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Question 1
Incorrect
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A 67-year-old man is admitted to the hospital with central crushing chest pain and undergoes a coronary angiogram. Arterial blockage can result from atherosclerosis, which can cause changes in the endothelium. What is an anticipated change in the endothelium?
Your Answer: Fatty infiltration by high density lipoproteins (HDLs)
Correct Answer: Reduced nitric oxide bioavailability
Explanation:Fatty infiltration in the subendothelial space is associated with LDL particles, but the endothelium undergoes changes that include reduced nitric oxide bioavailability, proliferation, and pro-inflammatory and pro-oxidant effects.
Understanding Atherosclerosis and its Complications
Atherosclerosis is a complex process that occurs over several years. It begins with endothelial dysfunction triggered by factors such as smoking, hypertension, and hyperglycemia. This leads to changes in the endothelium, including inflammation, oxidation, proliferation, and reduced nitric oxide bioavailability. As a result, low-density lipoprotein (LDL) particles infiltrate the subendothelial space, and monocytes migrate from the blood and differentiate into macrophages. These macrophages that phagocytose oxidized LDL, slowly turning into large ‘foam cells’. Smooth muscle proliferation and migration from the tunica media into the intima result in the formation of a fibrous capsule covering the fatty plaque.
Once a plaque has formed, it can cause several complications. For example, it can form a physical blockage in the lumen of the coronary artery, leading to reduced blood flow and oxygen to the myocardium, resulting in angina. Alternatively, the plaque may rupture, potentially causing a complete occlusion of the coronary artery and resulting in a myocardial infarction. It is essential to understand the process of atherosclerosis and its complications to prevent and manage cardiovascular diseases effectively.
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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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A 26-year-old man from Sub Saharan Africa comes to the clinic with complaints of lymphadenopathy and weight loss. The doctor suspects tuberculosis and performs a lymph node biopsy. Which staining agent is most likely to aid in identifying the causative organism?
Your Answer: Ziehl-Neelsen stain
Explanation:Ziehl-Neelsen stain is used for mycobacteria, not Gram staining. Van Gieson and Masson trichrome are for connective tissues, while Von Kossa identifies tissue mineralisation.
Understanding Tuberculosis: The Pathophysiology and Risk Factors
Tuberculosis is a bacterial infection caused by Mycobacterium tuberculosis. The pathophysiology of tuberculosis involves the migration of macrophages to regional lymph nodes, forming a Ghon complex. This complex leads to the formation of a granuloma, which is a collection of epithelioid histiocytes with caseous necrosis in the center. The inflammatory response is mediated by a type 4 hypersensitivity reaction. While healthy individuals can contain the disease, immunocompromised individuals are at risk of developing disseminated (miliary) TB.
Several risk factors increase the likelihood of developing tuberculosis. These include having lived in Asia, Latin America, Eastern Europe, or Africa for years, exposure to an infectious TB case, and being infected with HIV. Immunocompromised individuals, such as diabetics, patients on immunosuppressive therapy, malnourished individuals, or those with haematological malignancies, are also at risk. Additionally, silicosis and apical fibrosis increase the likelihood of developing tuberculosis. Understanding the pathophysiology and risk factors of tuberculosis is crucial in preventing and treating this infectious disease.
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This question is part of the following fields:
- General Principles
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Question 3
Incorrect
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Which nerve provides feeling to the nail bed of the middle finger?
Your Answer: Musculocutaneous
Correct Answer: Median
Explanation:Anatomy and Function of the Median Nerve
The median nerve is a nerve that originates from the lateral and medial cords of the brachial plexus. It descends lateral to the brachial artery and passes deep to the bicipital aponeurosis and the median cubital vein at the elbow. The nerve then passes between the two heads of the pronator teres muscle and runs on the deep surface of flexor digitorum superficialis. Near the wrist, it becomes superficial between the tendons of flexor digitorum superficialis and flexor carpi radialis, passing deep to the flexor retinaculum to enter the palm.
The median nerve has several branches that supply the upper arm, forearm, and hand. These branches include the pronator teres, flexor carpi radialis, palmaris longus, flexor digitorum superficialis, flexor pollicis longus, and palmar cutaneous branch. The nerve also provides motor supply to the lateral two lumbricals, opponens pollicis, abductor pollicis brevis, and flexor pollicis brevis muscles, as well as sensory supply to the palmar aspect of the lateral 2 ½ fingers.
Damage to the median nerve can occur at the wrist or elbow, resulting in various symptoms such as paralysis and wasting of thenar eminence muscles, weakness of wrist flexion, and sensory loss to the palmar aspect of the fingers. Additionally, damage to the anterior interosseous nerve, a branch of the median nerve, can result in loss of pronation of the forearm and weakness of long flexors of the thumb and index finger. Understanding the anatomy and function of the median nerve is important in diagnosing and treating conditions that affect this nerve.
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This question is part of the following fields:
- Neurological System
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Question 4
Incorrect
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A 75-year-old male presents to the GP clinic complaining of increased shortness of breath during physical activity and swelling in both ankles. The GP schedules an echocardiogram for him as an outpatient. During the echocardiogram, the patient's heart rate was 72 bpm and blood pressure was 136/88 mmHg. The results of the echocardiogram show an end-diastolic volume of 105ml and an end-systolic volume of 65ml. What is the left ventricular ejection fraction (LVEF) of this patient?
Your Answer: 60%
Correct Answer: 40%
Explanation: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 5
Incorrect
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A 42-year-old man is brought to the Emergency department from a rehabilitation center where he is receiving treatment for alcohol addiction. Upon examination, he is diagnosed with hypomagnesaemia. What are the possible symptoms that can arise due to this condition?
Your Answer: Somnolence
Correct Answer: Palpitations
Explanation:Hypomagnesaemia: Causes, Symptoms, and Treatment
Hypomagnesaemia, or low levels of magnesium in the blood, is a common electrolyte disturbance among inpatients. It can lead to serious complications, particularly cardiac arrhythmia, which can result in cardiac arrest. The condition is often caused by gastrointestinal loss of magnesium due to vomiting, high output stomas, fistulae, and malabsorption disorders. Poor nutritional input, renal losses of magnesium, and primary renal diseases can also contribute to hypomagnesaemia.
