MICROANATOMY

Detailed explanation-1: -Cardiac output during exercise increases greatly owing to the relatively high heart rates that are achieved during exercise. Heart rate increases proportionately with workload until heart rates close to maximal are attained.

Detailed explanation-2: -During exercise, more blood is sent to the active skeletal muscles, and, as body temperature increases, more blood is sent to the skin. This process is accomplished both by the increase in cardiac output and by the redistribution of blood flow away from areas of low demand, such as the splanch-nic organs.

Detailed explanation-3: -Cardiac output in humans is generally 5-6 L/min in an at-rest to more than 35 L/min in elite athletes during exercise.

Detailed explanation-4: -Which of the following is true of cardiac output? A Cardiac output equals the volume of blood pumped out of the ventricles per heart beat.

Detailed explanation-5: -Several factors increase cardiac output, including thyroid hormones, hypercalcemia (increased Ca2 + levels in the blood), and sympathetic activation. Similarly, any factor that decreases cardiac output will decrease blood pressure and blood flow.