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Question 1
Incorrect
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A 55-year-old woman comes to your clinic seeking help to quit smoking. She has been using nicotine patches for 6 months but has not been successful in her attempts. You decide to prescribe bupropion.
What is a typical side effect of bupropion?Your Answer: Hallucination
Correct Answer: Gastrointestinal disturbance
Explanation:Side Effects of Buproprion
Buproprion is a medication that can cause aggression and hallucination in some patients. However, the more common side effects are gastrointestinal disturbances such as diarrhoea, nausea, and dry mouth. These side effects are often experienced by patients taking buproprion. It is important to be aware of the potential side effects of any medication and to speak with a healthcare provider if any concerns arise. Additional information on buproprion and its potential side effects can be found in the electronic Medicines Compendium and Medicines Complete.
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This question is part of the following fields:
- Respiratory System
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Question 2
Correct
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Sophie, a 35-year-old female, is brought to the Emergency Department by ambulance after being involved in a car accident.
Upon conducting several tests, an X-ray reveals that she has sustained a mid shaft humeral fracture.
What is the structure that is typically most vulnerable to injury in cases of mid shaft humeral fractures?Your Answer: Radial nerve
Explanation:The humerus is a long bone that runs from the shoulder blade to the elbow joint. It is mostly covered by muscle but can be felt throughout its length. The head of the humerus is a smooth, rounded surface that connects to the body of the bone through the anatomical neck. The surgical neck, located below the head and tubercles, is the most common site of fracture. The greater and lesser tubercles are prominences on the upper end of the bone, with the supraspinatus and infraspinatus tendons inserted into the greater tubercle. The intertubercular groove runs between the two tubercles and holds the biceps tendon. The posterior surface of the body has a spiral groove for the radial nerve and brachial vessels. The lower end of the humerus is wide and flattened, with the trochlea, coronoid fossa, and olecranon fossa located on the distal edge. The medial epicondyle is prominent and has a sulcus for the ulnar nerve and collateral vessels.
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This question is part of the following fields:
- Musculoskeletal System And Skin
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Question 3
Correct
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A 68-year-old patient is admitted for surgery after fracturing their tibia in a car accident. 24 hours after the operation, the patient reports experiencing severe pain and tingling sensations. Upon examination, the anterior leg appears red, swollen, and feels cooler than the rest of the limb. Dorsiflexion of the foot is impaired, and there is a loss of sensation over the first and second toes. The intracompartmental pressure of the anterior compartment measures 40mmHg. A weak pulse is palpated just lateral to the extensor hallucis longus tendon. Which artery's pulse is felt at this anatomical site?
Your Answer: Dorsalis pedis artery
Explanation:The foot has two arches: the longitudinal arch and the transverse arch. The longitudinal arch is higher on the medial side and is supported by the posterior pillar of the calcaneum and the anterior pillar composed of the navicular bone, three cuneiforms, and the medial three metatarsal bones. The transverse arch is located on the anterior part of the tarsus and the posterior part of the metatarsus. The foot has several intertarsal joints, including the sub talar joint, talocalcaneonavicular joint, calcaneocuboid joint, transverse tarsal joint, cuneonavicular joint, intercuneiform joints, and cuneocuboid joint. The foot also has various ligaments, including those of the ankle joint and foot. The foot is innervated by the lateral plantar nerve and medial plantar nerve, and it receives blood supply from the plantar arteries and dorsalis pedis artery. The foot has several muscles, including the abductor hallucis, flexor digitorum brevis, abductor digit minimi, flexor hallucis brevis, adductor hallucis, and extensor digitorum brevis.
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This question is part of the following fields:
- Musculoskeletal System And Skin
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Question 4
Correct
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A senior citizen who is unfamiliar to you arrives with seizures. A companion describes that he had been experiencing a prickling sensation around his mouth and muscle contractions in his extremities.
What blood test outcomes would you anticipate from these indications?Your Answer: Hypocalcaemia
Explanation:The correct answer is hypocalcaemia, which is characterized by perioral paraesthesia, cramps, tetany, and convulsions. Hypophosphatemia and hypokalaemia are not the most appropriate answers, as they would not cause these symptoms. Sepsis is also an incorrect answer.