Mild magnesium deficiency usually results in few or no symptoms, but severe deficiency can cause hypokalaemia and hypocalcaemia, as well as overlapping clinical features with hypocalcaemia and hypokalaemia. These symptoms include tetany, neuromuscular excitability, hypertonicity, palpitations, fatigue, and cardiac arrhythmias.
Mild hypomagnesaemia can be treated with oral magnesium salts, while severe cases require cautious intravenous correction. It is important to monitor and correct magnesium levels to prevent the development of cardiac dysrhythmia and cardiac arrest.
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This question is part of the following fields:
- Clinical Sciences
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Question 6
Incorrect
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A 50-year-old man presents to the emergency department with acute chest pain. His ECG reveals ST depression in leads II, III, & aVF, and his troponin levels are elevated. He is diagnosed with NSTEMI and prescribed ticagrelor as part of his treatment plan.
What is the mechanism of action of ticagrelor?Your Answer: Inhibits prothrombinase complex-bound and clot-associated factor Xa
Correct Answer: Inhibits ADP binding to platelet receptors
Explanation:Clopidogrel and ticagrelor have a similar mechanism of action in that they both inhibit the binding of ADP to platelet receptors. Heparin activates antithrombin III, which in turn inhibits factor Xa and IIa. DOACs like rivaroxaban directly inhibit factor Xa that is bound to the prothrombinase complex and associated with clots. Aspirin works by inhibiting the production of prostaglandins, while warfarin inhibits VKORC1, which is responsible for the activation of vitamin K.
ADP receptor inhibitors, such as clopidogrel, prasugrel, ticagrelor, and ticlopidine, work by inhibiting the P2Y12 receptor, which leads to sustained platelet aggregation and stabilization of the platelet plaque. Clinical trials have shown that prasugrel and ticagrelor are more effective than clopidogrel in reducing short- and long-term ischemic events in high-risk patients with acute coronary syndrome or undergoing percutaneous coronary intervention. However, ticagrelor may cause dyspnea due to impaired clearance of adenosine, and there are drug interactions and contraindications to consider for each medication. NICE guidelines recommend dual antiplatelet treatment with aspirin and ticagrelor for 12 months as a secondary prevention strategy for ACS.
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This question is part of the following fields:
- Cardiovascular System
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Question 7
Incorrect
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A 20-year-old male arrives at the emergency department with a sudden worsening of his asthma symptoms. He is experiencing difficulty in speaking and breathing, with cyanosis of the lips and a respiratory rate of 33 breaths per minute. He reports feeling lightheaded. Although his airways are open, his chest sounds are faint upon auscultation. The patient is administered oxygen, nebulized salbutamol, and intravenous aminophylline.
What is the mechanism of action of aminophylline?Your Answer: Inhibits prostaglandin synthesis and reduces thromboxane A2 associated inflammation
Correct Answer: Binds to adenosine receptors and blocks adenosine-mediated bronchoconstriction
Explanation:Aminophylline works by binding to adenosine receptors and preventing adenosine-induced bronchoconstriction. This mode of action is different from antihistamines like loratadine, which is an incorrect option. Theophylline, a shorter acting form of aminophylline, competitively inhibits type III and type IV phosphodiesterase enzymes responsible for breaking down cyclic AMP in smooth muscle cells, leading to possible bronchodilation. Additionally, theophylline binds to the adenosine A2B receptor and blocks adenosine-mediated bronchoconstriction. In inflammatory conditions, theophylline activates histone deacetylase, which prevents the transcription of inflammatory genes that require histone acetylation for transcription to begin. Therefore, the last three options are incorrect. (Source: Drugbank)
Aminophylline infusions are utilized to manage acute asthma and COPD. In patients who have not received xanthines (theophylline or aminophylline) before, a loading dose of 5 mg/kg is administered through a slow intravenous injection lasting at least 20 minutes. For the maintenance infusion, 1g of aminophylline is mixed with 1 litre of normal saline to create a solution of 1 mg/ml. The recommended dose is 500-700 mcg/kg/hour, or 300 mcg/kg/hour for elderly patients. It is important to monitor plasma theophylline concentrations.
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This question is part of the following fields:
- Respiratory System
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Question 8
Correct
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What is the structure that extends downwards in the sagittal plane between the two cerebral hemispheres?
Your Answer: The falx cerebri
Explanation:Dura Mater Structures in the Brain
The brain is a complex organ that is protected by several layers of tissue. One of these layers is the dura mater, which is a thick, fibrous membrane that covers the brain and spinal cord. Within the dura mater, there are several structures that play important roles in the functioning of the brain.
The falx cerebri is one such structure. It is a large sheet of dura mater that partially separates the two cerebral hemispheres. This separation helps to prevent damage to one hemisphere from affecting the other, and also provides support for the brain.
Another important dura mater structure is the cavernous sinus. This structure is located within the middle cranial fossa and contains several important blood vessels and nerves. Damage to the cavernous sinus can lead to serious health problems, including vision loss and paralysis.
The diaphragma sellae is a flat piece of dura mater that allows for the passage of the pituitary stalk. This structure is important for the regulation of hormones in the body, and damage to it can lead to hormonal imbalances and other health problems.
Finally, the tentorium cerebelli is a structure that separates the cerebellum from the inferior areas of the occipital lobes. This separation helps to protect the cerebellum from damage and also provides support for the brain.
Overall, the dura mater structures in the brain play important roles in protecting and supporting the brain, as well as regulating important bodily functions.
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This question is part of the following fields:
- Clinical Sciences
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Question 9
Incorrect
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An 82-year-old woman with a history of chronic kidney disease presents to the general practice with a painful left foot. The pain is sharp in nature and is felt mostly towards the posterior of the sole of the foot. The pain is most severe when the patient takes her first few steps after getting out of bed in the morning. There is no history of trauma. You diagnose plantar fasciitis. The usual treatment of plantar fasciitis is with NSAIDs. However, NSAIDs are contraindicated in severe renal disease. What is the effect of NSAIDs on the glomerular filtration pressure?
Your Answer: Vasoconstriction of the efferent arteriole
Correct Answer: Vasoconstriction of the afferent arteriole
Explanation:The correct answer is vasoconstriction of the afferent arteriole, as explained in the following notes.
ACE inhibitors and ARBs cause vasodilation of the efferent arteriole, which reduces glomerular filtration pressure. This effect is particularly significant in individuals with renal artery stenosis, as their kidneys receive limited perfusion, including the glomeruli.
