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Question 1
Correct
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Which one of the following statements relating to malignant mesothelioma is not true?
Your Answer: It is linked to cigarette smoking independent of asbestos exposure.
Explanation:This type of cancer is not associated with smoking cigarettes. The preferred treatment option is a complete removal of the tumor if caught early. Radiation therapy is commonly administered before or after surgery, but this type of cancer is not highly responsive to radiation. The most effective treatment involves a combination of chemotherapy drugs, with many regimens utilizing cisplatin.
Occupational cancers are responsible for 5.3% of cancer deaths, with men being more affected than women. The most common types of cancer in men include mesothelioma, bladder cancer, non-melanoma skin cancer, lung cancer, and sino-nasal cancer. Occupations that have a high risk of developing tumors include those in the construction industry, coal tar and pitch workers, miners, metalworkers, asbestos workers, and those in the rubber industry. Shift work has also been linked to breast cancer in women.
The latency period between exposure to carcinogens and the development of cancer is typically 15 years for solid tumors and 20 years for leukemia. Many occupational cancers are rare, such as sino-nasal cancer, which is linked to wood dust exposure and is not strongly associated with smoking. Another rare occupational tumor is angiosarcoma of the liver, which is linked to working with vinyl chloride. In non-occupational contexts, these tumors are extremely rare.
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This question is part of the following fields:
- Haematology And Oncology
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Question 2
Incorrect
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At which of the following anatomical locations does the common peroneal nerve bifurcate into the superficial and deep peroneal nerves?
Your Answer: At the inferomedial aspect of the popliteal fossa
Correct Answer: At the lateral aspect of the neck of the fibula
Explanation:The point where the common peroneal nerve is most susceptible to injury is at the neck of the fibula, where it divides into two branches.
The common peroneal nerve originates from the dorsal divisions of the sacral plexus, specifically from L4, L5, S1, and S2. This nerve provides sensation to the skin and fascia of the anterolateral surface of the leg and dorsum of the foot, as well as innervating the muscles of the anterior and peroneal compartments of the leg, extensor digitorum brevis, and the knee, ankle, and foot joints. It is located laterally within the sciatic nerve and passes through the lateral and proximal part of the popliteal fossa, under the cover of biceps femoris and its tendon, to reach the posterior aspect of the fibular head. The common peroneal nerve divides into the deep and superficial peroneal nerves at the point where it winds around the lateral surface of the neck of the fibula in the body of peroneus longus, approximately 2 cm distal to the apex of the head of the fibula. It is palpable posterior to the head of the fibula. The nerve has several branches, including the nerve to the short head of biceps, articular branch (knee), lateral cutaneous nerve of the calf, and superficial and deep peroneal nerves at the neck of the fibula.
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This question is part of the following fields:
- Neurological System
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Question 3
Incorrect
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A 16-year-old male comes to the clinic after experiencing a seizure. During the history-taking, he reports that he first noticed shaking in his hand about an hour ago. The shaking continued for a few seconds before he lost consciousness and bit his tongue. He also experienced urinary incontinence. How would you describe this presentation?
Your Answer: Myoclonic seizure
Correct Answer: Partial seizure with secondary generalisation
Explanation:Epilepsy is a neurological condition that causes recurrent seizures. In the UK, around 500,000 people have epilepsy, and two-thirds of them can control their seizures with antiepileptic medication. While epilepsy usually occurs in isolation, certain conditions like cerebral palsy, tuberous sclerosis, and mitochondrial diseases have an association with epilepsy. It’s important to note that seizures can also occur due to other reasons like infection, trauma, or metabolic disturbance.
Seizures can be classified into focal seizures, which start in a specific area of the brain, and generalised seizures, which involve networks on both sides of the brain. Patients who have had generalised seizures may experience biting their tongue or incontinence of urine. Following a seizure, patients typically have a postictal phase where they feel drowsy and tired for around 15 minutes.
Patients who have had their first seizure generally undergo an electroencephalogram (EEG) and neuroimaging (usually a MRI). Most neurologists start antiepileptics following a second epileptic seizure. Antiepileptics are one of the few drugs where it is recommended that we prescribe by brand, rather than generically, due to the risk of slightly different bioavailability resulting in a lowered seizure threshold.
Patients who drive, take other medications, wish to get pregnant, or take contraception need to consider the possible interactions of the antiepileptic medication. Some commonly used antiepileptics include sodium valproate, carbamazepine, lamotrigine, and phenytoin. In case of a seizure that doesn’t terminate after 5-10 minutes, medication like benzodiazepines may be administered to terminate the seizure. If a patient continues to fit despite such measures, they are said to have status epilepticus, which is a medical emergency requiring hospital treatment.
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This question is part of the following fields:
- Neurological System
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Question 4
Incorrect
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Which human herpesvirus causes a childhood exanthem?
Your Answer:
Correct Answer: Roseola infantum
Explanation:Exanthema: Common Childhood Illnesses
An exanthema is a childhood illness that is characterized by a fever and a rash that blanches when pressure is applied. These illnesses are quite common in childhood and are usually mild and self-limiting. There are several types of exanthema, and some of them have been numbered for easy identification.
The first disease is measles, which is caused by a virus called paramyxoviridae. The second disease is scarlet fever, which is caused by a bacterium called Streptococcus pyogenes. The third disease is rubella, also known as German measles, which is caused by a virus called togaviridae. The fifth disease is erythema infectiosum, also known as slapped cheek disease, which is caused by a virus called parvoviridae. The sixth disease is roseola infantum, which is caused by two viruses called HHV6 and HHV7. The fourth disease is no longer recognized.
In addition to these numbered diseases, there are other viruses that can cause an exanthematous rash, including rhinovirus, mumps, and varicella zoster virus. Despite their prevalence, most exanthema illnesses are mild and do not require medical intervention.
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This question is part of the following fields:
- Microbiology
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Question 5
Incorrect
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A 57-year-old woman comes to you complaining of an itchy rash on her back and tummy that she noticed this morning. She has a medical history of diabetes, hypertension, stage II chronic kidney disease, and atrial fibrillation. During the examination, you observe a single stripe of vesicular rash extending from the mid-back to the abdomen. You prescribe a 5-day course of acyclovir and provide her with some crucial advice before discharging her.