Hypocalcaemia: Symptoms and Signs
Hypocalcaemia is a condition characterized by low levels of calcium in the blood. As calcium is essential for proper muscle and nerve function, many of the symptoms and signs of hypocalcaemia are related to neuromuscular excitability. The most common features of hypocalcaemia include muscle twitching, cramping, and spasms, as well as perioral paraesthesia. In chronic cases, patients may experience depression and cataracts. An electrocardiogram (ECG) may show a prolonged QT interval.
Two specific signs that are commonly used to diagnose hypocalcaemia are Trousseau’s sign and Chvostek’s sign. Trousseau’s sign is observed when the brachial artery is occluded by inflating the blood pressure cuff and maintaining pressure above systolic. This causes wrist flexion and fingers to be drawn together, which is seen in around 95% of patients with hypocalcaemia and around 1% of normocalcaemic people. Chvostek’s sign is observed when tapping over the parotid gland causes facial muscles to twitch. This sign is seen in around 70% of patients with hypocalcaemia and around 10% of normocalcaemic people. Overall, hypocalcaemia can cause a range of symptoms and signs that are related to neuromuscular excitability, and specific diagnostic signs can be used to confirm the diagnosis.
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This question is part of the following fields:
- Renal System
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Question 5
Incorrect
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A 75-year-old woman presents with a five-day history of difficulty initiating abduction of her right arm. She denies any pain or previous shoulder issues and has not experienced any trauma. During examination, her passive range of motion is normal, but she is unable to begin abduction from a neutral position. However, if she uses her left arm to lift her right arm to approximately 15 degrees, she is then able to continue abduction without difficulty. Which muscle is responsible for initiating shoulder abduction?
Your Answer: Subscapularis
Correct Answer: Supraspinatus
Explanation:The Supraspinatus muscle is responsible for starting the process of lifting the arm away from the body, up to a point of about 15 degrees. After this point, the Deltoid muscle takes over as the primary muscle responsible for continuing the arm’s upward movement. When the arm is lifted beyond 90 degrees, the Trapezius muscle comes into play, elevating the shoulder and rotating the scapula. Finally, the Infraspinatus muscle is responsible for producing lateral rotation of the arm at the shoulder.
Understanding the Rotator Cuff Muscles
The rotator cuff muscles are a group of four muscles that are responsible for the movement and stability of the shoulder joint. These muscles are known as the SItS muscles, which stands for Supraspinatus, Infraspinatus, teres minor, and Subscapularis. Each of these muscles has a specific function in the movement of the shoulder joint.
The Supraspinatus muscle is responsible for abducting the arm before the deltoid muscle. It is the most commonly injured muscle in the rotator cuff. The Infraspinatus muscle rotates the arm laterally, while the teres minor muscle adducts and rotates the arm laterally. Lastly, the Subscapularis muscle adducts and rotates the arm medially.
Understanding the functions of each of these muscles is important in diagnosing and treating rotator cuff injuries. By identifying which muscle is injured, healthcare professionals can develop a treatment plan that targets the specific muscle and promotes healing. Overall, the rotator cuff muscles play a crucial role in the movement and stability of the shoulder joint.
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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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Lauren formulates a null hypothesis that taking aspirin every day decreases the risk of a heart attack in individuals over the age of 50. When testing this hypothesis, she wants to determine the likelihood of avoiding a type II error.
What is the term used to describe this probability and how can it be improved?Your Answer: Power - increasing the sample size
Explanation:Power refers to the likelihood of correctly rejecting the null hypothesis when it is false, which is also the probability of avoiding a type II error. In contrast, a type II error occurs when the null hypothesis is accepted despite being false, resulting in a false negative. The sample size, or the number of subjects analyzed, plays a crucial role in determining power. Increasing the sample size leads to more precise results and a higher probability of correctly rejecting the null hypothesis, while decreasing the sample size results in less accurate results and a lower power. It is important to note that a type I error refers to rejecting the null hypothesis when it is actually true, while a type III error is not a recognized term in statistics.
Significance tests are used to determine the likelihood of a null hypothesis being true. The null hypothesis states that two treatments are equally effective, while the alternative hypothesis suggests that there is a difference between the two treatments. The p value is the probability of obtaining a result by chance that is at least as extreme as the observed result, assuming the null hypothesis is true. Two types of errors can occur during significance testing: type I, where the null hypothesis is rejected when it is true, and type II, where the null hypothesis is accepted when it is false. The power of a study is the probability of correctly rejecting the null hypothesis when it is false, and it can be increased by increasing the sample size.