In a healthy individual, the afferent arteriole remains dilated, while the efferent arteriole remains constricted to maintain a fine balance of glomerular pressure. Vasodilation of the afferent arteriole or vasoconstriction of the efferent arteriole would both increase glomerular filtration pressure.
The patient in the given question is experiencing symptoms that suggest plantar fasciitis, a common condition caused by inflammation of the plantar fascia in the foot.
The Impact of NSAIDs on Kidney Function
NSAIDs are commonly used anti-inflammatory drugs that work by inhibiting the enzymes COX-1 and COX-2, which are responsible for the synthesis of prostanoids such as prostaglandins and thromboxanes. In the kidneys, prostaglandins play a crucial role in vasodilating the afferent arterioles of the glomeruli, allowing for increased blood flow and a higher glomerular filtration rate (GFR).
However, when NSAIDs inhibit the COX enzymes, the levels of prostaglandins decrease, leading to a reduction in afferent arteriole vasodilation and subsequently, a decrease in renal perfusion and GFR. This can have negative consequences for kidney function, particularly in individuals with pre-existing kidney disease or those taking high doses of NSAIDs for prolonged periods of time.
It is important for healthcare providers to consider the potential impact of NSAIDs on kidney function and to monitor patients accordingly, especially those at higher risk for kidney damage. Alternative treatments or lower doses of NSAIDs may be recommended to minimize the risk of kidney injury.
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This question is part of the following fields:
- Renal System
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Question 10
Incorrect
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Into which of the following structures does the superior part of the fibrous capsule of the shoulder joint insert?
Your Answer: The surgical neck of the humerus
Correct Answer: The anatomical neck of the humerus
Explanation:Due to its shallow nature, the shoulder joint has a high degree of mobility, but this is achieved at the cost of stability. The fibrous capsule is connected to the anatomical neck in a superior position and the surgical neck in an inferior position.
The shoulder joint is a shallow synovial ball and socket joint that is inherently unstable but capable of a wide range of movement. Stability is provided by the muscles of the rotator cuff. The glenoid labrum is a fibrocartilaginous rim attached to the free edge of the glenoid cavity. The fibrous capsule attaches to the scapula, humerus, and tendons of various muscles. Movements of the shoulder joint are controlled by different muscles. The joint is closely related to important anatomical structures such as the brachial plexus, axillary artery and vein, and various nerves and vessels.
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This question is part of the following fields:
- Musculoskeletal System And Skin
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Question 11
Incorrect
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You are a doctor working in the intensive care unit. A 35-year-old man has been admitted to the ward due to suddenly vomiting large volumes of fresh blood. His blood pressure is 90/60 mmHg and his heart rate is 150bpm. He needs urgent intravenous fluids. Several attempts at intravenous cannulation have been made but to no avail. The on-call anaesthetist suggests performing a great saphenous vein cutdown.
Where should the anaesthetist make the incision?Your Answer: Posterior to the medial malleolus
Correct Answer: Anterior to the medial malleolus
Explanation:The long saphenous vein is often used for venous cutdown and passes in front of the medial malleolus. Venous cutdown involves surgically exposing a vein for cannulation.
On the other hand, the short saphenous vein is situated in front of the lateral malleolus and runs up the back of the thigh to drain into the popliteal vein at the popliteal fossa.
The long saphenous vein originates from the point where the first dorsal digital vein, which drains the big toe, joins the dorsal venous arch of the foot. It then passes in front of the medial malleolus, ascends the medial aspect of the thigh, and drains into the femoral vein by passing through the saphenous opening.
The femoral vein becomes the external iliac vein at the inferior margin of the inguinal ligament. It receives blood from the great saphenous and popliteal veins, and a deep vein thrombosis that blocks this vein can be life-threatening.
During a vascular examination of the lower limb, the dorsalis pedis artery is often palpated. It runs alongside the extensor digitorum longus.
Lastly, the posterior tibial vein is located at the back of the medial malleolus, together with other structures, within the tarsal tunnel.
The Anatomy of Saphenous Veins
The human body has two saphenous veins: the long saphenous vein and the short saphenous vein. The long saphenous vein is often used for bypass surgery or removed as a treatment for varicose veins. It originates at the first digit where the dorsal vein merges with the dorsal venous arch of the foot and runs up the medial side of the leg. At the knee, it runs over the posterior border of the medial epicondyle of the femur bone before passing laterally to lie on the anterior surface of the thigh. It then enters an opening in the fascia lata called the saphenous opening and joins with the femoral vein in the region of the femoral triangle at the saphenofemoral junction. The long saphenous vein has several tributaries, including the medial marginal, superficial epigastric, superficial iliac circumflex, and superficial external pudendal veins.
On the other hand, the short saphenous vein originates at the fifth digit where the dorsal vein merges with the dorsal venous arch of the foot, which attaches to the great saphenous vein. It passes around the lateral aspect of the foot and runs along the posterior aspect of the leg with the sural nerve. It then passes between the heads of the gastrocnemius muscle and drains into the popliteal vein, approximately at or above the level of the knee joint.
Understanding the anatomy of saphenous veins is crucial for medical professionals who perform surgeries or treatments involving these veins.
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This question is part of the following fields:
- Cardiovascular System
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Question 12
Correct
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A 29-year-old woman, who is 30 weeks' pregnant, visits your clinic to discuss breast feeding. She expresses her interest in trying to breast feed her baby but would like to know more about best practices in neonatal feeding.
What are the recommendations of the World Health Organization regarding breast feeding?Your Answer: 6 months' exclusive breast feeding with gradual introduction of solid foods after this point
Explanation:WHO Recommendations for Infant Feeding
The World Health Organization (WHO) recommends early initiation of breast feeding, ideally from birth. Infants who are exclusively breast fed until six months have reduced risks of gastrointestinal infections compared to those who start weaning onto solid foods at three to four months. Breast feeding should continue on demand to 24 months or beyond, while solid food should be introduced gradually from six months. There should be a gradual increase in the consistency and variety of food offered. Infants who do not have ongoing breast feeding after six months will require fluid to be provided in an alternative form.
In countries where there are particular risks of nutrient deficiencies, supplements can be provided. However, in most developed nations, nutrient supplements are not required. It is important to adhere to hygienic practices in the preparation of food. WHO recommends breast feeding in all situations, even for mothers who are HIV positive and infants who are HIV negative, provided that the mothers have satisfactory anti-retroviral therapy. In resource-poor situations, WHO considers that the positive benefits of breast feeding in a population causing improved infant mortality outweigh the risk of a minority of infants contracting HIV through breast milk.
