responses to acute exercise
How does the Cardiovascular System work?
The cardiovascular system serves five important functions during exercise. It delivers oxygen to working muscles, oxygenates blood by returning it to the lungs, Transports heat from the core to the skin, Delivers nutrients and fuel to active tissues and transports hormones. Exercise places an increased demand on the cardiovascular system which means that the muslces get thirsty for more oxygen. Metabolic processes speeds up and more waste is created. More nutrients are used and body temperature rises. To perform as efficiently as possible the cardiovascular system must regulate these changes and meet the bodys increasing demands.
Heart rate will increase during exercise because during exercise the energy needed to support muscle contracion increase. Your heart has to beat harder and faster to meet these increased demands. Before the start of exercise your heart rate rapidly increases above resting levels. This is known as the anticpatory heart rate and is caused by the release of adrenaline. The greatest anticipatory heart-rate response is observed in short sprint events. The heart rate will increase in direct proportion to exercise intensity. Chemoreceptors detect increases in carbon dioxide, Proprioceptors inform extent of movement that is taking place and thermoreceptors detect increases in body tempatures working in both the muscles and joints. All of these receptors send information to the cardiac control centre in the brain which stimulates the sino atrail node in the heart to contract the cardiac muscle more often to increase heart rate.
Increased blood pressure
Blood pressure is the pressure of the blood against the walls of your arteries and results from two different forces. One is created by the heart as it pumps blood into your arteries and through your circutalory system, the other is the force of your arteries as they resist blood flow. During exercise diastolic blood pressure stays the same as the intensity increases. Systolic blood pressure rises progressively and decreases slightly. Pulse rate rises and blood flow to your muscles increases.
At the start of exercise, or even slighlty before, nerve centres in your brain detect cardiovascular activity. This results in adjustments that increase the rate and the strength of your heart. At the same time regional blood flow is altered in proportion to the intensity of the activity taking place. This is achieved through vasodilation and vasoconstriction.
During exercise the vascular portion of active muscles increases through the arterioles, involving an increase in the diameter of the blood vessels and resulting in an increased blood flow to the muslces. When you start running blood vessels supplying your hamstring and quadriceps will vasodilate allowing more blood too reach these muscles.
During exercise vessels can also shut down blood flow to tissues, which can temporaily lessen their blood supply. This involves a decrease in blood flow to the other organs. This is called vasoconstriction. During exercise less blood is needed at the kidney, gut and liver therefore blood vessels supplying these organs vasoconstrict directing blood away to the muscles.