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Question 1
Correct
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Which of the following is NOT a common side effect of adenosine:
Your Answer: Yellow vision
Explanation:Common side effects of adenosine include:
Apprehension
Dizziness, flushing, headache, nausea, dyspnoea
Angina (discontinue)
AV block, sinus pause and arrhythmia (discontinue if asystole or severe bradycardia occur) -
This question is part of the following fields:
- Cardiovascular
- Pharmacology
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Question 2
Incorrect
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A patient suffers a lower limb fracture that causes damage to the nerve that innervates peroneus brevis.
Peroneus brevis receives its innervation from which of the following nerves? Select ONE answer only.Your Answer:
Correct Answer: Superficial peroneal nerve
Explanation:Peroneus brevis is innervated by the superficial peroneal nerve.
Peroneus longus is innervated by the superficial peroneal nerve.
Peroneus tertius is innervated by the deep peroneal nerve. -
This question is part of the following fields:
- Anatomy
- Lower Limb
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Question 3
Incorrect
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The primary mechanism of action of ketamine is:
Your Answer:
Correct Answer: N-methyl-D-aspartate (NMDA)-receptor antagonist
Explanation:Ketamine is a non-competitive antagonist of the calcium-ion channel in the NMDA (N-methyl-D-aspartate) receptor. It further inhibits the NMDA-receptor by binding to its phencyclidine binding site. Ketamine also acts at other receptors as an opioid receptor agonist (analgesic effects), as an muscarinic anticholinergic receptor antagonist (antimuscarinic effects) and by blocking fast sodium channels (local anaesthetic effect).
Overdose may lead to panic attacks and aggressive behaviour; rarely seizures, increased ICP, and cardiac arrest
Very similar in chemical makeup to PCP (phencyclidine), but it is shorter acting and less toxic
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This question is part of the following fields:
- Anaesthesia
- Pharmacology
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Question 4
Incorrect
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Regarding skeletal muscle contraction, which of the following statements is CORRECT:
Your Answer:
Correct Answer: The force of contraction of a muscle can be controlled by increasing recruitment of motor units.
Explanation:Each motor unit contracts in an all or nothing fashion, i.e. if a motor unit is excited, it will stimulate all of its muscle fibres to contract. The force of contraction of a muscle is controlled by varying the motor unit recruitment (spatial summation), and by varying the firing rate of the motor units (temporal summation). During a gradual increase in contraction of a muscle, the first units start to discharge and increase their firing rate, and, as the force needs to increase, new units are recruited and, in turn, also increase their firing rate. For most motor units, the firing rate for a steady contraction is between 5 and 8 Hz. Because the unitary firing rates for each motor unit are different and not synchronised, the overall effect is a smooth force profile from the muscle. Increasing the firing rate of motor units is temporal summation where the tension developed by the first action potential has not completely decayed when the second action potential and twitch is grafted onto the first and so on. If the muscle fibres are stimulated repeatedly at a faster frequency, a sustained contraction results where it is not possible to detect individual twitches. This is called tetanus.
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This question is part of the following fields:
- Basic Cellular
- Physiology
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Question 5
Incorrect
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Regarding Helicobacter pylori, which of the following statements is INCORRECT:
Your Answer:
Correct Answer: It is found as part of normal colonic flora.
Explanation:Helicobacter pyloriis a Gram-negative, helix shaped (curved rod), microaerophilic bacterium. It typically has 4-6 lophotrichous flagellae and is therefore highly motile. It has an outer membrane consisting of phospholipids and lipopolysaccharide.
Helicobacter pyloriIs found in the upper gastrointestinal tract of approximately 50% of the population.
Colonization withHelicobacter pyloriconfers a 10-20% lifetime risk of developing peptic ulcers and a 1-2% lifetime risk of developing gastric cancer.
There is a strong association between mucosa-associated lymphoid tissue (MALT) lymphoma andHelicobacter pyloricolonization.
The most reliable method for testing for colonization withHelicobacter pyloriis by biopsy during endoscopy and histological examination.
Typically eradication requires a 14-day course of triple therapy with amoxicillin, clarithromycin and a proton pump inhibitor. Metronidazole is also often used as an alternative antibiotic in a triple therapy regime.
Serum antibody levels fall slowly and therefore cannot be used to accurately assess eradication. Either of the 13C-urea breath test or the stool antigen test are viable options for assessing successful eradication. -
This question is part of the following fields:
- Microbiology
- Pathogens
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Question 6
Incorrect
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You see a patient in the Emergency Department with features consistent with a diagnosis of type I diabetes mellitus.