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This question is part of the following fields:
- Paediatrics
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Question 13
Correct
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A 39-year-old man presents to his doctor with a complaint of right hip pain that has been bothering him for the past 2 days. He had received his travel vaccinations via intramuscular injection to his buttock just 3 days ago.
Upon examination, the doctor notes slight tenderness over the right hip, reduced range of motion, and pain when the patient resists hip abduction. Additionally, when the patient raises his right leg while standing, the pelvis on the same side drops downward.
Which anatomical structure is most likely to be affected in this case?Your Answer: Superior gluteal nerve
Explanation:The patient exhibits a positive Trendelenburg sign, indicating weakness in the gluteus medius and minimus muscles responsible for hip abduction and pelvic stabilization. This is likely due to injury to the superior gluteal nerve. In contrast, injuries to the inferior gluteal nerve affect the gluteus maximus muscle and result in difficulty rising from a seated position or climbing stairs. The femoral nerve is responsible for knee extension and does not play a role in hip abduction. The lateral cutaneous nerve of the thigh causes pain in the posterolateral aspect of the thigh but does not cause motor impairment, while the obturator nerve controls thigh adduction and does not cause a positive Trendelenburg sign.
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 14
Correct
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A 38-year-old woman has made the decision to have a thyroidectomy for her Graves' disease. During the procedure, one of the blood vessels supplying the thyroid gland, the superior thyroid artery, will be ligated.
What is the correct description of the superior thyroid artery?Your Answer: A branch of the external carotid artery that supplies the superior portion of the thyroid gland
Explanation:The superior thyroid artery is the initial branch of the external carotid artery and is responsible for supplying the upper pole of the thyroid gland. It descends towards the gland after arising and generally provides blood to the superior and anterior regions. On the other hand, the inferior thyroid artery originates from the thyrocervical trunk, which is a branch of the subclavian artery. It travels in a superomedial direction to reach the inferior pole of the thyroid and typically supplies the postero-inferior aspect.
Anatomy of the Thyroid Gland
The thyroid gland is a butterfly-shaped gland located in the neck, consisting of two lobes connected by an isthmus. It is surrounded by a sheath from the pretracheal layer of deep fascia and is situated between the base of the tongue and the fourth and fifth tracheal rings. The apex of the thyroid gland is located at the lamina of the thyroid cartilage, while the base is situated at the fourth and fifth tracheal rings. In some individuals, a pyramidal lobe may extend from the isthmus and attach to the foramen caecum at the base of the tongue.
The thyroid gland is surrounded by various structures, including the sternothyroid, superior belly of omohyoid, sternohyoid, and anterior aspect of sternocleidomastoid muscles. It is also related to the carotid sheath, larynx, trachea, pharynx, oesophagus, cricothyroid muscle, and parathyroid glands. The superior and inferior thyroid arteries supply the thyroid gland with blood, while the superior and middle thyroid veins drain into the internal jugular vein, and the inferior thyroid vein drains into the brachiocephalic veins.
In summary, the thyroid gland is a vital gland located in the neck, responsible for producing hormones that regulate metabolism. Its anatomy is complex, and it is surrounded by various structures that are essential for its function. Understanding the anatomy of the thyroid gland is crucial for the diagnosis and treatment of thyroid disorders.
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This question is part of the following fields:
- Musculoskeletal System And Skin
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Question 15
Correct
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An 80-year-old patient is initiated on warfarin after being diagnosed with atrial fibrillation. The patient has a medical history of a metallic heart valve.
The patient is informed that INR levels will be used to monitor the effects of warfarin. INR is a ratio of the value during warfarin treatment to the normal value, which is used to measure a specific aspect of clotting.
What is the value that is utilized during this monitoring process?Your Answer: Prothrombin time
Explanation:Warfarin leads to an extended prothrombin time, which is the correct answer. The prothrombin time assesses the extrinsic and common pathways of the clotting cascade, and warfarin affects factor VII from the extrinsic pathway, as well as factor II (prothrombin) and factor X from the common pathway. This results in a prolonged prothrombin time, and the INR is a ratio of the prothrombin time during warfarin treatment to the normal prothrombin time.
The activated partial thromboplastin time is an incorrect answer. Although high levels of warfarin may prolong the activated partial thromboplastin time, the INR is solely based on the prothrombin time.
Bleeding time is also an incorrect answer. While warfarin can cause a prolonged bleeding time, the INR measures the prothrombin time.
Fibrinogen levels are another incorrect answer. Fibrinogen is necessary for blood clotting, and warfarin can decrease fibrinogen levels after prolonged use. However, fibrinogen levels are not used in the INR measurement.
Understanding Warfarin: Mechanism of Action, Indications, Monitoring, Factors, and Side-Effects
Warfarin is an oral anticoagulant that has been widely used for many years to manage venous thromboembolism and reduce stroke risk in patients with atrial fibrillation. However, it has been largely replaced by direct oral anticoagulants (DOACs) due to their ease of use and lack of need for monitoring. Warfarin works by inhibiting epoxide reductase, which prevents the reduction of vitamin K to its active hydroquinone form. This, in turn, affects the carboxylation of clotting factor II, VII, IX, and X, as well as protein C.
Warfarin is indicated for patients with mechanical heart valves, with the target INR depending on the valve type and location. Mitral valves generally require a higher INR than aortic valves. It is also used as a second-line treatment after DOACs for venous thromboembolism and atrial fibrillation, with target INRs of 2.5 and 3.5 for recurrent cases. Patients taking warfarin are monitored using the INR, which may take several days to achieve a stable level. Loading regimes and computer software are often used to adjust the dose.
Factors that may potentiate warfarin include liver disease, P450 enzyme inhibitors, cranberry juice, drugs that displace warfarin from plasma albumin, and NSAIDs that inhibit platelet function. Warfarin may cause side-effects such as haemorrhage, teratogenic effects, skin necrosis, temporary procoagulant state, thrombosis, and purple toes.
In summary, understanding the mechanism of action, indications, monitoring, factors, and side-effects of warfarin is crucial for its safe and effective use in patients. While it has been largely replaced by DOACs, warfarin remains an important treatment option for certain patients.