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This question is part of the following fields:
- General Principles
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Question 7
Incorrect
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A 63-year-old man is undergoing a left hemicolectomy for carcinoma of the descending colon. During mobilisation of the left colon, the registrar notices blood in the left paracolic gutter. What is the most likely source of bleeding in this scenario?
Your Answer: Marginal artery
Correct Answer: Spleen
Explanation:Traction injuries during colonic surgery often result in spleen tears, while bleeding from other structures would not be visible in the paracolic gutter before incision of the paracolonic peritoneal edge.
Anatomy of the Left Colon
The left colon is a part of the large intestine that passes inferiorly and becomes extraperitoneal in its posterior aspect. It is closely related to the ureter and gonadal vessels, which may be affected by disease processes. At a certain level, the left colon becomes the sigmoid colon, which is wholly intraperitoneal once again. The sigmoid colon is highly mobile and may even be found on the right side of the abdomen. As it passes towards the midline, the taenia blend marks the transition between the sigmoid colon and upper rectum.
The blood supply of the left colon comes from the inferior mesenteric artery. However, the marginal artery, which comes from the right colon, also contributes significantly. This contribution becomes clinically significant when the inferior mesenteric artery is divided surgically, such as during an abdominal aortic aneurysm repair. Understanding the anatomy of the left colon is important for diagnosing and treating diseases that affect this part of the large intestine.
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This question is part of the following fields:
- Gastrointestinal System
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Question 8
Incorrect
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What characteristic is shared by all fungi but not all bacteria?
Your Answer: Plasmids
Correct Answer: Membrane-bound nucleus
Explanation:Differences between Fungi and Bacteria
Fungi and bacteria are two types of microorganisms that have distinct differences in their cellular structure and genetic makeup. Fungi are eukaryotic organisms, meaning they have a membrane-bound nucleus that contains their genetic material. On the other hand, bacteria are prokaryotic and lack a nucleus. Instead, they have a nucleoid, which is a collection of genetic material that is not membrane-bound.
Both fungi and bacteria have cell walls, but the composition of these walls differs. Fungal cell walls contain chitin, which is not present in bacterial or plant cell walls. Additionally, while both types of microorganisms have endoplasmic reticulum and ribosomes, the ribosomes in bacteria are smaller than those in eukaryotes.
Another difference between fungi and bacteria is the presence of plasmids. Bacteria have plasmids, which are circular rings of DNA that can be transmitted between organisms. Fungi, however, do not have plasmids.
In summary, while fungi and bacteria share some similarities in their cellular structure, they have distinct differences in their genetic makeup and composition of their cell walls.
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This question is part of the following fields:
- Microbiology
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Question 9
Incorrect
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You are working on a general surgical receiving ward when a 70-year-old woman is admitted from the emergency department with sudden and severe abdominal pain that radiates to her back. The patient reports that she is normally healthy, but has been struggling with rheumatoid arthritis for the past few years, which is improving with treatment. She does not consume alcohol and has had an open cholecystectomy in the past, although she cannot recall when it occurred.
Blood tests were conducted in the emergency department:
- Hb 140 g/L (Male: 135-180, Female: 115-160)
- Platelets 350 * 109/L (150-400)
- WBC 12.9 * 109/L (4.0-11.0)
- Amylase 1200 U/L (70-300)
Based on the likely diagnosis, what is the most probable cause of this patient's presentation?Your Answer: Gallstones obstructing the common bile duct
Correct Answer: Azathioprine
Explanation:Acute pancreatitis can be caused by azathioprine.
It is important to note that the symptoms and blood tests suggest acute pancreatitis. The most common causes of this condition are gallstones and alcohol, but these have been ruled out through patient history. Although there is a possibility of retained stones in the common bile duct after cholecystectomy, it is unlikely given the time since the operation.
Other less common causes include trauma (which is not present in this case) and sodium valproate (which the patient has not been taking).
Therefore, the most likely cause of acute pancreatitis in this case is azathioprine, an immunosuppressive medication used to treat rheumatoid arthritis, which is known to have a side effect of acute pancreatitis.
