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Question 1
Incorrect
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What is the most frequent chromosomal abnormality seen in individuals with Down's syndrome, and how does it occur?
Your Answer: Trinucleotide repeat disorder
Correct Answer: Nondisjunction
Explanation:Down’s Syndrome: Epidemiology and Genetics
Down’s syndrome is a genetic disorder that is caused by the presence of an extra copy of chromosome 21. The risk of having a child with Down’s syndrome increases with maternal age, with a 1 in 1,500 chance at age 20 and a 1 in 50 or greater chance at age 45. This can be remembered by dividing the denominator by 3 for every extra 5 years of age starting at 1/1,000 at age 30.
There are three main types of Down’s syndrome: nondisjunction, Robertsonian translocation, and mosaicism. Nondisjunction accounts for 94% of cases and occurs when the chromosomes fail to separate properly during cell division. Robertsonian translocation, which usually involves chromosome 14, accounts for 5% of cases and occurs when a piece of chromosome 21 attaches to another chromosome. Mosaicism, which accounts for 1% of cases, occurs when there are two genetically different populations of cells in the body.
The risk of recurrence for Down’s syndrome varies depending on the type of genetic abnormality. If the trisomy 21 is a result of nondisjunction, the chance of having another child with Down’s syndrome is approximately 1 in 100 if the mother is less than 35 years old. If the trisomy 21 is a result of Robertsonian translocation, the risk is much higher, with a 10-15% chance if the mother is a carrier and a 2.5% chance if the father is a carrier.
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This question is part of the following fields:
- General Principles
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Question 2
Incorrect
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A 75-year-old man sustains a scaphoid bone fracture that is displaced. The medical team decides to use a screw to fix the fracture. What structure is located directly medial to the scaphoid?
Your Answer: None of the above
Correct Answer: Lunate
Explanation:The lunate is positioned towards the middle in the anatomical plane. Injuries that involve high velocity and result in scaphoid fractures may also lead to dislocation of the lunate.
The scaphoid bone has various articular surfaces for different bones in the wrist. It has a concave surface for the head of the capitate and a crescentic surface for the lunate. The proximal end has a wide convex surface for the radius, while the distal end has a tubercle that can be felt. The remaining articular surface faces laterally and is associated with the trapezium and trapezoid bones. The narrow strip between the radial and trapezial surfaces and the tubercle gives rise to the radial collateral carpal ligament. The tubercle also receives part of the flexor retinaculum and is the only part of the scaphoid bone that allows for the entry of blood vessels. However, this area is commonly fractured and can lead to avascular necrosis.
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This question is part of the following fields:
- Musculoskeletal System And Skin
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Question 3
Incorrect
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Which of the following is more frequently observed in individuals with Crohn's disease compared to those with ulcerative colitis?
Your Answer: Toxic megacolon
Correct Answer: Fat wrapping of the terminal ileum
Explanation:Smoking has been found to exacerbate Crohn’s disease, and it also increases the risk of disease recurrence after resection. Patients with ileal disease, which is the most common site of the disease, often exhibit fat wrapping of the terminal ileum. The mesenteric fat in patients with inflammatory bowel disease (IBD) is typically dense, hard, and prone to significant bleeding during surgery. During endoscopy, the mucosa in Crohn’s disease patients is described as resembling cobblestones, while ulcerative colitis patients often exhibit mucosal islands (pseudopolyps).
Understanding Crohn’s Disease
Crohn’s disease is a type of inflammatory bowel disease that can affect any part of the digestive tract, from the mouth to the anus. The exact cause of Crohn’s disease is unknown, but there is a strong genetic component. Inflammation occurs in all layers of the affected area, which can lead to complications such as strictures, fistulas, and adhesions.
Symptoms of Crohn’s disease typically appear in late adolescence or early adulthood and can include non-specific symptoms such as weight loss and lethargy, as well as more specific symptoms like diarrhea, abdominal pain, and perianal disease. Extra-intestinal features, such as arthritis, erythema nodosum, and osteoporosis, are also common in patients with Crohn’s disease.
To diagnose Crohn’s disease, doctors may look for raised inflammatory markers, increased faecal calprotectin, anemia, and low levels of vitamin B12 and vitamin D. It’s important to note that Crohn’s disease shares some features with ulcerative colitis, another type of inflammatory bowel disease, but there are also important differences between the two conditions. Understanding the symptoms and diagnostic criteria for Crohn’s disease can help patients and healthcare providers manage this chronic condition more effectively.
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This question is part of the following fields:
- Gastrointestinal System
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Question 4
Correct
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A 28-year-old female, who is 5 months postpartum, presents with a 4-week history of weight loss, heat intolerance, tremor, palpitation and diarrhoea. Pregnancy and birth were uncomplicated. On further questioning, she admits having taken off-license weight loss medication bought from the internet 2 months ago. Past medical history and family history are insignificant. She does not smoke or drink alcohol.
On physical examination, she has exophthalmos, brisk reflexes and fine tremor. Her vital signs were heart rate 100/minute, blood pressure 138/78 mmHg, temperature 36.6ºC. The thyroid gland was diffusely enlarged.
Thyroid Stimulating Hormone (TSH) 0.01 mU/l
Free thyroxine (T4) 25 pmol/l
Total thyroxine (T4) 155 nmol/l
What is the most likely diagnosis?Your Answer: Graves' Disease
Explanation:During the postnatal period, Graves’ disease may either present for the first time or worsen. Exophthalmos is a distinctive symptom of Graves’ disease that is not observed in other hyperthyroid conditions. Hypothyroidism is caused by Hashimoto’s thyroiditis. postpartum thyroiditis is characterized by initial hyperthyroidism after childbirth, followed by normal or occasionally reduced thyroid levels.
During pregnancy, there is an increase in the levels of thyroxine-binding globulin (TBG), which causes an increase in the levels of total thyroxine. However, this does not affect the free thyroxine level. If left untreated, thyrotoxicosis can increase the risk of fetal loss, maternal heart failure, and premature labor. Graves’ disease is the most common cause of thyrotoxicosis during pregnancy, but transient gestational hyperthyroidism can also occur due to the activation of the TSH receptor by HCG. Propylthiouracil has traditionally been the antithyroid drug of choice, but it is associated with an increased risk of severe hepatic injury. Therefore, NICE Clinical Knowledge Summaries recommend using propylthiouracil in the first trimester and switching to carbimazole in the second trimester. Maternal free thyroxine levels should be kept in the upper third of the normal reference range to avoid fetal hypothyroidism. Thyrotropin receptor stimulating antibodies should be checked at 30-36 weeks gestation to determine the risk of neonatal thyroid problems. Block-and-replace regimes should not be used in pregnancy, and radioiodine therapy is contraindicated.