What important advice do you give her?Your Answer:
Correct Answer: Maintain adequate hydration
Explanation:Due to the risk of crystalline nephropathy, caution should be exercised when administering acyclovir to patients with stage II chronic kidney disease. Adequate hydration should be maintained to prevent acute kidney injury.
It is not recommended to use adhesives or topical creams as they may cause irritation and delay the healing of the rash.
If the lesions are still oozing, they should be covered with loose clothing.
To reduce the risk of bacterial superinfection, it is important to keep the rash clean and dry.
Antiviral agents are drugs used to treat viral infections. They work by targeting specific mechanisms of the virus, such as inhibiting viral DNA polymerase or neuraminidase. Some common antiviral agents include acyclovir, ganciclovir, ribavirin, amantadine, oseltamivir, foscarnet, interferon-α, and cidofovir. Each drug has its own mechanism of action and indications for use, but they all aim to reduce the severity and duration of viral infections.
In addition to these antiviral agents, there are also specific drugs used to treat HIV, a retrovirus. Nucleoside analogue reverse transcriptase inhibitors (NRTI), protease inhibitors (PI), and non-nucleoside reverse transcriptase inhibitors (NNRTI) are all used to target different aspects of the HIV life cycle. NRTIs work by inhibiting the reverse transcriptase enzyme, which is needed for the virus to replicate. PIs inhibit a protease enzyme that is necessary for the virus to mature and become infectious. NNRTIs bind to and inhibit the reverse transcriptase enzyme, preventing the virus from replicating. These drugs are often used in combination to achieve the best possible outcomes for HIV patients.
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This question is part of the following fields:
- General Principles
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Question 6
Incorrect
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A 60-year-old male presents with increasing fatigue.
Three months ago, he was diagnosed with bronchial carcinoma and has undergone chemotherapy. Upon admission, his electrolyte levels were measured as follows:
- Sodium: 118 mmol/L (137-144)
- Potassium: 3.5 mmol/L (3.5-4.9)
- Urea: 3.2 mmol/L (2.5-7.5)
- Creatinine: 65 µmol/L (60-110)
What would be the most appropriate initial investigation for this patient?Your Answer:
Correct Answer: Urine osmolality and sodium concentration
Explanation:Hyponatraemia in Bronchial Carcinoma Patients
Hyponatraemia is a common condition in patients with bronchial carcinoma. It is characterized by a marked decrease in sodium levels, which appears to be dilutional based on other test results that fall within the lower end of the normal range. The most likely cause of this condition is the syndrome of inappropriate ADH secretion (SIADH), which occurs when the tumour produces ADH in an ectopic manner. However, the diagnosis of SIADH is one of exclusion, and other possibilities such as hypoadrenalism due to metastatic disease to the adrenals should also be considered.
To determine the cause of hyponatraemia, initial tests such as urine sodium and osmolality are recommended. These tests can help rule out other possible causes and confirm the diagnosis of SIADH. Treatment for this condition typically involves fluid restriction. It is important to note that measuring ADH concentrations is not a reliable diagnostic tool as it is not widely available and does not provide any useful information.
In summary, hyponatraemia is a common condition in bronchial carcinoma patients, and SIADH is the most likely cause. Initial tests such as urine sodium and osmolality can help confirm the diagnosis, and treatment involves fluid restriction.
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This question is part of the following fields:
- Endocrine System
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Question 7
Incorrect
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A 56-year-old male is admitted to the hospital with increasing fatigue and difficulty exercising. After undergoing various tests, including echocardiography and right heart catheterization, it is determined that he has pulmonary arterial hypertension (PAH) with a mean pulmonary artery pressure of 35 mmhg and a pulmonary capillary wedge pressure of 8mmhg. One of the medications prescribed for him is ambrisentan. What is the mechanism of action of this drug?
Your Answer:
Correct Answer: Endothelin-1 receptor antagonist
Explanation:Ambrisentan is an antagonist of endothelin-1 receptors, which are involved in vasoconstriction. In pulmonary arterial hypertension (PAH), the expression of endothelin-1 is increased, leading to constriction of blood vessels. Ambrisentan selectively targets ETA receptors found in vascular smooth muscle, reducing morbidity and mortality in PAH patients. Common side effects include peripheral edema, sinusitis, flushing, and nasal congestion. Prostacyclins like PGI2 can also be used to manage PPH by dilating blood vessels and inhibiting platelet aggregation. PGE2, an inflammatory mediator, is not used in PAH treatment. PDE inhibitors like sildenafil increase cGMP levels in pulmonary vessels, relaxing vascular smooth muscle and reducing pulmonary artery pressure.
Pulmonary arterial hypertension (PAH) is a condition where the resting mean pulmonary artery pressure is equal to or greater than 25 mmHg. The pathogenesis of PAH is thought to involve endothelin. It is more common in females and typically presents between the ages of 30-50 years. PAH is diagnosed in the absence of chronic lung diseases such as COPD, although certain factors increase the risk. Around 10% of cases are inherited in an autosomal dominant fashion.
The classical presentation of PAH is progressive exertional dyspnoea, but other possible features include exertional syncope, exertional chest pain, peripheral oedema, and cyanosis. Physical examination may reveal a right ventricular heave, loud P2, raised JVP with prominent ‘a’ waves, and tricuspid regurgitation.
Management of PAH should first involve treating any underlying conditions. Acute vasodilator testing is central to deciding on the appropriate management strategy. If there is a positive response to acute vasodilator testing, oral calcium channel blockers may be used. If there is a negative response, prostacyclin analogues, endothelin receptor antagonists, or phosphodiesterase inhibitors may be used. Patients with progressive symptoms should be considered for a heart-lung transplant.
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This question is part of the following fields:
- Cardiovascular System
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Question 8
Incorrect
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A 43-year-old female comes to the ENT clinic with a history of constant vertigo and right-sided deafness for the past year. She has no significant medical history. Upon conducting an audiogram, it is discovered that her right ear has reduced hearing to both bone and air conduction. During a cranial nerve exam, an absent corneal reflex is observed on the right side, and she has poor balance. Otoscopy of both ears is normal. What is the probable underlying pathology responsible for this patient's symptoms and signs?
