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Question 1
Incorrect
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A 50-year-old smoker visits his doctor complaining of a persistent mouth ulcer that has been present for the last 2 months. The ulcer is located on the base of the tip of his tongue. Upon biopsy, it is revealed that the ulcer is a squamous cell carcinoma. Further testing is conducted to determine if there is any lymphatic spread.
What are the primary regional lymph nodes that this tumor is likely to spread to?Your Answer: Nasolabial
Correct Answer: Submental
Explanation:The submental lymph nodes are the primary site of lymphatic drainage from the tip of the tongue. The lymph will then spread to the deep cervical lymph nodes.
Lymphatic Drainage of the Tongue
The lymphatic drainage of the tongue varies depending on the location of the tumour. The anterior two-thirds of the tongue have minimal communication of lymphatics across the midline, resulting in metastasis to the ipsilateral nodes being more common. On the other hand, the posterior third of the tongue has communicating networks, leading to early bilateral nodal metastases being more common in this area.
The tip of the tongue drains to the submental nodes and then to the deep cervical nodes, while the mid portion of the tongue drains to the submandibular nodes and then to the deep cervical nodes. If mid tongue tumours are laterally located, they will usually drain to the ipsilateral deep cervical nodes. However, those from more central regions may have bilateral deep cervical nodal involvement. Understanding the lymphatic drainage of the tongue is crucial in determining the spread of tumours and planning appropriate treatment.
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This question is part of the following fields:
- Haematology And Oncology
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Question 2
Incorrect
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A 25-year-old patient complains of abdominal pain and a recent alteration in bowel movements. Upon conducting a colonic biopsy, the results reveal the presence of granulomas, inflammation lesions that extend to the submucosa and muscularis, and areas of unaffected mucosa in the rectum. What is the probable diagnosis?
Your Answer: Ulcerative colitis
Correct Answer: Crohn's disease
Explanation:Inflammatory bowel disease should be considered in young adults with a change in bowel habit and raised inflammatory markers. Crohn’s disease has skip lesions and can affect anywhere from the mouth to anus, while ulcerative colitis affects a continuous stretch of bowel starting in the rectum. Biopsy of Crohn’s shows intramural inflammation with lymphocyte infiltration and granulomas, while ulcerative colitis only causes intramural inflammation without granulomas. Bacterial overgrowth syndrome occurs after major reconstructive bowel surgery and can cause diarrhea, flatulence, abdominal distension, and pain. Cryptosporidiosis is a protozoan infection that can cause severe colitis in immunocompromised patients with AIDS. Whipple’s disease is a rare infection caused by Tropheryma whipplei and mainly presents with symptoms of malabsorption.
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This question is part of the following fields:
- Clinical Sciences
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Question 3
Incorrect
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A 65-year-old man with heart failure visits his GP complaining of peripheral edema. Upon examination, he is diagnosed with fluid overload, leading to the release of atrial natriuretic peptide by the atrial myocytes. What is the mechanism of action of atrial natriuretic peptide?
Your Answer:
Correct Answer: Antagonist of angiotensin II
Explanation:Angiotensin II is opposed by atrial natriuretic peptide, while B-type natriuretic peptides inhibit the renin-angiotensin-aldosterone system and sympathetic activity. Additionally, aldosterone is antagonized by atrial natriuretic peptide. Renin catalyzes the conversion of angiotensinogen into angiotensin I.
Atrial natriuretic peptide is a hormone that is primarily secreted by the myocytes of the right atrium and ventricle in response to an increase in blood volume. It is also secreted by the left atrium, although to a lesser extent. This peptide hormone is composed of 28 amino acids and acts through the cGMP pathway. It is broken down by endopeptidases.
The main actions of atrial natriuretic peptide include promoting the excretion of sodium and lowering blood pressure. It achieves this by antagonizing the actions of angiotensin II and aldosterone. Overall, atrial natriuretic peptide plays an important role in regulating fluid and electrolyte balance in the body.
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This question is part of the following fields:
- Cardiovascular System
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Question 4
Incorrect
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A 50-year-old man has a laparotomy and repair of incisional hernia. Which hormone is most unlikely to be released in higher amounts after the surgery?
Your Answer:
Correct Answer: Insulin
Explanation:Reduced secretion of insulin and thyroxine is common after surgery, which can make it challenging to manage diabetes in people with insulin resistance due to the additional release of glucocorticoids.