On the other hand, thyroxine is safe during pregnancy, and serum thyroid-stimulating hormone should be measured in each trimester and 6-8 weeks postpartum. Women require an increased dose of thyroxine during pregnancy, up to 50% as early as 4-6 weeks of pregnancy. Breastfeeding is safe while on thyroxine. It is important to manage thyroid problems during pregnancy to ensure the health of both the mother and the baby.
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This question is part of the following fields:
- Endocrine System
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Question 5
Incorrect
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A 25-year-old man was in a car accident where two cars collided at around 60 miles per hour. After being stabilized, the doctor conducts a secondary survey and finds that the patient's right leg is adducted, flexed, and internally rotated. The diagnosis is a hip dislocation. What type of dislocation is probable and why?
Your Answer: Anterior dislocation as the ischiofemoral ligament is strongest
Correct Answer: Posterior dislocation as the iliofemoral ligament is strongest
Explanation:The iliofemoral ligament is the strongest ligament stabilizing the hip joint, making posterior dislocations more common. The deep acetabulum of the hip provides stability and reduces the risk of anterior dislocation. The ischiofemoral ligament is the weakest of the three capsular ligaments and does not play a significant role in hip stability. Therefore, the iliofemoral ligament is the most important factor in preventing hip dislocation.
Anatomy of the Hip Joint
The hip joint is formed by the articulation of the head of the femur with the acetabulum of the pelvis. Both of these structures are covered by articular hyaline cartilage. The acetabulum is formed at the junction of the ilium, pubis, and ischium, and is separated by the triradiate cartilage, which is a Y-shaped growth plate. The femoral head is held in place by the acetabular labrum. The normal angle between the femoral head and shaft is 130 degrees.
There are several ligaments that support the hip joint. The transverse ligament connects the anterior and posterior ends of the articular cartilage, while the head of femur ligament (ligamentum teres) connects the acetabular notch to the fovea. In children, this ligament contains the arterial supply to the head of the femur. There are also extracapsular ligaments, including the iliofemoral ligament, which runs from the anterior iliac spine to the trochanteric line, the pubofemoral ligament, which connects the acetabulum to the lesser trochanter, and the ischiofemoral ligament, which provides posterior support from the ischium to the greater trochanter.
The blood supply to the hip joint comes from the medial circumflex femoral and lateral circumflex femoral arteries, which are branches of the profunda femoris. The inferior gluteal artery also contributes to the blood supply. These arteries form an anastomosis and travel up the femoral neck to supply the head of the femur.
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This question is part of the following fields:
- Musculoskeletal System And Skin
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Question 6
Correct
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A 27-year-old male patient visits his doctor complaining of right eye discomfort and a feeling of having a foreign object in it. He mentions that the symptoms have been getting worse for the past 3 days after he went to a concert. He wears contact lenses and did not remove them for several days during the event, opting to wash his eyes with water instead.
What could be the probable reason for his visit?Your Answer: Acanthamoeba infection
Explanation:Wearing contact lenses increases the risk of acanthamoeba infection, which can cause keratitis. Symptoms include severe pain, haloes around lights, and blurred vision. Acute angle closure glaucoma may also cause eye pain, but the history of contact lens use makes acanthamoeba infection more likely. Temporal arteritis, chlamydial conjunctivitis, and thyroid eye disease have different symptoms and are less likely to be the cause of eye pain in this case.
Understanding Keratitis: Inflammation of the Cornea
Keratitis is a condition that refers to the inflammation of the cornea, which is the clear, dome-shaped surface that covers the front of the eye. While there are various causes of keratitis, microbial keratitis is a particularly serious form of the condition that can lead to vision loss if left untreated. Bacterial keratitis is often caused by Staphylococcus aureus, while Pseudomonas aeruginosa is commonly seen in contact lens wearers. Fungal and amoebic keratitis are also possible, with acanthamoebic keratitis accounting for around 5% of cases. Other factors that can cause keratitis include viral infections, environmental factors like photokeratitis, and contact lens-related issues like contact lens acute red eye (CLARE).
Symptoms of keratitis typically include a painful, red eye, photophobia, and a gritty sensation or feeling of a foreign body in the eye. In some cases, hypopyon may be seen. If a person is a contact lens wearer and presents with a painful red eye, an accurate diagnosis can only be made with a slit-lamp, meaning same-day referral to an eye specialist is usually required to rule out microbial keratitis.
Management of keratitis typically involves stopping the use of contact lenses until symptoms have fully resolved, as well as the use of topical antibiotics like quinolones and cycloplegic agents for pain relief. Complications of keratitis can include corneal scarring, perforation, endophthalmitis, and visual loss. It is important to seek urgent evaluation and treatment for microbial keratitis to prevent these potential complications.
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This question is part of the following fields:
- Neurological System
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Question 7
Incorrect
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A patient in his 50s has undergone a muscle biopsy for progressive muscle weakness. During his clinic visit, the doctor presents a histological specimen and indicates the sarcomere. What is the doctor referring to?
Your Answer: The interface between actin and myosin filaments
Correct Answer: The region between two Z-lines on the myofibril
Explanation:The area between Z lines is known as the sarcomere. The skeletal muscle is composed of the following elements, as shown in the diagram.
The Process of Muscle Contraction
Muscle contraction is a complex process that involves several steps. It begins with an action potential reaching the neuromuscular junction, which causes a calcium ion influx through voltage-gated calcium channels. This influx leads to the release of acetylcholine into the extracellular space, which activates nicotinic acetylcholine receptors, triggering an action potential. The action potential then spreads through the T-tubules, activating L-type voltage-dependent calcium channels in the T-tubule membrane, which are close to calcium-release channels in the adjacent sarcoplasmic reticulum. This causes the sarcoplasmic reticulum to release calcium, which binds to troponin C, causing a conformational change that allows tropomyosin to move, unblocking the binding sites. Myosin then binds to the newly released binding site, releasing ADP and pulling the Z bands towards each other. ATP binds to myosin, releasing actin.
The components involved in muscle contraction include the sarcomere, which is the basic unit of muscles that gives skeletal and cardiac muscles their striated appearance. The I-band is the zone of thin filaments that is not superimposed by thick filaments, while the A-band contains the entire length of a single thick filament. The H-zone is the zone of the thick filaments that is not superimposed by the thin filaments, and the M-line is in the middle of the sarcomere, cross-linking myosin. The sarcoplasmic reticulum releases calcium ion in response to depolarization, while actin is the thin filaments that transmit the forces generated by myosin to the ends of the muscle. Myosin is the thick filaments that bind to the thin filament, while titin connects the Z-line to the thick filament, altering the structure of tropomyosin. Tropomyosin covers the myosin-binding sites on actin, while troponin-C binds with calcium ions. The T-tubule is an invagination of the sarcoplasmic reticulum that helps co-ordinate muscular contraction.