Acute pancreatitis is a condition that is primarily caused by gallstones and alcohol consumption in the UK. However, there are other factors that can contribute to the development of this condition. A popular mnemonic used to remember these factors is GET SMASHED, which stands for gallstones, ethanol, trauma, steroids, mumps, autoimmune diseases, scorpion venom, hypertriglyceridaemia, hyperchylomicronaemia, hypercalcaemia, hypothermia, ERCP, and certain drugs. It is important to note that pancreatitis is seven times more common in patients taking mesalazine than sulfasalazine. CT scans can show diffuse parenchymal enlargement with oedema and indistinct margins in patients with acute pancreatitis.
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This question is part of the following fields:
- Gastrointestinal System
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Question 10
Incorrect
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Into which of the following veins does the middle thyroid vein drain?
Rewritten: At what age does the middle thyroid vein drain into one of the following veins?Your Answer: External jugular
Correct Answer: Internal jugular
Explanation:If a ligature slips, the copious bleeding is due to the fact that it drains to the internal jugular vein.
Anatomy of the Thyroid Gland
The thyroid gland is a butterfly-shaped gland located in the neck, consisting of two lobes connected by an isthmus. It is surrounded by a sheath from the pretracheal layer of deep fascia and is situated between the base of the tongue and the fourth and fifth tracheal rings. The apex of the thyroid gland is located at the lamina of the thyroid cartilage, while the base is situated at the fourth and fifth tracheal rings. In some individuals, a pyramidal lobe may extend from the isthmus and attach to the foramen caecum at the base of the tongue.
The thyroid gland is surrounded by various structures, including the sternothyroid, superior belly of omohyoid, sternohyoid, and anterior aspect of sternocleidomastoid muscles. It is also related to the carotid sheath, larynx, trachea, pharynx, oesophagus, cricothyroid muscle, and parathyroid glands. The superior and inferior thyroid arteries supply the thyroid gland with blood, while the superior and middle thyroid veins drain into the internal jugular vein, and the inferior thyroid vein drains into the brachiocephalic veins.
In summary, the thyroid gland is a vital gland located in the neck, responsible for producing hormones that regulate metabolism. Its anatomy is complex, and it is surrounded by various structures that are essential for its function. Understanding the anatomy of the thyroid gland is crucial for the diagnosis and treatment of thyroid disorders.
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This question is part of the following fields:
- Musculoskeletal System And Skin
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Question 11
Correct
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A 44-year-old female presents to her GP with persistent gastro-oesophageal reflux disease and complains of a burning pain in her chest. She is referred to a gastroenterologist who performs an endoscopy with biopsy, leading to a diagnosis of Barrett's oesophagus. Explain the metaplasia that occurs in Barrett's oesophagus and its association with an increased risk of oesophageal cancer.
Barrett's oesophagus is characterized by the metaplasia of the lower oesophageal epithelium from stratified squamous to simple columnar epithelium. This change from the normal stratified squamous epithelium increases the risk of oesophageal cancer by 30-fold and is often caused by gastro-oesophageal reflux disease.Your Answer: Stratified squamous epithelium to simple columnar
Explanation:Barrett’s oesophagus is characterized by the transformation of the lower oesophageal epithelial cells from stratified squamous to simple columnar epithelium. This change from the normal stratified squamous epithelium increases the risk of oesophageal cancer by 30 times and is often associated with gastro-oesophageal reflux disease.
Metaplasia is a reversible process where differentiated cells transform into another cell type. This change may occur as an adaptive response to stress, where cells sensitive to adverse conditions are replaced by more resilient cell types. Metaplasia can be a normal physiological response, such as the transformation of cartilage into bone. The most common type of epithelial metaplasia involves the conversion of columnar cells to squamous cells, which can be caused by smoking or Schistosomiasis. In contrast, metaplasia from squamous to columnar cells occurs in Barrett’s esophagus. If the metaplastic stimulus is removed, the cells will revert to their original differentiation pattern. However, if the stimulus persists, dysplasia may develop. Although metaplasia is not directly carcinogenic, factors that predispose to metaplasia may induce malignant transformation. The pathogenesis of metaplasia involves the reprogramming of stem cells or undifferentiated mesenchymal cells present in connective tissue, which differentiate along a new pathway.
