Question

Identify at least three physiological stimuli that affect heart rate and discuss how they differ between rest and exercise.

Answer 1

Ans - Three physiological stimuli that affact on haert rate:

A)Autonomic Nervous System
Heart rate can be affected by the autonomic nervous system. Changing heart rate is the body’s principal short-term mechanism of controlling cardiac output and blood pressure. When stroke volume decreases, the body attempts to maintain adequate cardiac output by increasing the rate and strength of cardiac contraction. The most important control of heart rate and strength of contraction is autonomic innervation.

B)Cardio acceleratory Center (CAC)

Sympathetic fibers that begin in the CAC innervate the SA node, the AV node, and parts of the myocardium. CAC stimulation causes these fibers to release norepinephrine, thereby increasing heart rate and contraction strength.

C)Hormones

Norepinephrine is released in the myocardium, and norepinephrine and epinephrine are released by the adrenal medullae. Norepinephrine increases heart rate and myocardial contractility. Epinephrine excites the SA node, thereby increasing the rate and strength of myocardial contraction. eg.Fight-or-Flight Respons

These factor are differ between rest and excercie because these factor happening not depend on our body rest or in exercise .these factor depend on our physiological condition and their affect on heart rate change accordingly when body physiological condition change.