Your Answer:
Correct Answer: Vestibular schwannoma (acoustic neuroma)
Explanation:If a patient presents with loss of the corneal reflex, the likely diagnosis is vestibular schwannoma (acoustic neuroma). This is a noncancerous tumor that affects the vestibular portion of the 8th cranial nerve, leading to sensorineural deafness, tinnitus, and vertigo. As the tumor grows, it can also press on other cranial nerves. Loss of the corneal reflex is a classic sign of early trigeminal (cranial nerve 5) involvement, which is unlikely in any of the other listed conditions.
Meniere’s disease is not the correct answer. This is a disorder of the middle ear that causes episodic vertigo, sensorineural hearing loss, and a sensation of aural fullness or pressure.
Otosclerosis is also incorrect. This is an inherited condition that causes conductive deafness and tinnitus, typically presenting in patients aged 20-40 years.
Vestibular mononeuritis is not the correct answer either. This condition is caused by inflammation of the vestibular nerve following a recent viral infection and presents with vertigo, but hearing is not affected.
Vestibular schwannomas, also known as acoustic neuromas, make up about 5% of intracranial tumors and 90% of cerebellopontine angle tumors. These tumors typically present with a combination of vertigo, hearing loss, tinnitus, and an absent corneal reflex. The specific symptoms can be predicted based on which cranial nerves are affected. For example, cranial nerve VIII involvement can cause vertigo, unilateral sensorineural hearing loss, and unilateral tinnitus. Bilateral vestibular schwannomas are associated with neurofibromatosis type 2.
If a vestibular schwannoma is suspected, it is important to refer the patient to an ear, nose, and throat specialist urgently. However, it is worth noting that these tumors are often benign and slow-growing, so observation may be appropriate initially. The diagnosis is typically confirmed with an MRI of the cerebellopontine angle, and audiometry is also important as most patients will have some degree of hearing loss. Treatment options include surgery, radiotherapy, or continued observation.
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This question is part of the following fields:
- Neurological System
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Question 9
Incorrect
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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:
Correct 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 10
Incorrect
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A 60-year-old man visits his physician with a complaint of double vision. During the examination, the physician observes that the left eye is in a 'down and out' position and the pupil is dilated. The physician suspects a cranial nerve palsy.
What is the probable reason for his nerve palsy?Your Answer:
Correct Answer: Posterior communicating artery aneurysm
Explanation:Consider compression as the likely cause of surgical third nerve palsy.
When the dilation of the pupil is involved, it is referred to as surgical third nerve palsy. This condition is caused by a lesion that compresses the pupillary fibers located on the outer part of the third nerve. Unlike vascular causes of third nerve palsy, which only affect the nerve and not the pupillary fibers.
Out of the given options, only answer 4 is a compressive cause of third nerve palsy. The other options are risk factors for vascular causes.
Understanding Third Nerve Palsy: Causes and Features
Third nerve palsy is a neurological condition that affects the third cranial nerve, which controls the movement of the eye and eyelid. The condition is characterized by the eye being deviated ‘down and out’, ptosis, and a dilated pupil. In some cases, it may be referred to as a ‘surgical’ third nerve palsy due to the dilation of the pupil.
There are several possible causes of third nerve palsy, including diabetes mellitus, vasculitis (such as temporal arteritis or SLE), uncal herniation through tentorium if raised ICP, posterior communicating artery aneurysm, and cavernous sinus thrombosis. In some cases, it may also be a false localizing sign. Weber’s syndrome, which is characterized by an ipsilateral third nerve palsy with contralateral hemiplegia, is caused by midbrain strokes. Other possible causes include amyloid and multiple sclerosis.
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This question is part of the following fields:
- Neurological System
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Question 11
Incorrect
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What is the estimated percentage of oxygen in the blood that is attached to haemoglobin?
Your Answer:
Correct Answer: 100%
Explanation:Calculation of Oxygen in Blood
The majority of oxygen in the blood is bound to haemoglobin, with the exact amount varying based on the oxygen saturation and haemoglobin level. To calculate the amount of oxygen per litre of blood, the formula (13.9 × Hb × sats/100) + (PaO2 × 0.03) can be used. For example, an average man with an Hb of 14, saturations of 98% on room air, and a PaO2 of 12 would have 191 ml of oxygen per litre of blood. It is important to note that only 0.36 ml of this oxygen is dissolved in the blood.
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This question is part of the following fields:
- Basic Sciences
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Question 12
Incorrect
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What is the name of the enzyme necessary for the synthesis of cholesterol in the liver?
Your Answer:
Correct Answer: HMG Co A reductase
Explanation:Enzymes and Proteins Involved in Cholesterol Metabolism
Cholesterol synthesis in the liver and body cells requires the enzyme HMG CoA reductase, which converts HMG CoA into mevalonic acid, the first step in cholesterol production. This enzyme is a rate-limiting step and plays a crucial role in controlling the rate of cholesterol production. Statin drugs inhibit HMG CoA reductase, reducing blood cholesterol levels.
Cholesterol ester transport protein aids in transporting cholesterol esters from VLDL to HDL, allowing excess lipids to be returned to the liver in reverse cholesterol transport. Hepatic lipase is responsible for making LDL from VLDL, while lipoprotein lipase hydrolyzes triglycerides, creating fatty acids and glycerol that can enter the body’s cells. Microsomal triglyceride transfer protein is responsible for making chylomicrons in the enterocytes of the small intestine.
the roles of these enzymes and proteins is crucial in managing cholesterol levels and preventing cardiovascular diseases.
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This question is part of the following fields:
- Clinical Sciences
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Question 13
Incorrect
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An 83-year-old woman comes to your clinic with a painful red swelling on her cheek that she noticed this morning. She has been feeling fatigued for a few days. The patient lives alone and has a history of pressure ulcers due to limited mobility. During the examination, you observe an erythematous swelling above the right angle of the mandible that is warm and tender to the touch. You suspect that the patient has a parotid gland infection. What is the nerve that provides sensation to the parotid gland capsule?