Surgery triggers a stress response that causes hormonal and metabolic changes in the body. This response is characterized by substrate mobilization, muscle protein loss, sodium and water retention, suppression of anabolic hormone secretion, activation of the sympathetic nervous system, and immunological and haematological changes. The hypothalamic-pituitary axis and the sympathetic nervous systems are activated, and the normal feedback mechanisms of control of hormone secretion fail. The stress response is associated with increased growth hormone, cortisol, renin, adrenocorticotrophic hormone (ACTH), aldosterone, prolactin, antidiuretic hormone, and glucagon, while insulin, testosterone, oestrogen, thyroid stimulating hormone, luteinizing hormone, and follicle stimulating hormone are decreased or remain unchanged. The metabolic effects of cortisol are enhanced, including skeletal muscle protein breakdown, stimulation of lipolysis, anti-insulin effect, mineralocorticoid effects, and anti-inflammatory effects. The stress response also affects carbohydrate, protein, lipid, salt and water metabolism, and cytokine release. Modifying the response can be achieved through opioids, spinal anaesthesia, nutrition, growth hormone, anabolic steroids, and normothermia.
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This question is part of the following fields:
- Endocrine System
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Question 5
Incorrect
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A 61-year-old man is starting amiodarone for persistent atrial fibrillation. What blood tests should be checked before beginning therapy?
Your Answer:
Correct Answer: Liver function tests, thyroid function tests and renal function tests
Explanation:Before and during amiodarone therapy, it is important to check thyroid and liver function tests.
Drug monitoring is an essential aspect of patient care to ensure the safe and effective use of medications. The tables below provide basic guidelines for monitoring common drugs in different therapeutic categories. It is important to note that these guidelines do not relate to monitoring the effectiveness of treatment, such as checking lipid levels for patients taking statins.
For cardiovascular drugs, statins require monitoring of liver function tests (LFTs) at baseline, 3 months, and 12 months. ACE inhibitors require monitoring of electrolytes (U&E) prior to treatment, after increasing the dose, and at least annually. Amiodarone requires monitoring of thyroid function tests (TFT), LFT, U&E, and chest X-ray prior to treatment, and TFT and LFT every 6 months.
In rheumatology, methotrexate requires monitoring of full blood count (FBC), LFT, and U&E before starting treatment, with weekly monitoring until therapy stabilizes, and then every 2-3 months. Azathioprine requires monitoring of FBC and LFT before treatment, weekly for the first 4 weeks, and every 3 months thereafter.
For neuropsychiatric drugs, lithium requires monitoring of lithium levels, TFT, and U&E prior to treatment, weekly until stabilized, and then every 3 months. TFT and U&E should be monitored every 6 months. Sodium valproate requires monitoring of LFT and FBC before treatment and periodically during the first 6 months.
Finally, for endocrine drugs, glitazones require monitoring of LFT before treatment and regularly during treatment. These guidelines serve as a starting point for drug monitoring and may be adjusted based on individual patient needs and clinical judgment.
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This question is part of the following fields:
- General Principles
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Question 6
Incorrect
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A 32-year-old first-time pregnant woman visits the antenatal clinic and has researched dietary limitations during pregnancy. What foods should she refrain from consuming?
Your Answer:
Correct Answer: Soft cheeses
Explanation:Pregnant women are advised to steer clear of soft cheeses as they have a higher risk of contracting Listeria infection. This infection is caused by Listeria monocytogenes, a gram-positive motile rod, which can be eliminated by cooking and pasteurisation. Therefore, consuming foods like raw/smoked meats and soft cheeses can lead to the transmission of this rare disease.
It is safe for pregnant women to consume packaged ice cream as it is usually pasteurised. However, ice cream made with unpasteurised milk or uncooked eggs may contain Salmonella.
Sea creatures like lobsters, swordfish, shrimp, and tuna are recommended for pregnant women as they are rich in iodine. Fetal hypothyroidism and impaired neurological development can occur due to iodine deficiency.
Understanding Listeria: Causes, Symptoms, and Treatment
Listeria monocytogenes is a type of bacteria that can cause serious infections in certain individuals. This Gram-positive bacillus has the unique ability to multiply at low temperatures, making it a common contaminant in unpasteurized dairy products. Those at highest risk for infection include the elderly, neonates, and individuals with weakened immune systems, particularly those taking glucocorticoids. Pregnant women are also at increased risk, as Listeria can lead to miscarriage and other complications.
Symptoms of Listeria infection can vary widely, ranging from gastroenteritis and diarrhea to more serious conditions like bacteraemia, flu-like illness, and central nervous system infections. In severe cases, Listeria can cause meningoencephalitis, ataxia, and seizures. Diagnosis typically involves blood cultures and cerebrospinal fluid analysis, which may reveal pleocytosis, raised protein, and reduced glucose.
