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Question 1
Incorrect
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A 29 week pregnant 26-year-old has been informed that her baby has hypoplasia of the cerebellar vermis, as shown by antenatal ultrasound and subsequent MRI. The baby has been diagnosed with Dandy-Walker syndrome. The neurologist explains to the mother that during embryonic development, the brain is formed from different swellings or vesicles of the neural tube, which eventually becomes the central nervous system.
What specific embryological vesicle has not developed properly in the affected baby?Your Answer: Mesencephalon
Correct Answer: Metencephalon
Explanation:During embryonic development, the metencephalon is responsible for the formation of the pons and cerebellum.
As the prosencephalon grows, it splits into two ear-shaped structures: the telencephalon (which develops into the hemispheres) and the diencephalon (which develops into the thalamus and hypothalamus).
The mesencephalon grows slowly, and its central cavity eventually becomes the cerebral aqueduct.
The rhombencephalon divides into two parts: the metencephalon (which forms the pons and cerebellum) and the myelencephalon (which forms the medulla).
Embryonic Development of the Nervous System
The nervous system develops from the embryonic neural tube, which gives rise to the brain and spinal cord. The neural tube is divided into five regions, each of which gives rise to specific structures in the nervous system. The telencephalon gives rise to the cerebral cortex, lateral ventricles, and basal ganglia. The diencephalon gives rise to the thalamus, hypothalamus, optic nerves, and third ventricle. The mesencephalon gives rise to the midbrain and cerebral aqueduct. The metencephalon gives rise to the pons, cerebellum, and superior part of the fourth ventricle. The myelencephalon gives rise to the medulla and inferior part of the fourth ventricle.
The neural tube is also divided into two plates: the alar plate and the basal plate. The alar plate gives rise to sensory neurons, while the basal plate gives rise to motor neurons. This division of the neural tube into different regions and plates is crucial for the proper development and function of the nervous system. Understanding the embryonic development of the nervous system is important for understanding the origins of neurological disorders and for developing new treatments for these disorders.
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This question is part of the following fields:
- Neurological System
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Question 2
Incorrect
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A 57-year-old man has been diagnosed with motor neuron disease, which is caused by dysregulation in RNA splicing. This dysregulation leads to the degeneration of both upper and lower motor neurons. In which cellular component does this dysregulation occur?
Your Answer: Ribosome
Correct Answer: Nucleus
Explanation:RNA splicing occurs in the nucleus.
Functions of Cell Organelles
The functions of major cell organelles can be summarized in a table. The rough endoplasmic reticulum (RER) is responsible for the translation and folding of new proteins, as well as the manufacture of lysosomal enzymes. It is also the site of N-linked glycosylation. Cells such as pancreatic cells, goblet cells, and plasma cells have extensive RER. On the other hand, the smooth endoplasmic reticulum (SER) is involved in steroid and lipid synthesis. Cells of the adrenal cortex, hepatocytes, and reproductive organs have extensive SER.
The Golgi apparatus modifies, sorts, and packages molecules that are destined for cell secretion. The addition of mannose-6-phosphate to proteins designates transport to lysosome. The mitochondrion is responsible for aerobic respiration and contains mitochondrial genome as circular DNA. The nucleus is involved in DNA maintenance, RNA transcription, and RNA splicing, which removes the non-coding sequences of genes (introns) from pre-mRNA and joins the protein-coding sequences (exons).
The lysosome is responsible for the breakdown of large molecules such as proteins and polysaccharides. The nucleolus produces ribosomes, while the ribosome translates RNA into proteins. The peroxisome is involved in the catabolism of very long chain fatty acids and amino acids, resulting in the formation of hydrogen peroxide. Lastly, the proteasome, along with the lysosome pathway, is involved in the degradation of protein molecules that have been tagged with ubiquitin.
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This question is part of the following fields:
- General Principles
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Question 3
Correct
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A 50-year-old woman with a recent diagnosis of COPD is admitted to the hospital for treatment of an exacerbation caused by infection. She reports smoking 10 cigarettes per day and has a family history of lung cancer. Her chest x-ray shows signs of emphysema, and she mentions that her parents and siblings also have the disease. She asks for advice on the best course of action to improve her prognosis.
Your Answer: Stop smoking
Explanation:The most crucial step to enhance the patient’s prognosis is to assist them in quitting smoking. While lung reduction surgery and long-term oxygen therapy may benefit certain patient groups, smoking cessation remains the top priority. Proper inhaler technique and adherence, as well as the use of home nebulizers, can provide symptomatic relief for the patient.