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This question is part of the following fields:
- Cardiovascular System
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Question 16
Correct
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A 50-year-old male is admitted with sepsis caused by a urinary tract infection from Escherichia coli. Despite taking trimethoprim for six days as prescribed by his doctor, he has not shown any improvement. He assures that he has followed the treatment regimen. What could be the probable reason for this lack of response?
Your Answer: The strain of the likely causative agent has developed extrinsic (acquired) resistance to the antibiotic
Explanation:Understanding Trimethoprim: Mechanism of Action, Adverse Effects, and Use in Pregnancy
Trimethoprim is an antibiotic that is commonly used to treat urinary tract infections. Its mechanism of action involves interfering with DNA synthesis by inhibiting dihydrofolate reductase. This may cause an interaction with methotrexate, which also inhibits dihydrofolate reductase. However, the use of trimethoprim may also lead to adverse effects such as myelosuppression and a transient rise in creatinine. The drug competitively inhibits the tubular secretion of creatinine, resulting in a temporary increase that reverses upon stopping the medication. Additionally, trimethoprim blocks the ENaC channel in the distal nephron, causing a hyperkalaemic distal RTA (type 4). It also inhibits creatinine secretion, which often leads to an increase in creatinine by around 40 points, but not necessarily causing AKI.
When it comes to the use of trimethoprim in pregnancy, caution is advised. The British National Formulary (BNF) warns of a teratogenic risk in the first trimester due to its folate antagonist properties. Manufacturers advise avoiding the use of trimethoprim during pregnancy. It is important to consult with a healthcare provider before taking any medication, especially during pregnancy, to ensure the safety of both the mother and the developing fetus.
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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 74-year-old woman has been brought to the emergency department by her husband after a fall at home. Upon assessment by the orthopaedics team, it is observed that she is holding her right arm adducted to her side and there is deformity of the proximal arm and shoulder with overlying skin ecchymosis and swelling. Neurovascular examination reveals palpable distal pulses and some paraesthesia over the deltoid region, but loss of active shoulder abduction is noted. What structure is likely to have been affected by this patient's injury?
Your Answer: Musculocutaneous nerve
Correct Answer: Axillary nerve
Explanation:The correct nerve that is likely injured in a patient with difficulty abducting their arm following a humeral neck fracture is the axillary nerve. This nerve provides motor function to the deltoid muscle, which is responsible for arm abduction at the shoulder joint, and cutaneous sensation to the deltoid region. Proximal humerus fractures, which are common in individuals of the patient’s age and gender, can often result in injury to the axillary nerve.
The brachial plexus is an incorrect answer as injuries to this nerve bundle are rare and would likely result in neurological dysfunction beyond the shoulder. The musculocutaneous nerve is also an incorrect answer as it provides motor function to the anterior compartment of the arm and sensation to the lateral forearm, but not to the deltoid region. The radial nerve is also an incorrect answer as it is typically injured in humeral shaft fractures and would result in wrist drop and paresthesia over the dorsal hand and wrist. The suprascapular nerve is also an incorrect answer as it provides motor innervation to different muscles and sensation to different joints than those affected in this case.
Upper limb anatomy is a common topic in examinations, and it is important to know certain facts about the nerves and muscles involved. The musculocutaneous nerve is responsible for elbow flexion and supination, and typically only injured as part of a brachial plexus injury. The axillary nerve controls shoulder abduction and can be damaged in cases of humeral neck fracture or dislocation, resulting in a flattened deltoid. The radial nerve is responsible for extension in the forearm, wrist, fingers, and thumb, and can be damaged in cases of humeral midshaft fracture, resulting in wrist drop. The median nerve controls the LOAF muscles and can be damaged in cases of carpal tunnel syndrome or elbow injury. The ulnar nerve controls wrist flexion and can be damaged in cases of medial epicondyle fracture, resulting in a claw hand. The long thoracic nerve controls the serratus anterior and can be damaged during sports or as a complication of mastectomy, resulting in a winged scapula. The brachial plexus can also be damaged, resulting in Erb-Duchenne palsy or Klumpke injury, which can cause the arm to hang by the side and be internally rotated or associated with Horner’s syndrome, respectively.
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This question is part of the following fields:
- Musculoskeletal System And Skin
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Question 18
Correct
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A 30-year-old woman presents with symptoms of dysuria, urgency to urinate, and foul-smelling urine. The physician suspects a urinary tract infection and prescribes a 3-day course of antibiotics that inhibit dihydrofolate reductase.
What class of antibiotics is being prescribed for this patient's urinary tract infection?Your Answer: Trimethoprim
Explanation: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.
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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 sailor has been diagnosed with scurvy.
What is the underlying cause of scurvy?Your Answer: Vitamin C deficiency
Explanation:The Importance of Vitamins and Their Deficiencies
Vitamins play a crucial role in maintaining the body’s overall health and well-being. Scurvy, a condition caused by a deficiency in vitamin C, is commonly observed in sailors who lack access to fresh fruits and vegetables during long sea voyages. The symptoms of scurvy include a widespread rash, bleeding mucous membranes, impaired wound healing, rough skin, fatigue, and depression. Vitamin C has several essential functions in the body, including acting as an antioxidant, reducing iron and copper, synthesizing collagen, producing energy from fats, synthesizing neurotransmitters, enhancing immune function, and acting as an antihistamine.
Deficiencies in other vitamins can also lead to various health problems. A lack of vitamin B3 can cause diarrhea, confusion, and skin changes known as pellagra. Vitamin B12 deficiency can lead to macrocytic anemia and paresthesia. Vitamin A toxicity can cause bone pain, dizziness, and blurred vision, while vitamin D toxicity can lead to vomiting, bone pain, and increased urinary frequency. It is essential to maintain a balanced diet and ensure adequate intake of all essential vitamins to prevent deficiencies and maintain optimal health.
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This question is part of the following fields:
- Clinical Sciences
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Question 20
Incorrect
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A 65-year-old man presents with a cough, headache, and fever. He has a medical history of hypertension and dyslipidemia and has taken ibuprofen for symptom relief. What is the mechanism of action for the antipyretic effect of the medication he took?
Your Answer:
Correct Answer: Reduction of prostaglandin E2
Explanation:Non-steroidal anti-inflammatory drugs (NSAIDs) reduce the production of prostaglandin E2 (PGE2), which is responsible for their antipyretic effect. NSAIDs inhibit the enzyme cyclooxygenase (COX), which is required for the production of thromboxanes, prostaglandins, and prostacyclins. By reducing the production of PGE2, NSAIDs decrease fever by acting on the thermoregulation centre in the hypothalamus. However, NSAIDs can have side effects such as gastric ulcer, acute kidney injury, indigestion, and an increased risk of heart failure. It is important to note that insulin-like growth factor 1 (IGF-1) is not affected by NSAIDs, as it is stimulated by growth hormones.
