Physiology, Health & Exercise Lesson 8 zEffect of exercise on CVS

2 Effect of exercise: zon heart rate zcardiac output z systolic & diastolic blood pressure zrecovery time zDistribution of blood to tissues during exercise

3 What happens to heart rate during exercise? zHeart rate increases in proportion to work done (length & intensity) zCVS must increase its delivery of O 2 and nutrients to exercising muscles zMust also remove waste products effectively zIncrease blood flow to & from muscles

4 What happens to heart rate during exercise? zIncrease cardiac output zRedistributing the circulation of blood zCardiac output increased by increasing both HR & SV zRemember CO = HR x SV

5 How are HR & SV increased? 1.Increased output from sympathetic nerves to heart  increases HR 2.Increased release of adrenaline into blood which increases HR & SV 3.Increase in blood volume returning to heart  increases rate of filling of heart chambers. Ventricles stretch and contract more forcibly  increased SV. SV can increase from ml per beat

6 What happens to blood pressure during exercise? zSystolic blood pressure increases zCan increase from mm Hg zWalls of ventricles working much harder than usual zDiastolic blood pressure remains fairly constant

7 Effect of exercise on recovery time zWhat is recovery time? zRegular exercise improves recovery time

8 Distribution of blood to tissues during exercise zAll parts of body require an adequate supply of blood to function efficiently zThe demands made by different parts of the body are not equal or constant zAt rest vegetative functions are promoted e.g. digestion, urine production zBlood flow diverted to small intestine and kidney zDuring strenuous exercise blood is diverted to skeletal muscles

9 Distribution of blood to tissues during exercise Body tissueEffect of exercise on rate of blood flow Explanation Cardiac muscleIncrease supply energy demands BrainNo change energy demands or cells remain unaffected KidneysDecrease Blood flow diverted to muscles SkinIncrease To liberate extra heat Gut, liver etcDecrease Blood flow diverted to muscles Skeletal musclesIncrease supply increased energy demand

10 Distribution of blood to tissues during exercise zChange in supply of blood to different parts of the body is due to vasodilation (widening) and zvasoconstriction (narrowing) of arterioles supplying these regions.

11 Distribution of blood to tissues during exercise