The National Institute for Health and Care Excellence (NICE) updated its guidelines on the management of chronic obstructive pulmonary disease (COPD) in 2018. The guidelines recommend general management strategies such as smoking cessation advice, annual influenzae vaccination, and one-off pneumococcal vaccination. Pulmonary rehabilitation is also recommended for patients who view themselves as functionally disabled by COPD.
Bronchodilator therapy is the first-line treatment for patients who remain breathless or have exacerbations despite using short-acting bronchodilators. The next step is determined by whether the patient has asthmatic features or features suggesting steroid responsiveness. NICE suggests several criteria to determine this, including a previous diagnosis of asthma or atopy, a higher blood eosinophil count, substantial variation in FEV1 over time, and substantial diurnal variation in peak expiratory flow.
If the patient does not have asthmatic features or features suggesting steroid responsiveness, a long-acting beta2-agonist (LABA) and long-acting muscarinic antagonist (LAMA) should be added. If the patient is already taking a short-acting muscarinic antagonist (SAMA), it should be discontinued and switched to a short-acting beta2-agonist (SABA). If the patient has asthmatic features or features suggesting steroid responsiveness, a LABA and inhaled corticosteroid (ICS) should be added. If the patient remains breathless or has exacerbations, triple therapy (LAMA + LABA + ICS) should be offered.
NICE only recommends theophylline after trials of short and long-acting bronchodilators or to people who cannot use inhaled therapy. Azithromycin prophylaxis is recommended in select patients who have optimised standard treatments and continue to have exacerbations. Mucolytics should be considered in patients with a chronic productive cough and continued if symptoms improve.
Cor pulmonale features include peripheral oedema, raised jugular venous pressure, systolic parasternal heave, and loud P2. Loop diuretics should be used for oedema, and long-term oxygen therapy should be considered. Smoking cessation, long-term oxygen therapy in eligible patients, and lung volume reduction surgery in selected patients may improve survival in patients with stable COPD. NICE does not recommend the use of ACE-inhibitors, calcium channel blockers, or alpha blockers
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This question is part of the following fields:
- Respiratory System
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Question 4
Correct
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A 65-year-old woman with confirmed heart failure visits her GP with swelling and discomfort in both legs. During the examination, the GP observes pitting edema and decides to prescribe a brief trial of a diuretic. Which diuretic targets the thick ascending limb of the loop of Henle?
Your Answer: Furosemide (loop diuretic)
Explanation:Loop Diuretics: Mechanism of Action and Clinical Applications
Loop diuretics, such as furosemide and bumetanide, are medications that inhibit the Na-K-Cl cotransporter (NKCC) in the thick ascending limb of the loop of Henle. By doing so, they reduce the absorption of NaCl, resulting in increased urine output. Loop diuretics act on NKCC2, which is more prevalent in the kidneys. These medications work on the apical membrane and must first be filtered into the tubules by the glomerulus before they can have an effect. Patients with poor renal function may require higher doses to ensure sufficient concentration in the tubules.
Loop diuretics are commonly used in the treatment of heart failure, both acutely (usually intravenously) and chronically (usually orally). They are also indicated for resistant hypertension, particularly in patients with renal impairment. However, loop diuretics can cause adverse effects such as hypotension, hyponatremia, hypokalemia, hypomagnesemia, hypochloremic alkalosis, ototoxicity, hypocalcemia, renal impairment, hyperglycemia (less common than with thiazides), and gout. Therefore, careful monitoring of electrolyte levels and renal function is necessary when using loop diuretics.
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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 25-year-old male has been struggling with anger issues for a while. Following a disagreement with a relative, he vents his frustration by punching the wall, resulting in a cut on his hand. At the hospital, the medical team orders an x-ray to rule out any fractures and discovers a 'boxer's fracture.'
What bone did this young man break?Your Answer: 2nd metacarpal
Correct Answer: 5th metacarpal
Explanation:A fracture of the 5th metacarpal, known as a ‘Boxer fracture’, is commonly caused by punching a hard surface. This type of fracture is typically minimally displaced. Fracture of the scaphoid bone in the wrist can lead to avascular necrosis. The 2nd metacarpal is not typically fractured in punching injuries, while the lunate and hamate bones in the wrist are not commonly affected by this type of injury.