There are two types of skeletal muscle fibres: type I and type II. Type I fibres have a slow contraction time, are red in colour due to the presence of myoglobin, and are used for sustained force. They have a high mitochondrial density and use triglycerides as
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This question is part of the following fields:
- Musculoskeletal System And Skin
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Question 8
Correct
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A 25-year-old man is having a wedge excision of his big toenail. When the surgeon inserts a needle to give local anaesthetic, the patient experiences a sudden sharp pain. What is the pathway through which this sensation will be transmitted to the central nervous system?
Your Answer: Spinothalamic tract
Explanation:The Spinothalamic Tract and its Function in Sensory Transmission
The spinothalamic tract is responsible for transmitting impulses from receptors that measure crude touch, pain, and temperature. It is composed of two tracts, the lateral and anterior spinothalamic tracts, with the former transmitting pain and temperature and the latter crude touch and pressure.
Before decussating in the spinal cord, neurons transmitting these signals ascend by one or two vertebral levels in Lissaurs tract. Once they have crossed over, they pass rostrally in the cord to connect at the thalamus. This pathway is crucial in the transmission of sensory information from the body to the brain, allowing us to perceive and respond to various stimuli.
Overall, the spinothalamic tract plays a vital role in our ability to sense and respond to our environment. Its function in transmitting sensory information is essential for our survival and well-being.
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This question is part of the following fields:
- Neurological System
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Question 9
Correct
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A 10-year-old boy presents to your clinic with his mother. He has been diagnosed with asthma for two years and is currently on a low dose inhaled corticosteroid and reliever inhaler. However, his mother is concerned as he still experiences symptoms and needs to use his reliever inhaler four to five times per week. You plan to prescribe a medication that targets leukotrienes, which are known to contribute to bronchoconstriction. What is the mechanism of action of this drug?
Your Answer: It blocks leukotriene binding to and activating smooth muscle, preventing leukotriene-induced bronchoconstriction
Explanation:Montelukast is a drug that works as a leukotriene receptor antagonist, which means it blocks the activation of smooth muscle by leukotrienes and prevents bronchoconstriction. Mast cell stabilising drugs, on the other hand, do not have any effect on leukotriene-induced bronchoconstriction as they only prevent the release of histamine and other inflammatory cell mediators. Nedocromil is an example of a mast cell stabiliser used for asthma. Montelukast does not affect mucus production or leukotriene synthesis or recycling. It specifically blocks leukotriene binding to smooth muscle receptors in the airways.
Arachidonic Acid Metabolism: The Role of Leukotrienes and Endoperoxides
Arachidonic acid is a fatty acid that plays a crucial role in the body’s inflammatory response. The metabolism of arachidonic acid involves the production of various compounds, including leukotrienes and endoperoxides. Leukotrienes are produced by leukocytes and can cause constriction of the lungs. LTB4 is produced before leukocytes arrive, while the rest of the leukotrienes (A, C, D, and E) cause lung constriction.
Endoperoxides, on the other hand, are produced by the cyclooxygenase enzyme and can lead to the formation of thromboxane and prostacyclin. Thromboxane is associated with platelet aggregation and vasoconstriction, which can lead to thrombosis. Prostacyclin, on the other hand, has the opposite effect and can cause vasodilation and inhibit platelet aggregation.
Understanding the metabolism of arachidonic acid and the role of these compounds can help in the development of treatments for inflammatory conditions and cardiovascular diseases.
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This question is part of the following fields:
- General Principles
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Question 10
Incorrect
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A teenage girl is walking home from a party when she is approached by three men on the street. She becomes scared and experiences a fight-or-flight reaction, causing her heart rate and breathing rate to increase. What is the name of the neurotransmitter released by the postganglionic neurons responsible for this response?
Your Answer: Adrenaline
Correct Answer: Noradrenaline
Explanation:The neurotransmitter released by postganglionic neurons of the sympathetic nervous system is noradrenaline. This system triggers the fight-or-flight response and uses acetylcholine and noradrenaline as neurotransmitters. In contrast, the parasympathetic nervous system uses acetylcholine for both pre- and postganglionic neurons. Adrenaline is released by the adrenal glands into the bloodstream, while dopamine and serotonin are neurotransmitters in the central nervous system and do not play a role in the autonomic nervous system.
Understanding Norepinephrine: Its Synthesis and Effects on Mental Health
Norepinephrine is a neurotransmitter that is synthesized in the locus ceruleus, a small region in the brainstem. This neurotransmitter plays a crucial role in the body’s fight or flight response, which is activated in response to stress or danger. When released, norepinephrine increases heart rate, blood pressure, and breathing rate, preparing the body to respond to a perceived threat.
In terms of mental health, norepinephrine levels have been linked to anxiety and depression. Elevated levels of norepinephrine have been observed in individuals with anxiety, which can lead to symptoms such as increased heart rate, sweating, and trembling. On the other hand, depleted levels of norepinephrine have been associated with depression, which can cause feelings of sadness, hopelessness, and low energy.
It is important to note that norepinephrine is just one of many neurotransmitters that play a role in mental health. However, understanding its synthesis and effects can provide insight into the complex interplay between brain chemistry and mental health. By studying neurotransmitters like norepinephrine, researchers can develop new treatments and therapies for individuals struggling with anxiety, depression, and other mental health conditions.
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This question is part of the following fields:
- General Principles
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Question 11
Incorrect
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A 25-year-old man is being assessed on the ward after 10 days of laparotomy. The wound is examined and appears to be healing properly. What process is unlikely to be happening in the wound at this point?
Your Answer: Proliferation of fibroblasts
Correct Answer: Necrosis of fibroblasts
Explanation:Vasculogenesis involves the formation of new blood vessels from existing mesenchyme, while angiogenesis is the process of sprouting off new vessels from pre-existing arteries. Fibroblasts play a crucial role in wound healing by proliferating in the early stages and releasing matrix metalloproteinases to aid in matrix remodelling. Necrosis is uncommon in healing wounds as angiogenesis typically occurs by this point.
The Stages of Wound Healing and Common Problems with Scars
Wound healing is a complex process that involves several stages, including haemostasis, inflammation, regeneration, and remodeling. During haemostasis, the body forms a clot to stop bleeding. Inflammation occurs next, where immune cells migrate to the wound and release growth factors to stimulate the production of new tissue. Regeneration involves the formation of new blood vessels and the production of collagen to rebuild the damaged tissue. Finally, during remodeling, the body remodels the new tissue to form a scar.