Fortunately, Listeria is sensitive to certain antibiotics, including amoxicillin and ampicillin. In cases of Listeria meningitis, treatment typically involves a combination of IV amoxicillin/ampicillin and gentamicin. Pregnant women who develop Listeria infections may require treatment with amoxicillin, as fetal/neonatal infection can occur both transplacentally and vertically during childbirth.
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This question is part of the following fields:
- General Principles
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Question 7
Incorrect
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A 36/40 primigravida woman arrives at the Emergency Department in labour and expresses her worry about being exposed to cat litter during pregnancy. She has heard that it can have an impact on the baby. Following delivery, the infant is diagnosed with congenital toxoplasmosis. What is one clinical manifestation of this condition?
Your Answer:
Correct Answer: Cerebral calcification
Explanation:Most cases of intracerebral hemorrhage are linked to chronic arterial hypertension, while other risk factors include bleeding disorders and recent head trauma. It is incorrect to associate macrosomia with congenital toxoplasmosis, as the latter is associated with intrauterine growth retardation rather than an unusually large body for a neonate. Macrosomia is instead linked to maternal diabetes and other conditions.
Congenital Infections: Rubella, Toxoplasmosis, and Cytomegalovirus
Congenital infections are infections that are present at birth and can cause various health problems for the newborn. The three most common congenital infections encountered in medical examinations are rubella, toxoplasmosis, and cytomegalovirus. Of these, cytomegalovirus is the most common in the UK, and maternal infection is usually asymptomatic.
Each of these infections can cause different characteristic features in newborns. Rubella can cause sensorineural deafness, congenital cataracts, congenital heart disease, glaucoma, cerebral calcification, chorioretinitis, hydrocephalus, low birth weight, and purpuric skin lesions. Toxoplasmosis can cause growth retardation, hepatosplenomegaly, purpuric skin lesions, ‘salt and pepper’ chorioretinitis, microphthalmia, cerebral palsy, anaemia, and microcephaly. Cytomegalovirus can cause visual impairment, learning disability, encephalitis/seizures, pneumonitis, hepatosplenomegaly, anaemia, jaundice, and cerebral palsy.
It is important for healthcare professionals to be aware of these congenital infections and their potential effects on newborns. Early detection and treatment can help prevent or minimize the health problems associated with these infections.
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This question is part of the following fields:
- General Principles
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Question 8
Incorrect
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Which of the following medications used in the treatment of hyperlipidemia is most likely to cause flushing?
Your Answer:
Correct Answer: Nicotinic acid
Explanation:Side-effects of drugs used in hyperlipidaemia
Hyperlipidaemia is a condition characterized by high levels of lipids in the blood. Drugs used to treat this condition have different mechanisms of action and can cause various adverse effects. Statins, which are HMG CoA reductase inhibitors, work by reducing the production of cholesterol in the liver. However, they can cause myositis (muscle inflammation) and deranged liver function tests (LFTs). Ezetimibe, on the other hand, decreases cholesterol absorption in the small intestine, but it can cause headaches. Nicotinic acid decreases hepatic VLDL secretion, but it can cause flushing and myositis. Fibrates, which are agonists of PPAR-alpha and increase lipoprotein lipase expression, can cause myositis, pruritus, and cholestasis. Cholestyramine decreases bile acid reabsorption in the small intestine, upregulating the amount of cholesterol that is converted to bile acid, but it can cause gastrointestinal side-effects. It is important to weigh the benefits and risks of each drug when choosing a treatment for hyperlipidaemia.
Overall, the table above summarizes the different mechanisms of action and adverse effects of drugs used in hyperlipidaemia. It is important to note that each drug has its own set of benefits and risks, and patients should discuss their options with their healthcare provider to determine the best course of treatment. Proper monitoring and management of adverse effects can help ensure the safety and effectiveness of these medications.
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This question is part of the following fields:
- General Principles
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Question 9
Incorrect
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A 45-year-old woman comes to the doctor complaining of a headache and fever that has lasted for 3 days. She mentions that she recently returned from a backpacking trip to Indonesia where she was exposed to insect bites while hiking. She did not receive any travel immunisation or prophylaxis and is only taking paracetamol from a nearby pharmacy. Her blood pressure and pulse are normal, but her temperature is 38ºC. During the examination, a maculopapular rash is found on her trunk with some areas unaffected. There is no tenderness or organomegaly in her abdomen, and her lungs sound clear. The Giemsa stain of her thick and thin blood films did not show any parasites, but the dengue NS1 antigen test was positive.