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This question is part of the following fields:
- Gastrointestinal System
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Question 12
Incorrect
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A 50-year-old female is admitted with a seizure that is unresponsive to 5 mg lorazepam. An IV loading dose of phenytoin is administered, followed by once daily oral maintenance dose. However, the patient later develops ataxia and nystagmus, raising concerns of phenytoin toxicity. What is the probable reason for phenytoin toxicity in this case?
Your Answer: First-order elimination
Correct Answer: Zero-order elimination
Explanation:Most drugs are eliminated through first order elimination kinetics when used at therapeutic concentrations. However, some drugs exhibit zero order elimination kinetics, which occurs when the clearance rate is dependent on a saturable enzyme system. Once the system is saturated, the clearance rate remains constant, leading to a higher risk of drug toxicity. Examples of drugs that exhibit zero-order kinetics include phenytoin, alcohol, and salicylates.
Phenytoin has an average half-life of 14 hours, which is considered long and can lead to drug accumulation. Therefore, therapeutic drug monitoring is often necessary to determine the appropriate dosing interval. Phenytoin is primarily metabolized by the liver and excreted in bile as an inactive metabolite, with minimal renal excretion. Even in cases of severe renal dysfunction, dose modification is not required.
In the case of a patient taking a once-daily dose of phenytoin, the long half-life is unlikely to be the main factor contributing to drug toxicity. Instead, it is more likely due to the zero-order pharmacokinetics of the drug.
Pharmacokinetics of Excretion
Pharmacokinetics refers to the study of how drugs are absorbed, distributed, metabolized, and eliminated by the body. One important aspect of pharmacokinetics is excretion, which is the process by which drugs are removed from the body. The rate of drug elimination is typically proportional to drug concentration, a phenomenon known as first-order elimination kinetics. However, some drugs exhibit zero-order kinetics, where the rate of excretion remains constant regardless of changes in plasma concentration. This occurs when the metabolic process responsible for drug elimination becomes saturated. Examples of drugs that exhibit zero-order kinetics include phenytoin and salicylates. Understanding the pharmacokinetics of excretion is important for determining appropriate dosing regimens and avoiding toxicity.
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This question is part of the following fields:
- General Principles
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Question 13
Incorrect
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Which of the following is the least probable cause of hypercalcemia?
Your Answer: Sarcoidosis
Correct Answer: Coeliac disease
Explanation:Patients with coeliac disease are prone to developing hypocalcaemia as a result of calcium malabsorption by the bowel.
Understanding the Causes of Hypercalcaemia
Hypercalcaemia is a medical condition characterized by high levels of calcium in the blood. The two most common causes of hypercalcaemia are primary hyperparathyroidism and malignancy. Primary hyperparathyroidism is the most common cause in non-hospitalized patients, while malignancy is the most common cause in hospitalized patients. Malignancy-related hypercalcaemia may be due to various processes, including PTHrP from the tumor, bone metastases, and myeloma. Measuring parathyroid hormone levels is crucial in diagnosing hypercalcaemia.
Other causes of hypercalcaemia include sarcoidosis, tuberculosis, histoplasmosis, vitamin D intoxication, acromegaly, thyrotoxicosis, milk-alkali syndrome, drugs such as thiazides and calcium-containing antacids, dehydration, Addison’s disease, and Paget’s disease of the bone. Paget’s disease of the bone usually results in normal calcium levels, but hypercalcaemia may occur with prolonged immobilization.
In summary, hypercalcaemia can be caused by various medical conditions, with primary hyperparathyroidism and malignancy being the most common. It is essential to identify the underlying cause of hypercalcaemia to provide appropriate treatment.
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This question is part of the following fields:
- Endocrine System
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Question 14
Incorrect
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A study measures a patient's blood pressure before and after a new antihypertensive medication has been administered. What type of significance test should be utilized to analyze the results?
Your Answer: Student's unpaired t-test
Correct Answer: Student's paired t-test
Explanation:Types of Significance Tests
Significance tests are used to determine whether the results of a study are statistically significant or simply due to chance. The type of significance test used depends on the type of data being analyzed. Parametric tests are used for data that can be measured and are usually normally distributed, while non-parametric tests are used for data that cannot be measured in this way.
