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  • Question 1 - A 45-year-old woman has been referred to a specialist neurology clinic due to...

    Incorrect

    • A 45-year-old woman has been referred to a specialist neurology clinic due to ongoing muscle stiffness and rigidity affecting her lower back, shoulders, neck, and hips, which has been progressively worsening over the past year. Additionally, she experiences muscle spasms in her legs when exposed to loud noises or stress. Her medical history includes pernicious anaemia and Hashimoto's thyroiditis. The doctor suspects Stiff person syndrome and plans to initiate benzodiazepine therapy to manage her symptoms.

      What is the underlying cause of this woman's symptoms, which are attributed to low levels of a specific neurotransmitter?

      Your Answer: Glycine

      Correct Answer: GABA

      Explanation:

      Stiff person syndrome is a condition that arises due to the presence of autoantibodies against the glutamic acid decarboxylase (GAD) enzyme. This enzyme plays a crucial role in the synthesis of gamma-aminobutyric acid (GABA), a neurotransmitter that helps to regulate muscle contractions. When GAD is attacked by autoantibodies, GABA levels in the central nervous system (CNS) decrease, leading to increased signaling to muscles and resulting in muscle stiffness and spasms.

      The fact that the neurologist wants to prescribe benzodiazepines as a treatment for this condition is another indication that GABA may be the neurotransmitter involved. Benzodiazepines are known to be GABA agonists, which means that they can help to replace the low levels of GABA in the CNS and counteract the excitatory signaling caused by glutamate.

      In contrast, Parkinson’s disease is characterized by low levels of dopamine, which would not be expected to cause the symptoms seen in stiff person syndrome.

      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.

    • This question is part of the following fields:

      • General Principles
      56
      Seconds
  • Question 2 - A father brings his 14-year-old son to see you as he is concerned...

    Correct

    • A father brings his 14-year-old son to see you as he is concerned about his growth. He is taller than his peers, has not yet experienced puberty and has developed excessive body hair. He is referred to a specialist who diagnoses mild congenital adrenal hyperplasia.

      What is the most frequent deficiency leading to this condition?

      Your Answer: 21-hydroxylase deficiency

      Explanation:

      The most common cause of congenital adrenal hyperplasia is 21-hydroxylase deficiency, while 17-hydroxylase deficiency is a rare cause. 17β-hydroxysteroid dehydrogenase deficiency results in a rare condition of sexual development, while 5-alpha reductase deficiency affects male sexual development.

      Understanding Congenital Adrenal Hyperplasia

      Congenital adrenal hyperplasia is a group of genetic disorders that affect the production of adrenal steroids. It is an autosomal recessive disorder, which means that both parents must carry the gene for the disorder to be passed on to their child. The most common cause of congenital adrenal hyperplasia is a deficiency in the enzyme 21-hydroxylase, which is responsible for the production of cortisol and aldosterone. This deficiency leads to low levels of cortisol, which triggers the anterior pituitary gland to produce high levels of adrenocorticotropic hormone (ACTH). ACTH then stimulates the adrenal glands to produce excess androgens, which can cause virilization in female infants.

      Other less common forms of congenital adrenal hyperplasia include 11-beta hydroxylase deficiency and 17-hydroxylase deficiency. These conditions also affect the production of adrenal steroids and can lead to similar symptoms.

      It is important to diagnose and treat congenital adrenal hyperplasia early to prevent complications such as adrenal crisis, growth failure, and infertility. Treatment typically involves hormone replacement therapy to replace the deficient hormones and suppress the excess androgens. With proper management, individuals with congenital adrenal hyperplasia can lead healthy and normal lives.

    • This question is part of the following fields:

      • Endocrine System
      3.9
      Seconds
  • Question 3 - A 59-year-old man comes to the GP complaining of lower back pain, weight...

    Correct

    • A 59-year-old man comes to the GP complaining of lower back pain, weight loss, an abdominal mass, and visible haematuria. The GP eliminates the possibility of a UTI and refers him through a 2-week wait pathway. An ultrasound reveals a tumour, and a biopsy confirms renal cell carcinoma. From which part of the kidney does his cancer originate?

