Exercise and Coronary Blood Flow Flashcards
Describe the increase in cardiac output during moderate and intense exercise?
It increases to about 15-30L/min due to active hyperaemia
What occurs to the skin during exercise?
An increase in core temperature which is detected by the hypothalamus, then there is a decrease in sympathetic innervation to the skin
Describe the effects of moderate exercise on mean arterial pressure
It may increase a small amount, if at all.
Describe the effects of exercise on pulse pressure
It will increase as systolic pressure increases due to an increase in stroke volume and speed of ejection
Describe how exercise effects cardiac output
It increases as the heart rate increases due to a decrease of PSNS innervation of SAN and an increase in SNS innervation of SAN. It also increases stroke volume by increase contractility (frank starlings)
Describe the factors that promote venous return to the heart
Increased skeletal muscle pump activity, increased frequency and depth of inspiration and increase venous tone via sympathetic innervation
Describe the effects of static exercise on the circulatory system
ANS input increases cardiac output however as the contraction of muscles are for a prolonged period of time it increases venous return to the heart and occludes arteries which prevents tissue perfusion. This therefore significantly increases total peripheral resistance (TPR) and there is a huge increase in mean arterial pressure
Describe how the body prepares for exercise what is this called
It is feedforward control. These are anticipatory changes to CVS in preparation. It does this by decreasing PSNS tone and increasing SNS activity. ADH is released to promote retention of water and decreased urine production. Also allows resetting of baroreceptors upwards to mute effects of an increased arterial pressure.
Describe the effects of vasodilation of muscle arterioles on the cardiovascular system
Use of muscle increases their metabolic activity which leads to an accumulation of local factors that stimulate vasodilation. However this vasodilation decreases TPR, reducing blood flow to non essential organs can help restrict the amount that TPR decreases by as a result on increased muscle blood flow.
Describe how a whole body intensive exercise effects TPR
In this form of exercise there is increased blood flow to skeletal muscle that may outweigh whats conserved by reducing blood flow to non-essential organs. Therefore overall effect = drop in TPR, cardiac output therefore has to increase to maintain arterial BP.
Describe the changes in cardiac output that occur during exercise
Increased SNS and decreased PSNS control of heart increases cardiac output but raising HR and stroke volume. Venous return to heart increases due to compression of veins within working muscles. This causes a minor increase to EDV because of increased HR and contractility
Describe the effects of moderate exercise of the mean arterial BP
It may increase slightly but is generally not elevated greatly due to changes in cardiac output and total peripheral resistance balancing out. Pulse pressure may increase due to increases systolic and decrease in diastolic pressure