Your Answer:
Correct Answer: Greater auricular nerve
Explanation:The greater auricular nerve (GAN) supplies sensation to the parotid gland, skin overlying the gland, mastoid process, and outer ear. The facial nerve supplies muscles of facial expression, taste from the anterior two-thirds of the tongue, and sensation from parts of the external acoustic meatus, auricle, and retro-auricular area. The mandibular nerve carries sensory and motor fibers, supplying sensation to the lower lip, lower teeth and gingivae, chin, and jaw, and motor innervation to muscles of mastication. The lingual nerve supplies sensation to the tongue and travels with taste fibers from the chorda tympani of the facial nerve. The glossopharyngeal nerve carries taste and sensation from the posterior third of the tongue, sensation from the pharyngeal wall and tonsils, the middle ear, external auditory canal, and auricle, and parasympathetic fibers that supply the parotid gland. Infective parotitis is uncommon and has increased risk in dehydrated or intubated elderly patients.
The parotid gland is located in front of and below the ear, overlying the mandibular ramus. Its salivary duct crosses the masseter muscle, pierces the buccinator muscle, and drains adjacent to the second upper molar tooth. The gland is traversed by several structures, including the facial nerve, external carotid artery, retromandibular vein, and auriculotemporal nerve. The gland is related to the masseter muscle, medial pterygoid muscle, superficial temporal and maxillary artery, facial nerve, stylomandibular ligament, posterior belly of the digastric muscle, sternocleidomastoid muscle, stylohyoid muscle, internal carotid artery, mastoid process, and styloid process. The gland is supplied by branches of the external carotid artery and drained by the retromandibular vein. Its lymphatic drainage is to the deep cervical nodes. The gland is innervated by the parasympathetic-secretomotor, sympathetic-superior cervical ganglion, and sensory-greater auricular nerve. Parasympathetic stimulation produces a water-rich, serous saliva, while sympathetic stimulation leads to the production of a low volume, enzyme-rich saliva.
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This question is part of the following fields:
- Gastrointestinal System
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Question 14
Incorrect
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A 26-year-old arrives at the emergency department with a dislocated shoulder after playing basketball. The joint is relocated, but he experiences pain and limited mobility in his affected arm. During the examination, it is observed that his right shoulder's flexion, extension, abduction, and external rotation are weakened. Additionally, he reports a loss of sensation in the lateral upper arm on the right side.
Which muscle/s receive innervation from the affected nerve in this case?Your Answer:
Correct Answer: Deltoid and teres minor
Explanation:The axillary nerve is responsible for supplying the deltoid and teres minor muscles, which allow for flexion, extension, abduction, and external rotation of the shoulder joint. Damage to this nerve can result in a loss of sensation over the ‘regimental badge’ area of the upper arm and impaired shoulder movement.
The biceps brachii, brachialis, and coracobrachialis muscles are innervated by the musculocutaneous nerve and are responsible for forearm flexion and shoulder adduction. Damage to this nerve would cause sensory impairment of the lateral aspect of the forearm.
The serratus anterior muscle is innervated by the long thoracic nerve and is responsible for stabilizing and upwardly rotating the scapula. Damage to this nerve would cause ‘winging’ of the scapula.
The supraspinatus and infraspinatus muscles are innervated by the suprascapular nerve and are responsible for initiating the first 15 degrees of abduction at the shoulder joint and externally rotating the shoulder, respectively.
The trapezius muscle is innervated by the accessory nerve and the ventral rami of the C3 and C4 spinal nerves. It acts to rotate and stabilize the scapula to enable movements of the upper limb.
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 15
Incorrect
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A 44-year-old man from India is staying with relatives in the UK. He presents to the doctor with concerns about difficulty reading the newspaper in the morning. He is unsure if it is due to blurry vision or difficulty distinguishing colors. He has a medical history of tuberculosis and is currently undergoing quadruple therapy. Which medication in his regimen could be causing his symptoms?
Your Answer:
Correct Answer: Ethambutol
Explanation:The standard quadruple therapy consists of ethambutol, isoniazid, pyrazinamide, and rifampicin.
Tuberculosis is a bacterial infection that can be treated with a combination of drugs. Each drug has a specific mechanism of action and can also cause side-effects. Rifampicin works by inhibiting bacterial DNA dependent RNA polymerase, which prevents the transcription of DNA into mRNA. However, it is a potent liver enzyme inducer and can cause hepatitis, orange secretions, and flu-like symptoms.
Isoniazid, on the other hand, inhibits mycolic acid synthesis. It can cause peripheral neuropathy, which can be prevented with pyridoxine (Vitamin B6). It can also cause hepatitis and agranulocytosis, but it is a liver enzyme inhibitor.
Pyrazinamide is converted by pyrazinamidase into pyrazinoic acid, which inhibits fatty acid synthase (FAS) I. However, it can cause hyperuricaemia, leading to gout, as well as arthralgia and myalgia. It can also cause hepatitis.
Finally, Ethambutol inhibits the enzyme arabinosyl transferase, which polymerizes arabinose into arabinan. However, it can cause optic neuritis, so it is important to check visual acuity before and during treatment. The dose also needs adjusting in patients with renal impairment.
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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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Sophie, a 19-year-old girl with type 1 diabetes mellitus, arrives at the emergency department with confusion, vomiting, and abdominal pain. Upon examination, she displays tachycardia and tachypnea. The medical team orders various tests, including an arterial blood gas.
The results are as follows:
pH 7.29 mmol/l
K+ 6.0 mmol/l
Glucose 15mmol/l
The doctors initiate treatment for diabetic ketoacidosis.
What ECG abnormality can be observed in relation to Sophie's potassium level?Your Answer:
Correct Answer: Tall tented T waves and flattened P waves
Explanation:When a person has hyperkalaemia, their blood has an excess of potassium which can lead to cardiac arrhythmias. One of the common ECG abnormalities seen in hyperkalaemia is tall tented T waves. Other possible ECG changes include wide QRS complexes and flattened P waves. In contrast, hypokalaemia can cause T wave depression, U waves, and tall P waves on an ECG. Delta waves are typically seen in patients with Wolfe-Parkinson-White syndrome.
ECG Findings in Hyperkalaemia
Hyperkalaemia is a condition characterized by high levels of potassium in the blood. This condition can have serious consequences on the heart, leading to abnormal ECG findings. The ECG findings in hyperkalaemia include peaked or ‘tall-tented’ T waves, loss of P waves, broad QRS complexes, sinusoidal wave pattern, and ventricular fibrillation.
