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Question 1
Correct
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Monoamine oxidase is primarily involved in the degradation of which of the following:
Your Answer: Noradrenaline
Explanation:Catecholamines are broken down extracellularly and in the liver by catechol-O-methyltransferase (COMT) and intracellularly by monoamine oxidase (MAO).
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This question is part of the following fields:
- Endocrine
- Physiology
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Question 2
Correct
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Which of the following statements regarding the pituitary gland is CORRECT:
Your Answer: Cortisol inhibits release of adrenocorticotropic hormone (ACTH) from the anterior pituitary.
Explanation:Anterior pituitary hormones are released under the control of hypothalamic releasing or inhibiting hormones originating from small neurons with their cell bodies in the hypothalamus and released into the blood at the median eminence. These hypothalamic hormones are transported directly to the anterior pituitary via hypophyseal portal vessels. The anterior pituitary hormones (and the hormones released by their target organs) inhibit further release of hypothalamic and anterior pituitary hormones by negative feedback mechanisms e.g. cortisol inhibits the release of ACTH. Prolactin release from the anterior pituitary is inhibited by dopamine.The posterior pituitary is really a direct extension of the hypothalamus. Oxytocin and ADH are manufactured in the cell bodies of large neurons in the hypothalamus and are transported down the axons of these cells to their terminals on capillaries originating from the inferior hypophyseal artery within the posterior pituitary gland. ADH release is controlled by negative feedback mechanisms based on plasma osmolality and blood volume, oxytocin however is involved in positive feedback mechanisms.
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This question is part of the following fields:
- Endocrine
- Physiology
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Question 3
Correct
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Which of the following is NOT a typical clinical feature of osteomalacia:
Your Answer: Hypercalcaemia
Explanation:Features of osteomalacia include:
Bone pain (particularly bone, pelvis, ribs)
Neuromuscular dysfunction (particularly in the gluteal muscles, leading to waddling gait
Pseudofractures on x-ray (looser zones)
Elevated alkaline phosphatase, hypocalcaemia and low phosphate due to secondary hyperparathyroidism -
This question is part of the following fields:
- Endocrine
- Physiology
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Question 4
Correct
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Which of the following hormones is dysfunctional in diabetes insipidus:
Your 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
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Question 5
Correct
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Which of the following causes type 1 diabetes mellitus?
Your Answer: Autoimmune destruction of beta-cells results in insulin deficiency
Explanation:Type 1 diabetes mellitus results from autoimmune destruction of the insulin-producing beta cells in the islets of Langerhans. This process occurs in genetically susceptible subjects, is probably triggered by one or more environmental agents, and usually progresses over many months or years during which the subject is asymptomatic and euglycemic.
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This question is part of the following fields:
- Endocrine
- Physiology
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Question 6
Correct
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Which of the following is a primary action of calcitonin:
Your Answer: Decreased bone resorption through inhibition of osteoclast activity
Explanation:Calcitonin is a 32 amino acid polypeptide that is primarily synthesised and released by the parafollicular cells (C-cells) of the thyroid gland in response to rising or high levels of plasma Ca2+ions. Its primary role is to reduce the plasma calcium concentration, therefore opposing the effects of parathyroid hormone.
Secretion of calcitonin is stimulated by:
– Increased plasma calcium concentration
– Gastrin
– Pentagastrin
– The main actions of calcitonin are:
– Inhibition of osteoclastic activity (decreasing calcium and phosphate resorption from bone)
– Stimulation of osteoblastic activity
– Decreases renal calcium reabsorption
– Decreases renal phosphate reabsorption -
This question is part of the following fields:
- Endocrine
- Physiology
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Question 7
Correct
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A 32 year old woman presents with episodes of flushing, headaches and palpitations. On examination her blood pressure is significantly elevated. Which of the following is the most likely diagnosis:
Your Answer: Pheochromocytoma
Explanation:Phaeochromocytomas are catecholamine-secreting tumours which occur in about 0.1% of patients with hypertension. In about 90% of cases they arise from the adrenal medulla. The remaining 10%, which arise from extra-adrenal chromaffin tissue, are termed paragangliomas. Common presenting symptoms include one or more of headache, sweating, pallor and palpitations. Less commonly, patients describe anxiety, panic attacks and pyrexia. Hypertension, whether sustained or episodic, is present in at least 90% of patients. Left untreated phaeochromocytoma can occasionally lead to hypertensive crisis, encephalopathy, hyperglycaemia, pulmonary oedema, cardiac arrhythmias, or even death.