Boxer fracture is a type of fracture that occurs in the fifth metacarpal bone. It is usually caused by punching a hard surface, such as a wall. The fracture is typically minimally displaced, meaning that the bone is still in its proper position but has a small crack or break. This injury is commonly seen in boxers, hence the name, but can also occur in other individuals who engage in activities that involve punching or striking objects. The treatment for a boxer fracture may involve immobilization of the affected hand with a cast or splint, and in some cases, surgery may be necessary.
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This question is part of the following fields:
- Musculoskeletal System And Skin
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Question 6
Incorrect
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A 40-year-old teacher has come to your office seeking information about a new cancer treatment. She was recently diagnosed with melanoma and her oncologist has recommended treatment with an immune checkpoint inhibitor called Pembrolizumab (Keytruda).
She is curious about how this class of drugs works to treat cancer.
Could you explain the mechanism of action of immune checkpoint inhibitors to her?
Thank you.Your Answer: By damaging the DNA of cancer cells
Correct Answer: They work by reactivating and increasing the body’s own T-cell population
Explanation:To treat solid tumours, immune checkpoint inhibitors are becoming a popular substitute for cytotoxic chemotherapy. These inhibitors function by reactivating and boosting the body’s T-cell population. While radiotherapy harms cancer cell DNA, chemotherapy directly impacts the growth and multiplication of cancer cells.
Understanding Immune Checkpoint Inhibitors
Immune checkpoint inhibitors are a type of immunotherapy that is becoming increasingly popular in the treatment of certain types of cancer. Unlike traditional therapies such as chemotherapy, these targeted treatments work by harnessing the body’s natural anti-cancer immune response. They boost the immune system’s ability to attack and destroy cancer cells, rather than directly affecting their growth and proliferation.
T-cells are an essential part of our immune system that helps destroy cancer cells. However, some cancer cells produce high levels of proteins that turn T-cells off. Checkpoint inhibitors block this process and reactivate and increase the body’s T-cell population, enhancing the immune system’s ability to recognize and fight cancer cells.
There are different types of immune checkpoint inhibitors, including Ipilimumab, Nivolumab, Pembrolizumab, Atezolizumab, Avelumab, and Durvalumab. These drugs block specific proteins found on T-cells and cancer cells, such as CTLA-4, PD-1, and PD-L1. They are administered by injection or intravenous infusion and can be given as a single-agent treatment or combined with chemotherapy or each other.
However, the mechanism of action of these drugs can result in side effects termed ‘Immune-related adverse events’ that are inflammatory and autoimmune in nature. This is because all immune cells are boosted by these drugs, not just the ones that target cancer. The overactive T-cells can produce side effects such as dry, itchy skin and rashes, nausea and vomiting, decreased appetite, diarrhea, tiredness and fatigue, shortness of breath, and a dry cough. Management of such side effects reflects the inflammatory nature, often involving corticosteroids. It is important to monitor liver, kidney, and thyroid function as these drugs can affect these organs.
In conclusion, the early success of immune checkpoint inhibitors in solid tumors has generated tremendous interest in further developing and exploring these strategies across the oncology disease spectrum. Ongoing testing in clinical trials creates new hope for patients affected by other types of disease.
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This question is part of the following fields:
- Haematology And Oncology
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Question 7
Incorrect
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Sarah, a 73-year-old woman, is currently admitted to the medical ward after experiencing chest pain. A recent blood test revealed low levels of potassium. The doctors explained that potassium plays a crucial role in the normal functioning of the heart and any changes in its concentration can affect the heart's ability to contract and relax properly.
How does potassium contribute to a normal cardiac action potential?Your Answer: The movement of this electrolyte maintains the resting action potential
Correct Answer: A slow influx of the electrolyte causes a plateau in the myocardial action potential
Explanation:Calcium causes a plateau in the cardiac action potential, prolonging contraction and reflected in the ST-segment of an ECG. A low concentration of calcium ions can result in a prolonged QT-segment. Sodium ions cause depolarisation, potassium ions cause repolarisation, and their movement maintains the resting potential. Calcium ions also bind to troponin-C to trigger muscle contraction.
Understanding the Cardiac Action Potential and Conduction Velocity
The cardiac action potential is a series of electrical events that occur in the heart during each heartbeat. It is responsible for the contraction of the heart muscle and the pumping of blood throughout the body. The action potential is divided into five phases, each with a specific mechanism. The first phase is rapid depolarization, which is caused by the influx of sodium ions. The second phase is early repolarization, which is caused by the efflux of potassium ions. The third phase is the plateau phase, which is caused by the slow influx of calcium ions. The fourth phase is final repolarization, which is caused by the efflux of potassium ions. The final phase is the restoration of ionic concentrations, which is achieved by the Na+/K+ ATPase pump.