Which of these is MOST suggestive of type I diabetes mellitus?
Your Answer:
Correct Answer: History of recent weight loss
Explanation:A history of recent weight loss is very suggestive of an absolute deficiency of insulin seen in type I diabetes mellitus.
An age of onset of less than 20 years makes a diagnosis of type I diabetes mellitus more likely. However, an increasing number of obese children and young people are being diagnosed with type II diabetes.
Microalbuminuria, peripheral neuropathy, and retinopathy all occur in both type I and type II diabetes mellitus. They are not more suggestive of type I DM.
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This question is part of the following fields:
- Endocrine Physiology
- Physiology
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Question 7
Incorrect
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Campylobacter jejuni is primarily spread via which of the following routes:
Your Answer:
Correct Answer: Faecal-oral route
Explanation:Campylobacter spp. are a common cause of acute infective gastroenteritis, particularly in children, with Campylobacter jejuni responsible for 90% of Campylobacter gastroenteritis. Infection typically follows ingestion of contaminated meat (most frequently undercooked poultry), unpasteurised milk or contaminated water, following which the microorganism invades and colonises the mucosa of the small intestine.
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This question is part of the following fields:
- Microbiology
- Pathogens
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Question 8
Incorrect
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Surface area of the absorptive surface in the small intestine is increased by all but which of the following:
Your Answer:
Correct Answer: Teniae coli
Explanation:Factors increasing the surface area include:The small intestine is very long – about 5 m in length.The inner wall of the small intestine is covered by numerous folds of mucous membrane called plicae circulares.The lining of the small intestine is folded into many finger-like projections called villi.The surface of the villi is covered with a layer of epithelial cells which, in turn, have many small projections called microvilli that project towards the lumen of the intestine (forming the brush border).
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This question is part of the following fields:
- Gastrointestinal
- Physiology
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Question 9
Incorrect
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Which of the following is an example of continuous data:
Your Answer:
Correct Answer: Height
Explanation:Continuous data is data where there is no limitation on the numerical value that the variable can take e.g. weight, height.
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This question is part of the following fields:
- Evidence Based Medicine
- Statistics
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Question 10
Incorrect
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A 5-year-old girl presents in a paediatric clinic with symptoms of viral gastroenteritis. You encourage the mother to treat the child at home with oral rehydration therapy (ORT), e.g. dioralyte.
Out of the following, which statement is FALSE regarding the use of ORT in the management of gastroenteritis?Your Answer:
Correct Answer: ORT is sugar-free
Explanation:One of the major complications of gastroenteritis is dehydration. Choosing the correct fluid replacement therapy is essential according to a patient’s hydration status.
Oral rehydration therapy (ORT) refers to the restitution of water and electrolyte deficits in dehydrated patients using an oral rehydration salt (ORS) solution. It is a fluid replacement strategy that is less invasive than other strategies for fluid replacement and has successfully lowered the mortality rate of diarrhoea in developing countries.
Some characteristics of Oral rehydration solutions are:
– slightly hypo-osmolar (about 250 mmol/litre) to prevent the possible induction of osmotic diarrhoea.
– contain glucose (e.g. 90 mmol/L in dioralyte). The addition of glucose improves sodium and water absorption in the bowel and prevents hypoglycaemia.
– also contains essential mineral saltsCurrent NICE guidance recommends that 50 ml/kg is given over 4 hours to treat mild dehydration.
Once rehydrated, a child should continue with their usual daily fluid intake plus 200 ml ORT after each loose stool. In an infant, give ORT at 1-1.5 x the normal feed volume and in an adult, give 200-400 ml after each loose stool. -
This question is part of the following fields:
- Fluids & Electrolytes
- Pharmacology
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Question 11
Incorrect
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An analytical cohort study aimed to determine a relationship between intake of dietary calcium and incidence of hip fractures among post-menopausal women. The following are the data obtained from the study:
No. of post-menopausal women who took Calcium: 500
No. of post-menopausal women who took Calcium and suffered a hip fracture: 10
No. of post-menopausal women who took placebo: 500
No. of post-menopausal women who took placebo and suffered a hip fracture: 25
Compute for the absolute risk reduction of a hip fracture.Your Answer:
Correct Answer: 0.03
Explanation:Absolute risk reduction (ARR) is computed as the difference between the absolute risk in the control group (ARC) and the absolute risk in the treatment group (ART).
