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  • Question 1 - Regarding the flexor digitorum profundus muscle, which of the following is true? ...

    Incorrect

    • Regarding the flexor digitorum profundus muscle, which of the following is true?

      Your Answer: The medial aspect of the muscle is innervated by the median nerve

      Correct Answer: The medial aspect of the muscle is innervated by the ulnar nerve

      Explanation:

      Flexor digitorum profundus is a fusiform muscle located deep within the anterior (flexor) compartment of the forearm. Along with the flexor pollicis longus and pronator quadratus muscles, it comprises the deep flexor compartment of the forearm.

      Flexor digitorum profundus has a dual innervation:

      (1) The medial part of the muscle, that inserts to the fourth and fifth digits, is innervated by the ulnar nerve (C8-T1);

      (2) The lateral part, that inserts to the second and third digits, is innervated by the median nerve, via anterior interosseous branch (C8-T1).

    • This question is part of the following fields:

      • Anatomy
      • Upper Limb
      3
      Seconds

  • Question 2 - A 39-year-old guy comes to the emergency room with a persistent nasal bleed....

    Incorrect

    • A 39-year-old guy comes to the emergency room with a persistent nasal bleed. You suspect the bleeding is coming from Little's area based on your examination. Which of the blood vessels listed below is most likely to be involved:

      Your Answer:

      Correct Answer: Sphenopalatine and superior labial arteries

      Explanation:

      The Kiesselbach plexus is a vascular network formed by five arteries that supply oxygenated blood to the nasal septum, which refers to the wall separating the right and left sides of the nose. The five arteries that form the Kiesselbach plexus: the sphenopalatine artery, which branches from the maxillary artery originating behind the jawbone; the anterior ethmoidal artery, which branches from the ophthalmic artery behind the eye; the posterior ethmoidal artery, which also branches from the ophthalmic artery; the septal branch of the superior labial artery, which is a branch of the facial artery supplying blood to all of the superficial features of the face; and finally, the greater palatine artery, which is a terminal branch of the maxillary artery.

    • This question is part of the following fields:

      • Anatomy
      • Head And Neck
      0
      Seconds

  • Question 3 - Which of the following statements is correct with regards to heparin-induced thrombocytopaenia (HIT)?...

    Incorrect

    • Which of the following statements is correct with regards to heparin-induced thrombocytopaenia (HIT)?

      Your Answer:

      Correct Answer: HIT typically develops 5-10 days after starting heparin.

      Explanation:

      Heparin-induced thrombocytopenia (HIT) is a prothrombotic disorder caused by antibodies that recognize complexes of platelet factor 4 (PF4) and heparin. HIT is frequently considered in the differential diagnosis of thrombocytopenia occurring in patients on heparin therapy. HIT is a challenging diagnosis because of routine heparin use in hospitalized patients, the common occurrence of thrombocytopenia. The process of heparin dependent IgG antibodies binding to heparin/platelet factor 4 complexes activates platelets and produces a hypercoagulable state. This syndrome typically develops 5-10 days (range 4-15 days) after heparin is commenced. It can occur with unfractionated heparin, low molecular weight heparin, or, rarely, fondaparinux. The diagnosis of HIT requires the combination of a compatible clinical picture and laboratory confirmation of the presence of heparin dependent platelet activating HIT antibodies. Discontinuation of heparin alone or initiation of a vitamin K antagonist alone like warfarin, is not sufficient to stop the development of thrombosis in patients with acute HIT. If there is moderate clinical suspicion for HIT, all sources of heparin must be discontinued and there must be consideration of anticoagulant treatment with a non-heparin drug.

    • This question is part of the following fields:

      • Cardiovascular
      • Pharmacology
      0
      Seconds

  • Question 4 - All of the following single clinical risk groups is considered eligible to receive...