      Your Answer: Proximal renal tubular epithelium

      Explanation:

      Renal cell carcinoma originates from the proximal renal tubular epithelium, while the other options, such as blood vessels, distal renal tubular epithelium, and glomerular basement membrane, are all parts of the kidney but not the site of origin for renal cell carcinoma. Transitional cell carcinoma, on the other hand, arises from the transitional cells in the lining of the renal pelvis.

      Renal cell cancer, also known as hypernephroma, is a primary renal neoplasm that accounts for 85% of cases. It originates from the proximal renal tubular epithelium and is commonly associated with smoking and conditions such as von Hippel-Lindau syndrome and tuberous sclerosis. The clear cell subtype is the most prevalent, comprising 75-85% of tumors.

      Renal cell cancer is more common in middle-aged men and may present with classical symptoms such as haematuria, loin pain, and an abdominal mass. Other features include endocrine effects, such as the secretion of erythropoietin, parathyroid hormone-related protein, renin, and ACTH. Metastases are present in 25% of cases at presentation, and paraneoplastic syndromes such as Stauffer syndrome may also occur.

      The T category criteria for renal cell cancer are based on tumor size and extent of invasion. Management options include partial or total nephrectomy, depending on the tumor size and extent of disease. Patients with a T1 tumor are typically offered a partial nephrectomy, while alpha-interferon and interleukin-2 may be used to reduce tumor size and treat metastases. Receptor tyrosine kinase inhibitors such as sorafenib and sunitinib have shown superior efficacy compared to interferon-alpha.

      In summary, renal cell cancer is a common primary renal neoplasm that is associated with various risk factors and may present with classical symptoms and endocrine effects. Management options depend on the extent of disease and may include surgery and targeted therapies.

    • This question is part of the following fields:

      • Renal System
      9.2
      Seconds
  • Question 4 - What factor causes a shift of the oxygen dissociation curve to the left?...

    Incorrect

    • What factor causes a shift of the oxygen dissociation curve to the left?

      Your Answer: Increased CO2

      Correct Answer: Increased pH

      Explanation:

      The Oxygen Dissociation Curve and its Effects on Oxygen Saturation

      The oxygen dissociation curve is a graph that compares the oxygen saturation of hemoglobin (Hb) at different partial pressures of oxygen. When more oxygen is needed by the tissues, the curve shifts to the right. This means that at the same partial pressure of oxygen, less oxygen is bound to Hb, allowing it to be released to the tissues. This effect is caused by increased levels of CO2 and temperature, which assist in the transfer of oxygen to more metabolically active tissues. Additionally, increased levels of 2,3-DPG also aid in this process.

      On the other hand, a left shift in the curve reflects conditions where there is less need for oxygen in the tissues, such as in the lungs. This allows for increased binding of oxygen to Hb, allowing it to be taken up before transport to the tissues that require it. Overall, the oxygen dissociation curve plays a crucial role in regulating oxygen saturation in the body and ensuring that oxygen is delivered to the tissues that need it most.

    • This question is part of the following fields:

      • Basic Sciences
      7.8
      Seconds
  • Question 5 - Where is the area postrema located in the brain? A 16-year-old girl was...

    Incorrect

    • Where is the area postrema located in the brain? A 16-year-old girl was prescribed erythromycin for her severe acne, but after three days, she had to stop taking it due to severe nausea that made her unable to function.

      Your Answer: Thalamus

      Correct Answer: Floor of the 4th ventricle

      Explanation:

      The vomiting process is initiated by the chemoreceptor trigger zone, which receives signals from various sources such as the gastrointestinal tract, hormones, and drugs. This zone is located in the area postrema, which is situated on the floor of the 4th ventricle in the medulla. It is noteworthy that the area postrema is located outside the blood-brain barrier. The nucleus of tractus solitarius, which is also located in the medulla, contains autonomic centres that play a role in the vomiting reflex. This nucleus receives signals from the chemoreceptor trigger zone. The vomiting centres in the brain receive inputs from different areas, including the gastrointestinal tract and the vestibular system of the inner ear.

