1.1.b. Cardiovascular system Typeit

There are various systems in operation that influence the amount of blood arriving at the muscle and returning to the heart during exercise and recovery. Let's explore a couple of these below.

During Exercise

Redistribution of cardiac output:

Skeletal muscles aren't the only type of muscle that demand blood supply; there are also smooth muscles in the digestive system that require oxygen to move food through the stomach. However, the reliance on oxygen is greater in the skeletal muscles during exercise and it must therefore be redistributed away from these organs and directed towards the working muscles. This is called the  mechanism and is regulated by various systems:

The  centre – located in the medulla oblongata – senses indicators of exercise stress such as a greater temperature and carbon dioxide presence in the blood, and then acts by stimulating the sympathetic nervous system to change the vasoconstriction of the arterioles and pre-capillary sphincters. Stimulation of the sympathetic nervous system causes , small branches of blood vessels, to at the working muscles and  at muscles of lower priority during exercise, improving blood flow from the arteries to the capillaries. A similar effect is seen in pre-capillary sphincters (smooth muscle fibre structures that surround the entry of capillaries), as these at working muscles to facilitate the blood flow into the capillaries and restrict the blood flow to the capillaries around low-priority organs. 

Venous return:

To meet the high exercising cardiac output values, the amount of deoxygenated blood returning to the heart from the muscles must be equally as much. This departure of blood from the muscle to the heart is known as venous return and is facilitated by several mechanisms:

1. Pocket  –  force blood to flow in one direction, preventing any backflow
2. Muscle – Veins are squeezed by the contraction of skeletal muscles, increasing the speed of blood flow towards the heart
3. Veins feature smooth muscles which help contract and decrease resistance of blood flow back to the heart
4. helps blood return from the upper part of the body
5. – movement of the chest and abdominal cavity during inspiration and expiration causes changes in pressure that work to squeeze blood back towards the heart

During Recovery

The mechanisms that regulate vascular shunting will initially continue to function before gradually reducing as the body returns towards a resting state. The pattern of cardiac output during recovery will be matched by venous return. Both will remain elevated for a short period of time after exercise to repay oxygen debt and clear waste products, before activation of the parasympathetic nervous system results in a steady decline in heart rate.