    Incorrect

    • All of the following single clinical risk groups is considered eligible to receive the seasonal influenza vaccination, except:

      Your Answer:

      Correct Answer: Patients with hypertension

      Explanation:

      The following is the list of all the health and age factors that are known to increase a person’s risk of getting serious complications from flu:
      – Adults 65 years and older
      – Children younger than 2 years old
      – Asthma
      – Neurological and neurodevelopmental conditions
      – Blood disorders (such as sickle cell disease)
      – Chronic lung disease (such as chronic obstructive pulmonary disease [COPD] and cystic fibrosis)
      – Endocrine disorders (such as diabetes mellitus)
      – Heart disease (such as congenital heart disease, congestive heart failure and coronary artery disease)
      – Kidney diseases
      – Liver disorders
      – Metabolic disorders (such as inherited metabolic disorders and mitochondrial disorders)
      – People who are obese with a body mass index [BMI] of 40 or higher
      – People younger than 19 years old on long-term aspirin- or salicylate-containing medications.
      – People with a weakened immune system due to disease (such as people with HIV or AIDS, or some cancers such as leukaemia) or medications (such as those receiving chemotherapy or radiation treatment for cancer, or persons with chronic conditions requiring chronic corticosteroids or other drugs that suppress the immune system)
      – People who have had a stroke
      – Pregnant people and people up to 2 weeks after the end of pregnancy
      – People who live in nursing homes and other long-term care facilities

    • This question is part of the following fields:

      • Microbiology
      • Principles Of Microbiology
      0
      Seconds

  • Question 5 - The functional residual capacity (FRC) will be increased in which of the following:...

    Incorrect

    • The functional residual capacity (FRC) will be increased in which of the following:

      Your Answer:

      Correct Answer: Emphysema

      Explanation:

      Factors increasing FRC:
      Emphysema
      Air trapping in asthma
      Ageing (due to loss of elastic properties)
      Increasing height of patient

    • This question is part of the following fields:

      • Physiology
      • Respiratory
      0
      Seconds

  • Question 6 - A patient presents with a laceration on his hand and wrist that has...

    Incorrect

    • A patient presents with a laceration on his hand and wrist that has cut the nerve that innervates opponens pollicis.
      The opponens pollicis muscle is innervated by which of the following nerves? Select ONE answer only.

      Your Answer:

      Correct Answer: The recurrent branch of the median nerve

      Explanation:

      Opponens pollicis is a small, triangular muscle that forms part of the thenar eminence. It originates from the flexor retinaculum and the tubercle of trapezium bone and inserts into the whole length of the first metacarpal bone on its radial side.
      Opponens pollicis is innervated by the recurrent branch of the median nerve and receives its blood supply from the superficial palmar arch.
      The main action of opponens pollicis is to flex the first metacarpal bone at the carpometacarpal joint, which opposes the thumb towards the centre of the palm. It also medially rotates the first metacarpal bone at the carpometacarpal joint.

    • This question is part of the following fields:

      • Anatomy
      • Upper Limb
      0
      Seconds

  • Question 7 - Which of the following is a well recognised adverse effect of prochlorperazine: ...

    Incorrect

    • Which of the following is a well recognised adverse effect of prochlorperazine:

      Your Answer:

      Correct Answer: Acute dystonic reaction

      Explanation:

      Adverse actions include anticholinergic effects such as drowsiness, dry mouth, and blurred vision, extrapyramidal effects, and postural hypotension. Phenothiazines can all induce acute dystonic reactions such as facial and skeletal muscle spasms and oculogyric crises; children (especially girls, young women, and those under 10 kg) are particularly susceptible.

    • This question is part of the following fields:

      • Central Nervous System
      • Pharmacology
      0
      Seconds

  • Question 8 - Which of the following is NOT a typical effect caused by adrenaline: ...