The first ECG finding in hyperkalaemia is the appearance of peaked or ‘tall-tented’ T waves. This is followed by the loss of P waves, which are the small waves that represent atrial depolarization. The QRS complexes, which represent ventricular depolarization, become broad and prolonged. The sinusoidal wave pattern is a characteristic finding in severe hyperkalaemia, where the ECG tracing appears as a series of undulating waves. Finally, ventricular fibrillation, a life-threatening arrhythmia, can occur in severe hyperkalaemia.
In summary, hyperkalaemia can have serious consequences on the heart, leading to abnormal ECG findings. These findings include peaked or ‘tall-tented’ T waves, loss of P waves, broad QRS complexes, sinusoidal wave pattern, and ventricular fibrillation. It is important to recognize these ECG findings in hyperkalaemia as they can guide appropriate management and prevent life-threatening complications.
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This question is part of the following fields:
- Gastrointestinal System
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Question 17
Incorrect
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What is the net ATP production per glucose molecule during glycolysis?
Your Answer:
Correct Answer: Net production of 2 molecules of ATP per molecule glucose
Explanation:ATP Production during Glycolysis
During glycolysis, two molecules of ATP are initially used up. One molecule is utilized to convert glucose to glucose 6 phosphate, while the other is used for the conversion of fructose 6 phosphate to fructose 1,6 bisphosphate. The fructose 1,6 bisphosphate is then split into two 3-carbon molecules, each of which can generate 2 molecules of ATP. As a result, for each molecule of glucose, two molecules of ATP are consumed, and four are produced, resulting in a net gain of two molecules of ATP.
It is important to note that glycolysis does not require oxygen to function. In the absence of oxygen, the glycolysis pathway can still operate, resulting in a small net gain of ATP. However, when oxygen is available, the net ATP gain is much higher for each molecule of glucose. This is because the pyruvate generated during glycolysis can be further metabolized during the Kreb cycle and electron transfer chain.
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This question is part of the following fields:
- Clinical Sciences
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Question 18
Incorrect
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A 26-year-old male comes to the emergency department after sustaining a foot injury from a sliding tackle while playing soccer. He is a healthy young man with no notable medical history and is a non-smoker.
During the examination, it is observed that he has lost sensation in the posterolateral leg and lateral foot.
Which nerve is most likely to have been damaged?Your Answer:
Correct Answer: Sural nerve
Explanation:The sural nerve provides sensory innervation to the posterolateral leg and lateral foot, while the saphenous nerve innervates the medial aspect of the leg and foot. The lateral femoral cutaneous nerve supplies the lateral thigh.
Cutaneous Sensation in the Foot
Cutaneous sensation in the foot is the ability to feel touch, pressure, temperature, and pain on the skin of the foot. Different regions of the foot are innervated by different nerves, which are responsible for transmitting sensory information to the brain. The lateral plantar region is innervated by the sural nerve, while the dorsum (excluding the 1st web space) is innervated by the superficial peroneal nerve. The 1st web space is innervated by the deep peroneal nerve, and the extremities of the toes are innervated by the medial and lateral plantar nerves. The proximal plantar region is innervated by the tibial nerve, while the medial plantar region is innervated by the medial plantar nerve and the lateral plantar region is innervated by the lateral plantar nerve. Understanding the innervation of the foot is important for diagnosing and treating conditions that affect cutaneous sensation in this area.
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This question is part of the following fields:
- Musculoskeletal System And Skin
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Question 19
Incorrect
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A 9-month-old baby girl is brought to the clinic by her parents who recently moved from the Philippines. The baby has a noticeable mass in her abdomen, resembling a sausage shape. During questioning, the father mentions that the baby had vomited green substance a few hours ago. The baby is immediately referred to the hospital. What is the probable diagnosis?
Your Answer:
Correct Answer: Intussusception
Explanation:Understanding Intussusception
Intussusception is a medical condition where one part of the bowel folds into the lumen of the adjacent bowel, usually around the ileocecal region. This condition is most common in infants between 6-18 months old, with boys being affected twice as often as girls. Symptoms of intussusception include severe, crampy abdominal pain, inconsolable crying, vomiting, and bloodstained stool, which is a late sign. During a paroxysm, the infant will draw their knees up and turn pale, and a sausage-shaped mass may be felt in the right upper quadrant.
To diagnose intussusception, ultrasound is now the preferred method of investigation, which may show a target-like mass. Treatment for intussusception involves reducing the bowel by air insufflation under radiological control, which is now widely used first-line compared to the traditional barium enema. If this method fails, or the child has signs of peritonitis, surgery is performed. Understanding the symptoms and treatment options for intussusception is crucial for parents and healthcare professionals to ensure prompt and effective management of this condition.
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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 26-year-old woman has been diagnosed with iron deficiency and prescribed oral iron supplements. As a first-time user, she is concerned about other substances that may hinder the absorption of iron. Can you suggest any substance that can enhance the absorption of the supplement?
Your Answer:
Correct Answer: Vitamin C
Explanation:Vitamin C, also known as ascorbic acid, can assist in the absorption of iron from the gastrointestinal tract by converting Fe3+ to Fe2+. This is due to the acidic nature of vitamin C, which lowers the pH of the stomach and aids in the reduction of iron from its ferric to ferrous form. The ferrous form is more easily absorbed by the mucosal cells of the duodenum. On the other hand, milk and tea can hinder iron absorption, while fish oil has no known interactions with iron. It is recommended to take iron supplements separately from other medications to avoid any potential interactions.
Iron Metabolism: Absorption, Distribution, Transport, Storage, and Excretion
Iron is an essential mineral that plays a crucial role in various physiological processes. The absorption of iron occurs mainly in the upper small intestine, particularly the duodenum. Only about 10% of dietary iron is absorbed, and ferrous iron (Fe2+) is much better absorbed than ferric iron (Fe3+). The absorption of iron is regulated according to the body’s need and can be increased by vitamin C and gastric acid. However, it can be decreased by proton pump inhibitors, tetracycline, gastric achlorhydria, and tannin found in tea.
The total body iron is approximately 4g, with 70% of it being present in hemoglobin, 25% in ferritin and haemosiderin, 4% in myoglobin, and 0.1% in plasma iron. Iron is transported in the plasma as Fe3+ bound to transferrin. It is stored in tissues as ferritin, and the lost iron is excreted via the intestinal tract following desquamation.
