Question

Which of the following can increase the rate of heart beat?
(A) Sympathetic neural signal
(B) Parasympathetic neural signal
(C)Adrenal medullary hormones
(D) Vagus nerve
(E) Thyroxine hormone
(F) Acetylcholine

• A. A,C,E
• B. D,E,F
• C. A,C,D
• D. B,D,F

Answer 1

Answer: (A)

A,C,E

The correct answer is A.

A) The sympathetic nervous system (SNS) releases the hormones (catecholamines - epinephrine and norepinephrine) to accelerate the heart rate.

C) The adrenal medulla, the inner part of an adrenal gland, controls hormones that initiate the flight or fight response. The main hormones secreted by the adrenal medulla include epinephrine (adrenaline) and norepinephrine (noradrenaline), which have similar functions.

E) Thyroxine increases resting heart rate and left ventricular contractility. $T_3$ causes decreased systemic vascular resistance (SVR) by a direct effect on the arteriolar smooth muscle cells.