ARR = ARC-ART
ARR = (25/500) – (10/500)
ARR = 0.03 -
This question is part of the following fields:
- Evidence Based Medicine
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Question 12
Incorrect
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Following a road traffic collision, a patient sustains damage to the long thoracic nerve. Which of the following clinical findings would you most expect to see on examination:
Your Answer:
Correct Answer: Winged scapula deformity
Explanation:Damage to the long thoracic nerve results in weakness/paralysis of the serratus anterior muscle. Loss of function of this muscle causes the medial border, and particularly the inferior angle, of the scapula to elevate away from the thoracic wall, resulting in the characteristic ‘winging’ of the scapula. This deformity becomes more pronounced if the patient presses the upper limb against a wall. Furthermore, normal elevation of the arm is no longer possible.
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This question is part of the following fields:
- Anatomy
- Upper Limb
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Question 13
Incorrect
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You are attending to a patient that has presented with a severe headache in the Emergency Department. The patient has signs of cerebral oedema and raised intracranial pressure.
You discuss the case with the on-call neurology registrar and decide to prescribe Mannitol. The nurse assisting you asks you to reconsider this management plan as she suspects the patient has a contraindication to Mannitol.
Out of the following, what is a contraindication to mannitol?Your Answer:
Correct Answer: Severe cardiac failure
Explanation:Mannitol is the most widely used osmotic diuretic that is most commonly used to reduce cerebral oedema and intracranial pressure.
It is recommended to use mannitol for the reduction of CSF pressure/cerebral oedema in a dose of 0.25-2 g/kg as an intravenous infusion over 30-60 minutes. This can be repeated 1-2 times after 4-8 hours if needed.Mannitol has several contraindications and some of them are listed below:
1. Anuria due to renal disease
2. Acute intracranial bleeding (except during craniotomy)
3. Severe cardiac failure
4. Severe dehydration
5. Severe pulmonary oedema or congestion
6. Known hypersensitivity to mannitol -
This question is part of the following fields:
- Cardiovascular Pharmacology
- Pharmacology
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Question 14
Incorrect
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Which of the following decreases activation of vitamin D:
Your Answer:
Correct Answer: Chronic renal failure
Explanation:Calcium deficiency (low Ca2+ diet or hypocalcemia) activates 1-alpha-hydroxylase in the cells of the renal proximal tubule which catalyses the conversion of vitamin D to its active form, 1,25-dihydroxycholecalciferol. Increased parathyroid hormone (PTH) and hypophosphatemia also stimulate the enzyme. Chronic renal failure is associated with a constellation of bone diseases, including osteomalacia caused by failure of the diseased renal tissue to produce the active form of vitamin D.
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This question is part of the following fields:
- Endocrine
- Physiology
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Question 15
Incorrect
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Gentamicin is contraindicated in which of the following:
Your Answer:
Correct Answer: Myasthenia gravis
Explanation:Gentamicin is the aminoglycoside of choice in the UK and is used widely for the treatment of serious infections. It has a broad spectrum but is inactive against anaerobes and has poor activity against haemolytic streptococci and pneumococci. When used for the blind therapy of undiagnosed serious infections it is usually given in conjunction with a penicillin or metronidazole (or both). The main toxic effects are nephrotoxicity and ototoxicity due to damage to the vestibulocochlear nerve (CN VIII).
Gentamicin is contraindicated in myasthenia gravis and should be used with caution in renal disease which may result in accumulation and a greater risk of toxic side effects.
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This question is part of the following fields:
- Infections
- Pharmacology
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Question 16
Incorrect
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Question 17
Incorrect
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A 20-year-old with type I diabetes mellitus has an episode of hypoglycaemia following inadvertent administration of too much insulin.
The mechanism by which insulin causes glucose to be transported into cells is?
Your Answer:
Correct Answer: Facilitated diffusion
Explanation:The only mechanism by which insulin facilitates uptake of glucose into cells is by facilitated diffusion through a family of hexose transporters.
The major transporter used for glucose uptake is GLUT4. GLUT4 is made available in the plasma membrane by the action of insulin.
When insulin concentrations are low, GLUT4 transporters are present in cytoplasmic vesicles, where they are cannot be used for transporting glucose. -
This question is part of the following fields:
- Endocrine Physiology
- Physiology
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Question 18
Incorrect
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Regarding renal clearance, which of the following statements is CORRECT:
Your Answer:
Correct Answer: The MDRD equation uses plasma creatinine to estimate the GFR making an adjustment for age, sex and race.