Parametric tests include the Student’s t-test, which can be paired or unpaired, and Pearson’s product-moment coefficient, which is used for correlation analysis. Non-parametric tests include the Mann-Whitney U test, which compares ordinal, interval, or ratio scales of unpaired data, and the Wilcoxon signed-rank test, which compares two sets of observations on a single sample. The chi-squared test is used to compare proportions or percentages, while Spearman and Kendall rank are used for correlation analysis.
It is important to choose the appropriate significance test for the type of data being analyzed in order to obtain accurate and reliable results. By understanding the different types of significance tests available, researchers can make informed decisions about which test to use for their particular study.
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This question is part of the following fields:
- General Principles
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Question 15
Incorrect
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A 45-year-old patient is hospitalized for suspected typhoid fever and started on an antibiotic. After a week, she experiences extreme fatigue and blood tests show anaemia, neutropenia, and thrombocytopenia. Which antibiotic is the most probable cause of these symptoms?
Your Answer: Doxycycline
Correct Answer: Chloramphenicol
Explanation:Aplastic anaemia is a severe side effect of chloramphenicol, which is often used to treat typhoid fever. Ciprofloxacin can increase the risk of tendon rupture and lower the seizure threshold. Clindamycin is known to cause C. difficile diarrhoea, while doxycycline can lead to discolouration of teeth and photosensitivity.
Antibiotics that inhibit protein synthesis work by targeting specific components of the bacterial ribosome, which is responsible for translating genetic information into proteins. Aminoglycosides bind to the 30S subunit of the ribosome, causing errors in the reading of mRNA. Tetracyclines also bind to the 30S subunit, but block the binding of aminoacyl-tRNA. Chloramphenicol and clindamycin both bind to the 50S subunit, inhibiting different steps in the process of protein synthesis. Macrolides also bind to the 50S subunit, but specifically inhibit the movement of tRNA from the acceptor site to the peptidyl site.
While these antibiotics can be effective in treating bacterial infections, they can also have adverse effects. Aminoglycosides are known to cause nephrotoxicity and ototoxicity, while tetracyclines can cause discolouration of teeth and photosensitivity. Chloramphenicol is associated with a rare but serious side effect called aplastic anaemia, and clindamycin is a common cause of C. difficile diarrhoea. Macrolides can cause nausea, especially erythromycin, and can also inhibit the activity of certain liver enzymes (P450) and prolong the QT interval. Despite these potential side effects, these antibiotics are still commonly used in clinical practice, particularly in patients who are allergic to penicillin.
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This question is part of the following fields:
- General Principles
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Question 16
Incorrect
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An individual in their mid-20s is identified to have a superior vena cava on the left side. What is the most probable route for blood from this system to reach the heart?
Your Answer: Directly into the roof of the right atrium
Correct Answer: Via the coronary sinus
Explanation:The Superior Vena Cava: Anatomy, Relations, and Developmental Variations
The superior vena cava (SVC) is a large vein that drains blood from the head and neck, upper limbs, thorax, and part of the abdominal walls. It is formed by the union of the subclavian and internal jugular veins, which then join to form the right and left brachiocephalic veins. The SVC is located in the anterior margins of the right lung and pleura, and is related to the trachea and right vagus nerve posteromedially, and the posterior aspects of the right lung and pleura posterolaterally. The pulmonary hilum is located posteriorly, while the right phrenic nerve and pleura are located laterally on the right side, and the brachiocephalic artery and ascending aorta are located laterally on the left side.
Developmental variations of the SVC are recognized, including anomalies of its connection and interruption of the inferior vena cava (IVC) in its abdominal course. In some individuals, a persistent left-sided SVC may drain into the right atrium via an enlarged orifice of the coronary sinus, while in rare cases, the left-sided vena cava may connect directly with the superior aspect of the left atrium, usually associated with an un-roofing of the coronary sinus. Interruption of the IVC may occur in patients with left-sided atrial isomerism, with drainage achieved via the azygos venous system.
Overall, understanding the anatomy, relations, and developmental variations of the SVC is important for medical professionals in diagnosing and treating related conditions.
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This question is part of the following fields:
- Cardiovascular System
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Question 17
Incorrect
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A 35-year-old vegan mother comes to the clinic seeking dietary advice for her upcoming pregnancy. She wants to ensure her child's optimal health without consuming any animal-based products.