In summary, iron metabolism involves the absorption, distribution, transport, storage, and excretion of iron in the body. Understanding these processes is crucial in maintaining iron homeostasis and preventing iron-related disorders.
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This question is part of the following fields:
- General Principles
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Question 21
Incorrect
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You are attending a seminar on adolescent eating disorders.
What hormonal alteration is common in post-pubertal teenagers with extreme undernourishment?Your Answer:
Correct Answer: Hypogonadotrophic hypogonadism
Explanation:Endocrine System Adaptations during Starvation
During periods of starvation or severe malnutrition, the body undergoes various adaptations to cope with reduced food intake. One of the systems affected is the endocrine system, which experiences several changes. Glucagon levels increase, stimulating gluconeogenesis, while aldosterone, epinephrine, norepinephrine, and growth hormone levels also rise. Conversely, insulin production decreases, and there is a reduction in free and total T3, contributing to a lower metabolic rate. Prolonged starvation can also lead to a decrease in free T4. Hypogonadotrophic hypogonadism may occur, causing infertility, menstrual disturbances, amenorrhea, premature ovarian failure, and osteoporosis in women. Men may experience infertility, erectile dysfunction, and osteoporosis.
In summary, the endocrine system undergoes significant adaptations during starvation or severe malnutrition. These changes include alterations in hormone levels, such as increased glucagon and decreased insulin production, as well as reduced free and total T3. Hypogonadotrophic hypogonadism may also occur, leading to various reproductive and bone-related issues. these adaptations is crucial in managing individuals experiencing starvation or malnutrition.
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This question is part of the following fields:
- Clinical Sciences
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Question 22
Incorrect
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A man in his early fifties comes to the clinic complaining of vomiting undigested food for the past few weeks. He reports no abdominal pain, changes in bowel habits, fever, or vertigo. He has type 2 diabetes that is not well controlled. What could be the probable reason for his vomiting?
Your Answer:
Correct Answer: Gastric paresis
Explanation:The correct answer is gastric paresis, which is a type of autonomic neuropathy commonly linked to type 2 diabetes. Its symptoms include vomiting undigested food due to the stomach’s inability to digest it properly.
Gastroenteritis, on the other hand, is characterized by vomiting and diarrhea, along with fever and diffuse abdominal pain. It is caused by an infection.
Peptic ulcers typically cause upper abdominal pain and can lead to haematemesis, which is not present in this patient’s case.
Vestibular neuritis may also cause vomiting, but it is usually accompanied by severe vertigo and nystagmus.
Autonomic Neuropathy: Causes and Features
Autonomic neuropathy is a condition that affects the autonomic nervous system, which controls involuntary bodily functions such as heart rate, blood pressure, and sweating. The features of autonomic neuropathy include impotence, inability to sweat, and postural hypotension, which is a sudden drop in blood pressure upon standing up. Other symptoms include a loss of decrease in heart rate following deep breathing and dilated pupils following adrenaline instillation.
There are several causes of autonomic neuropathy, including diabetes, Guillain-Barre syndrome, multisystem atrophy (MSA), Shy-Drager syndrome, Parkinson’s disease, and infections such as HIV, Chagas’ disease, and neurosyphilis. Certain medications, such as antihypertensives and tricyclics, can also cause autonomic neuropathy. In rare cases, a craniopharyngioma, a type of brain tumor, can lead to autonomic neuropathy.
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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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A 15-year-old girl comes to the clinic with her father. She has lost 10kg in the last 2 months. Recently, her father found her vomiting in the bathroom. The girl admits to struggling with her self-esteem and body image, and has been inducing vomiting after meals. She feels anxious in social situations. During the examination, you observe swelling above the angle of the mandible, indicating parotid gland enlargement. Which nerve supplies the parasympathetic fibers to the parotid gland?
Your Answer:
Correct Answer: Glossopharyngeal nerve
Explanation:The correct answer is the glossopharyngeal nerve, which is the ninth cranial nerve. It provides parasympathetic innervation to the parotid gland and carries taste and sensation from the posterior third of the tongue, pharyngeal wall, tonsils, middle ear, external auditory canal, and auricle. It also supplies baroreceptors and chemoreceptors of the carotid sinus.
The facial nerve, the seventh cranial nerve, supplies the muscles of facial expression, taste from the anterior two-thirds of the tongue, and sensation from parts of the external acoustic meatus, auricle, and retro-auricular area. It also provides parasympathetic fibers to the submandibular gland, sublingual gland, nasal glands, and lacrimal glands.
The hypoglossal nerve, the twelfth cranial nerve, supplies the intrinsic muscles of the tongue and all but one of the extrinsic muscles of the tongue.
The greater auricular nerve is a superficial cutaneous branch of the cervical plexus that supplies sensation to the capsule of the parotid gland, skin overlying the gland, and skin over the mastoid process and outer ear.
The mandibular nerve, the third division of the trigeminal nerve, carries sensory and motor fibers. It carries sensation from the lower lip, lower teeth and gingivae, chin, and jaw. It also supplies motor innervation to the muscles of mastication, mylohyoid, the anterior belly of digastric, tensor veli palatini, and tensor tympani.
The patient in the question has sialadenosis, a benign, non-inflammatory enlargement of a salivary gland, in the parotid glands, which can be caused by bulimia nervosa.
The parotid gland is located in front of and below the ear, overlying the mandibular ramus. Its salivary duct crosses the masseter muscle, pierces the buccinator muscle, and drains adjacent to the second upper molar tooth. The gland is traversed by several structures, including the facial nerve, external carotid artery, retromandibular vein, and auriculotemporal nerve. The gland is related to the masseter muscle, medial pterygoid muscle, superficial temporal and maxillary artery, facial nerve, stylomandibular ligament, posterior belly of the digastric muscle, sternocleidomastoid muscle, stylohyoid muscle, internal carotid artery, mastoid process, and styloid process. The gland is supplied by branches of the external carotid artery and drained by the retromandibular vein. Its lymphatic drainage is to the deep cervical nodes. The gland is innervated by the parasympathetic-secretomotor, sympathetic-superior cervical ganglion, and sensory-greater auricular nerve. Parasympathetic stimulation produces a water-rich, serous saliva, while sympathetic stimulation leads to the production of a low volume, enzyme-rich saliva.