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This question is part of the following fields:
- Endocrine
- Physiology
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Question 8
Correct
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All of the following are physiological effects of thyroid hormones except:
Your Answer: Increased glycogenesis
Explanation:Thyroid hormones have multiple physiological effects on the body. These include:
1. Heat production (thermogenesis)
2. Increased basal metabolic rate
3. Metabolic effects:
(a) Increase in protein turnover (both synthesis and degradation are increased, although overall effect is catabolic)
(b) Increase in lipolysis
(c)Increase in glycogenolysis and gluconeogenesis
4. Enhanced catecholamine effect – Increase in heart rate, stroke volume and thus cardiac output
5. Important role in growth and development -
This question is part of the following fields:
- Endocrine
- Physiology
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Question 9
Correct
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When treating diabetic ketoacidosis (DKA), which of the following should be given if the systolic blood pressure is initially less than 90 mmHg:
Your Answer: 500 mL sodium chloride 0.9% intravenous infusion over 10 - 15 minutes
Explanation:If SBP is less than 90 mmHg , 500 mL sodium chloride 0.9 percent should be administered intravenously over 10–15 minutes, and repeated if SBP remains less than 90 mmHg. When SBP is greater than 90 mmHg, sodium chloride infusion must be maintained at a rate that replaces the deficit.
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This question is part of the following fields:
- Endocrine
- Pharmacology
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Question 10
Correct
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Which of the following statements is correct regarding hyponatraemia?
Your Answer: Correction of serum sodium that is too rapid can precipitate central pontine myelinolysis.
Explanation:Hyponatraemia refers to a serum sodium concentration < 135 mmol/L.
It is safer to quickly correct acute hyponatremia than chronic hyponatremia but correction should not be too fast, especially in chronic hyponatraemia, because of the risk of central pontine myelinolysis. Hyponatraemia is usually associated with a low plasma osmolality.
Under normal circumstances, if serum osmolality is low, then urine osmolality should also be low because the kidneys should be trying to retain solute.
In SIADH, excess ADH causes water retention, but not the retention of solute. Therefore, urine that is concentrated and relatively high in sodium is produced, even though the serum sodium is low (urine osmolality > 100 mosmol/kg). -
This question is part of the following fields:
- Endocrine
- Physiology
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Question 11
Correct
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Which of the following corticosteroids has the most potent mineralocorticoid effect:
Your Answer: Fludrocortisone
Explanation:Fludrocortisone has the most potent mineralocorticosteroid activity, making it ideal for mineralocorticoid replacement in adrenal insufficiency.
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This question is part of the following fields:
- Endocrine
- Pharmacology
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Question 12
Incorrect
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Which of the following acts to inhibit antidiuretic hormone (ADH) release from the posterior pituitary:
Your Answer: Angiotensin II
Correct Answer: Atrial natriuretic peptide
Explanation:ADH release is inhibited by low plasma osmolality, alcohol, caffeine, glucocorticoids and atrial natriuretic peptide (ANP).
ADH release is stimulated primarily by raised plasma osmolality detected by osmoreceptors in the anterior hypothalamus. Other factors that increase ADH release include: extracellular fluid volume depletion, angiotensin II, nausea, pain, stress, exercise, emotion, hypoglycaemia.
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This question is part of the following fields:
- Endocrine
- Physiology
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Question 13
Correct
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Adrenocorticotropic hormone release from the anterior pituitary is stimulated by which of the following:
Your Answer: Corticotropin-releasing hormone
Explanation:ACTH secretion is stimulated by corticotropin-releasing hormone (CRH) from the hypothalamus.
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This question is part of the following fields:
- Endocrine
- Physiology
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Question 14
Correct
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Which of the following is a physiological function that is mediated by a hormone released by the posterior pituitary:
Your Answer: Water retention
Explanation:Antidiuretic hormone (ADH), released by the posterior pituitary, acts on the kidneys to increase water permeability in the distal nephron allowing greater water reabsorption and concentration of urine. Prolactin, from the anterior pituitary, is responsible for milk production. The thyroid hormones, from the thyroid gland, are responsible for an increase in basal metabolic rate (stimulated by TSH from the anterior pituitary). FSH/LH, from the anterior pituitary, are responsible for maturation of egg and sperm. Calcitonin, from the thyroid gland, is responsible for decreasing calcium levels.