However, several factors can affect the wound healing process, including vascular disease, shock, sepsis, and jaundice. Additionally, some scars may develop problems, such as hypertrophic scars, which contain excessive amounts of collagen within the scar and may develop contractures. Keloid scars are another type of problematic scar that extends beyond the boundaries of the original injury and does not regress over time.
Several drugs can also impair wound healing, including non-steroidal anti-inflammatory drugs, steroids, immunosuppressive agents, and anti-neoplastic drugs. Closure of the wound can occur through delayed primary closure or secondary closure, depending on the timing of the closure and the presence of granulation tissue.
In summary, wound healing is a complex process that involves several stages, and several factors can affect the process and lead to problematic scars. Understanding the stages of wound healing and common problems with scars can help healthcare professionals provide better care for patients with wounds.
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This question is part of the following fields:
- General Principles
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Question 12
Incorrect
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Which of the following symptoms is least commonly associated with salicylate overdose?
Your Answer: Hyperventilation
Correct Answer: Tremor
Explanation:Salicylate overdose can cause a combination of respiratory alkalosis and metabolic acidosis. The respiratory center is initially stimulated, leading to hyperventilation and respiratory alkalosis. However, the direct acid effects of salicylates, combined with acute renal failure, can later cause metabolic acidosis. In children, metabolic acidosis tends to be more prominent. Other symptoms of salicylate overdose include tinnitus, lethargy, sweating, pyrexia, nausea/vomiting, hyperglycemia and hypoglycemia, seizures, and coma.
The treatment for salicylate overdose involves general measures such as airway, breathing, and circulation support, as well as administering activated charcoal. Urinary alkalinization with intravenous sodium bicarbonate can help eliminate aspirin in the urine. In severe cases, hemodialysis may be necessary. Indications for hemodialysis include a serum concentration of over 700 mg/L, metabolic acidosis that is resistant to treatment, acute renal failure, pulmonary edema, seizures, and coma.
Salicylates can also cause the uncoupling of oxidative phosphorylation, which leads to decreased adenosine triphosphate production, increased oxygen consumption, and increased carbon dioxide and heat production. It is important to recognize the symptoms of salicylate overdose and seek prompt medical attention to prevent serious complications.
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This question is part of the following fields:
- General Principles
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Question 13
Correct
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A 67-year-old man presents with hypertension and a history of angina and peripheral vascular disease. During the physical examination, you detect a renal bruit on the left side. What is the most effective approach to evaluate renal blood flow in this individual?
Your Answer: Para-aminohippurate (PAH) clearance
Explanation:Renal artery stenosis is the likely diagnosis for the patient, as it causes a reduction in renal blood flow. To measure renal plasma flow, the gold standard method in renal physiology is the use of para-aminohippurate (PAH) clearance.
Inulin is an ideal substance for measuring creatinine clearance (CrCl) as it is completely filtered at the glomerulus and not secreted or reabsorbed by the tubules. The Modification of Diet in Renal Disease (MDRD) and Cockcroft-Gault equation are commonly used to estimate creatinine clearance.
Reabsorption and Secretion in Renal Function
In renal function, reabsorption and secretion play important roles in maintaining homeostasis. The filtered load is the amount of a substance that is filtered by the glomerulus and is determined by the glomerular filtration rate (GFR) and the plasma concentration of the substance. The excretion rate is the amount of the substance that is eliminated in the urine and is determined by the urine flow rate and the urine concentration of the substance. Reabsorption occurs when the filtered load is greater than the excretion rate, and secretion occurs when the excretion rate is greater than the filtered load.
The reabsorption rate is the difference between the filtered load and the excretion rate, and the secretion rate is the difference between the excretion rate and the filtered load. Reabsorption and secretion can occur in different parts of the nephron, including the proximal tubule, loop of Henle, distal tubule, and collecting duct. These processes are regulated by various hormones and signaling pathways, such as aldosterone, antidiuretic hormone (ADH), and atrial natriuretic peptide (ANP).
Overall, reabsorption and secretion are important mechanisms for regulating the composition of the urine and maintaining fluid and electrolyte balance in the body. Dysfunction of these processes can lead to various renal disorders, such as diabetes insipidus, renal tubular acidosis, and Fanconi syndrome.
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This question is part of the following fields:
- Renal System
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Question 14
Incorrect
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What is the medical term used to describe the existence of numerous small tuberculous granulomas spread throughout the lungs?
Your Answer: Latent tuberculosis
Correct Answer: Miliary tuberculosis
Explanation:The different manifestations of tuberculosis are crucial in diagnosing and treating the disease effectively. Tuberculosis can manifest in various ways depending on the site and stage of infection. When a person first contracts tuberculosis, it can cause mid-lower zone pneumonic consolidation, which is known as the Ghon focus. Bacteria and inflammatory cells then travel to perihilar lymph nodes, forming a Ghon complex.
In most cases, the immune system will clear the active infection, leaving some dormant granulomas and asymptomatic mycobacteria in the lungs. This stage is called latent tuberculosis. However, some patients may develop a more severe form of the disease, known as primary tuberculous bronchopneumonia, where consolidation spreads from the Ghon focus to a more widespread bronchopneumonia. Other organs may also be affected.
In most cases, latent tuberculosis remains dormant for the rest of a person’s life. However, certain factors such as immunosuppression can cause the infection to become active again, leading to primary tuberculosis. This can affect any organ, but often causes an upper lobe bronchopneumonia. Miliary tuberculosis is another manifestation of the disease, caused by the systemic dissemination of tuberculosis via haematogenous spread.
This form of tuberculosis has a particular preference for forming multiple, small lesions throughout both lung fields and other organs.
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This question is part of the following fields:
- Clinical Sciences
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Question 15
Incorrect
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A 26-year-old gardener presents to her GP with a two week history of elbow swelling. She reports a gradual onset of the swelling, with no apparent triggers, and experiences pain and warmth upon touch. She denies any swelling in other areas and is generally in good health.
The patient has a medical history of well-managed rheumatoid arthritis and is currently taking methotrexate. There are no other known medical conditions.
During the physical examination, a tender, soft, fluctuant mass is palpated on the posterior aspect of the patient's elbow.
Based on the above information, what is the most probable diagnosis?Your Answer: Lateral epicondylitis
Correct Answer: Olecranon bursitis
Explanation:Understanding Olecranon Bursitis
Olecranon bursitis is a condition that occurs when the olecranon bursa, a fluid-filled sac located over the olecranon process at the proximal end of the ulna, becomes inflamed. This bursa serves to reduce friction between the elbow joint and the surrounding soft tissues. The inflammation can be caused by trauma, infection, or systemic conditions such as rheumatoid arthritis or gout. It is also commonly known as student’s elbow due to the repetitive mild trauma of leaning on a desk using the elbows.