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This question is part of the following fields:
- Gastrointestinal System
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Question 24
Incorrect
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A 20-year-old man has a tonsillectomy due to recurrent acute tonsillitis. During recovery, he experiences a postoperative bleeding. Which vessel is the most probable cause of the bleeding?
Your Answer:
Correct Answer: External palatine vein
Explanation:If the external palatine vein is harmed during tonsillectomy, it can result in reactionary bleeding and is located adjacent to the tonsil.
Tonsil Anatomy and Tonsillitis
The tonsils are located in the pharynx and have two surfaces, a medial and lateral surface. They vary in size and are usually supplied by the tonsillar artery and drained by the jugulodigastric and deep cervical nodes. Tonsillitis is a common condition that is usually caused by bacteria, with group A Streptococcus being the most common culprit. It can also be caused by viruses. In some cases, tonsillitis can lead to the development of an abscess, which can distort the uvula. Tonsillectomy is recommended for patients with recurrent acute tonsillitis, suspected malignancy, or enlargement causing sleep apnea. The preferred technique for tonsillectomy is dissection, but it can be complicated by hemorrhage, which is the most common complication. Delayed otalgia may also occur due to irritation of the glossopharyngeal nerve.
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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 68-year-old man arrives at the emergency department complaining of intense abdominal pain that spreads to his back. His medical history shows that he has an abdominal aortic aneurysm. During a FAST scan, it is discovered that the abdominal aorta is widely dilated, with the most significant expansion occurring at the point where it divides into the iliac arteries. What vertebral level corresponds to the location of the most prominent dilation observed in the FAST scan?
Your Answer:
Correct Answer: L4
Explanation:The abdominal aorta divides into two branches at the level of the fourth lumbar vertebrae. At the level of T12, the coeliac trunk arises, while at L1, the superior mesenteric artery branches off. The testicular artery and renal artery originate at L2, and at L3, the inferior mesenteric artery is formed.
The aorta is a major blood vessel that carries oxygenated blood from the heart to the rest of the body. At different levels along the aorta, there are branches that supply blood to specific organs and regions. These branches include the coeliac trunk at the level of T12, which supplies blood to the stomach, liver, and spleen. The left renal artery, at the level of L1, supplies blood to the left kidney. The testicular or ovarian arteries, at the level of L2, supply blood to the reproductive organs. The inferior mesenteric artery, at the level of L3, supplies blood to the lower part of the large intestine. Finally, at the level of L4, the abdominal aorta bifurcates, or splits into two branches, which supply blood to the legs and pelvis.
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This question is part of the following fields:
- Cardiovascular System
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Question 26
Incorrect
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A 27-year-old Afro-Caribbean woman visits her GP with concerns about well-defined patches of significantly lighter skin. At first, this was only on her hands, but she has recently noticed similar patches on her face. She has a medical history of Hashimoto's thyroid disease and takes levothyroxine.
During the examination, the GP observes well-demarcated areas of hypopigmentation on her hands, arms, and face. Based on the most probable diagnosis, which layer of the epidermis is affected?Your Answer:
Correct Answer: Stratum germinativum
Explanation:The deepest layer of the epidermis is called the stratum germinativum, which is responsible for producing keratinocytes and contains melanocytes. Vitiligo, a condition characterized by depigmented patches, affects this layer by causing the loss of melanocytes.
The stratum corneum is the topmost layer of the epidermis, consisting of dead cells filled with keratin.
The stratum granulosum is where keratin production occurs in the epidermis.
The stratum lucidum is only present in the palms of the hands and soles of the feet.
The Layers of the Epidermis
The epidermis is the outermost layer of the skin and is made up of a stratified squamous epithelium with a basal lamina underneath. It can be divided into five layers, each with its own unique characteristics. The first layer is the stratum corneum, which is made up of flat, dead, scale-like cells filled with keratin. These cells are continually shed and replaced with new ones. The second layer, the stratum lucidum, is only present in thick skin and is a clear layer. The third layer, the stratum granulosum, is where cells form links with their neighbors. The fourth layer, the stratum spinosum, is the thickest layer of the epidermis and is where squamous cells begin keratin synthesis. Finally, the fifth layer is the stratum germinativum, which is the basement membrane and is made up of a single layer of columnar epithelial cells. This layer gives rise to keratinocytes and contains melanocytes. Understanding the layers of the epidermis is important for understanding the structure and function of the skin.
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This question is part of the following fields:
- Musculoskeletal System And Skin
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Question 27
Incorrect
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A 65-year-old man presents to the emergency department with a two-day history of rectal bleeding. He has had diarrhoea eight times in the past 24 hours with visible blood mixed with stool. He also complains of nausea and abdominal pain. His past medical history includes ulcerative colitis, hypertension and type 2 diabetes. He is currently taking mesalazine enteric coated 800 mg twice daily, amlodipine 10mg once daily and metformin 500mg twice daily.
Upon examination, he appears pale and has a temperature of 38ºC. His heart rate is 108/min with a blood pressure of 112/74mmHg. Abdominal exam shows generalised tenderness and guarding, but no rebound tenderness. His blood results are as follows:
- Hb 137 g/L Male: (135-180)
- Platelets 550 * 109/L (150 - 400)
- WBC 14.1 * 109/L (4.0 - 11.0)
- Na+ 144 mmol/L (135 - 145)
- K+ 3.4 mmol/L (3.5 - 5.0)
- Urea 8.4 mmol/L (2.0 - 7.0)
- Creatinine 134 µmol/L (55 - 120)
- CRP 110 mg/L (< 5)
- ESR 45 mm/hr Men: < (age / 2)
What is the most appropriate next step in managing this patient?Your Answer:
Correct Answer: Urgent hospital admission
Explanation:A severe flare-up of ulcerative colitis necessitates urgent hospital admission for IV corticosteroids. This is the correct answer as the patient’s symptoms indicate a severe flare-up according to Truelove and Witts’ severity index. The patient is experiencing more than 6 bowel movements per day with systemic upset (fever and tachycardia) and an ESR of over 30. NICE recommends urgent hospital admission for assessment and treatment with IV corticosteroids.