    Incorrect

    • Which of the following is NOT a typical effect caused by adrenaline:

      Your Answer:

      Correct Answer: Bronchoconstriction

      Explanation:

      Actions of adrenaline:
      Cardiovascular system
      – Increased rate and force of cardiac contraction
      – Vasoconstriction of vessels in skin, mucous membranes and splanchnic bed
      – Vasodilation of skeletal muscle vessels
      – Increased cardiac output and blood pressure
      Respiratory system
      – Bronchodilation
      – Increased ventilation rate
      Gastrointestinal system
      – Smooth muscle relaxation
      – Contraction of sphincters
      – Metabolism
      – Decreased insulin release
      – Increased glucagon release
      – Increased thermogenesis
      – Increased glycolysis
      – Increased lipolysis
      Eye
      – Pupillary dilation

    • This question is part of the following fields:

      • Endocrine
      • Physiology
      0
      Seconds

  • Question 9 - Regarding benzodiazepines, which of the following statements is INCORRECT: ...

    Incorrect

    • Regarding benzodiazepines, which of the following statements is INCORRECT:

      Your Answer:

      Correct Answer: Diazepam is a short-acting benzodiazepine.

      Explanation:

      Diazepam is used to produce mild sedation with amnesia. It is a long-acting drug with active metabolites and a second period of drowsiness can occur several hours after its administration. Midazolam is a water-soluble benzodiazepine that is often used in preference to intravenous diazepam; recovery is faster than from diazepam, but may be significantly longer in the elderly, in patients with a low cardiac output, or after repeated dosing. Midazolam is associated with profound sedation when high doses are given intravenously or when it is used with certain other drugs.

    • This question is part of the following fields:

      • Anaesthesia
      • Pharmacology
      0
      Seconds

  • Question 10 - A 25 year old man presents to the emergency room with abdominal pain,...

    Incorrect

    • A 25 year old man presents to the emergency room with abdominal pain, vomiting and constipation. A CT scan is done which is suggestive of Meckel's diverticulum. Where does the blood supply of the Meckel's diverticulum originate?

      Your Answer:

      Correct Answer: Superior mesenteric artery

      Explanation:

      Meckel’s diverticulum has certain classic characteristics.
      1. It lies on the antimesenteric border of the middle-to-distal ileum
      2. It is approximately 2 feet proximal to the ileocaecal junction
      3. It appears as a blind-ended tubular outpouching of bowel
      4. It is about 2 inches long,
      5. It occurs in about 2% of the population,
      6. It may contain two types of ectopic tissue (gastric and pancreatic).
      7. The diverticulum is supplied by the superior mesenteric artery.
      8. Proximal to the major duodenal papilla the duodenum is supplied by the gastroduodenal artery (branch of the coeliac trunk)
      9. Distal to the major duodenal papilla it is supplied by the inferior pancreaticoduodenal artery (branch of superior mesenteric artery).
      10. The arterial supply to the jejunoileum is from the superior mesenteric artery.

    • This question is part of the following fields:

      • Abdomen
      • Anatomy
      0
      Seconds

  • Question 11 - Na+ is reabsorbed via the Na+/K+/2Cl-symporter in which part of the loop of...

    Incorrect

    • Na+ is reabsorbed via the Na+/K+/2Cl-symporter in which part of the loop of Henle?

      Your Answer:

      Correct Answer: Thick ascending limb

      Explanation:

      In the thick ascending limb is the part of the loop of Henle in which there is active reabsorption of Na+and Cl- ions from the tubular fluid. This occurs via the Na+/K+/2Cl-symporter on the apical membrane.
      This mechanism is by:
      1. Na+ions are transported across the basolateral membrane by Na+pumps and the Cl-ions by diffusion.
      2. K+leaks back into the tubular fluid via apical ROMK K+channels which creates a positive charge.
      3. This positive charge drives the reabsorption of cations (Na+, K+, Ca2+, Mg2+) through paracellular pathways.
      4. Due to the thick ascending limb being impermeable to water, the tubular fluid osmolality is reduced by ion reabsorption, the interstitial fluid osmolality is increased, and an osmotic difference is created.