The condition is more common in men and typically presents between the ages of 30 and 60. Causes of olecranon bursitis include repetitive trauma, direct trauma, infection, gout, rheumatoid arthritis, and idiopathic reasons. Patients with non-septic olecranon bursitis typically present with swelling over the olecranon process, which is often the only symptom. Some patients may also experience tenderness and erythema over the bursa. On the other hand, patients with septic bursitis are more likely to have pain and fever.
Signs of olecranon bursitis include swelling over the posterior aspect of the elbow, tenderness on palpation of the swollen area, redness and warmth of the overlying skin, fever, skin abrasion overlying the bursa, effusions in other joints if associated with rheumatoid arthritis, and tophi if associated with gout. Movement at the elbow joint should be painless until the swollen bursa is compressed in full flexion.
Investigations are not always needed if a clinical diagnosis can be made and there is no concern about septic arthritis. However, if septic bursitis is suspected, aspiration of bursal fluid for microscopy and culture is essential. Purulent fluid suggests infection, while straw-coloured bursal fluid favours a non-infective cause. Understanding the causes, symptoms, and signs of olecranon bursitis can help in its diagnosis and management.
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This question is part of the following fields:
- Musculoskeletal System And Skin
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Question 16
Correct
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A 27-year-old male arrives at the Emergency Department following a fall on the street. He reports experiencing difficulty breathing and sharp, stabbing pain upon inhalation. A chest X-ray reveals a pneumothorax located at the lung's apex. Which bone is most likely fractured, resulting in the pneumothorax?
Your Answer: Clavicle
Explanation:The apex of the pleural cavity is situated behind the middle third of the clavicle, which can be susceptible to breaking if there is force applied through the shoulders. Unlike the clavicle, the 1st and 2nd ribs are not commonly broken except in severe trauma such as road traffic accidents. The acromion is also an uncommon site for fractures, typically occurring from falling on outstretched hands. Similarly, the coracoid process is rarely fractured and is usually associated with shoulder dislocation.
Anatomy of the Clavicle
The clavicle is a bone that runs from the sternum to the acromion and plays a crucial role in preventing the shoulder from falling forwards and downwards. Its inferior surface is marked by ligaments at each end, including the trapezoid line and conoid tubercle, which provide attachment to the coracoclavicular ligament. The costoclavicular ligament attaches to the irregular surface on the medial part of the inferior surface, while the subclavius muscle attaches to the intermediate portion’s groove.
The superior part of the clavicle’s medial end has a raised surface that gives attachment to the clavicular head of sternocleidomastoid, while the posterior surface attaches to the sternohyoid. On the lateral end, there is an oval articular facet for the acromion, and a disk lies between the clavicle and acromion. The joint’s capsule attaches to the ridge on the margin of the facet.
In summary, the clavicle is a vital bone that helps stabilize the shoulder joint and provides attachment points for various ligaments and muscles. Its anatomy is marked by distinct features that allow for proper function and movement.
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This question is part of the following fields:
- Musculoskeletal System And Skin
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Question 17
Correct
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A 48-year-old woman presents to the clinic with complaints of abdominal pain and constipation. During the examination, you observe blue lines on the gum margin. She also reports experiencing weakness in her legs over the past few days. What is the probable diagnosis?
Your Answer: Lead poisoning
Explanation:Lead poisoning is a condition that should be considered when a patient presents with abdominal pain and neurological symptoms, along with acute intermittent porphyria. This condition is caused by defective ferrochelatase and ALA dehydratase function. Symptoms of lead poisoning include abdominal pain, peripheral neuropathy (mainly motor), neuropsychiatric features, fatigue, constipation, and blue lines on the gum margin (which is rare in children and only present in 20% of adult patients).
To diagnose lead poisoning, doctors typically measure the patient’s blood lead level, with levels greater than 10 mcg/dl considered significant. A full blood count may also be performed, which can reveal microcytic anemia and red cell abnormalities such as basophilic stippling and clover-leaf morphology. Additionally, raised serum and urine levels of delta aminolaevulinic acid may be seen, which can sometimes make it difficult to differentiate from acute intermittent porphyria. Urinary coproporphyrin is also increased, while urinary porphobilinogen and uroporphyrin levels are normal to slightly increased. In children, lead can accumulate in the metaphysis of the bones, although x-rays are not typically part of the standard work-up.
Various chelating agents are currently used to manage lead poisoning, including dimercaptosuccinic acid (DMSA), D-penicillamine, EDTA, and dimercaprol. These agents work to remove the lead from the body and can help alleviate symptoms.
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This question is part of the following fields:
- Haematology And Oncology
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Question 18
Incorrect
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A 50-year-old patient who has a history of three heart attacks in the past five years visits you with a newspaper article in hand. The headline claims that olive oil reduces the risk of heart attacks by 50%. Upon reading the article, you discover that the study was a cohort study involving 15,000 participants, half of whom used olive oil in cooking while the other half used animal fat. What is one disadvantage of conducting a cohort study?
Your Answer:
Correct Answer: When the outcome of interest is rare a very large sample size is needed
Explanation:A cohort study involves tracking a group of people over a period of time to investigate whether a specific cause has an impact on the occurrence of a disease. These studies can be costly and time-consuming, but they offer the advantage of being able to examine rare exposure factors and being less prone to recall bias than case-control studies. Additionally, they can determine the incidence or risk of a disease. Typically, the findings are presented as the relative risk of developing the disease due to exposure to the cause.
There are different types of studies that researchers can use to investigate various phenomena. One of the most rigorous types of study is the randomised controlled trial, where participants are randomly assigned to either an intervention or control group. However, practical or ethical issues may limit the use of this type of study. Another type of study is the cohort study, which is observational and prospective. Researchers select two or more groups based on their exposure to a particular agent and follow them up to see how many develop a disease or other outcome. The usual outcome measure is the relative risk. Examples of cohort studies include the Framingham Heart Study.
On the other hand, case-control studies are observational and retrospective. Researchers identify patients with a particular condition (cases) and match them with controls. Data is then collected on past exposure to a possible causal agent for the condition. The usual outcome measure is the odds ratio. Case-control studies are inexpensive and produce quick results, making them useful for studying rare conditions. However, they are prone to confounding. Lastly, cross-sectional surveys provide a snapshot of a population and are sometimes called prevalence studies. They provide weak evidence of cause and effect.
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This question is part of the following fields:
- General Principles
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Question 19
Incorrect
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Throughout the process of embryonic development, what is the accurate source of the pancreas?
Your Answer:
Correct Answer: Ventral and dorsal endodermal outgrowths of the duodenum
Explanation:The pancreas originates from two outgrowths of the duodenum – one from the ventral side and the other from the dorsal side. The ventral outgrowth is located near or together with the hepatic diverticulum, while the larger dorsal outgrowth emerges slightly above the ventral one and extends into the mesoduodenum and mesogastrium. After the two buds merge, the duct of the ventral outgrowth becomes the primary pancreatic duct.