      Vomiting is the involuntary act of expelling the contents of the stomach and sometimes the intestines. This is caused by a reverse peristalsis and abdominal contraction. The vomiting center is located in the medulla oblongata and is activated by receptors in various parts of the body. These include the labyrinthine receptors in the ear, which can cause motion sickness, the over distention receptors in the duodenum and stomach, the trigger zone in the central nervous system, which can be affected by drugs such as opiates, and the touch receptors in the throat. Overall, vomiting is a reflex action that is triggered by various stimuli and is controlled by the vomiting center in the brainstem.

    • This question is part of the following fields:

      • Neurological System
      2.1
      Seconds
  • Question 6 - A 55-year-old male presents with fever, night sweats, weight loss, and upper abdominal...

    Incorrect

    • A 55-year-old male presents with fever, night sweats, weight loss, and upper abdominal pain. Upon examination, his liver and spleen are enlarged. A complete blood count shows elevated levels of basophils, eosinophils, and neutrophils. What is the most probable cause of these symptoms?

      Your Answer: pRB

      Correct Answer: BCR-ABL

      Explanation:

      The symptoms displayed by this individual suggest the presence of chronic myeloid leukemia (CML), which is identified by the Philadelphia chromosome. This chromosome results from a genetic abnormality where chromosome 9 and 22 exchange genetic material, leading to the formation of the BCR-ABL gene.

      Understanding Chronic Myeloid Leukaemia and its Management

      Chronic myeloid leukaemia (CML) is a type of cancer that affects the blood and bone marrow. It is characterized by the presence of the Philadelphia chromosome in more than 95% of patients. This chromosome is formed due to a translocation between chromosomes 9 and 22, resulting in the fusion of the ABL proto-oncogene and the BCR gene. The resulting BCR-ABL gene produces a fusion protein that has excessive tyrosine kinase activity.

      CML typically affects individuals between the ages of 60-70 years and presents with symptoms such as anaemia, weight loss, sweating, and splenomegaly. The condition is also associated with an increase in granulocytes at different stages of maturation and thrombocytosis. In some cases, CML may undergo blast transformation, leading to acute myeloid leukaemia (AML) or acute lymphoblastic leukaemia (ALL).

      The management of CML involves various treatment options, including imatinib, which is considered the first-line treatment. Imatinib is an inhibitor of the tyrosine kinase associated with the BCR-ABL defect and has a very high response rate in chronic phase CML. Other treatment options include hydroxyurea, interferon-alpha, and allogenic bone marrow transplant. With proper management, individuals with CML can lead a normal life.

    • This question is part of the following fields:

      • Haematology And Oncology
      1.7
      Seconds
  • Question 7 - During a placement in general practice, a 56-year-old woman comes in with new...

    Incorrect

    • During a placement in general practice, a 56-year-old woman comes in with new nipple discharge and skin dimpling over her breast. The GP conducts a breast examination, including the lymph nodes surrounding the area. Which lymph nodes receive the most breast lymph?

      Your Answer: Internal thoracic chain

      Correct Answer: Axilliary lymph nodes

      Explanation:

      The lymphatic system of the breast is responsible for draining excess fluid and waste products. Lymph from the upper outer quadrant of the breast drains to the axillary lymph nodes, while lymph from the inner quadrants drains to the parasternal lymph nodes. Additionally, some lymph from the lower quadrants drains to the inferior phrenic lymph nodes.

      Lymphatic drainage is the process by which lymphatic vessels carry lymph, a clear fluid containing white blood cells, away from tissues and organs and towards lymph nodes. The lymphatic vessels that drain the skin and follow venous drainage are called superficial lymphatic vessels, while those that drain internal organs and structures follow the arteries and are called deep lymphatic vessels. These vessels eventually lead to lymph nodes, which filter and remove harmful substances from the lymph before it is returned to the bloodstream.