    • This question is part of the following fields:

      • Physiology
      • Renal
      0
      Seconds

  • Question 12 - A patient who is taking ramipril for high blood pressure complains of a...

    Incorrect

    • A patient who is taking ramipril for high blood pressure complains of a dry persistent cough. What is the mechanism of cough in ACE inhibitor therapy:

      Your Answer:

      Correct Answer: Decreased bradykinin breakdown

      Explanation:

      Blocking ACE also diminishes the breakdown of the potent vasodilator bradykinin which is the cause of the persistent dry cough. Angiotensin-II receptor blockers do not have this effect, therefore they are useful alternative for patients who have to discontinue an ACE inhibitor because of persistent cough.

    • This question is part of the following fields:

      • Cardiovascular
      • Pharmacology
      0
      Seconds

  • Question 13 - Regarding hepatitis B, which of the following statements is CORRECT: ...

    Incorrect

    • Regarding hepatitis B, which of the following statements is CORRECT:

      Your Answer:

      Correct Answer: Chronic hepatitis B infection is indicated by the persistence of HBsAg for more than 6 months.

      Explanation:

      Chronic hepatitis B infection is indicated by the persistence of HBsAg for more than 6 months. Hepatitis B has a long incubation period of about 2 – 6 months. Hepatitis B vaccine has recently been introduced to the routine childhood immunisation schedule – given at 2, 3 and 4 months. It is also given to babies born to hepatitis B infected mothers at birth, four weeks and 12 months old. Treatment of acute hepatitis is supportive. Treatment with antivirals should be considered in chronic infection as responders have a reduced risk of liver damage and liver cancer in the long term.

    • This question is part of the following fields:

      • Microbiology
      • Pathogens
      0
      Seconds

  • Question 14 - Which of the following is the most likely causative organism of acute epiglottitis...

    Incorrect

    • Which of the following is the most likely causative organism of acute epiglottitis in a 6 year old?

      Your Answer:

      Correct Answer: Streptococcus pneumoniae

      Explanation:

      Since the introduction of the HIB vaccine, most cases of acute epiglottitis are now caused by Streptococcus spp. The condition is now rare in children.

    • This question is part of the following fields:

      • Microbiology
      • Specific Pathogen Groups
      0
      Seconds

  • Question 15 - A 35 year old man presents with a deep laceration to the proximal...

    Incorrect

    • A 35 year old man presents with a deep laceration to the proximal part of the forearm. On further assessment, the patient is unable to flex the metacarpophalangeal joints and interphalangeal joints of the index, middle finger and the thumb.

      The ring and little fingers are intact but there is weakness at the proximal interphalangeal joint.

      There is also loss of sensation over the lateral palm and the palmar surface of the lateral three and a half fingers.

      Which of these nerve(s) has most likely been affected?

      Your Answer:

      Correct Answer: Median nerve

      Explanation:

      A median nerve injury affecting the extrinsic and intrinsic muscles of the hand will present with:

      Loss of sensation to the lateral palm and the lateral three and a half fingers.

      Weakness of flexion at the metacarpophalangeal joints of the index and middle finger. This is because of paralysis of the lateral two lumbricals.

      Weakness of flexion of the proximal interphalangeal joints of all four fingers due to paralysis of the flexor digitorum superficialis

      Weakness of flexion at the distal interphalangeal joints of the index and middle finger following paralysis of the lateral half of the flexor digitorum profundus.
      Weakness of thumb flexion, abduction and opposition due to paralysis of the flexor pollicis longus and thenar muscles

    • This question is part of the following fields:

      • Anatomy
      • Upper Limb
      0
      Seconds

  • Question 16 - The normal range of arterial HCO3- is: ...