Anatomy of the Pancreas
The pancreas is located behind the stomach and is a retroperitoneal organ. It can be accessed surgically by dividing the peritoneal reflection that connects the greater omentum to the transverse colon. The pancreatic head is situated in the curvature of the duodenum, while its tail is close to the hilum of the spleen. The pancreas has various relations with other organs, such as the inferior vena cava, common bile duct, renal veins, superior mesenteric vein and artery, crus of diaphragm, psoas muscle, adrenal gland, kidney, aorta, pylorus, gastroduodenal artery, and splenic hilum.
The arterial supply of the pancreas is through the pancreaticoduodenal artery for the head and the splenic artery for the rest of the organ. The venous drainage for the head is through the superior mesenteric vein, while the body and tail are drained by the splenic vein. The ampulla of Vater is an important landmark that marks the transition from foregut to midgut and is located halfway along the second part of the duodenum. Overall, understanding the anatomy of the pancreas is crucial for surgical procedures and diagnosing pancreatic diseases.
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This question is part of the following fields:
- Gastrointestinal System
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Question 20
Incorrect
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A one-year-old is brought to the paediatric team for assessment. The parents report that the child's right arm hangs loosely and does not move in coordination with the other limbs.
Upon examination, an adducted, internally rotated right upper limb with an extended elbow is observed. However, movement of the right wrist appears normal.
Based on these findings, where is the most likely location of the lesion?Your Answer:
Correct Answer: C5 and C6
Explanation:The infant’s arm is observed to be hanging loosely after a difficult forceps delivery, with adduction and internal rotation and extension of the elbow, indicating an injury to the upper trunk of the brachial plexus involving nerve roots C5 and C6. This is known as Erb’s palsy, which is commonly associated with difficult forceps deliveries and requires specialized management. Lower brachial plexus injuries affecting nerve roots C7 and C8 are less frequent and would cause wrist and forearm pathology rather than shoulder and elbow weakness. Isolated damage to the C6 nerve root is unlikely, as it is typically affected alongside the C5 nerve root.
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 21
Incorrect
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A 54-year-old man was admitted 2 weeks ago for pneumonia and was prescribed oral antibiotics. However, the antibiotics were changed after he developed a Clostridium difficile infection 9 days ago, which he is still recovering from. Fortunately, his pneumonia has improved.
He has no significant medical history and is not taking any long-term medications.
What are the expected results of his arterial blood gas test?Your Answer:
Correct Answer: Normal anion gap metabolic acidosis
Explanation:Diarrhoea caused by a Clostridium difficile infection can result in a normal anion gap metabolic acidosis due to the loss of bicarbonate. The body compensates for this by increasing chloride concentration, which maintains a normal anion gap. Low anion gap metabolic acidosis, normal anion gap metabolic alkalosis, and raised anion gap metabolic acidosis are all incorrect as they do not accurately reflect the compensatory mechanisms in this scenario.
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.
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This question is part of the following fields:
- Renal System
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Question 22
Incorrect
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A 35-year-old man suffers a hemisection of the spinal cord at the level T5 due to a stabbing in his back. You conduct an evaluation of the patient's sensory function, including temperature, vibration, and fine touch, as well as muscle strength. What signs would you anticipate observing?
Your Answer:
Correct Answer: Contralateral loss of temperature, ipsilateral loss of fine touch and vibration, ipsilateral spastic paresis
Explanation:The spinothalamic tract carries sensory fibers for pain and temperature and decussates at the same level as the nerve root entering the spinal cord. As a result, contralateral temperature loss occurs. The dorsal column medial lemniscus carries sensory fibers for fine touch, vibration, and unconscious proprioception. It decussates at the medulla, leading to ipsilateral loss of fine touch and vibration. The corticospinal tract is a descending tract that has already decussated at the medulla and is responsible for inhibiting muscle movement. If affected in the spinal cord, it causes an upper motor neuron lesion on the ipsilateral side.
The spinal cord is a central structure located within the vertebral column that provides it with structural support. It extends rostrally to the medulla oblongata of the brain and tapers caudally at the L1-2 level, where it is anchored to the first coccygeal vertebrae by the filum terminale. The cord is characterised by cervico-lumbar enlargements that correspond to the brachial and lumbar plexuses. It is incompletely divided into two symmetrical halves by a dorsal median sulcus and ventral median fissure, with grey matter surrounding a central canal that is continuous with the ventricular system of the CNS. Afferent fibres entering through the dorsal roots usually terminate near their point of entry but may travel for varying distances in Lissauer’s tract. The key point to remember is that the anatomy of the cord will dictate the clinical presentation in cases of injury, which can be caused by trauma, neoplasia, inflammatory diseases, vascular issues, or infection.
One important condition to remember is Brown-Sequard syndrome, which is caused by hemisection of the cord and produces ipsilateral loss of proprioception and upper motor neuron signs, as well as contralateral loss of pain and temperature sensation. Lesions below L1 tend to present with lower motor neuron signs. It is important to keep a clinical perspective in mind when revising CNS anatomy and to understand the ways in which the spinal cord can become injured, as this will help in diagnosing and treating patients with spinal cord injuries.
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This question is part of the following fields:
- Neurological System
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Question 23
Incorrect
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What is true about the Salmonella species?
Your Answer:
Correct Answer: A relative bradycardia is often seen in typhoid fever
Explanation:Enteric fever, also known as typhoid or paratyphoid, is caused by Salmonella typhi and Salmonella paratyphi respectively. These bacteria are not normally found in the gut and are transmitted through contaminated food and water or the faecal-oral route. The symptoms of enteric fever include headache, fever, and joint pain, as well as abdominal pain and distension. Constipation is more common in typhoid than diarrhoea, and rose spots may appear on the trunk in 40% of patients with paratyphoid. Possible complications of enteric fever include osteomyelitis, gastrointestinal bleeding or perforation, meningitis, cholecystitis, and chronic carriage. Chronic carriage is more likely in adult females and occurs in 1% of cases.
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This question is part of the following fields:
- General Principles
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Question 24
Incorrect
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A 48-year-old man visits his local doctor complaining of chest pain that occurs during physical activity and subsides with rest. He first noticed it 10 months ago and feels that it has gradually worsened. He now experiences this pain while climbing a few stairs. Previously, he could walk down to the newsagent and back, a distance of 200 yards, without any discomfort. He has a medical history of hypertension and appendectomy.
His close friend had similar symptoms that were relieved by sublingual glyceryl nitrates. He asks the doctor to prescribe something similar.
