Consider the following statements regarding function of adrenal medullary hormones :
(A) It causes p

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Question

Consider the following statements regarding function of adrenal medullary hormones :
(A) It causes pupilary constriction.
(B) It is a hyperglycemic hormone.
(C) It causes piloerection.
(D) It increases strength of heart contraction.
Choose the correct answer from the options given below :
(1) D only
(2) C and D only
(3) B, C and D only
(4) A, C and D only

Accepted Answer

Correct Answer: C — B, C and D onlyStep-by-step Solution:The adrenal medulla (the inner core of the adrenal gland, derived from neural crest cells) secretes catecholamines — primarily epinephrine (adrenaline) and norepinephrine (noradrenaline) — into the bloodstream in response to stress (the 'fight-or-flight' response). Evaluating each statement:(A) Pupillary constriction — FALSE: Catecholamines act on α-adrenergic receptors in the radial muscle of the iris, causing pupillary dilation (mydriasis) — NOT constriction. Dilation allows more light to enter the eye, improving vision in stressful situations. Pupillary constriction (miosis) is caused by the parasympathetic system (muscarinic receptors, acetylcholine).(B) Hyperglycemic hormone — TRUE: Epinephrine stimulates glycogenolysis (breakdown of glycogen to glucose) in the liver and muscles, and gluconeogenesis, leading to increased blood glucose levels (hyperglycemia). This provides immediate energy for the fight-or-flight response.(C) Piloerection — TRUE: Catecholamines act on α₁-adrenergic receptors of arrector pili muscles (small smooth muscles attached to hair follicles), causing contraction and resulting in piloerection (goosebumps, hair standing on end). This is a vestigial defense mechanism in humans.(D) Increases strength of heart contraction — TRUE: Epinephrine acts on β₁-adrenergic receptors in the heart, producing a positive inotropic effect (increased force of contraction) and positive chronotropic effect (increased heart rate). This increases cardiac output to deliver more oxygen and nutrients to muscles.Extended Explanation:Other effects of adrenal medullary hormones include: bronchodilation (β₂ receptors, relaxes bronchial smooth muscle — hence epinephrine is used in anaphylaxis); peripheral vasoconstriction (α receptors, redirects blood to vital organs); increased metabolic rate; inhibition of peristalsis (decreased digestion); increased sweating; inhibition of insulin secretion (→ further hyperglycemia). Epinephrine is also called the 'emergency hormone' or 'hormone of fight, fright, and flight.'Key Concepts: Adrenal medulla, catecholamines, epinephrine, norepinephrine, fight-or-flight response, hyperglycemia, piloerection, cardiac stimulation, mydriasis.

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