    Incorrect

    • The normal range of arterial HCO3- is:

      Your Answer:

      Correct Answer: 24 - 30 mmol/L

      Explanation:

      Normal ranges:
      pH = 7.35 – 7.45
      pO2(on air) = 11 -14 kPa
      pCO2= 4.5 – 6.0 kPa
      HCO3-= 24 – 30 mmol/L
      BE = +/- 2 mmol/L

    • This question is part of the following fields:

      • Physiology
      • Renal
      0
      Seconds

  • Question 17 - Regarding cortical areas, which one is found in the posterior part of the...

    Incorrect

    • Regarding cortical areas, which one is found in the posterior part of the inferior frontal gyrus?

      Your Answer:

      Correct Answer: Broca’s area

      Explanation:

      Broca’s area is involved in the expressive aspects of spoken and written language (production of sentences constrained by the rules of grammar and syntax). It corresponds to the opercular and triangular parts of the inferior frontal gyrus (BA 44 and 45). These areas are defined by two rami (branches) of the lateral sulcus (one ascending, one horizontal) which ‘slice into’ the inferior frontal gyrus. In keeping with its role in speech and language, Broca’s area is immediately anterior to the motor and premotor representations of the face, tongue and larynx. A homologous area in the opposite hemisphere is involved in non-verbal communication such as facial expression, gesticulation and modulation of the rate, rhythm and intonation of speech.

    • This question is part of the following fields:

      • Anatomy
      • Central Nervous System
      0
      Seconds

  • Question 18 - Bordetella pertussis causes which of the following infectious diseases: ...

    Incorrect

    • Bordetella pertussis causes which of the following infectious diseases:

      Your Answer:

      Correct Answer: Whooping cough

      Explanation:

      Bordetella pertussis causes whooping cough. Acute bronchiolitis is typically caused by respiratory syncytial virus. Parainfluenza virus is the most common cause of croup. Acute epiglottitis is usually caused by an infection with Haemophilus influenzae type b (Hib) bacteria. The common cold may be caused by a number of viruses including rhinovirus and coronavirus.

    • This question is part of the following fields:

      • Microbiology
      • Pathogens
      0
      Seconds

  • Question 19 - Which of the following hormones is dysfunctional in diabetes insipidus: ...

    Incorrect

    • Which of the following hormones is dysfunctional in diabetes insipidus:

      Your Answer:

      Correct Answer: Antidiuretic hormone

      Explanation:

      Diabetes insipidus (DI) may result from a deficiency of ADH secretion (cranial DI) or from an inappropriate renal response to ADH (nephrogenic DI). As a result, fluid reabsorption at the kidneys is impaired, resulting in large amounts of hypotonic, dilute urine being passed with a profound unquenchable polydipsia.
      The biochemical hallmarks of DI are:
      High plasma osmolality (> 295 mOsm/kg)
      Low urine osmolality (< 300 mOsm/kg)
      Hypernatraemia (> 145 mmol/L)
      High urine volume

    • This question is part of the following fields:

      • Endocrine
      • Physiology
      0
      Seconds

  • Question 20 - A 45-old woman is on several medications and being treated for epilepsy and...

    Incorrect

    • A 45-old woman is on several medications and being treated for epilepsy and bipolar disorder. In the ward rounds, you are asked to examine her in detail and discover she has a noticeable tremor. You believe that one of her medications may be responsible for this new onset tremor.

      Which of the following medications is least likely to be responsible for this tremor?

      Your Answer:

      Correct Answer: Carbamazepine

      Explanation:

      The only medication that does not commonly cause tremors is carbamazepine.

      The other drugs present with the following types of tremors as a side effect to their usage:
      1. Sodium valproate – Postural tremor is most common, but a resting tremor can also occur. Approximately 25% of patients taking sodium valproate are found to develop a tremor within 12 months of starting therapy.
      2. Lithium – fine hand tremor is very commonly seen and reported in as many as 50% of patients during the first week of therapy. The tremor tends to reduce with time and is only present in around 5% of patients taking the medication two years or longer.
      3. Atypical antipsychotics, such as olanzapine and quetiapine – tremor and limb shakiness.