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This question is part of the following fields:
- Endocrine
- Physiology
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Question 15
Correct
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What is the effect of activated vitamin D on the renal handling of calcium:
Your Answer: Increases calcium reabsorption in the distal tubule
Explanation:Activated vitamin D acts to:
GUT:increase calcium and phosphate absorption in the small intestine (the main action)
KIDNEYS:increase renal calcium reabsorption (in the distal tubule via activation of a basolateral Ca2+ATPase pump), increase renal phosphate reabsorption, inhibit 1-alpha-hydroxylase activity in the kidneys (negative feedback)
PARATHYROID GLANDS:inhibit PTH secretion from the parathyroid glands -
This question is part of the following fields:
- Endocrine
- Physiology
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Question 16
Incorrect
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Antidiuretic hormone (ADH) has which of the following effects:
Your Answer: Increases water retention by increasing sodium reabsorption in the distal convoluted tubule
Correct Answer: Increases urine osmolality
Explanation:ADH binds V2 receptors on renal principal cells in the late distal tubule and collecting ducts, raising cAMP levels and causing intracellular vesicles to fuse with the apical membrane. In their membrane these vesicles have water channels called aquaporins, which increase the water permeability allowing greater water reabsorption and concentration of urine. ADH also binds to V1 receptor receptors on vascular smooth muscle, causing vasoconstriction and enhancing the effect of aldosterone on sodium reabsorption in the distal tubule. ADH release is stimulated primarily by raised plasma osmolality detected by osmoreceptors in the anterior hypothalamus. Other factors that increase ADH release include: extracellular fluid volume depletion, angiotensin II, nausea, pain, stress, exercise, emotion, hypoglycaemia. ADH release is inhibited by low plasma osmolality, alcohol, caffeine, glucocorticoids and atrial natriuretic peptide (ANP). ADH deficiency (or an inadequate response to ADH) results in diabetes insipidus. Excess levels of ADH results in syndrome of inappropriate ADH secretion (SIADH).
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This question is part of the following fields:
- Endocrine
- Physiology
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Question 17
Correct
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All of the following are actions of insulin except:
Your Answer: Increased gluconeogenesis
Explanation:Major Actions of Insulin:
↑ Glucose uptake into cells
↑ Glycogenesis
↓ Glycogenolysis
↓ Gluconeogenesis
↑ Protein synthesis
↓ Protein degradation
↑ Fat deposition
↓ Lipolysis
↓ Ketoacid production
↑ K+ uptake into cellsMajor Actions of Glucagon:
↓ Glycogenesis
↑ Glycogenolysis
↑ Gluconeogenesis
↓ Fatty acid synthesis
↑ Lipolysis
↑ Ketoacid production -
This question is part of the following fields:
- Endocrine
- Physiology
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Question 18
Correct
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Regarding hypernatraemia, which of the following statements is INCORRECT:
Your Answer: In acute severe hypernatraemia, seizures and intracranial vascular haemorrhage can occur as a result of brain cell lysis.
Explanation:Acute severe hypernatraemia is a medical emergency and requires inpatient management in a high dependency setting. Seizures and intracranial vascular haemorrhage as a result of brain cell crenation can occur. The cause is most commonly excessive water loss and the key aspect of treatment is aggressive fluid replacement (typically with normal saline as this is relatively hypotonic). If urine osmolality is low, diabetes insipidus (DI )should be considered and a trial of synthetic ADH given. In patients with known DI, it is essential to ensure synthetic ADH is given parenterally and that close fluid balance is observed.
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This question is part of the following fields:
- Endocrine
- Physiology
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Question 19
Incorrect
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Question 20
Correct
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Dehydration causes a significant increase in the amount of this hormone?
Your Answer: Antidiuretic hormone
Explanation:Antidiuretic hormone induces the kidneys to release less water, resulting in reduced urine production.
In the case of dehydration, ADH levels rise, resulting in a considerable decrease in urine output as well as an increase in plasma protein, blood Hct, and serum osmolality.
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This question is part of the following fields:
- Endocrine
- Physiology
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