Understanding Non-Steroidal Anti-Inflammatory Drugs (NSAIDs) and COX-2 Selective NSAIDs
Non-steroidal anti-inflammatory drugs (NSAIDs) are medications that work by inhibiting the activity of cyclooxygenase enzymes, which are responsible for producing key mediators involved in inflammation such as prostaglandins. By reducing the production of these mediators, NSAIDs can help alleviate pain and reduce inflammation. Examples of NSAIDs include ibuprofen, diclofenac, naproxen, and aspirin.
However, NSAIDs can also have important and common side-effects, such as peptic ulceration and exacerbation of asthma. To address these concerns, COX-2 selective NSAIDs were developed. These medications were designed to reduce the incidence of side-effects seen with traditional NSAIDs, particularly peptic ulceration. Examples of COX-2 selective NSAIDs include celecoxib and etoricoxib.
Despite their potential benefits, COX-2 selective NSAIDs are not widely used due to ongoing concerns about cardiovascular safety. This led to the withdrawal of rofecoxib (‘Vioxx’) in 2004. As with any medication, it is important to discuss the potential risks and benefits of NSAIDs and COX-2 selective NSAIDs with a healthcare provider before use.
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This question is part of the following fields:
- Musculoskeletal System And Skin
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Question 21
Incorrect
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A 57-year-old woman comes to you complaining of an itchy rash on her back and tummy that she noticed this morning. She has a medical history of diabetes, hypertension, stage II chronic kidney disease, and atrial fibrillation. During the examination, you observe a single stripe of vesicular rash extending from the mid-back to the abdomen. You prescribe a 5-day course of acyclovir and provide her with some crucial advice before discharging her.
What important advice do you give her?Your Answer:
Correct Answer: Maintain adequate hydration
Explanation:Due to the risk of crystalline nephropathy, caution should be exercised when administering acyclovir to patients with stage II chronic kidney disease. Adequate hydration should be maintained to prevent acute kidney injury.
It is not recommended to use adhesives or topical creams as they may cause irritation and delay the healing of the rash.
If the lesions are still oozing, they should be covered with loose clothing.
To reduce the risk of bacterial superinfection, it is important to keep the rash clean and dry.
Antiviral agents are drugs used to treat viral infections. They work by targeting specific mechanisms of the virus, such as inhibiting viral DNA polymerase or neuraminidase. Some common antiviral agents include acyclovir, ganciclovir, ribavirin, amantadine, oseltamivir, foscarnet, interferon-α, and cidofovir. Each drug has its own mechanism of action and indications for use, but they all aim to reduce the severity and duration of viral infections.
In addition to these antiviral agents, there are also specific drugs used to treat HIV, a retrovirus. Nucleoside analogue reverse transcriptase inhibitors (NRTI), protease inhibitors (PI), and non-nucleoside reverse transcriptase inhibitors (NNRTI) are all used to target different aspects of the HIV life cycle. NRTIs work by inhibiting the reverse transcriptase enzyme, which is needed for the virus to replicate. PIs inhibit a protease enzyme that is necessary for the virus to mature and become infectious. NNRTIs bind to and inhibit the reverse transcriptase enzyme, preventing the virus from replicating. These drugs are often used in combination to achieve the best possible outcomes for HIV patients.
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This question is part of the following fields:
- General Principles
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Question 22
Incorrect
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You come across a patient in the medical assessment unit who has been admitted with a two-day history of haematemesis. An endoscopy revealed bleeding oesophageal varices that were banded and ligated. The consultant informs you that this patient has cirrhosis of the liver due to excessive alcohol consumption.
What other vein is likely to be dilated in this patient?Your Answer:
Correct Answer: Superior rectal vein
Explanation:The Relationship between Liver Cirrhosis and Varices
Liver cirrhosis is a condition that occurs in patients with alcohol-related liver disease due to the accumulation of aldehyde, which is formed during the metabolism of alcohol. The excessive amounts of aldehyde produced cannot be processed by hepatocytes, leading to the release of inflammatory mediators. These mediators activate hepatic stellate cells, which constrict off the inflamed sinusoids by depositing collagen in the space of Disse. This collagen deposition increases the resistance against the sinusoidal vascular bed, leading to portal hypertension.
To relieve excess pressure, the portal system forces blood back into systemic circulation at portosystemic anastomotic points. These anastomoses exist at various locations, including the distal end of the oesophagus, splenorenal ligament, retroperitoneum, anal canal, and abdominal wall. The high pressure causes the systemic veins to dilate, becoming varices, because the weak thin walls do not oppose resistance and pressure.
The superior rectal vein is the only vein that forms a collateral blood supply with systemic circulation. Therefore, the pressure from the superior rectal vein is passed onto the systemic veins, causing them to dilate and leading to the formation of haemorrhoids. The other veins listed are part of systemic circulation and have no collateral anastomoses with the portal circulatory system. In summary, liver cirrhosis can lead to varices due to the increased pressure in the portal system, which forces blood back into systemic circulation and causes systemic veins to dilate.
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This question is part of the following fields:
- Gastrointestinal System
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Question 23
Incorrect
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A 42-year-old female presents to the emergency department with severe generalised abdominal pain and haematemesis. The patient reports ongoing epigastric pain over the past few months which was worse after eating meals. She had a similar but milder episode about 4 years ago, which was treated with omeprazole. Past medical history includes osteoarthritis for which she takes ibuprofen.
Clinical observations reveal a heart rate of 120 beats per minute, blood pressure of 90/78 mmHg, respiratory rate of 25/min, oxygen saturations of 98% on air and a temperature of 37.5ºC. On examination, the patient has severe epigastric tenderness on palpation.
What is the first-line treatment for the likely diagnosis?Your Answer:
Correct Answer: Endoscopic intervention
Explanation:The most likely diagnosis for the patient is a perforated peptic ulcer, which may have been caused by their use of ibuprofen. The recommended first-line treatment according to NICE guidelines is endoscopic intervention, which can confirm the diagnosis and stop the bleeding. This involves injecting adrenaline into the bleeding site and using cautery and/or clip application. Helicobacter pylori eradication therapy is not appropriate in this case, as the patient’s symptoms suggest a perforated peptic ulcer rather than peptic ulcer disease caused by H. pylori. IV proton-pump inhibitor infusion may be considered later, but the patient requires immediate management with endoscopic intervention.