What recommendations should be provided to her?Your Answer: All nutrients can be adequately supplemented in a plant-based diet
Correct Answer: Vitamin B12 will need to be supplemented to ensure adequate levels
Explanation:As vitamin B12 can only be obtained from animal-based foods in a human diet, it is necessary to provide this patient with vitamin B12 supplementation to prevent serious complications such as neural tube defects during pregnancy. It would be incorrect to reassure the patient that a plant-based diet can provide all necessary nutrients, as this could lead to vitamin B12 deficiency and harm the baby. While it is important to check for iron deficiency given the patient’s dietary patterns, not all plant-based foods lack iron, and dietary education on this topic is necessary. The use of supplemental vitamins can help ensure a healthy pregnancy with a plant-based diet. Therefore, it is untrue to suggest that the baby’s growth will be significantly impeded and that there is a high risk of pregnancy complications.
Vitamin B12 is a type of water-soluble vitamin that belongs to the B complex group. Unlike other vitamins, it can only be found in animal-based foods. The human body typically stores enough vitamin B12 to last for up to 5 years. This vitamin plays a crucial role in various bodily functions, including acting as a co-factor for the conversion of homocysteine into methionine through the enzyme homocysteine methyltransferase, as well as for the isomerization of methylmalonyl CoA to Succinyl Co A via the enzyme methylmalonyl mutase. Additionally, it is used to regenerate folic acid in the body.
However, there are several causes of vitamin B12 deficiency, including pernicious anaemia, Diphyllobothrium latum infection, and Crohn’s disease. When the body lacks vitamin B12, it can lead to macrocytic, megaloblastic anaemia and peripheral neuropathy. To prevent these consequences, it is important to ensure that the body has enough vitamin B12 through a balanced diet or supplements.
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This question is part of the following fields:
- General Principles
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Question 18
Correct
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During your placement on the paediatric ward, you are examining the chest x-ray of a 9-year-old boy from Ghana. He came to the UK 2 months ago and was hospitalized after falling from the monkey bars and breaking his collarbone. Despite being in good health, he has not experienced any chest pain or shortness of breath. Upon reviewing the radiologist's report, you notice that a Ghon complex is present. What medical condition does this suggest?
Your Answer: TB
Explanation:Childhood respiratory infection is the typical manifestation of primary TB, which is often asymptomatic and leads to the formation of a Ghon focus and mediastinal lymphadenopathy. These two conditions together are known as the Ghon complex. The infection usually resolves on its own with minimal symptoms.
Understanding Tuberculosis: The Pathophysiology and Risk Factors
Tuberculosis is a bacterial infection caused by Mycobacterium tuberculosis. The pathophysiology of tuberculosis involves the migration of macrophages to regional lymph nodes, forming a Ghon complex. This complex leads to the formation of a granuloma, which is a collection of epithelioid histiocytes with caseous necrosis in the center. The inflammatory response is mediated by a type 4 hypersensitivity reaction. While healthy individuals can contain the disease, immunocompromised individuals are at risk of developing disseminated (miliary) TB.
Several risk factors increase the likelihood of developing tuberculosis. These include having lived in Asia, Latin America, Eastern Europe, or Africa for years, exposure to an infectious TB case, and being infected with HIV. Immunocompromised individuals, such as diabetics, patients on immunosuppressive therapy, malnourished individuals, or those with haematological malignancies, are also at risk. Additionally, silicosis and apical fibrosis increase the likelihood of developing tuberculosis. Understanding the pathophysiology and risk factors of tuberculosis is crucial in preventing and treating this infectious disease.
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This question is part of the following fields:
- General Principles
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Question 19
Incorrect
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A 55-year-old Caucasian man presents to the ENT clinic with complaints of gradual hearing loss over the past year. He reports having to turn up the volume on his television to the maximum to hear it comfortably. There are no associated symptoms such as tinnitus or dizziness, and the patient has no significant medical history.
Upon examination, a Weber and Rinne test reveal conductive hearing loss in the left ear. Otoscope examination shows no signs of middle ear effusion or tympanic membrane involvement in either ear. A pure tone audiometry confirms conductive hearing loss in the left ear, with a Carhart's notch present.
The physician diagnoses the patient with otosclerosis and discusses treatment options.