What is the mechanism by which nitrates work?Your Answer:
Correct Answer: Nitrates cause a decrease in intracellular calcium which results in smooth muscle relaxation
Explanation:The reason why nitrates cause a decrease in intracellular calcium is because nitric oxide triggers the activation of smooth muscle soluble guanylyl cyclase (GC) to produce cGMP. This increase in intracellular cGMP inhibits calcium entry into the cell, resulting in a reduction in intracellular calcium levels and inducing smooth muscle relaxation. Additionally, nitric oxide activates K+ channels, leading to hyperpolarization and relaxation. Furthermore, nitric oxide stimulates a cGMP-dependent protein kinase that activates myosin light chain phosphatase, which dephosphorylates myosin light chains, ultimately leading to relaxation. Therefore, the correct answer is the second option.
Understanding Nitrates and Their Effects on the Body
Nitrates are a type of medication that can cause blood vessels to widen, which is known as vasodilation. They are commonly used to manage angina and treat heart failure. One of the most frequently prescribed nitrates is sublingual glyceryl trinitrate, which is used to relieve angina attacks in patients with ischaemic heart disease.
The mechanism of action for nitrates involves the release of nitric oxide in smooth muscle, which activates guanylate cyclase. This enzyme then converts GTP to cGMP, leading to a decrease in intracellular calcium levels. In the case of angina, nitrates dilate the coronary arteries and reduce venous return, which decreases left ventricular work and reduces myocardial oxygen demand.
However, nitrates can also cause side effects such as hypotension, tachycardia, headaches, and flushing. Additionally, many patients who take nitrates develop tolerance over time, which can reduce their effectiveness. To combat this, the British National Formulary recommends that patients who develop tolerance take the second dose of isosorbide mononitrate after 8 hours instead of 12 hours. This allows blood-nitrate levels to fall for 4 hours and maintains effectiveness. It’s important to note that this effect is not seen in patients who take modified release isosorbide mononitrate.
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This question is part of the following fields:
- Cardiovascular System
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Question 25
Incorrect
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A 24-year-old boxer presents to a physiotherapist with a wrist drop in his right arm, 8 weeks after sustaining a midshaft humeral fracture resulting in radial nerve palsy. An MRI scan reveals marked atrophy in the muscle inserting at the lateral supracondylar ridge of the humerus. To address this, the physiotherapist prescribes reverse dumbbell wrist curls to strengthen the affected muscle. Which muscle has undergone significant atrophy in this patient, based on the MRI findings and treatment plan?
Your Answer:
Correct Answer: Extensor carpi radialis longus
Explanation:The extensor carpi radialis longus muscle is innervated by the radial nerve. However, in a patient with a radial nerve palsy due to a midshaft humeral fracture, this muscle may be the only forearm extensor directly supplied by the radial nerve. Therefore, it is the most likely correct answer when considering exercises to strengthen the affected muscle.
The extensor carpi radialis brevis muscle, which originates from the lateral epicondyle of the humerus, is also innervated by a branch of the radial nerve. However, its insertion point is different from that described in the MRI, making it an unlikely answer.
The extensor digitorum brevis muscle, which assists in extending the toes, is not relevant to the patient’s wrist condition.
The extensor digitorum longus muscle, which is involved in foot dorsiflexion and toe extension, is also not relevant to the patient’s wrist condition.
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 26
Incorrect
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Which one of the following statements relating to blood transfusions is not true?
Your Answer:
Correct Answer: Patients should be transfused to achieve a target haemoglobin of 10 g/dl and a haematocrit of 30%
Explanation:As long as the patient’s Hb level is 7 or higher, transfusion may not be necessary for their management. However, this threshold may vary depending on individual factors such as co-existing medical conditions. It is important to avoid using old blood during massive transfusions as its effectiveness may be compromised.
Blood Products and Cell Saver Devices
Blood products are essential in various medical procedures, especially in cases where patients require transfusions due to anaemia or bleeding. Packed red cells, platelet-rich plasma, platelet concentrate, fresh frozen plasma, and cryoprecipitate are some of the commonly used whole blood fractions. Fresh frozen plasma is usually administered to patients with clotting deficiencies, while cryoprecipitate is a rich source of Factor VIII and fibrinogen. Cross-matching is necessary for all blood products, and cell saver devices are used to collect and re-infuse a patient’s own blood lost during surgery.
Cell saver devices come in two types, those that wash the blood cells before re-infusion and those that do not. The former is more expensive and complicated to operate but reduces the risk of re-infusing contaminated blood. The latter avoids the use of donor blood and may be acceptable to Jehovah’s witnesses. However, it is contraindicated in malignant diseases due to the risk of facilitating disease dissemination.
In some surgical patients, the use of warfarin can pose specific problems and may require the use of specialised blood products. Warfarin reversal can be achieved through the administration of vitamin K, fresh frozen plasma, or human prothrombin complex. Fresh frozen plasma is used less commonly now as a first-line warfarin reversal, and human prothrombin complex is preferred due to its rapid action. However, it should be given with vitamin K as factor 6 has a short half-life.
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This question is part of the following fields:
- Haematology And Oncology
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Question 27
Incorrect
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A 50-year-old female is brought to the emergency department by an ambulance after she was found collapsed on the street by a bystander. Within a few minutes of arrival she developed severe abdominal pain and became severely agitated.
Her respiratory rate is 35 breaths per minute, heart rate 110 beats per minute, temperature 39.3ºC. Her prothrombin time and activated partial thromboplastin time are increased, and her fibrinogen levels are lower than normal. Her D-dimer is positive.
Hb 96 g/l
Platelets 85 * 109/l
WBC 14 * 109/l
Blood smears are sent to the laboratory.
What is most likely to be seen in the blood smears?Your Answer:
Correct Answer: Schistocytes
Explanation:DIC, also known as consumptive coagulopathy, is a condition where the coagulation cascade is overactivated, leading to unchecked bleeding. This is due to the depletion of clotting mechanisms. Normally, clot formation and breakdown are balanced, with thrombin playing a key role in both processes. In DIC, patients may have prolonged coagulation times, thrombocytopenia, high levels of fibrin degradation products, elevated D-dimer levels, and microangiopathic pathology on peripheral smears. The excess fibrin strands in the intravascular circulation cause mechanical damage to red blood cells, resulting in schistocyte formation, thrombocytopenia, and consumption of clotting factors. Bite cells are abnormally shaped red blood cells with semicircular portions removed from the cell margin, seen in G6PD deficiency. Dacrocytes are teardrop-shaped cells seen in myelofibrosis and marrow disorders, while elliptocytes are red cells varying in shape from elongated to oval, seen in various disorders.