If the exacerbation is mild or moderate, oral corticosteroids may be appropriate. Therefore, send home with a course of oral corticosteroids is an incorrect answer.
Gastroenteritis requires oral rehydration therapy, but this patient’s symptoms suggest an exacerbation of ulcerative colitis. Therefore, oral rehydration therapy is an incorrect answer.
Loperamide may be used in the management of ulcerative colitis, but urgent hospital assessment is necessary due to the patient’s hemodynamic compromise. Therefore, send home with loperamide and send home with safety net advice alone are incorrect answers.
Ulcerative colitis can be managed through inducing and maintaining remission. The severity of the condition is classified as mild, moderate, or severe based on the number of stools per day, the amount of blood, and the presence of systemic upset. Treatment for mild-to-moderate cases of proctitis involves using topical aminosalicylate, while proctosigmoiditis and left-sided ulcerative colitis may require a combination of oral and topical medications. Severe cases should be treated in a hospital setting with intravenous steroids or ciclosporin.
To maintain remission, patients with proctitis and proctosigmoiditis may use topical aminosalicylate alone or in combination with an oral aminosalicylate. Those with left-sided and extensive ulcerative colitis may require a low maintenance dose of an oral aminosalicylate. Patients who have experienced severe relapses or multiple exacerbations may benefit from oral azathioprine or mercaptopurine. Methotrexate is not recommended for UC management, but probiotics may help prevent relapse in mild to moderate cases.
In summary, the management of ulcerative colitis involves a combination of inducing and maintaining remission. Treatment options vary depending on the severity and location of the condition, with mild-to-moderate cases typically treated with topical aminosalicylate and severe cases requiring hospitalization and intravenous medication. Maintaining remission may involve using a combination of oral and topical medications or a low maintenance dose of an oral aminosalicylate. While methotrexate is not recommended, probiotics may be helpful in preventing relapse in mild to moderate cases.
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This question is part of the following fields:
- Gastrointestinal System
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Question 28
Incorrect
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A 45-year-old man undergoes a routine medical exam and his blood pressure is measured at 155/95 mmHg, which is unusual as it has been normal for the past five annual check-ups. What could be the reason for this sudden change?
Your Answer:
Correct Answer: An undersized blood pressure cuff
Explanation:Ensuring Accurate Blood Pressure Measurements
Blood pressure is a crucial physiological measurement in medicine, and it is essential to ensure that the values obtained are accurate. Inaccurate readings can occur due to various reasons, such as using the wrong cuff size, incorrect arm positioning, and unsupported arms. For instance, using a bladder that is too small can lead to an overestimation of blood pressure, while using a bladder that is too large can result in an underestimation of blood pressure. Similarly, lowering the arm below heart level can lead to an overestimation of blood pressure, while elevating the arm above heart level can result in an underestimation of blood pressure.
It is recommended to measure blood pressure in both arms when considering a diagnosis of hypertension. If there is a difference of more than 20 mmHg between the readings obtained from both arms, the measurements should be repeated. If the difference remains greater than 20 mmHg, subsequent blood pressures should be recorded from the arm with the higher reading. By following these guidelines, healthcare professionals can ensure that accurate blood pressure measurements are obtained, which is crucial for making informed medical decisions.
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This question is part of the following fields:
- Cardiovascular System
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Question 29
Incorrect
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A 17-year-old girl is scheduled for surgery to remove a thyroglossal cyst, which will involve removing a part of the hyoid bone. Can you identify the cervical level where the hyoid bone is located?
Your Answer:
Correct Answer: C3
Explanation:Levels of Hyoid Bone, Thyroid Cartilage, and Cricoid Cartilage in the Neck
The neck contains several important structures, including the hyoid bone, thyroid cartilage, and cricoid cartilage. These structures are located at specific levels in the cervical spine. The hyoid bone is situated at the level of the third cervical vertebrae (C3). The thyroid cartilage, which forms the Adam’s apple in males, is located at the level of the fourth and fifth cervical vertebrae (C4 and C5). Finally, the cricoid cartilage, which is the only complete ring of cartilage in the trachea, is situated at the level of the sixth cervical vertebrae (C6). the location of these structures is important for medical professionals who may need to perform procedures or surgeries in the neck region.
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This question is part of the following fields:
- Clinical Sciences
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Question 30
Incorrect
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A 65-year-old woman comes to the COPD clinic complaining of increasing breathlessness over the past 3 months. She is currently receiving long-term oxygen therapy at home.
During the examination, the patient's face appears plethoric, but there is no evidence of dyspnea at rest.
The patient's FEV1/FVC ratio remains unchanged at 0.4, and her peak flow is 50% of the predicted value. However, her transfer factor is unexpectedly elevated.
What could be the possible cause of this unexpected finding?Your Answer:
Correct Answer: Polycythaemia
Explanation:The transfer factor is typically low in most conditions that impair alveolar diffusion, except for polycythaemia, asthma, haemorrhage, and left-to-right shunts, which can cause an increased transfer of carbon monoxide. In this case, the patient’s plethoric facies suggest polycythaemia as the cause of their increased transfer factor. It’s important to note that exacerbations of COPD, pneumonia, and pulmonary fibrosis typically result in a low transfer factor, not an increased one.
Understanding Transfer Factor in Lung Function Testing
The transfer factor is a measure of how quickly a gas diffuses from the alveoli into the bloodstream. This is typically tested using carbon monoxide, and the results can be given as either the total gas transfer (TLCO) or the transfer coefficient corrected for lung volume (KCO). A raised TLCO may be caused by conditions such as asthma, pulmonary haemorrhage, left-to-right cardiac shunts, polycythaemia, hyperkinetic states, male gender, or exercise. On the other hand, a lower TLCO may be indicative of pulmonary fibrosis, pneumonia, pulmonary emboli, pulmonary oedema, emphysema, anaemia, or low cardiac output.
KCO tends to increase with age, and certain conditions may cause an increased KCO with a normal or reduced TLCO. These conditions include pneumonectomy/lobectomy, scoliosis/kyphosis, neuromuscular weakness, and ankylosis of costovertebral joints (such as in ankylosing spondylitis). Understanding transfer factor is important in lung function testing, as it can provide valuable information about a patient’s respiratory health and help guide treatment decisions.
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This question is part of the following fields:
- Respiratory System
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