      The lymphatic system is divided into two main ducts: the right lymphatic duct and the thoracic duct. The right lymphatic duct drains the right side of the head and right arm, while the thoracic duct drains everything else. Both ducts eventually drain into the venous system.

      Different areas of the body have specific primary lymph node drainage sites. For example, the superficial inguinal lymph nodes drain the anal canal below the pectinate line, perineum, skin of the thigh, penis, scrotum, and vagina. The deep inguinal lymph nodes drain the glans penis, while the para-aortic lymph nodes drain the testes, ovaries, kidney, and adrenal gland. The axillary lymph nodes drain the lateral breast and upper limb, while the internal iliac lymph nodes drain the anal canal above the pectinate line, lower part of the rectum, and pelvic structures including the cervix and inferior part of the uterus. The superior mesenteric lymph nodes drain the duodenum and jejunum, while the inferior mesenteric lymph nodes drain the descending colon, sigmoid colon, and upper part of the rectum. Finally, the coeliac lymph nodes drain the stomach.

    • This question is part of the following fields:

      • Haematology And Oncology
      1.2
      Seconds
  • Question 8 - A four-year-old child presents with symptoms of an eye infection four days after...

    Incorrect

    • A four-year-old child presents with symptoms of an eye infection four days after a cold. The child has conjunctivitis with purulent discharge and swollen eyelids. Treatment is initiated promptly to prevent complications.

      What are the two most commonly associated organisms with this presentation?

      Your Answer: Rhinovirus and astrovirus

      Correct Answer: Chlamydia trachomatis and Neisseria gonorrhoeae

      Explanation:

      The two main organisms responsible for ophthalmia neonatorum, also known as conjunctivitis of the newborn, are Chlamydia trachomatis and Neisseria gonorrhoeae. Adenovirus, varicella-zoster virus, Treponema pallidum, and Staphylococcus aureus are not as commonly associated with this condition. Rhinovirus and astrovirus are not known to cause ophthalmia neonatorum, as they typically cause upper respiratory infections and diarrhea, respectively.

      Understanding Ophthalmia Neonatorum

      Ophthalmia neonatorum is a term used to describe an infection that affects the eyes of newborn babies. This condition is caused by two main organisms, namely Chlamydia trachomatis and Neisseria gonorrhoeae. It is important to note that suspected cases of ophthalmia neonatorum should be referred for immediate ophthalmology or paediatric assessment.

      To prevent complications, it is crucial to identify and treat ophthalmia neonatorum as soon as possible. This condition can cause severe damage to the eyes and even lead to blindness if left untreated. Therefore, parents and healthcare providers should be vigilant and seek medical attention if they notice any signs of eye infection in newborns. With prompt diagnosis and treatment, the prognosis for ophthalmia neonatorum is generally good.

    • This question is part of the following fields:

      • General Principles
      0.9
      Seconds
  • Question 9 - A 25-year-old man comes to the doctor complaining of difficulty with bowel movements....

    Incorrect

    • A 25-year-old man comes to the doctor complaining of difficulty with bowel movements. He reports having a good appetite and drinking enough fluids. He denies experiencing weight loss, night sweats, or fevers. The patient has a history of rhinitis and indigestion. He takes two medications regularly, but he cannot recall their names. Additionally, he has a learning disability.

      Which of the following medications could be responsible for his constipation?

      Your Answer: Clindamycin

      Correct Answer: Chlorphenamine

      Explanation:

      Antihistamines for Allergic Rhinitis and Urticaria

      Antihistamines, specifically H1 inhibitors, are effective in treating allergic rhinitis and urticaria. Sedating antihistamines like chlorpheniramine have antimuscarinic properties that can cause dry mouth and urinary retention. On the other hand, non-sedating antihistamines like loratadine and cetirizine are less likely to cause drowsiness. However, there is some evidence that cetirizine may still cause some level of drowsiness compared to other non-sedating antihistamines. Overall, antihistamines are a valuable treatment option for those suffering from allergic rhinitis and urticaria.

    • This question is part of the following fields:

      • Musculoskeletal System And Skin
      2.6
      Seconds
  • Question 10 - A 65-year-old smoker visits his doctor complaining of a persistent mouth ulcer that...