What is the most appropriate treatment for this 45-year-old woman?Your Answer:
Correct Answer: Intravenous fluid administration and analgesia
Explanation:The patient’s travel history and positive dengue NS1 antigen test confirm that she has dengue fever, a viral infection transmitted by mosquitoes. Symptoms include fever, headache, and a maculopapular rash. Treatment is entirely symptomatic, with fluid resuscitation and analgesia. Malaria is unlikely given the short incubation period and negative blood film results. Antivirals are not currently available for dengue. As the patient does not display warning signs or hemodynamic instability, blood transfusion is not necessary. Analgesia alone is insufficient, and fluid replacement is required to manage symptoms.
Understanding Dengue Fever
Dengue fever is a viral infection that can lead to viral haemorrhagic fever, which includes diseases like yellow fever, Lassa fever, and Ebola. The dengue virus is an RNA virus that belongs to the Flavivirus genus and is transmitted by the Aedes aegypti mosquito. The incubation period for dengue fever is seven days.
Patients with dengue fever can be classified into three categories: those without warning signs, those with warning signs, and those with severe dengue (dengue haemorrhagic fever). Symptoms of dengue fever include fever, headache (often retro-orbital), myalgia, bone pain, arthralgia (also known as ‘break-bone fever’), pleuritic pain, facial flushing, maculopapular rash, and haemorrhagic manifestations such as a positive tourniquet test, petechiae, purpura/ecchymosis, and epistaxis. Warning signs include abdominal pain, hepatomegaly, persistent vomiting, and clinical fluid accumulation (ascites, pleural effusion). Severe dengue (dengue haemorrhagic fever) is a form of disseminated intravascular coagulation (DIC) that results in thrombocytopenia and spontaneous bleeding. Around 20-30% of these patients go on to develop dengue shock syndrome (DSS).
Typically, blood tests are used to diagnose dengue fever, which may show leukopenia, thrombocytopenia, and raised aminotransferases. Diagnostic tests such as serology, nucleic acid amplification tests for viral RNA, and NS1 antigen tests may also be used. Treatment for dengue fever is entirely symptomatic, including fluid resuscitation and blood transfusions. Currently, there are no antivirals available for the treatment of dengue fever.
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This question is part of the following fields:
- General Principles
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Question 10
Incorrect
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A 35-year-old female patient with a history of relapsing-remitting multiple sclerosis presents with new-onset double vision. She reports that in the last week, she has noticed double vision when trying to focus on objects on the left side of her visual field. She reports no double vision when looking to the right.
During examination, asking the patient to track the examiner's finger and look to the left (i.e. left horizontal conjugate gaze) elicits double vision, with the patient reporting that images appear 'side by side.' Additionally, there is a failure of the right eye to adduct past the midline, and nystagmus is noted in the left eye. Asking the patient to look to the right elicits no symptoms or abnormal findings. Asking the patient to converge her eyes on a nearby, midline object elicits no abnormalities, and the patient can abduct both eyes.
Which part of the nervous system is most likely responsible for this patient's symptoms?Your Answer:
Correct Answer: Paramedian area of midbrain and pons
Explanation:The medial longitudinal fasciculus is a pathway located in the paramedian area of the midbrain and pons that coordinates horizontal conjugate gaze by connecting the abducens nerve nucleus (CN VI) with the contralateral oculomotor nerve nucleus (CN III). Lesions in the MLF can result in internuclear ophthalmoplegia (INO), which is commonly caused by demyelinating disorders like multiple sclerosis. Bilateral INO is often associated with multiple sclerosis.
The other options listed in the vignette can also cause visual disturbances, but they are not the cause of the patient’s INO. Lesions in the occipital lobe can cause contralateral homonymous, macular-sparing quadrantanopia or hemianopia. Lateral medullary lesions (Wallenberg syndrome) can cause an ipsilateral Horner’s syndrome marked by ptosis, miosis, and anhidrosis. Optic neuritis, which is common in multiple sclerosis, can cause blurred vision, colour desaturation, and eye pain, but it would not result in binocular diplopia that improves on covering the unaffected eye. Lesions affecting the oculomotor nerve nucleus would also affect the ipsilateral eye’s ability to abduct on horizontal conjugate gaze, but the test of convergence can help distinguish this from an MLF lesion.
Understanding Internuclear Ophthalmoplegia
Internuclear ophthalmoplegia is a condition that affects the horizontal movement of the eyes. It is caused by a lesion in the medial longitudinal fasciculus (MLF), which is responsible for interconnecting the IIIrd, IVth, and VIth cranial nuclei. This area is located in the paramedian region of the midbrain and pons. The main feature of this condition is impaired adduction of the eye on the same side as the lesion, along with horizontal nystagmus of the abducting eye on the opposite side.