    • This question is part of the following fields:

      • CNS Pharmacology
      • Pharmacology
      0
      Seconds

  • Question 21 - A 33 year old female patient presents to emergency room with some symptoms...

    Incorrect

    • A 33 year old female patient presents to emergency room with some symptoms that she thinks might be due to a drug that she has recently started. She was started on hyoscine butyl bromide for symptomatic relief of irritable bowel syndrome. The least likely expected side effect of this drug in this patient is:

      Your Answer:

      Correct Answer: Diarrhoea

      Explanation:

      One of the commonest antispasmodic medications that is used is hyoscine butylbromide. It is an antimuscarinic and typical side effects of this class of drugs include:
      – dilation of pupils with loss of accommodation (cycloplegia)
      -photophobia resulting in blurred vision (Blind as a bat)
      -dry mouth, eyes and skin (Dry as a bone),
      -elevated temperature (Hot as a hare)
      -skin flushing (Red as a beet)
      -confusion or agitation particularly in the elderly (Mad as a hatter)
      -reduced bronchial secretions
      -transient bradycardia followed by tachycardia, palpitation and arrhythmias
      -urinary retention and/or constipation

    • This question is part of the following fields:

      • Gastrointestinal
      • Pharmacology
      0
      Seconds

  • Question 22 - A 45-year-old woman presents with persistent palpitations for the past two days. She...

    Incorrect

    • A 45-year-old woman presents with persistent palpitations for the past two days. She has a good haemodynamic balance. An ECG is performed, which reveals that she has atrial flutter. The patient is examined by a cardiology registrar, who recommends using a 'rate control' strategy while she waits for cardioversion.

      Which of the drugs listed below is the best fit for this strategy?

      Your Answer:

      Correct Answer: Bisoprolol

      Explanation:

      In atrial flutter, ventricular rate control is usually used as a stopgap measure until sinus rhythm can be restored. A beta-blocker (such as bisoprolol), diltiazem, or verapamil can be used to lower the heart rate.

      Electrical cardioversion, pharmacological cardioversion, or catheter ablation can all be used to restore sinus rhythm. Cardioversion should not be attempted until the patient has been fully anticoagulated for at least three weeks if the duration of atrial flutter is unknown or has lasted for more than 48 hours. Emergency electrical cardioversion is the treatment of choice when there is an acute presentation with haemodynamic compromise. For the treatment of recurrent atrial flutter, catheter ablation is preferred.

    • This question is part of the following fields:

      • Cardiovascular Pharmacology
      • Pharmacology
      0
      Seconds

  • Question 23 - You are giving a teaching session to a group of final year medical...

    Incorrect

    • You are giving a teaching session to a group of final year medical students regarding lower limb neurology. Which of the following clinical features would be expected in an obturator nerve palsy:

      Your Answer:

      Correct Answer: Weakness of hip adduction

      Explanation:

      Damage to the obturator nerve results in weak adduction of the hip with lateral swinging of the limb during walking due to unopposed abduction.

    • This question is part of the following fields:

      • Anatomy
      • Lower Limb
      0
      Seconds

  • Question 24 - Which of the following occurs primarily to produce passive expiration: ...

    Incorrect

    • Which of the following occurs primarily to produce passive expiration:

      Your Answer:

      Correct Answer: Relaxation of diaphragm and external intercostal muscles

      Explanation:

      Passive expiration is produced primarily by relaxation of the inspiratory muscles (diaphragm and external intercostal muscles) and the elastic recoil of the lungs. In expiration, depression of the sternal ends of the ribs (‘pump handle’ movement), depression of the lateral shafts of the ribs (‘bucket handle’ movement) and elevation of the diaphragm result in a reduction of the thorax in an anteroposterior, transverse and vertical direction respectively. This results in a decreased intrathoracic volume and increased intrathoracic pressure and thus air is forced out of the lungs.