    Correct

    • A 65-year-old smoker visits his doctor complaining of a persistent mouth ulcer that has not healed with conventional treatment for the past 3 months. The ulcer is situated in the middle of the right side of his tongue. Upon biopsy, it is revealed that the ulcer is a squamous cell carcinoma. Further examination is conducted to determine the possibility of lymphatic spread.

      What is the primary group of regional lymph nodes that may be affected by the spread of this tumor?

      Your Answer: Submandibular

      Explanation:

      The submandibular lymph nodes are the primary drainage site for the mid-portion of the tongue. Subsequently, the lymphatic fluid will 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.

    • This question is part of the following fields:

      • Haematology And Oncology
      1.2
      Seconds
  • Question 11 - A 22-year-old female patient arrives at the emergency department complaining of continuous dizziness...

    Correct

    • A 22-year-old female patient arrives at the emergency department complaining of continuous dizziness and headache. The laboratory is requested to perform a full blood count and other tests. Upon manual examination of the specimen, the biochemist observes increased levels of haemoglobin with a normal appearance, indicating polycythemia. What characteristic of this protein suggests that it possesses quaternary structure?

      Your Answer: It comprises multiple polypeptide chains

      Explanation:

      A protein with a quaternary structure is haemoglobin, which is composed of multiple polypeptide subunits. While some quaternary proteins contain inorganic subgroups, others do not. Haemoglobin has four subunits, but the number of subunits in other quaternary proteins may vary. It is not exclusive to quaternary proteins to experience loss of function when a subunit changes. The size of a protein is not a determining factor in its structure.

      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.

    • This question is part of the following fields:

      • General Principles
      20
      Seconds
  • Question 12 - A motorcyclist in his 30s is involved in a road traffic accident and...

    Incorrect

    • A motorcyclist in his 30s is involved in a road traffic accident and sustains a severe closed head injury. He was not wearing a helmet at the time of the accident. As a result, he develops raised intracranial pressure. Which cranial nerve is most likely to be affected first by this process?

      Your Answer: Motor branch of the trigeminal

      Correct Answer: Abducens

      Explanation:

      The abducens nerve, also known as CN VI, is vulnerable to increased pressure within the skull due to its lengthy path within the cranial cavity. Additionally, it travels over the petrous temporal bone, making it susceptible to sixth nerve palsies that can occur in cases of mastoiditis.

      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.

    • This question is part of the following fields:

      • Neurological System
      1.9
      Seconds
  • Question 13 - A 25-year-old male presents with a painless swelling of the testis. Histologically the...

    Incorrect

    • A 25-year-old male presents with a painless swelling of the testis. Histologically the stroma has a lymphocytic infiltrate. What is the most likely diagnosis?

      Seminoma is the most common type of testicular tumor and is frequently seen in males aged between 25-40 years. The classical subtype is the most prevalent, and histology shows a lymphocytic stromal infiltrate. Other subtypes include spermatocytic, anaplastic, and syncytiotrophoblast giant cells. A teratoma is more common in males aged 20-30 years.

      Your Answer: Differentiated teratoma

      Correct Answer: Classical seminoma

      Explanation:

      The most prevalent form of testicular tumor is seminoma, which is typically found in males between the ages of 30 and 40. The classical subtype of seminoma is the most common and is characterized by a lymphocytic stromal infiltrate. Other subtypes include spermatocytic, which features tumor cells that resemble spermatocytes and has a favorable prognosis, anaplastic, and syncytiotrophoblast giant cells, which contain β HCG. Teratoma, on the other hand, is more frequently observed in males between the ages of 20 and 30.

      Overview of Testicular Disorders

      Testicular disorders can range from benign conditions to malignant tumors. Testicular cancer is the most common malignancy in men aged 20-30 years, with germ-cell tumors accounting for 95% of cases. Seminomas are the most common subtype, while non-seminomatous germ cell tumors include teratoma, yolk sac tumor, choriocarcinoma, and mixed germ cell tumors. Risk factors for testicular cancer include cryptorchidism, infertility, family history, Klinefelter’s syndrome, and mumps orchitis. The most common presenting symptom is a painless lump, but pain, hydrocele, and gynecomastia may also be present.

