on the positive predictive value of individual risk factors. A review in the BMJ concluded that these assessments may not be useful in guiding decision making, as 50% of suicides occur in patients deemed low risk. However, certain factors have been associated with an increased risk of suicide, such as male sex, history of deliberate self-harm, alcohol or drug misuse, mental illness, depression, schizophrenia, chronic disease, advancing age, unemployment or social isolation, and being unmarried, divorced, or widowed.
If a patient has attempted suicide, there are additional factors that increase the risk of completed suicide in the future, such as efforts to avoid discovery, planning, leaving a written note, final acts such as sorting out finances, and using a violent method. On the other hand, there are protective factors that can reduce the risk of suicide, such as having family support, having children at home, and having a religious belief.
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This question is part of the following fields:
- Psychiatry
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Question 33
Correct
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A 16-year-old presents to the Emergency Department with her father, who has noticed a yellowish tint to her eyes. Upon further inquiry, she reports having a flu-like illness a few days ago, which has since resolved. She has no medical history and is not taking any medications. On examination, scleral icterus is the only significant finding. The following are her blood test results:
Hb 130 g/L Male: (135-180) Female: (115 - 160)
Platelets 320 * 109/L (150 - 400)
WBC 6.0 * 109/L (4.0 - 11.0)
Bilirubin 80 µmol/L (3 - 17)
ALP 42 u/L (30 - 100)
ALT 30 u/L (3 - 40)
γGT 50 u/L (8 - 60)
Albumin 45 g/L (35 - 50)
What is the most probable cause of her symptoms?Your Answer: Gilbert's syndrome
Explanation:Gilbert’s syndrome is characterized by an inherited deficiency of an enzyme used to conjugate bilirubin, resulting in elevated levels of unconjugated bilirubin in the blood. This can lead to isolated jaundice of the sclera or mouth during times of physiological stress.
Crigler Najjar syndrome, on the other hand, is a rare genetic disorder that causes an inability to convert and clear bilirubin from the body, resulting in jaundice shortly after birth.
Gallstones, which can be asymptomatic or present with right upper quadrant pain following a meal, are associated with risk factors such as being overweight, over 40 years old, female, or fertile.
Primary sclerosing cholangitis (PSC) is characterized by scarring and fibrosis of the bile ducts inside and outside the liver, and may occur alone or in combination with inflammatory diseases such as ulcerative colitis. Symptoms of PSC include jaundice, right upper quadrant pain, itching, fatigue, and weight loss.
Gilbert’s syndrome is a genetic disorder that affects the way bilirubin is processed in the body. It is caused by a deficiency of UDP glucuronosyltransferase, which leads to unconjugated hyperbilirubinemia. This means that bilirubin is not properly broken down and eliminated from the body, resulting in jaundice. However, jaundice may only be visible during certain conditions such as fasting, exercise, or illness. The prevalence of Gilbert’s syndrome is around 1-2% in the general population.
To diagnose Gilbert’s syndrome, doctors may look for a rise in bilirubin levels after prolonged fasting or the administration of IV nicotinic acid. However, treatment is not necessary for this condition. While the exact mode of inheritance is still debated, it is known to be an autosomal recessive disorder.
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This question is part of the following fields:
- Gastrointestinal System
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Question 34
Correct
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A 9-month-old girl is brought to the hospital by her parents after being referred by her pediatrician due to developmental regression. The parents are worried because she has lost the ability to sit up and crawl.
During the examination, the baby is found to have decreased muscle tone throughout her body and an exaggerated startle response to loud noises. Her abdominal exam is normal. Fundoscopy shows a cherry red spot on the macula.
What is the probable diagnosis?Your Answer: Tay-Sachs disease
Explanation:Inherited Metabolic Disorders: Types and Deficiencies
Inherited metabolic disorders are a group of genetic disorders that affect the body’s ability to process certain substances. These disorders can be categorized into different types based on the specific substance that is affected. One type is glycogen storage disease, which is caused by deficiencies in enzymes involved in glycogen metabolism. This can lead to the accumulation of glycogen in various organs, resulting in symptoms such as hypoglycemia, lactic acidosis, and hepatomegaly.
Another type is lysosomal storage disease, which is caused by deficiencies in enzymes involved in lysosomal metabolism. This can lead to the accumulation of various substances within lysosomes, resulting in symptoms such as hepatosplenomegaly, developmental delay, and optic atrophy. Examples of lysosomal storage diseases include Gaucher’s disease, Tay-Sachs disease, and Fabry disease.
Finally, mucopolysaccharidoses are a group of disorders caused by deficiencies in enzymes involved in the breakdown of glycosaminoglycans. This can lead to the accumulation of these substances in various organs, resulting in symptoms such as coarse facial features, short stature, and corneal clouding. Examples of mucopolysaccharidoses include Hurler syndrome and Hunter syndrome.
Overall, inherited metabolic disorders can have a wide range of symptoms and can affect various organs and systems in the body. Early diagnosis and treatment are important in managing these disorders and preventing complications.