The most common causes of internuclear ophthalmoplegia are multiple sclerosis and vascular disease. It is important to note that this condition can also be a sign of other underlying neurological disorders.
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This question is part of the following fields:
- Neurological System
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Question 11
Incorrect
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A 24-year-old man has been admitted to the emergency department after falling off a roof and has been diagnosed with a Colles' fracture by the radiologist. The medical team plans to perform a closed reduction of the fracture, and they intend to use a haematoma block with lidocaine to facilitate a quick and painless reduction. What is a potential side effect that may occur after a haematoma block with lidocaine?
Your Answer:
Correct Answer: Mental status change
Explanation:Lidocaine has been known to affect mental status by crossing the blood-brain barrier quickly and blocking inhibitory neurons in the brain. This can lead to a decrease in seizure threshold and a decline in mental function. While hypertension is a recognized side effect of lidocaine, it does not cause hypotension. While constipation can be a side effect of lidocaine, it is not known to cause diarrhea. While there is no evidence to suggest that lidocaine causes sexual dysfunction, it is used in the treatment of premature ejaculation. Lidocaine is a class 1b anti-arrhythmic drug used to treat ventricular arrhythmias and does not cause them.
Overview of Local Anaesthetic Agents
Local anaesthetic agents are drugs that block nerve impulses and provide pain relief in a specific area of the body. Lidocaine is a commonly used amide local anaesthetic that is also used as an antiarrhythmic drug. It is metabolized in the liver, protein-bound, and excreted in the urine. Toxicity can occur with excessive administration or in patients with liver dysfunction or low protein states. Acidosis can also cause lidocaine to detach from protein binding. Treatment for local anaesthetic toxicity involves the use of IV 20% lipid emulsion. Drug interactions with lidocaine include beta blockers, ciprofloxacin, and phenytoin. Cocaine is another local anaesthetic agent that is rarely used in mainstream surgical practice. Bupivacaine has a longer duration of action than lidocaine and is useful for topical wound infiltration. However, it is cardiotoxic and contraindicated in regional blockage. Levobupivacaine is a less cardiotoxic alternative. Prilocaine is less cardiotoxic than other local anaesthetic agents and is preferred for intravenous regional anaesthesia. Adrenaline can be added to local anaesthetic drugs to prolong their duration of action and permit higher doses, but it is contraindicated in patients taking MAOI’s or tricyclic antidepressants. The maximum total doses of local anaesthetic agents depend on the type of drug and are based on ideal body weight.
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This question is part of the following fields:
- General Principles
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Question 12
Incorrect
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A 79-year-old man presents with chronic feeding difficulties. He had a stroke 3 years ago, and a neurology report indicates that the ischaemia affected his right mid-pontine region. Upon examination, you observe atrophy of the right temporalis and masseter muscles. He is able to swallow water without any signs of aspiration. Which cranial nerve is most likely affected by this stroke?
Your Answer:
Correct Answer: CN V
Explanation:When a patient complains of difficulty with eating, it is crucial to determine whether the issue is related to a problem with swallowing or with the muscles used for chewing.
The correct answer is CN V. This nerve, also known as the trigeminal nerve, controls the muscles involved in chewing. Damage to this nerve, which can occur due to various reasons including stroke, can result in weakness or paralysis of these muscles on the same side of the face. In this case, the patient’s stroke occurred two years ago, and he likely has some wasting of the mastication muscles due to disuse atrophy. As a result, he may have difficulty chewing food, but his ability to swallow is likely unaffected.
The other options are incorrect. CN IV, also known as the trochlear nerve, controls a muscle involved in eye movement and is not involved in eating. CN VII, or the facial nerve, controls facial movements but not the muscles of mastication. Damage to this nerve can result in facial weakness, but it would not affect the ability to chew. CN X, or the vagus nerve, is important for swallowing, but the stem indicates that the patient’s swallow is functional, making it less likely that this nerve is involved in his eating difficulties.
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 13
Incorrect
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A 55-year-old man with chronic kidney disease presents with pain in his right leg.