    • This question is part of the following fields:

      • Anatomy
      • Thorax
      0
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  • Question 25 - You've been summoned to the resuscitation area to assist a patient who is...

    Incorrect

    • You've been summoned to the resuscitation area to assist a patient who is having a seizure. As part of the treatment protocol, a benzodiazepine dose is given.

      Which of the following statements about the use of benzodiazepines in seizures is correct?

      Your Answer:

      Correct Answer: Lorazepam can be given by the rectal route

      Explanation:

      A single dose of IV benzodiazepine will terminate the seizure in 60 to 80 percent of patients who present with seizures.

      Because benzodiazepines are lipid-soluble, they cross the blood-brain barrier quickly. This explains their quick onset of action.

      As a first-line treatment, IV lorazepam should be given. If IV lorazepam is not available, IV diazepam can be used instead, and buccal midazolam can be used if intravenous access cannot be established quickly. Lorazepam can be administered via the rectal route, but it is less reliable and has a lower absorption rate and bioavailability.

    • This question is part of the following fields:

      • CNS Pharmacology
      • Pharmacology
      0
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  • Question 26 - Which of the following statements is correct regarding the neuronal action potential? ...

    Incorrect

    • Which of the following statements is correct regarding the neuronal action potential?

      Your Answer:

      Correct Answer: Initial depolarisation occurs as a result of a Na + influx.

      Explanation:

      The resting potential in most neurons has a value of approximately -70 mV.
      The threshold potential is generally around -55 mV.
      Initial depolarisation when there is Na+influx through ligand-gated Na+channels.
      Action potential is an all or nothing response. The size of the action potential is constant and so, the intensity of the stimulus is coded by the frequency of firing of a neuron.
      K+efflux is responsible for repolarisation.

    • This question is part of the following fields:

      • Basic Cellular
      • Physiology
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      Seconds

  • Question 27 - Cardiac muscle and skeletal muscle are alike, but there are a few key variations. 

    Which...

    Incorrect

    • Cardiac muscle and skeletal muscle are alike, but there are a few key variations. 

      Which of the following is NOT a characteristic of skeletal muscle but is a characteristic of cardiac muscle? 

      Your Answer:

      Correct Answer: The presence of intercalated discs

      Explanation:

      Cardiac muscle is striated, and the sarcomere is the contractile unit, similar to skeletal muscle. Contracture is mediated by the interaction of calcium, troponins, and myofilaments, much as it occurs in skeletal muscle. Cardiac muscle, on the other hand, differs from skeletal muscle in a number of ways.

      In contrast to skeletal muscle cells, cardiac myocytes have a nucleus in the middle of the cell and sometimes two nuclei. The cells are striated because the thick and thin filaments are arranged in an orderly fashion, although the arrangement is less well-organized than in skeletal muscle.

      Intercalated discs, which work similarly to the Z band in skeletal muscle in defining where one cardiac muscle cell joins the next, are a very significant component of cardiac muscle.

      Adherens junctions and desmosomes, which are specialized structures that hold the cardiac myocytes together, are formed by the transverse sections. The lateral sections produce gap junctions, which join the cytoplasm of two cells directly, allowing for rapid action potential conduction. These critical properties allow the heart to contract in a coordinated manner, allowing for more efficient blood pumping.

      Cardiac myocytes have the ability to create their own action potentials, which is referred to as myogenic’. They can depolarize spontaneously to initiate a cardiac action potential. Pacemaker cells, as well as the sino-atrial (SA) and atrioventricular (AV) nodes, control this.