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This question is part of the following fields:
- General Principles
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Question 35
Correct
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Which of the following methods would be best for identifying and measuring a viral protein?
Your Answer: Western blotting
Explanation:PCR (Polymerase Chain Reaction)
GEL (Gel Electrophoresis)
BLAST (Basic Local Alignment Search Tool)Overview of Molecular Biology Techniques
Molecular biology techniques are essential tools used in the study of biological molecules such as DNA, RNA, and proteins. These techniques are used to detect and analyze these molecules in various biological samples. The most commonly used techniques include Southern blotting, Northern blotting, Western blotting, and enzyme-linked immunosorbent assay (ELISA).
Southern blotting is a technique used to detect DNA, while Northern blotting is used to detect RNA. Western blotting, on the other hand, is used to detect proteins. This technique involves the use of gel electrophoresis to separate native proteins based on their 3-D structure. It is commonly used in the confirmatory HIV test.
ELISA is a biochemical assay used to detect antigens and antibodies. This technique involves attaching a colour-changing enzyme to the antibody or antigen being detected. If the antigen or antibody is present in the sample, the sample changes colour, indicating a positive result. ELISA is commonly used in the initial HIV test.
In summary, molecular biology techniques are essential tools used in the study of biological molecules. These techniques include Southern blotting, Northern blotting, Western blotting, and ELISA. Each technique is used to detect specific molecules in biological samples and is commonly used in various diagnostic tests.
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This question is part of the following fields:
- General Principles
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Question 36
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Which food is a rich source of vitamin D in the diet?
Your Answer: Oily fish
Explanation:Sources of Vitamin D
Vitamin D is a type of fat-soluble vitamin that can be found in certain foods such as cheese, butter, eggs, and oily fish. However, vegetable sources of vitamin D are limited, although some foods are fortified with this vitamin. For instance, 100 grams of sundried shiitake mushrooms contain 1600 IU of vitamin D, while one egg contains 20 IU. Wild salmon is also a good source of vitamin D, with 100 grams containing 800 IU, while farmed salmon contains 200 IU.
Aside from food sources, sunlight is also a good source of vitamin D. Exposure of arms and legs to sunlight for 10-15 minutes can provide 3000 IU of vitamin D. However, it is difficult to obtain the daily requirement of 25-50 IU of vitamin D through sunlight alone, especially for people living in temperate climates. As a result, many people may have insufficient vitamin D levels. It is important to ensure that we get enough vitamin D through a combination of food sources and sunlight exposure.
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This question is part of the following fields:
- Basic Sciences
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Question 37
Correct
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The external validity of a research pertains to what?
Your Answer: The degree to which the conclusions in a study would hold for other persons in other places and at other times
Explanation:Validity refers to how accurately something measures what it claims to measure. There are two main types of validity: internal and external. Internal validity refers to the confidence we have in the cause and effect relationship in a study. This means we are confident that the independent variable caused the observed change in the dependent variable, rather than other factors. There are several threats to internal validity, such as poor control of extraneous variables and loss of participants over time. External validity refers to the degree to which the conclusions of a study can be applied to other people, places, and times. Threats to external validity include the representativeness of the sample and the artificiality of the research setting. There are also other types of validity, such as face validity and content validity, which refer to the general impression and full content of a test, respectively. Criterion validity compares tests, while construct validity measures the extent to which a test measures the construct it aims to.
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This question is part of the following fields:
- General Principles
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Question 38
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A 32-year-old woman who is a primigravida at 15 weeks gestation presents to the emergency department with drooped features on the left side of her face and a runny nose. She noticed this in the morning when washing her face. There is no limb weakness, visual disturbance, or dysphagia noted.
What other symptoms would be indicative of this diagnosis?Your Answer: Loss of taste sensation
Explanation:The patient is exhibiting symptoms consistent with Bell’s palsy, which is an acute, unilateral, and idiopathic facial nerve paralysis. It is believed to be linked to the herpes simplex virus and is most commonly seen in individuals aged 20-40 years and pregnant women. The patient’s facial droop is unilateral with lower motor neuron involvement and hyperacusis in the ear on the affected side. Loss of taste sensation in the anterior two-thirds of the tongue on the same side may also be present.
Hyperlacrimation is not typically associated with Bell’s palsy, and patients may experience dry eyes due to reduced blinking on the affected side. Loss of smell sensation is not usually seen in Bell’s palsy and may indicate an alternative diagnosis, such as a neurodegenerative syndrome. Pins and needles in the limbs are not typically associated with Bell’s palsy, and if present, alternative diagnoses should be considered.
The presence of a vesicular rash around the ear strongly suggests Ramsay Hunt syndrome, which is caused by the reactivation of the varicella-zoster virus in the geniculate ganglion of the seventh cranial nerve. It presents with auricular pain, facial nerve palsy, a vesicular rash around the ear, and vertigo/tinnitus.