During physical examination, a clearly demarcated fiery-red lesion is observed on the anterior aspect of the right leg. The lesion is raised above the level of the surrounding skin. Laboratory testing results are as follows:
- WBC: 15 * 109/L (normal range: 4.0 - 11.0)
- CRP: 36 mg/L (normal range: < 5)
Based on the clinical picture and laboratory findings, erysipelas is suspected. What is the most likely causative organism in this scenario?Your Answer:
Correct Answer: Streptococcus pyogenes
Explanation:Erysipelas is a skin infection that is localized and caused by Streptococcus pyogenes, a Group A streptococcus (GAS) bacterium. This infection affects the upper dermis and can spread to the superficial cutaneous lymphatics. Streptococcus pyogenes is a Gram-positive coccus that grows in chains.
Escherichia coli is a bacterium that normally resides in the intestines of healthy individuals and animals. However, some strains of Escherichia coli produce toxins that can cause gastrointestinal illness or urinary tract infections.
Neisseria meningitidis is a Gram-negative bacterium that can cause meningitis and other forms of meningococcal disease, such as meningococcemia, which is a life-threatening sepsis.
Staphylococcus aureus is a bacterium that colonizes the skin and mucous membranes of humans and animals. It can cause cellulitis, which is an infection of the deeper skin tissues. Cellulitis typically presents as an ill-defined rash, in contrast to erysipelas, which has a sharper edge and is raised.
Understanding Erysipelas: A Superficial Skin Infection
Erysipelas is a skin infection that is caused by Streptococcus pyogenes. It is a less severe form of cellulitis, which is a more widespread skin infection. Erysipelas is a localized infection that affects the skin’s upper layers, causing redness, swelling, and warmth. The infection can occur anywhere on the body, but it is most commonly found on the face, arms, and legs.
The treatment of choice for erysipelas is flucloxacillin, an antibiotic that is effective against Streptococcus pyogenes. Other antibiotics may also be used, depending on the severity of the infection and the patient’s medical history.
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This question is part of the following fields:
- Musculoskeletal System And Skin
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Question 14
Incorrect
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A patient in their 50s experiences hypotension, wheezing, and shortness of breath after undergoing head and neck surgery. The possibility of a significant air embolism is being considered.
What factors may have contributed to the occurrence of this event?Your Answer:
Correct Answer: Negative atrial pressures
Explanation:Air embolisms can occur during head and neck surgeries due to negative pressures in the venous circulation and atria caused by thoracic wall movement. If a vein is cut during the surgery, air can enter the veins and cause an air embolism. Atherosclerosis may cause other types of emboli, such as clots. It is important to note that a pneumothorax refers to air in the thoracic cavity, not an embolus in the vessels.
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 15
Incorrect
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Which nerve is most vulnerable to damage when there is a cut on the upper lateral margin of the popliteal fossa in older adults?
Your Answer:
Correct Answer: Common peroneal nerve
Explanation:The lower infero-lateral aspect of the fossa is where the sural nerve exits, and it is at a higher risk during short saphenous vein surgery. On the other hand, the tibial nerve is located more medially and is less susceptible to injury in this area.
Anatomy of the Popliteal Fossa
The popliteal fossa is a diamond-shaped space located at the back of the knee joint. It is bound by various muscles and ligaments, including the biceps femoris, semimembranosus, semitendinosus, and gastrocnemius. The floor of the popliteal fossa is formed by the popliteal surface of the femur, posterior ligament of the knee joint, and popliteus muscle, while the roof is made up of superficial and deep fascia.
The popliteal fossa contains several important structures, including the popliteal artery and vein, small saphenous vein, common peroneal nerve, tibial nerve, posterior cutaneous nerve of the thigh, genicular branch of the obturator nerve, and lymph nodes. These structures are crucial for the proper functioning of the lower leg and foot.
Understanding the anatomy of the popliteal fossa is important for healthcare professionals, as it can help in the diagnosis and treatment of various conditions affecting the knee joint and surrounding structures.
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This question is part of the following fields:
- Cardiovascular System
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Question 16
Incorrect
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A 22-year-old male comes to the clinic complaining of dark urine after finishing an ultra-marathon. Upon examination, a urine dipstick reveals myoglobin and the patient is diagnosed with rhabdomyolysis.
What specific amino acid components contribute to the tertiary structure of this protein?Your Answer:
Correct Answer: R group
Explanation:Proteins and Peptides: Structure and Function
Proteins and peptides are essential molecules in the human body, made up of 20 amino acids bonded together by peptide bonds. Peptides are short chains of amino acids, while proteins are longer chains of 100 or more amino acids with more complex structures. The process of protein synthesis begins in the nucleus, where DNA is transcribed into messenger RNA, which is then translated by transfer RNA on cell ribosomes. The resulting protein folds into its destined structure, with primary, secondary, tertiary, and quaternary modifications.