      Benign testicular disorders include epididymo-orchitis, which is an acute inflammation of the epididymis often caused by bacterial infection. Testicular torsion, which results in testicular ischemia and necrosis, is most common in males aged between 10 and 30. Hydrocele presents as a mass that transilluminates and may occur as a result of a patent processus vaginalis in children. Treatment for these conditions varies, with orchidectomy being the primary treatment for testicular cancer. Surgical exploration is necessary for testicular torsion, while epididymo-orchitis and hydrocele may require medication or surgical procedures depending on the severity of the condition.

    • This question is part of the following fields:

      • Renal System
      2.4
      Seconds
  • Question 14 - A 40-year-old male comes to the emergency department complaining of a severe headache...

    Incorrect

    • A 40-year-old male comes to the emergency department complaining of a severe headache that started today. He reports that the pain is situated at the back of his head and worsens when he coughs and bends forward. He has vomited twice and is experiencing some blurred vision. An MRI scan is ordered, which reveals a downward herniation of the cerebellar tonsils.

      What brain structure has the cerebellar tonsils herniated into, based on the most probable diagnosis?

      Your Answer: Cerebral aqueduct

      Correct Answer: Foramen magnum

      Explanation:

      Arnold-Chiari malformation refers to the cerebellar tonsils herniating downwards through the foramen magnum. This condition has four types, with type one being the most prevalent.

      The fourth ventricle is situated in front of the cerebellum and serves as a pathway for cerebrospinal fluid (CSF) from the cerebral aqueduct.

      The thalamus is a central structure located between the midbrain and cerebral cortex. It comprises various nuclei that transmit sensory and motor signals to the cerebral cortex.

      The cerebral aqueduct is positioned between the third and fourth ventricle and facilitates the flow of CSF.

      The hypothalamus is a subdivision of the diencephalon that primarily regulates homeostasis.

      Understanding Arnold-Chiari Malformation

      Arnold-Chiari malformation is a condition where the cerebellar tonsils are pushed downwards through the foramen magnum. This can occur either due to a congenital defect or as a result of trauma. The condition can lead to non-communicating hydrocephalus, which is caused by the obstruction of cerebrospinal fluid outflow. Patients with Arnold-Chiari malformation may experience headaches and syringomyelia, which is a condition where fluid-filled cysts form in the spinal cord.

    • This question is part of the following fields:

      • Neurological System
      1.6
      Seconds
  • Question 15 - A 55-year-old man is having a radical gastrectomy for stomach cancer. What structure...

    Incorrect

    • A 55-year-old man is having a radical gastrectomy for stomach cancer. What structure must be divided to access the coeliac axis during the procedure?

      Your Answer: Gastrosplenic ligament

      Correct Answer: Lesser omentum

      Explanation:

      The division of the lesser omentum is necessary during a radical gastrectomy as it constitutes one of the nodal stations that must be removed.

      The Coeliac Axis and its Branches

      The coeliac axis is a major artery that supplies blood to the upper abdominal organs. It has three main branches: the left gastric, hepatic, and splenic arteries. The hepatic artery further branches into the right gastric, gastroduodenal, right gastroepiploic, superior pancreaticoduodenal, and cystic arteries. Meanwhile, the splenic artery gives off the pancreatic, short gastric, and left gastroepiploic arteries. Occasionally, the coeliac axis also gives off one of the inferior phrenic arteries.

      The coeliac axis is located anteriorly to the lesser omentum and is related to the right and left coeliac ganglia, as well as the caudate process of the liver and the gastric cardia. Inferiorly, it is in close proximity to the upper border of the pancreas and the renal vein.

      Understanding the anatomy and branches of the coeliac axis is important in diagnosing and treating conditions that affect the upper abdominal organs, such as pancreatic cancer or gastric ulcers.