Disseminated Intravascular Coagulation: A Condition of Simultaneous Coagulation and Haemorrhage
Disseminated intravascular coagulation (DIC) is a medical condition characterized by simultaneous coagulation and haemorrhage. It is caused by the initial formation of thrombi that consume clotting factors and platelets, ultimately leading to bleeding. DIC can be caused by various factors such as infection, malignancy, trauma, liver disease, and obstetric complications.
Clinically, bleeding is usually the dominant feature of DIC, accompanied by bruising, ischaemia, and organ failure. Blood tests can reveal prolonged clotting times, thrombocytopenia, decreased fibrinogen, and increased fibrinogen degradation products. The treatment of DIC involves addressing the underlying cause and providing supportive management.
In summary, DIC is a serious medical condition that requires prompt diagnosis and management. It is important to identify the underlying cause and provide appropriate treatment to prevent further complications. With proper care and management, patients with DIC can recover and regain their health.
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This question is part of the following fields:
- Haematology And Oncology
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Question 28
Incorrect
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You are currently interested in the outcome of a clinical trial comparing a new medication for non-valvular atrial fibrillation against the four currently existing direct oral anti-coagulants with the primary outcome measure being the reduction in stroke events.
The trial is being conducted across multiple regions and includes a total of 5000 enrolled patients.
What phase is this clinical trial currently in?Your Answer:
Correct Answer: Phase 3
Explanation:Phase 3 studies involve a larger number of actual patients and compare the new treatment with currently available treatments. These studies typically involve around 500-5000 patients. In contrast, Phase 0 studies involve very few people and are primarily focused on testing low doses of treatment to ensure safety. Phase 1 studies involve around 100 healthy volunteers and are used to assess pharmacodynamics and pharmacokinetics. Phase 2 studies involve around 100-300 actual patients and aim to examine efficacy and identify any adverse effects.
Stages of Drug Development
Drug development is a complex process that involves several stages before a drug can be approved for marketing. The process begins with Phase 1, which involves small studies on healthy volunteers to assess the pharmacodynamics and pharmacokinetics of the drug. This phase typically involves around 100 participants.
Phase 2 follows, which involves small studies on actual patients to examine the drug’s efficacy and adverse effects. This phase typically involves between 100-300 patients.
Phase 3 is the largest phase and involves larger studies of between 500-5,000 patients. This phase examines the drug’s efficacy and adverse effects and may compare it with existing treatments. Special groups such as the elderly or those with renal issues may also be studied during this phase.
If the drug is shown to be safe and effective, it may be approved for marketing. However, Phase 4, also known as post-marketing surveillance, is still necessary. This phase involves monitoring the drug’s safety and effectiveness in a larger population over a longer period of time.
In summary, drug development involves several stages, each with its own specific purpose and participant size. The process is rigorous to ensure that drugs are safe and effective before they are marketed to the public.
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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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A 45-year-old woman from Afghanistan visits her GP complaining of weakness and bony pain in her legs. She denies experiencing any abdominal pain or changes in bowel habits and has no significant medical or surgical history. Upon conducting a blood test, the following results were obtained:
- Calcium: 1.8 mmol/L (normal range: 2.1-2.6)
- Phosphate: 0.5 mmol/L (normal range: 0.8-1.4)
- ALP: 240 u/L (normal range: 30-100)
- PTH: 78 pg/ml (normal range: 15-65)
What is the most probable diagnosis?Your Answer:
Correct Answer: Osteomalacia
Explanation:The correct diagnosis for this patient is osteomalacia, which is characterized by low serum calcium, low serum phosphate, raised ALP, and raised PTH. It is important to identify the risk factors for osteomalacia, such as decreased sunlight exposure, which can lead to vitamin D deficiency and subsequent hypocalcaemia. In response to hypocalcaemia, PTH levels increase, as seen in this case.
Acute pancreatitis is an incorrect diagnosis as it does not fit the patient’s clinical picture. Osteoarthritis is also an incorrect diagnosis as it would not cause changes in serum calcium, ALP, or PTH levels. Primary hyperparathyroidism is also an incorrect diagnosis as it is associated with high levels of PTH and calcium, which is not seen in this patient.
Lab Values for Bone Disorders
When it comes to bone disorders, certain lab values can provide important information about the condition. In cases of osteoporosis, calcium, phosphate, alkaline phosphatase (ALP), and parathyroid hormone (PTH) levels are typically normal. However, in osteomalacia, calcium and phosphate levels are decreased while ALP and PTH levels are increased. Primary hyperparathyroidism, which can lead to osteitis fibrosa cystica, is characterized by increased calcium and PTH levels but decreased phosphate levels. Chronic kidney disease can result in secondary hyperparathyroidism, which is marked by decreased calcium levels and increased phosphate and PTH levels. Paget’s disease, on the other hand, typically shows normal calcium and phosphate levels but increased ALP levels. Finally, osteopetrosis is associated with normal levels of calcium, phosphate, ALP, and PTH. By analyzing these lab values, healthcare professionals can better diagnose and treat bone disorders.
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This question is part of the following fields:
- Musculoskeletal System And Skin
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Question 30
Incorrect
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A 50-year-old man comes to you with a cough that initially started as dry but has now progressed to producing sputum with flecks of blood. He has been experiencing fever and nausea for the past 5 days. Upon further inquiry, he mentions that he had recently gone on vacation and spent a lot of time in a hot tub. A sample of his sputum is sent for analysis and microbiology identifies a gram-negative coccobacillus. What is the probable pathogen responsible for his symptoms?
Your Answer:
Correct Answer: Legionella pneumophila
Explanation:This man is exhibiting symptoms of Legionnaires disease, which is caused by the aerosolization of Legionella pneumophila. This bacterium is known to thrive in water and can be transmitted through various means such as showers, hot tubs, and air conditioning systems. The fact that he had used a hot tub during his vacation and the microbiological findings of a gram-negative coccobacillus point towards his exposure to Legionella pneumophila.
Legionnaire’s Disease: Symptoms, Diagnosis, and Management
Legionnaire’s disease is a type of pneumonia caused by the Legionella pneumophilia bacterium. It is commonly found in water tanks and air-conditioning systems, and is often associated with foreign travel. Unlike other types of pneumonia, Legionnaire’s disease cannot be transmitted from person to person. Symptoms of the disease include flu-like symptoms such as fever, dry cough, confusion, and lymphopaenia. In addition, patients may experience hyponatraemia, deranged liver function tests, and pleural effusion in around 30% of cases.
Diagnosis of Legionnaire’s disease is typically done through a urinary antigen test. Treatment involves the use of antibiotics such as erythromycin or clarithromycin. Chest x-rays may show non-specific features, but often include patchy consolidation in the mid-to-lower zones and pleural effusions. It is important to be aware of the symptoms and risk factors associated with Legionnaire’s disease in order to ensure prompt diagnosis and treatment.
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This question is part of the following fields:
- General Principles
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