The function of the digestive system is to absorb and assimilate key nutrients which are required to maintain and regulate other systems in the body. Enzymes secreted within the digestive system have a role of breaking down food from proteins into amino acids, starch into glucose and fats into a mixture of fatty acids and glycerol. The main function of the respiratory system is to inhale oxygen and exhale the waste product carbon dioxide. Oxygen is breathed through the mouth and nostrils into the lungs.
The gas then diffuses through the alveolar walls and into red blood cells (erythrocytes). Carbon dioxide carried back within red blood cells diffuses back through the alveolar walls and is exhaled out through the mouth. The cardiovascular system has a role of circulating blood around the body. The contents of blood being circulated include nutrients, gases and waste products. The main organs involved within this process are blood, arteries, veins, heart and the lungs. How cardiovascular, respiratory and digestive system are interrelated when exercising!
When exercising you need Glucose, oxygen and water (H2O). That’s where the digestive, cardiovascular and respiratory system are used. The digestive system dissolves food which provides the water and glucose for the respiratory and cardiovascular system, the respiratory system inhales oxygen which is diffused through the alveolar walls in to the red blood cells and diffuses the carbon dioxide back through the walls to be exhaled, the red blood cells with the water, oxygen and glucose in are pumped through the bodies arteries and veins by the cardiovascular system round the body.