    • This question is part of the following fields:

      • Cardiovascular System
      2.9
      Seconds
  • Question 16 - Samantha is an 80-year-old woman who has been experiencing painless obstructive jaundice. Upon...

    Incorrect

    • Samantha is an 80-year-old woman who has been experiencing painless obstructive jaundice. Upon investigation, a malignancy is discovered. The surgeon recommends a Whipple's procedure to remove the malignancy.

      What type of malignancy is the most probable diagnosis?

      Your Answer: Insulinoma

      Correct Answer: Adenocarcinoma

      Explanation:

      Ductal adenocarcinoma is the most frequently occurring type of pancreatic cancer, particularly in the head of the pancreas. Endocrine tumors of the pancreas are uncommon.

      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.

    • This question is part of the following fields:

      • Gastrointestinal System
      1
      Seconds
  • Question 17 - Which muscle is not innervated by the trigeminal nerve? ...

    Incorrect

    • Which muscle is not innervated by the trigeminal nerve?

      Your Answer: Mylohyoid

      Correct Answer: Stylohyoid

      Explanation:

      The facial nerve provides innervation to the stylohyoid.

      The trigeminal nerve is the main sensory nerve of the head and also innervates the muscles of mastication. It has sensory distribution to the scalp, face, oral cavity, nose and sinuses, and dura mater, and motor distribution to the muscles of mastication, mylohyoid, anterior belly of digastric, tensor tympani, and tensor palati. The nerve originates at the pons and has three branches: ophthalmic, maxillary, and mandibular. The ophthalmic and maxillary branches are sensory only, while the mandibular branch is both sensory and motor. The nerve innervates various muscles, including the masseter, temporalis, and pterygoids.

    • This question is part of the following fields:

      • Neurological System
      1.8
      Seconds
  • Question 18 - A 30-year-old man presents to the emergency department with complaints of abdominal pain,...

    Incorrect

    • A 30-year-old man presents to the emergency department with complaints of abdominal pain, nausea, and vomiting for a few hours. He has a history of type 1 diabetes mellitus, which is managed with insulin. He admits to running out of his insulin a few days ago. On examination, his temperature is 37.8ºC, pulse is 120/min, respirations are 25/min, and blood pressure is 100/70 mmHg. Dry mucous membranes are noted, and he has a fruity odour on his breath.

      The following laboratory results are obtained:

      Hb 142 g/L Male: (135-180)
      Female: (115 - 160)
      Platelets 250 * 109/L (150 - 400)
      WBC 11.2 * 109/L (4.0 - 11.0)
      Na+ 138 mmol/L (135 - 145)
      K+ 5.2 mmol/L (3.5 - 5.0)
      Urea 2.8 mmol/L (2.0 - 7.0)
      Creatinine 110 µmol/L (55 - 120)
      Glucose 28 mmol/L (4 - 7)

      Which of the following laboratory findings is most likely to be seen in this patient?

      Your Answer: PH 7.4; pCO2 3.3 kPa; Anion Gap 23

      Correct Answer: PH 7.1; pCO2 2.3 kPa; Anion Gap 21

      Explanation:

      The patient is experiencing diabetic ketoacidosis, which results in a raised anion gap metabolic acidosis. To determine the correct answer, we must eliminate options with a normal or raised pH (7.4 and 7.5), as well as those with respiratory acidosis (as the patient has an increased respiratory rate and should have a low pCO2). The anion gap is also a crucial factor, with a normal range of 3 to 16. Therefore, the correct option is the one with an anion gap of 21.

      Understanding Metabolic Acidosis

      Metabolic acidosis is a condition that can be classified based on the anion gap, which is calculated by subtracting the sum of chloride and bicarbonate from the sum of sodium and potassium. The normal range for anion gap is 10-18 mmol/L. If a question provides the chloride level, it may be an indication to calculate the anion gap.