Managing Acute Bleeding in Peptic Ulcer Disease
Peptic ulcer disease is a condition that can lead to acute bleeding, which is the most common complication of the disease. In fact, bleeding accounts for about three-quarters of all problems associated with peptic ulcer disease. The gastroduodenal artery is often the source of significant gastrointestinal bleeding in patients with this condition. The most common symptom of acute bleeding in peptic ulcer disease is haematemesis, but patients may also experience melaena, hypotension, and tachycardia.
When managing acute bleeding in peptic ulcer disease, an ABC approach should be taken, as with any upper gastrointestinal haemorrhage. Intravenous proton pump inhibitors are the first-line treatment, and endoscopic intervention is typically the preferred approach. However, if endoscopic intervention fails (which occurs in approximately 10% of patients), urgent interventional angiography with transarterial embolization or surgery may be necessary. By following these management strategies, healthcare providers can effectively address acute bleeding in patients with peptic ulcer disease.
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This question is part of the following fields:
- Gastrointestinal System
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Question 24
Incorrect
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A 46-year-old man visits his doctor complaining of nosebleeds and bruising that started yesterday. He denies any recent injuries. The patient has a medical history of Crohn's disease and had a recent flare-up that required treatment. The doctor suspects that the patient may have a deficiency in vitamin K, which clotting factor is most likely to be affected?
Your Answer:
Correct Answer: Factor VII
Explanation:In cases of malabsorption, such as Crohn’s disease, a deficiency in fat soluble vitamins (A,D,E and K) may occur. This can lead to symptoms such as easy bruising and epistaxis. Among the vitamin K dependent factors (II, VII, IX and X), factor VII is the first to decrease in the event of a deficiency. With a half-life of only 6 hours, a deficiency in factor VII can occur quickly and is likely responsible for the patient’s symptoms.
Understanding Vitamin K
Vitamin K is a type of fat-soluble vitamin that plays a crucial role in the carboxylation of clotting factors such as II, VII, IX, and X. This vitamin acts as a cofactor in the process, which is essential for blood clotting. In clinical settings, vitamin K is used to reverse the effects of warfarinisation, a process that inhibits blood clotting. However, it may take up to four hours for the INR to change after administering vitamin K.
Vitamin K deficiency can occur in conditions that affect fat absorption since it is a fat-soluble vitamin. Additionally, prolonged use of broad-spectrum antibiotics can eliminate gut flora, leading to a deficiency in vitamin K. It is essential to maintain adequate levels of vitamin K to ensure proper blood clotting and prevent bleeding disorders.
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This question is part of the following fields:
- General Principles
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Question 25
Incorrect
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A patient comes to the clinic with a few months of experiencing head fullness and vision deterioration. After undergoing various blood tests, all results appear normal except for an Hb level of 188 g/L. What is linked to primary polycythemia in this case?
Your Answer:
Correct Answer: JAK2 mutation
Explanation:JAK2 Mutation and Primary Polycythaemia
Polycythaemia is a condition characterized by an increase in the number of red blood cells in the body. In primary polycythaemia, over 95% of cases are associated with a mutation in the JAK2 pathway. This mutation causes the pathway to be constantly active, leading to the production of red blood cells even in the absence of erythropoietin (EPO). The most common mutation occurs in exon 12, affecting position V617F.
On the other hand, secondary causes of polycythaemia include COPD and smoking, which lower blood oxygenation and trigger the secretion of EPO by the kidney’s peritubular cells. ADPKD also promotes the secretion of increased EPO, resulting in the production and release of more red blood cells. Dehydration, on the other hand, reduces plasma volume, leading to an apparent/relative polycythaemia. While these factors can cause an increase in red blood cells, they are not associated with a primary haematological disorder like the JAK2 mutation.
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This question is part of the following fields:
- Haematology And Oncology
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Question 26
Incorrect
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A new treatment for arthritis in elderly patients is being studied. The research focuses on the reduction of joint pain after 6 months. The given data is as follows:
Number of patients Number who experienced joint pain reduction within 6 months
New treatment 150 75
Placebo 300 150
What is the percentage of relative risk reduction?Your Answer:
Correct Answer: 20%
Explanation:Understanding Relative Risk in Clinical Trials
Relative risk (RR) is a measure used in clinical trials to compare the risk of an event occurring in the experimental group to the risk in the control group. It is calculated by dividing the experimental event rate (EER) by the control event rate (CER). If the resulting ratio is greater than 1, it means that the event is more likely to occur in the experimental group than in the control group. Conversely, if the ratio is less than 1, the event is less likely to occur in the experimental group.
To calculate the relative risk reduction (RRR) or relative risk increase (RRI), the absolute risk change is divided by the control event rate. This provides a percentage that indicates the magnitude of the difference between the two groups. Understanding relative risk is important in evaluating the effectiveness of interventions and treatments in clinical trials. By comparing the risk of an event in the experimental group to the control group, researchers can determine whether the intervention is beneficial or not.
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This question is part of the following fields:
- General Principles
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Question 27
Incorrect
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An 80-year-old woman comes to the emergency department with a painless visual disturbance that started 2 hours ago. She has a medical history of hypertension and dyslipidemia.
During the examination, there is no facial asymmetry, and the patient appears comfortable. The visual field test shows homonymous hemianopia on the right side, and automated perimetry indicates macular sparing. The patient is unable to name familiar objects, such as a pen or a spoon.
Which artery is most likely to have been occluded?Your Answer:
Correct Answer: Posterior cerebral artery
Explanation:The correct answer is the posterior cerebral artery. When a lesion occurs in the posterior cerebral artery, it can result in contralateral homonymous hemianopia with macular sparing and visual agnosia. This is because the visual cortex is supplied by the posterior cerebral artery, which is responsible for the patient’s symptoms. The macula is usually spared because the posterior pole of the occipital cortex, which processes visual signals from the macula, receives collateral flow from the middle cerebral artery.