Explanation:Clearance is defined as the volume of plasma that is cleared of a substance per unit time. Inulin clearance is the gold standard for measurement of GFR but creatinine clearance is typically used instead. Creatinine is freely filtered and not reabsorbed, but there is a little creatinine tubular secretion. In practice, GFR is usually estimated from the plasma creatinine using a formula e.g. the MDRD equation making an adjustment for age, sex and race.
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This question is part of the following fields:
- Physiology
- Renal
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Question 19
Incorrect
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A 23-year-old male presents to his family physician with the complaint of repeated episodes of abdominal pain and the passage of dark coloured urine every morning. He also reports increasing fatigue over the past several months. On examination, there are raised, painful red nodules over the skin of the back. Laboratory workup shows haemolytic anaemia, leukopenia and thrombocytopenia.
Which one of the following disorders is this patient most likely to have?Your Answer:
Correct Answer: Paroxysmal nocturnal haemoglobinuria
Explanation:Paroxysmal nocturnal haemoglobinuria is an acquired genetic disorder that causes a decrease in red blood cells due to a membrane defect that allows increased complement binding to RBCs, causing haemolysis. Patients complain of dark-coloured urine first in the morning due to haemoglobinuria secondary to lysis of red blood cells overnight.
Thrombosis occurs, which affects hepatic, abdominal, cerebral and subdermal veins. Thrombosis of hepatic veins can lead to Budd-Chiari syndrome, thrombosis of subdermal veins can lead to painful nodules on the skin, and thrombosis of cerebral vessels can lead to stroke. The presence of dark urine in the morning only and at no other time differentiates this condition from other conditions.
Multiple myeloma would present with bone pain, signs of radiculopathy if there were nerve root compression and a history of repeated infections.
Patients with Non-Hodgkin Lymphoma would complain of enlarged lymph nodes, fatigue, fever, weight loss and a history of repeated infections.
Acute lymphoblastic leukaemia presents more commonly in children than in adults. The patient would complain of bone pain, and on examination, there would be hepatosplenomegaly.
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This question is part of the following fields:
- Haematology
- Pathology
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Question 20
Incorrect
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A 60-year-old man with insulin-controlled diabetes mellitus asks you about how his ability to drive is affected. He owns a car as well as a motorcycle.
Which of the following statements about driving with diabetes under insulin control is correct?Your Answer:
Correct Answer: He must monitor his blood glucose levels every 2 hours whilst driving
Explanation:The DVLA sends a detailed information sheet about their licence and driving to all drivers with diabetes mellitus. The primary danger of driving while diabetic is hypoglycaemia.
The DVLA must be notified of the following diabetic patients:
All of the drivers are on insulin. (Licenses are being reviewed more frequently.)
Those who are at high risk of hypoglycaemia and have had more than one episode of severe hypoglycaemia in the previous year. (Severe hypoglycaemia is defined as requiring the assistance of another person to manage.)
Those who are unaware of their hypoglycaemia
Anyone who has ever been in a car accident due to hypoglycaemia
Anyone with diabetic retinopathy who needs laser treatment (to both eyes or to a second eye if sight only in one eye)
Patients with diabetes complications that impair their ability to drive.To drive, drivers with insulin-treated diabetes must meet the following requirements:
They need to be aware of hypoglycaemia.
They must not have had more than one episode of hypoglycaemia in the previous 12 months that necessitated the assistance of another person.
They must check their blood glucose levels no later than 2 hours before the first journey.
While driving, they must check their blood glucose levels every two hours.
The visual acuity and visual field standards must be met.Any significant changes in their condition must be reported to the DVLA. Furthermore, on days when they are not driving, group 2 licence holders must test their blood glucose twice daily using a metre that can store three months’ worth of readings.
In addition to this advice, the DVLA also offers the following advice to diabetic patients:
When taking tablets that have the potential to cause hypoglycaemia (such as sulfonylureas and glinides), monitoring may be necessary if there has been more than one episode of severe hypoglycaemia.
Drivers must show good control and be able to recognise hypoglycaemia.
Verify that your vision meets the required standard.If a patient feels hypoglycaemic or has a blood glucose level of less than 4.0 mmol/L, they should not drive. Driving should not be resumed until blood glucose levels have returned to normal, which should take 45 minutes.