The primary structure of a protein refers to the order of amino acids in the basic chain, while the secondary structure refers to the spatial arrangement of the primary structure. The tertiary structure is formed from structural changes and influences the protein’s role, while the quaternary structure is formed from multiple proteins to make a functional protein. The function of a protein is governed by its structure, with globular proteins having a wide range of roles, including enzymes.
Enzymes have an active site with a structure specific for one substrate, and when substrate and enzyme meet, they temporarily bond to form the enzyme-substrate complex. The substrate undergoes a biochemical change facilitated by the enzyme, resulting in the breakdown of the complex. Proteins also have structural roles, forming structures within the body such as keratin and collagen, and key roles in cell signaling and homeostasis, acting as mediators of transmembrane transport, cell receptors, and cell signaling. The endocrine system is an example of this, where hormones bind to cell surface receptors, triggering a cascade of protein interactions.
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This question is part of the following fields:
- General Principles
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Question 17
Incorrect
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A high school football player comes to the emergency department after a hard tackle. He complains of pain in the front of his shoulder, limited movement in his affected arm, and notices that his collarbone is protruding outward. An X-ray shows that his clavicle is displaced, particularly at the lateral end, but still intact. The medial end of the clavicle is still in contact with the sternum, and there are no other bone abnormalities. Given the extent of the dislocation, you suspect that multiple ligaments have been torn. Which of the following ligaments is the least likely to be affected?
Your Answer:
Correct Answer: Coracoacromial ligament
Explanation:The coracoacromial ligament is not likely to be damaged in a clavicle dislocation, as it does not connect to the clavicle. The ligaments that attach to the lateral end of the clavicle include the acromioclavicular ligament, trapezoid ligament, and conoid ligament (collectively known as the coracoclavicular ligament). In the case of an acromioclavicular joint dislocation, the severity of the injury depends on which ligaments are damaged. Mild cases may involve only a sprain or rupture of the acromioclavicular ligament, while more severe cases may involve rupture of all ligaments attaching to the lateral end of the clavicle.
Anatomy of the Clavicle
The clavicle is a bone that runs from the sternum to the acromion and plays a crucial role in preventing the shoulder from falling forwards and downwards. Its inferior surface is marked by ligaments at each end, including the trapezoid line and conoid tubercle, which provide attachment to the coracoclavicular ligament. The costoclavicular ligament attaches to the irregular surface on the medial part of the inferior surface, while the subclavius muscle attaches to the intermediate portion’s groove.
The superior part of the clavicle’s medial end has a raised surface that gives attachment to the clavicular head of sternocleidomastoid, while the posterior surface attaches to the sternohyoid. On the lateral end, there is an oval articular facet for the acromion, and a disk lies between the clavicle and acromion. The joint’s capsule attaches to the ridge on the margin of the facet.
In summary, the clavicle is a vital bone that helps stabilize the shoulder joint and provides attachment points for various ligaments and muscles. Its anatomy is marked by distinct features that allow for proper function and movement.
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This question is part of the following fields:
- Musculoskeletal System And Skin
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Question 18
Incorrect
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Which structure divides the cephalic vein and the brachial artery in the antecubital fossa?
Your Answer:
Correct Answer: Biceps muscle
Explanation:The Antecubital Fossa: Anatomy and Clinical Significance
The antecubital fossa is a depression located on the anterior aspect of the arm, between the arm and forearm. It is an important area for medical professionals as it is where venous blood samples are typically taken from. The borders of the antecubital fossa are the brachioradialis muscle laterally, the pronator teres medially, and a line between the medial and lateral epicondyles superiorly.
There are both deep and superficial structures found in the antecubital fossa. Deep structures include the radial nerve, tendon of the biceps muscle, brachial artery, and medial nerve. Superficial structures consist of a network of veins, including the cephalic vein and basilic vein, which come together as the median cubital vein.
The main clinical relevance of the antecubital fossa is its use for blood sampling and cannulation. However, it is also important to have a working knowledge of the anatomy as structures can become damaged. Excessive straining of the biceps tendon can cause it to rupture, leading to a ‘Popeye sign’. Damage to the medial nerve can also occur, resulting in muscle paralysis in the forearm and hand. Overall, understanding the anatomy and clinical significance of the antecubital fossa is crucial for medical professionals.
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This question is part of the following fields:
- Musculoskeletal System And Skin
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Question 19
Incorrect
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A 68-year-old man is brought to the Emergency Department on Thursday evening after falling and hitting his head on the pavement. He was found to be heavily intoxicated and unable to stand. A CT scan of his head reveals a crescent-shaped hematoma on the right side. The patient undergoes a burr-hole craniostomy with irrigation, which goes smoothly. However, two days later, the nursing staff notices that he is restless and agitated. He is speaking to his deceased wife, who passed away 15 years ago, and does not recognize any of the nurses. Additionally, he has developed hand tremors.