      The Purkinje cells and the cells of the bundle of His are likewise capable of spontaneous depolarization. While the bundle of His is made up of specialized myocytes, it’s vital to remember that Purkinje cells are not myocytes and have distinct characteristics. They are larger than myocytes, with fewer filaments and more gap junctions than myocytes. They conduct action potentials more quickly, allowing the ventricles to contract synchronously.
      Cardiac myocytes contract by excitation-contraction coupling, just like skeletal myocytes. Heart myocytes, on the other hand, utilise a calcium-induced calcium release mechanism that is unique to cardiac muscle (CICR). The influx of calcium ions (Ca2+) into the cell causes a ‘calcium spark,’ which causes more ions to be released into the cytoplasm.

      An influx of sodium ions induces an initial depolarisation, much as it does in skeletal muscle; however, in cardiac muscle, the inflow of Ca2+ sustains the depolarisation, allowing it to remain longer. Due to potassium ion (K+) inflow, CICR causes a plateau phase in which the cells remain depolarized for a short time before repolarizing. Skeletal muscle, on the other hand, repolarizes almost instantly.

      Comparison of skeletal and cardiac muscle:
      Skeletal muscle
      Cardiac muscle
      Striation
      Striated but arrangement less organised
      Multiple nuclei located peripherally
      Usually single nucleus (but can be two), located centrally
      Discs None
      Intercalated discs
      No Gap junctions
      Gap junctions
      No Pacemaker
      Pacemaker
      Electrical stimulation: Nervous system (excitation)
      Pacemaker (excitation)

    • This question is part of the following fields:

      • Basic Cellular Physiology
      • Physiology
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  • Question 28 - Leukaemia has been diagnosed in a 6-year-old child on your list. He comes...

    Incorrect

    • Leukaemia has been diagnosed in a 6-year-old child on your list. He comes to the ER with a complication related to this diagnosis.

      Which type of leukaemia do you think this is?

      Your Answer:

      Correct Answer: Acute lymphoblastic leukaemia

      Explanation:

      Acute lymphoblastic leukaemia (ALL) is the most common childhood cancer that primarily affects children. ALL is most common between the ages of 2 and 4, and it is uncommon in adults.

    • This question is part of the following fields:

      • Haematology
      • Pathology
      0
      Seconds

  • Question 29 - Regarding Gaussian sample distribution, which of the following statements is false? ...

    Incorrect

    • Regarding Gaussian sample distribution, which of the following statements is false?

      Your Answer:

      Correct Answer: It can be skewed left or right

      Explanation:

      Gaussian distribution, also known as normal distribution, is the most important probability distribution in statistics because it fits many natural phenomena. The normal distribution is a probability function that describes how the values of a variable are distributed. Below are its characteristics:

      (1) Bell-shaped and symmetrical about the mean
      (2) The mean, median, mode are all equal
      (3) The total area under the curve and above the x-axis is equal to 1
      (4) It has long tapering tails extending infinitely but never touching the x-axis
      (5) It is determined by its parameters: its mean and standard deviation
      (6) The standard deviation becomes a more meaningful quality than merely being a measure of dispersion

      The mean is the most common measure of central tendency. It is the sum of all observed values divided by the number of observation, and is also known as the ‘average’.

      The median is the value that falls in the middle position when the observations are ranked in order from the smallest to the largest. If the number of observations is odd, the median is the middle number. If it is even, the median is the average of the two middle numbers.

      The mode is the value that occurs with the greatest frequency in a set of observations, and is commonly used in public health statistics, such as the top 10 causes of mortality.

    • This question is part of the following fields:

      • Evidence Based Medicine
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  • Question 30 - The sensation produced by touching the arm with a vibrating tuning fork during...

    Incorrect

    • The sensation produced by touching the arm with a vibrating tuning fork during a neurological examination is mediated by which of the following spinal tracts:

      Your Answer:

      Correct Answer: Posterior column

      Explanation:

      Fine-touch, proprioception and vibration sensation are mediated by the posterior column-medial lemniscus pathway.

    • This question is part of the following fields:

      • Anatomy
      • Central Nervous System
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