If there are any warning signs, patients should carry rapidly absorbed sugar in their vehicle and stop, turn off the ignition, and eat it.
If resuscitation is required, a card stating which medications they are taking should be carried.
If hypoglycaemia causes an accident, a diabetic driver may be charged with driving under the influence of drugs.
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This question is part of the following fields:
- Endocrine Pharmacology
- Pharmacology
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Question 21
Incorrect
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Regarding Clostridium difficile, which of the following statements is CORRECT:
Your Answer:
Correct Answer: It is normally found in gut flora.
Explanation:C. difficile is normally found in the gut flora but its growth is normally suppressed by more dominant anaerobes. It has exotoxin-mediated effects causing profuse diarrhoea. Oral clindamycin (a broad spectrum antibiotic) is commonly implicated in precipitating C. difficile colitis; first line treatment is with oral metronidazole. Tetanolysin is a toxin produced by Clostridium tetani bacteria.
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This question is part of the following fields:
- Microbiology
- Pathogens
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Question 22
Incorrect
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Compliance is decreased by all but which one of the following:
Your Answer:
Correct Answer: Aging
Explanation:Factors increasing compliance:
Old age
EmphysemaFactors decreasing compliance:
Pulmonary fibrosis
Pulmonary oedema
Atelectasis
Extremes of lung volumes (at higher lung volumes the compliance of the lung becomes less as the lung becomes stiffer) -
This question is part of the following fields:
- Physiology
- Respiratory
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Question 23
Incorrect
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What is the average healing time for a femoral shaft fracture under normal circumstances? Choose ONE answer.
Your Answer:
Correct Answer: 12 weeks
Explanation:The process of fracture healing occurs naturally after traumatic bone disruption and begins with haemorrhage, then progresses through Inflammatory, reparative, and remodelling stages
Average healing times of common fractures are:
Femoral shaft: 12 weeks
Tibia: 10 weeks
Phalanges: 3 weeks
Metacarpals: 4-6 weeks
Distal radius: 4-6 weeks
Humerus: 6-8 weeks -
This question is part of the following fields:
- General Pathology
- Pathology
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Question 24
Incorrect
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A 32-year-old female is diagnosed case of bipolar disorder and is on medication. She presents to her psychiatric team with symptoms of severe depression. She is currently taking Lithium.
Out of the following, which is TRUE regarding lithium?Your Answer:
Correct Answer: It commonly causes a tremor
Explanation:Lithium is the drug of choice for bipolar disorders but is commonly associated with side effects and toxicity.
Fine hand tremor is very commonly seen and reported in as many as 50% of patients during the first week of therapy with Lithium. The tremor tends to reduce with time and is only present in around 5% of patients taking the medication two years or longer. Lithium tremors are more common with older age, presumably due to the additive effects of age-related essential tremors.
Option The normal therapeutic range is 2.0-2.5 mmol/l: Lithium should be carefully monitored as it has a very low therapeutic index. The normal therapeutic range is 0.4-0.8 mmol/l. Levels should be checked one week after starting therapy and one week after every change in dosage. (Option Levels should be checked one month after starting therapy)
Option It can induce hyperthyroidism: Lithium has a known effect on thyroid function. Lithium decreases the production of T4 and T3 and commonly causes hypothyroidism. More rarely, lithium causes hyperthyroidism due to thyroiditis.
Option It can induce diabetes mellitus: Lithium can induce nephrogenic diabetes insipidus but not diabetes mellitus.
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This question is part of the following fields:
- CNS Pharmacology
- Pharmacology
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Question 25
Incorrect
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After what time period should intravenous phenytoin be used as second-line treatment of status epilepticus?
Your Answer:
Correct Answer: 25 minutes
Explanation:If seizures recur or fail to respond after initial treatment with benzodiazepines within 25 minutes of onset, phenytoin sodium, fosphenytoin sodium, or phenobarbital sodium should be used.
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This question is part of the following fields:
- Central Nervous System
- Pharmacology
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Question 26
Incorrect
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Blood flows from the left atrium into the left ventricle via:
Your Answer:
Correct Answer: The mitral valve
Explanation:Blood flows from the right atrium into the right ventricle via the tricuspid atrioventricular valve and from the left atrium into the left ventricle via the mitral atrioventricular valve. Blood is ejected from the right ventricle through the pulmonary semilunar valve into the pulmonary artery and from the left ventricle via the aortic semilunar valve into the aorta.