Conduction velocity is the speed at which the electrical signal travels through the heart. The speed varies depending on the location of the signal. Atrial conduction spreads along ordinary atrial myocardial fibers at a speed of 1 m/sec. AV node conduction is much slower, at 0.05 m/sec. Ventricular conduction is the fastest in the heart, achieved by the large diameter of the Purkinje fibers, which can achieve velocities of 2-4 m/sec. This allows for a rapid and coordinated contraction of the ventricles, which is essential for the proper functioning of the heart. Understanding the cardiac action potential and conduction velocity is crucial for diagnosing and treating heart conditions.
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This question is part of the following fields:
- Cardiovascular System
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Question 8
Correct
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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 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 9
Correct
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A 28-year-old woman presents with symptoms of carpal tunnel syndrome and requires surgical exploration of the carpal tunnel. What structure will be closest to the hamate bone within the carpal tunnel during the procedure?
Your Answer: The tendons of flexor digitorum profundus
Explanation:The nine flexor tendons found in the carpal tunnel include the flexor digitorum profundus, flexor digitorum superficialis, and flexor pollicis longus. Among these tendons, the flexor digitorum profundus is situated deepest in the tunnel and is therefore closest to the hamate bone.
Carpal Bones: The Wrist’s Building Blocks
The wrist is composed of eight carpal bones, which are arranged in two rows of four. These bones are convex from side to side posteriorly and concave anteriorly. The trapezium is located at the base of the first metacarpal bone, which is the base of the thumb. The scaphoid, lunate, and triquetrum bones do not have any tendons attached to them, but they are stabilized by ligaments.
In summary, the carpal bones are the building blocks of the wrist, and they play a crucial role in the wrist’s movement and stability. The trapezium bone is located at the base of the thumb, while the scaphoid, lunate, and triquetrum bones are stabilized by ligaments. Understanding the anatomy of the wrist is essential for diagnosing and treating wrist injuries and conditions.
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This question is part of the following fields:
- Musculoskeletal System And Skin
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Question 10
Incorrect
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Mr Stent is a 56-year-old man who has been scheduled for a laparoscopic right hemicolectomy. However, he has several comorbidities that were discovered during the anaesthetic clinic. These include constipation, a latex allergy, coronary artery disease, moderately raised intracranial pressure due to a benign space occupying brain tumour, and a protein C deficiency. Considering his medical history, which of the following is an absolute contraindication to laparoscopic surgery?
Your Answer: Constipation
Correct Answer: Raised intracranial pressure
Explanation:Laparoscopic surgery should not be performed in patients with significantly raised intracranial pressure. It is important to understand the indications, complications, and contraindications of both laparoscopic and open surgery. Thrombophilia can be managed with anticoagulation, constipation is not a contraindication but may increase the risk of bowel perforation, a patient with a latex allergy should have all latex equipment removed and the theatre cleaned, and a patient with coronary artery disease may be at higher risk during anaesthesia but this will be assessed before surgery in the anaesthetics clinic.
Risks and Complications of Laparoscopy
Laparoscopy is a minimally invasive surgical procedure that involves the insertion of a small camera and instruments through small incisions in the abdomen. While it is generally considered safe, there are some risks and complications associated with the procedure.
One of the general risks of laparoscopy is the use of anaesthetic, which can cause complications such as allergic reactions or breathing difficulties. Additionally, some patients may experience a vasovagal reaction, which is a sudden drop in blood pressure and heart rate in response to abdominal distension.
Another potential complication of laparoscopy is extra-peritoneal gas insufflation, which can cause surgical emphysema. This occurs when gas used to inflate the abdomen during the procedure leaks into the surrounding tissues, causing swelling and discomfort.
Injuries to the gastro-intestinal tract and blood vessels are also possible complications of laparoscopy. These can include damage to the common iliacs or deep inferior epigastric artery, which can cause bleeding and other serious complications.
Overall, while laparoscopy is generally considered safe, it is important for patients to be aware of the potential risks and complications associated with the procedure. Patients should discuss these risks with their healthcare provider before undergoing laparoscopy.
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This question is part of the following fields:
- Gastrointestinal System
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