Cardiac Muscle Synthesis Essay

When we are exercising, body cells undergo (aerobic) respiration to provide energy to us. CO2 is produced by respiration and it builds up in blood. It results in the lowering of pH which is detected by the chemoreceptors in aortic bodies, carotid bodies and medulla oblongata. The receptors send nervous signal to the cardiovascular centre in medulla oblongata. The cardiovascular centre then stimulates the cardiac function through the cooperation with the endocrine system (adrenal gland) and the sympathetic nervous pathway. Although the decline in pH of blood is the main stimulus in stimulating cardiac function during exercise, other factors, like the increased contraction of skeletal muscle, will also be discussed.

The cardiovascular centre stimulates the adrenal medulla through sympathetic nervous pathway. The adrenal medulla secretes adrenaline. Adrenaline travels along the bloodstream and reaches the heart. There are two types of adrenaline receptors in the blood vessels, namely the alpha and beta-2 receptors. When adrenaline bind to alpha receptors, it leads to vasoconstriction; whereas binding to beta-2 receptor leads to vasodilation. In cardiac muscles, beta-2 receptors are predominant in the coronary arteriole. During exercise, adrenaline binds to the beta-2 receptors and causes vasodilation of coronary arteriole. It is believed that the blood flow to cardiac muscle will be increased. With more oxygen and nutrient delivered to cardiac muscle, it can contract stronger and faster. The cardiac output is eventually increased. …show more content…
After adrenaline binds to the specific metabotropic receptor and trigger a series of actions, the conductance of ions (e.g. Na+, Ca2+) into the cell of SA node increased. Having a faster rate of depolarization, the frequency of action potential fired is higher. It results in a faster cardiac contraction