On the other hand, lesions in the anterior cerebral artery, which supplies the frontal cortex, can cause contralateral hemiparesis, altered sensorium, and aphasia. Meanwhile, occlusion of the anterior inferior cerebellar artery, which supplies the lateral pons, can lead to sudden onset vertigo, vomiting, ataxia, nystagmus, and dysarthria.
Lastly, the central retinal artery is not the correct answer as occlusion of this artery typically results in amaurosis fugax, which is a painless transient ‘descending curtain’ visual field defect, rather than homonymous hemianopia.
Stroke can affect different parts of the brain depending on which artery is affected. If the anterior cerebral artery is affected, the person may experience weakness and loss of sensation on the opposite side of the body, with the lower extremities being more affected than the upper. If the middle cerebral artery is affected, the person may experience weakness and loss of sensation on the opposite side of the body, with the upper extremities being more affected than the lower. They may also experience vision loss and difficulty with language. If the posterior cerebral artery is affected, the person may experience vision loss and difficulty recognizing objects.
Lacunar strokes are a type of stroke that are strongly associated with hypertension. They typically present with isolated weakness or loss of sensation on one side of the body, or weakness with difficulty coordinating movements. They often occur in the basal ganglia, thalamus, or internal capsule.
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This question is part of the following fields:
- Neurological System
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Question 28
Incorrect
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A 12-year-old boy is brought to the emergency department by his mother after she found him having seizures. She reports that he has not eaten anything all day. The child is hyperventilating.
Blood results reveal:
- Low fasting glucose
- High urea
- Normal sodium
- Normal potassium
- High triglycerides
- pH of 7.29
Upon palpation of his abdomen, hepatomegaly is noted.
An ultrasound scan of the abdomen shows enlarged kidneys.
Based on these findings, what is the most likely diagnosis and underlying cause of this child's presentation?Your Answer:
Correct Answer: A defect in glucose-6-phosphatase
Explanation:Glucose-6-phosphatase deficiency is the cause of Von Gierke’s disease. This condition is characterized by an inability to maintain adequate blood glucose levels during the post-absorptive hours of each day, which can lead to seizures due to hypoglycemia. Excessive lactate and urate generation also occur, resulting in hyperuricemia and organ damage. Children are typically diagnosed at 2 years of age and may present with hepatomegaly, hyperventilation, respiratory distress, vomiting, and other manifestations of hypoglycemia. Other enzyme deficiencies and their associated conditions include galactocerebrosidase deficiency in Krabbe’s disease, alpha-L iduronidase deficiency in Hurler’s disease, N-acetylglucosamine-1-phosphate transferase deficiency in Inclusion cell disease, lysosomal acid alpha-glucosidase deficiency in Pompe disease, Hexosaminidase A deficiency in Tay-Sachs disease, and alpha-galactosidase deficiency in Fabry’s disease.
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 29
Incorrect
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Whilst in general practice, you review John, a 50-year-old patient with hypertension. Despite taking lisinopril, his blood pressure remains clinically elevated. Based on current guidelines you consider add-on therapy with a thiazide-like diuretic.
Which of the following electrolyte imbalances may arise with this new treatment?Your Answer:
Correct Answer: Hypokalaemia
Explanation:Hypokalaemia may be caused by thiazides
Thiazide diuretics can lead to hypokalaemia by stimulating aldosterone production and inhibiting the Na-Cl symporter. This inhibition results in more sodium being available to activate the Na/K-ATPase channel, leading to increased potassium loss in the urine and hypokalaemia.
Thiazide diuretics may also cause other side effects such as hypocalciuria, hypomagnesemia, and hyperlipidemia. The other options that describe the opposite of these disturbances are incorrect.
Thiazide diuretics are medications that work by blocking the thiazide-sensitive Na+-Cl− symporter, which inhibits sodium reabsorption at the beginning of the distal convoluted tubule (DCT). This results in the loss of potassium as more sodium reaches the collecting ducts. While thiazide diuretics are useful in treating mild heart failure, loop diuretics are more effective in reducing overload. Bendroflumethiazide was previously used to manage hypertension, but recent NICE guidelines recommend other thiazide-like diuretics such as indapamide and chlorthalidone.
Common side effects of thiazide diuretics include dehydration, postural hypotension, and electrolyte imbalances such as hyponatremia, hypokalemia, and hypercalcemia. Other potential adverse effects include gout, impaired glucose tolerance, and impotence. Rare side effects may include thrombocytopenia, agranulocytosis, photosensitivity rash, and pancreatitis.
It is worth noting that while thiazide diuretics may cause hypercalcemia, they can also reduce the incidence of renal stones by decreasing urinary calcium excretion. According to current NICE guidelines, the management of hypertension involves the use of thiazide-like diuretics, along with other medications and lifestyle changes, to achieve optimal blood pressure control and reduce the risk of cardiovascular disease.
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This question is part of the following fields:
- Cardiovascular System
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Question 30
Incorrect
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You are attending a journal club run for the senior doctors of the geriatrics department, where you are completing a rotation. In this session, one of the doctors presents a paper that is examining the impact of a new medication on elderly patients.
Throughout the presentation, the doctor highlights several limitations of the study and mentions that the likelihood of a type II error is significant.
What does this mean in terms of the study's findings?Your Answer:
Correct Answer: The null hypothesis may have been accepted incorrectly
Explanation:A type II error occurs when the null hypothesis is accepted even though it is false. This means that the study fails to detect a difference that actually exists. It is important to note that a type II error does not necessarily indicate a flaw in the study design, but rather a lack of sufficient evidence to reject the null hypothesis.
It is possible for a study to use appropriate methods and still produce a type II error. Therefore, it is important to analyze the evidence separately from the study design.
In contrast, a type I error occurs when the null hypothesis is rejected incorrectly.
The probabilities of type I and type II errors are not directly related, as they are influenced by different factors.
The P value is a measure of the likelihood that the results are due to chance, and should be considered separately from the possibility of a type II error.
Significance tests are used to determine the likelihood of a null hypothesis being true. The null hypothesis states that two treatments are equally effective, while the alternative hypothesis suggests that there is a difference between the two treatments. The p value is the probability of obtaining a result by chance that is at least as extreme as the observed result, assuming the null hypothesis is true. Two types of errors can occur during significance testing: type I, where the null hypothesis is rejected when it is true, and type II, where the null hypothesis is accepted when it is false. The power of a study is the probability of correctly rejecting the null hypothesis when it is false, and it can be increased by increasing the sample size.
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This question is part of the following fields:
- General Principles
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