What is the underlying pathology of otosclerosis?Your Answer: Accumulation of desquamated, stratified squamous epithelium within the middle ear, causing erosion of the ossicles
Correct Answer: Replacement of normal bone by vascular spongy bone
Explanation:Otosclerosis is a condition where normal bone is replaced by spongy bone with a high vascularity. This leads to progressive conductive hearing loss, without any other neurological impairments. The replacement of the normal endochondral layer of the bony labyrinth by spongy bone affects the ability of the stapes to act as a piston, resulting in the conduction of sound from the middle ear to the inner ear being affected. Caucasians are most commonly affected by this condition.
Benign paroxysmal positional vertigo (BPPV) is caused by the dislodgement of otoliths into the semicircular canals. This condition results in vertiginous dizziness upon positional changes, but does not affect auditory function.
Meniere’s disease is caused by endolymphatic hydrops, which is the accumulation of fluid in the inner ear. The pathophysiology of this condition is not well understood, but it leads to vertigo, tinnitus, hearing loss, and aural fullness.
Cholesteatoma is caused by the accumulation of desquamated, stratified squamous epithelium. This leads to the formation of a mass that can gradually enlarge and erode the ossicle chain, resulting in conductive hearing loss.
Presbycusis is a type of sensorineural hearing loss that occurs as a result of aging. The degeneration of the organ of Corti is one of the underlying pathological mechanisms that causes this condition. This leads to the destruction of outer hair cells and a decrease in hearing sensitivity.
Understanding Otosclerosis: A Progressive Conductive Deafness
Otosclerosis is a medical condition that occurs when normal bone is replaced by vascular spongy bone. This condition leads to a progressive conductive deafness due to the fixation of the stapes at the oval window. It is an autosomal dominant condition that typically affects young adults, with onset usually occurring between the ages of 20-40 years.
The main features of otosclerosis include conductive deafness, tinnitus, a normal tympanic membrane, and a positive family history. In some cases, patients may also experience a flamingo tinge, which is caused by hyperemia and affects around 10% of patients.
Management of otosclerosis typically involves the use of a hearing aid or stapedectomy. A hearing aid can help to improve hearing, while a stapedectomy involves the surgical removal of the stapes bone and replacement with a prosthesis.
Overall, understanding otosclerosis is important for individuals who may be at risk of developing this condition. Early diagnosis and management can help to improve hearing and prevent further complications.
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This question is part of the following fields:
- Respiratory System
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Question 20
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A 36-year-old woman visits her doctor complaining of fatigue and overall sluggishness. She informs her doctor that she has been following a new diet for the past month, which involves severely limiting her calorie intake and consuming only white rice. Upon examination, the doctor observes that she has difficulty moving her eyes, an unsteady gait, and seems disoriented.
What are the organs that are typically affected by the vitamin deficiency responsible for her symptoms?Your Answer: Brain and heart
Explanation:The brain and heart, which are highly aerobic tissues, are impacted by thiamine deficiency, leading to conditions like Wernicke-Korsakoff syndrome and wet beriberi. This is because thiamine plays a crucial role in the breakdown of sugars and amino acids. On the other hand, vitamin D deficiency affects bones, while vitamin A deficiency affects the eyes.
The Importance of Vitamin B1 (Thiamine) in the Body
Vitamin B1, also known as thiamine, is a water-soluble vitamin that belongs to the B complex group. It plays a crucial role in the body as one of its phosphate derivatives, thiamine pyrophosphate (TPP), acts as a coenzyme in various enzymatic reactions. These reactions include the catabolism of sugars and amino acids, such as pyruvate dehydrogenase complex, alpha-ketoglutarate dehydrogenase complex, and branched-chain amino acid dehydrogenase complex.
Thiamine deficiency can lead to clinical consequences, particularly in highly aerobic tissues like the brain and heart. The brain can develop Wernicke-Korsakoff syndrome, which presents symptoms such as nystagmus, ophthalmoplegia, and ataxia. Meanwhile, the heart can develop wet beriberi, which causes dilated cardiomyopathy. Other conditions associated with thiamine deficiency include dry beriberi, which leads to peripheral neuropathy, and Korsakoff’s syndrome, which causes amnesia and confabulation.
The primary causes of thiamine deficiency are alcohol excess and malnutrition. Alcoholics are routinely recommended to take thiamine supplements to prevent deficiency. Overall, thiamine is an essential vitamin that plays a vital role in the body’s metabolic processes.
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This question is part of the following fields:
- General Principles
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