Bell’s palsy is a sudden, one-sided facial nerve paralysis of unknown cause. It typically affects individuals between the ages of 20 and 40, and is more common in pregnant women. The condition is characterized by a lower motor neuron facial nerve palsy that affects the forehead, while sparing the upper face. Patients may also experience postauricular pain, altered taste, dry eyes, and hyperacusis.
The management of Bell’s palsy has been a topic of debate, with various treatment options proposed in the past. However, there is now consensus that all patients should receive oral prednisolone within 72 hours of onset. The addition of antiviral medications is still a matter of discussion, with some experts recommending it for severe cases. Eye care is also crucial to prevent exposure keratopathy, and patients may need to use artificial tears and eye lubricants. If they are unable to close their eye at bedtime, they should tape it closed using microporous tape.
Follow-up is essential for patients who show no improvement after three weeks, as they may require urgent referral to ENT. Those with more long-standing weakness may benefit from a referral to plastic surgery. The prognosis for Bell’s palsy is generally good, with most patients making a full recovery within three to four months. However, untreated cases can result in permanent moderate to severe weakness in around 15% of patients.
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This question is part of the following fields:
- Neurological System
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Question 39
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Jill, who is in her mid-30s, has just completed a half marathon and is now dehydrated. The decreased perfusion pressure in her kidneys is detected by baroreceptors, leading to the activation of the renin-angiotensin-aldosterone system (RAAS). As a result, renin cleaves angiotensinogen to angiotensin I, which is then converted to angiotensin II by angiotensin-converting enzyme (ACE). What effect does angiotensin II have on the arteriole that branches off from the renal artery and carries blood away from the glomerulus? And how does this impact Jill's glomerular filtration rate (GFR)?
Your Answer: Vasoconstriction - increases GFR
Explanation:Angiotensin II causes vasoconstriction of the efferent arteriole, which increases the pressure difference between the afferent and efferent arterioles. This increase in pressure leads to an increase in filtration pressure and thus an increase in GFR. Therefore, efferent arteriole constriction increases GFR.
Reabsorption and Secretion in Renal Function
In renal function, reabsorption and secretion play important roles in maintaining homeostasis. The filtered load is the amount of a substance that is filtered by the glomerulus and is determined by the glomerular filtration rate (GFR) and the plasma concentration of the substance. The excretion rate is the amount of the substance that is eliminated in the urine and is determined by the urine flow rate and the urine concentration of the substance. Reabsorption occurs when the filtered load is greater than the excretion rate, and secretion occurs when the excretion rate is greater than the filtered load.
The reabsorption rate is the difference between the filtered load and the excretion rate, and the secretion rate is the difference between the excretion rate and the filtered load. Reabsorption and secretion can occur in different parts of the nephron, including the proximal tubule, loop of Henle, distal tubule, and collecting duct. These processes are regulated by various hormones and signaling pathways, such as aldosterone, antidiuretic hormone (ADH), and atrial natriuretic peptide (ANP).
Overall, reabsorption and secretion are important mechanisms for regulating the composition of the urine and maintaining fluid and electrolyte balance in the body. Dysfunction of these processes can lead to various renal disorders, such as diabetes insipidus, renal tubular acidosis, and Fanconi syndrome.
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This question is part of the following fields:
- Renal System
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Question 40
Correct
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Which one of the following does not pass through the inferior orbital fissure?
Your Answer: ophthalmic artery
Explanation:The ophthalmic artery originates from the internal carotid as soon as it penetrates the dura and arachnoid. It travels through the optic canal beneath the optic nerve and within its dural and arachnoid coverings. It ends as the supratrochlear and dorsal nasal arteries.
Foramina of the Base of the Skull
The base of the skull contains several openings called foramina, which allow for the passage of nerves, blood vessels, and other structures. The foramen ovale, located in the sphenoid bone, contains the mandibular nerve, otic ganglion, accessory meningeal artery, and emissary veins. The foramen spinosum, also in the sphenoid bone, contains the middle meningeal artery and meningeal branch of the mandibular nerve. The foramen rotundum, also in the sphenoid bone, contains the maxillary nerve.
The foramen lacerum, located in the sphenoid bone, is initially occluded by a cartilaginous plug and contains the internal carotid artery, nerve and artery of the pterygoid canal, and the base of the medial pterygoid plate. The jugular foramen, located in the temporal bone, contains the inferior petrosal sinus, glossopharyngeal, vagus, and accessory nerves, sigmoid sinus, and meningeal branches from the occipital and ascending pharyngeal arteries.
The foramen magnum, located in the occipital bone, contains the anterior and posterior spinal arteries, vertebral arteries, and medulla oblongata. The stylomastoid foramen, located in the temporal bone, contains the stylomastoid artery and facial nerve. Finally, the superior orbital fissure, located in the sphenoid bone, contains the oculomotor nerve, recurrent meningeal artery, trochlear nerve, lacrimal, frontal, and nasociliary branches of the ophthalmic nerve, and abducent nerve.
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This question is part of the following fields:
- Neurological System
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