What medication has been overlooked by the medical team caring for this patient?Your Answer:
Correct Answer: Chlordiazepoxide
Explanation:Long-acting benzodiazepines are administered in decreasing doses to manage alcohol withdrawal symptoms in patients with a history of alcohol abuse. A man with such a history presents with anxiety, restlessness, visual and auditory hallucinations, and tremors 48 hours after his last alcohol intake. Chlordiazepoxide, a benzodiazepine, is prescribed to alleviate acute alcohol withdrawal and anxiety. Mannitol is indicated for cerebral edema, furosemide is a diuretic, and escitalopram is commonly used to treat anxiety and depression.
Alcohol withdrawal occurs when an individual who has been consuming alcohol chronically suddenly stops or reduces their intake. This is due to the fact that chronic alcohol consumption enhances GABA-mediated inhibition in the central nervous system (CNS), similar to benzodiazepines, and inhibits NMDA-type glutamate receptors. When alcohol consumption is stopped, the opposite occurs, resulting in decreased inhibitory GABA and increased NMDA glutamate transmission.
Symptoms of alcohol withdrawal typically start within 6-12 hours and include tremors, sweating, tachycardia, and anxiety. Seizures are most likely to occur at around 36 hours, while delirium tremens, which is characterized by coarse tremors, confusion, delusions, auditory and visual hallucinations, fever, and tachycardia, is most likely to occur at around 48-72 hours.
Patients with a history of complex withdrawals from alcohol, such as delirium tremens, seizures, or blackouts, should be admitted to the hospital for monitoring until their withdrawals stabilize. The first-line treatment for alcohol withdrawal is long-acting benzodiazepines, such as chlordiazepoxide or diazepam, which are typically given as part of a reducing dose protocol. Lorazepam may be preferable in patients with hepatic failure. Carbamazepine is also effective in treating alcohol withdrawal, while phenytoin is said not to be as effective in the treatment of alcohol withdrawal seizures.
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This question is part of the following fields:
- Psychiatry
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Question 20
Incorrect
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An 80-year-old female presents to the emergency department after falling two days ago. She is now experiencing double vision and haziness in her right eye. She tripped on a carpet in her living room and hit her head, but did not lose consciousness. She has a medical history of polymyalgia rheumatica, stable angina, bilateral cataract surgeries, and one previous transient ischaemic attack. There is no family history of genetic conditions.
During the examination, she is alert and oriented to time, place, and person. No peripheral focal neurology is found, and Romberg's test is negative. Her right eye has reduced visual acuity, but her pupils are equal and reactive to light, and her eye movements are unimpaired. The conjunctiva is not injected, and ophthalmoscopy shows normal visualization of the retina on the left and difficulty on the right due to light reflecting from behind the iris.
Blood tests reveal an ESR of 34mm/h (1-40mm/h) and CRP of 3 mg/L (<5 mg/L). What is the most likely cause of her visual symptoms?Your Answer:
Correct Answer: Dislocated intraocular lens (IOL)
Explanation:Inherited connective tissue disorders can lead to natural lens dislocation, while replacement lenses may become dislodged after cataract surgery. Temporal arteritis is a rare condition that affects small to medium arteries and is typically accompanied by a headache, blurred vision, and jaw claudication. Transient ischaemic attacks cause focal neurology and resolve within 24 hours. Although rare, complications of cataract surgery can include infection, damage to the capsule, posterior cataract formation, and glaucoma. Lens dislocation can occur due to trauma, uveitis, previous vitreoretinal surgery, or congenital connective tissue disorders such as Marfan’s syndrome. Acute angle-closure crisis, also known as acute glaucoma, presents with a red, painful eye with mid-dilated and poorly reactive pupils.
Causes of Lens Dislocation
Lens dislocation can occur due to various reasons. One of the most common causes is Marfan’s syndrome, which causes the lens to dislocate upwards. Another cause is homocystinuria, which leads to the lens dislocating downwards. Ehlers-Danlos syndrome is also a contributing factor to lens dislocation. Trauma, uveal tumors, and autosomal recessive ectopia lentis are other causes of lens dislocation. It is important to identify the underlying cause of lens dislocation to determine the appropriate treatment plan. Proper diagnosis and management can prevent further complications and improve the patient’s quality of life.
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This question is part of the following fields:
- Neurological System
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