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This question is part of the following fields:
- Cardiovascular
- Physiology
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Question 27
Incorrect
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A patient noticed ankle swelling and has passed very little urine over the past 24 hours. He also has nausea and vomiting, reduced urine output and his blood results reveal a sudden rise in his creatinine levels over the past 48 hours. You make a diagnosis of acute kidney injury (AKI).
Which one of these is a prerenal cause of AKI?
Your Answer:
Correct Answer: Cardiac failure
Explanation:The causes of AKI can be divided into pre-renal, intrinsic renal and post-renal causes. Majority of AKI developing in the community is due to a pre-renal causes (90% of cases).
Pre-renal causes: Haemorrhage, severe vomiting or diarrhoea, burns, cardiac failure, liver cirrhosis, nephrotic syndrome, hypotension, severe cardiac failure, NSAIDs, COX-2 inhibitors, ACE inhibitors or ARBs, Abdominal aortic aneurysm, renal artery stenosis, hepatorenal syndrome,
Intrinsic (renal) causes:
Eclampsia, glomerulonephritis, thrombosis, haemolytic-uraemic syndrome, acute tubular necrosis (ATN), acute interstitial nephritis, drugs ( NSAIDs), infection or autoimmune diseases, vasculitis, polyarteritis nodosa, thrombotic microangiopathy, cholesterol emboli, renal vein thrombosis, malignant hypertensionPost-renal causes: Renal stones, Blood clot, Papillary necrosis, Urethral stricture, Prostatic hypertrophy or malignancy, Bladder tumour, Radiation fibrosis, Pelvic malignancy, Retroperitoneal fibrosis
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This question is part of the following fields:
- General Pathology
- Pathology
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Question 28
Incorrect
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A possible diagnosis of Cushing's illness is being investigated in an overweight patient with resistant hypertension. A CRH (corticotropin-releasing hormone) test is scheduled.
Which of the following statements about corticotropin-releasing hormone is correct?
Your Answer:
Correct Answer: It is produced by cells within the paraventricular nucleus of the hypothalamus
Explanation:Corticotropin-releasing hormone (CRH) is a neurotransmitter and peptide hormone. It is generated by cells in the hypothalamic paraventricular nucleus (PVN) and released into the hypothalamo-hypophyseal portal system at the median eminence through neurosecretory terminals of these neurons. Stress causes the release of CRH.
The CRH is carried to the anterior pituitary through the hypothalamo-hypophyseal portal system, where it activates corticotrophs to release adrenocorticotropic hormone (ACTH). Cortisol, glucocorticoids, mineralocorticoids, and DHEA are all produced in response to ACTH.
Excessive CRH production causes the size and quantity of corticotrophs in the anterior pituitary to expand, which can lead to the creation of a corticotrope tumour that generates too much ACTH.
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This question is part of the following fields:
- Endocrine Physiology
- Physiology
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Question 29
Incorrect
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In the foetus at 4 months gestation, where does haematopoiesis mainly occur?
Your Answer:
Correct Answer: Liver and spleen
Explanation:The first place that haematopoiesis occurs in the foetus is in the yolk sac. Later on, it occurs in the liver and spleen, which are the major hematopoietic organs from about 6 weeks until 6 – 7 months gestation. At this point, the bone marrow becomes the most important site. Haemopoiesis is restricted to the bone marrow in normal childhood and adult life.
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This question is part of the following fields:
- Basic Cellular
- Physiology
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Question 30
Incorrect
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Regarding defaecation, which of the following statements is CORRECT:
Your Answer:
Correct Answer: Colonic mass movement occurs shortly after a meal due to distension of the stomach and duodenum.
Explanation:Colonic mass movement describes the intense contraction that begins halfway along the transverse colon and pushes the intestinal contents in the proximal colon towards the rectum. It occurs shortly after a meal due to distension of the stomach and duodenum as part of the gastrocolic reflex and if faeces is present in the rectum, stimulates the urge to defecate. Distention of the rectum causes firing of afferent cholinergic parasympathetic fibres. The internal sphincter is made up of circular smooth muscle innervated by the autonomic fibres, and the more distal external sphincter is composed of striated muscle innervated by motor fibres from the pudendal nerve. During defaecation, relaxation of pelvic muscles straightens the rectum.
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This question is part of the following fields:
- Gastrointestinal
- Physiology
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SESSION STATS - PERFORMANCE PER SPECIALTY