      Hyperchloraemic metabolic acidosis is a type of metabolic acidosis with a normal anion gap. It can be caused by gastrointestinal bicarbonate loss, prolonged diarrhea, ureterosigmoidostomy, fistula, renal tubular acidosis, drugs like acetazolamide, ammonium chloride injection, and Addison’s disease. On the other hand, raised anion gap metabolic acidosis is caused by lactate, ketones, urate, acid poisoning, and other factors.

      Lactic acidosis is a type of metabolic acidosis that is caused by high lactate levels. It can be further classified into two types: lactic acidosis type A, which is caused by sepsis, shock, hypoxia, and burns, and lactic acidosis type B, which is caused by metformin. Understanding the different types and causes of metabolic acidosis is important in diagnosing and treating the condition.

    • This question is part of the following fields:

      • Renal System
      2.5
      Seconds
  • Question 19 - A 45-year-old male is admitted with cellulitis of his left lower limbs. A...

    Correct

    • A 45-year-old male is admitted with cellulitis of his left lower limbs. A swab culture grows MRSA sensitive to vancomycin, teicoplanin and linezolid. You opt to treat him with teicoplanin.

      What is the mode of action of teicoplanin?

      Your Answer: Inhibits bacterial cell wall formation

      Explanation:

      Teicoplanin, a glycopeptide antibiotic similar to vancomycin, has a longer duration of action, allowing for once daily administration after the initial dose. Its mechanism of action involves inhibiting bacterial cell wall formation. Other antibiotics that inhibit bacterial protein synthesis include macrolides, aminoglycosides, and tetracyclines, while those that inhibit bacterial DNA synthesis include quinolones like ciprofloxacin. Rifampicin inhibits bacterial RNA synthesis, while trimethoprim and co-trimoxazole inhibit bacterial folic acid formation.

      Antibiotics work in different ways to kill or inhibit the growth of bacteria. The commonly used antibiotics can be classified based on their gross mechanism of action. The first group inhibits cell wall formation by either preventing peptidoglycan cross-linking (penicillins, cephalosporins, carbapenems) or peptidoglycan synthesis (glycopeptides like vancomycin). The second group inhibits protein synthesis by acting on either the 50S subunit (macrolides, chloramphenicol, clindamycin, linezolid, streptogrammins) or the 30S subunit (aminoglycosides, tetracyclines) of the bacterial ribosome. The third group inhibits DNA synthesis (quinolones like ciprofloxacin) or damages DNA (metronidazole). The fourth group inhibits folic acid formation (sulphonamides and trimethoprim), while the fifth group inhibits RNA synthesis (rifampicin). Understanding the mechanism of action of antibiotics is important in selecting the appropriate drug for a particular bacterial infection.

    • This question is part of the following fields:

      • General Principles
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  • Question 20 - Which of the following is true of correlation and regression when analyzing data?...

    Correct

    • Which of the following is true of correlation and regression when analyzing data?

      Your Answer: Regression allows one variable to be predicted from another variable

      Explanation:

      Understanding Correlation and Linear Regression

      Correlation and linear regression are two statistical methods used to analyze the relationship between variables. While they are related, they are not interchangeable. Correlation is used to determine if there is a relationship between two variables, while regression is used to predict the value of one variable based on the value of another variable.

      The degree of correlation is measured by the correlation coefficient, which can range from -1 to +1. A coefficient of 1 indicates a strong positive correlation, while a coefficient of -1 indicates a strong negative correlation. A coefficient of 0 indicates no correlation between the variables. However, correlation coefficients do not provide information on how much the variable will change or the cause and effect relationship between the variables.

      Linear regression, on the other hand, can be used to predict how much one variable will change when another variable is changed. A regression equation can be formed to calculate the value of the dependent variable based on the value of the independent variable. The equation takes the form of y = a + bx, where y is the dependent variable, a is the intercept value, b is the slope of the line or regression coefficient, and x is the independent variable.

      In summary, correlation and linear regression are both useful tools for analyzing the relationship between variables. Correlation determines if there is a relationship, while regression predicts the value of one variable based on the value of another variable. Understanding these concepts can help in making informed decisions and drawing accurate conclusions from data analysis.

    • This question is part of the following fields:

      • General Principles
      21.3
      Seconds

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