The Human Body: The Circulatory System

The human body is composed of eleven major systems that all work together to hold a stable internal environment: homeostasis. Each system consists of different organs that all play important roles in maintaining homeostasis. The circulatory, respiratory and renal systems greatly affect each other in the keeping of the internal environment. Homeostasis is defined as the tendency of an organism or a cell to regulate its internal conditions, usually by a system of feedback controls, so as to stabilize health and functioning, regardless of outside changing conditions. In other words, humans are able to maintain a constant internal environment despite the change in external conditions. For example, people maintain an internal temperature of about …show more content…
The circulatory system works together with the pulmonary system by pumping deoxygenated blood into the lungs to be oxygenated in the alveoli and then returned to the heart to pump oxygenated blood to the rest of the body. The lungs oxygenated the blood because oxygen is a vital element for survival and all organs rely on it in order to function properly. If the lungs did not oxygenate the blood, anaerobic respiration would occur causing lactic acid to build up and cause pain. If in fact the blood is not adequately being perfused and not getting enough oxygen to the rest of the body, a person will become hypoxic and the kidneys step in and produce erythropoietin which stimulates red blood cell production so that there is more hemoglobin for oxygen to attach to. This way lactic acid will not build. The kidneys also filter the blood and remove any waste before being returned to the heart. Waste removal is crucial because is balances the pH of the blood and regulates how much potassium, sodium, calcium, magnesium, phosphate, and chloride ions can continue through the blood stream. If there is excess the kidneys will excrete it through urine because too many of these ions can be dangerous to the body. This would be considered a negative feedback loop because it is removing ions to reduce the effect of a stimulus. When the body is hypotensive, the kidneys produce an enzyme called renin. Renin catalyzes angiotensinogen which is further catalyzed into angiotensin I and again further catalyzed into angiotensin II. The renin-angiotensin system plays a huge role in the regulation of blood pressure because angiotensin II stimulates the adrenal cortex which tells the body to produce aldosterone. The hormone aldosterone tells the kidneys to increase the reabsorption of water and sodium ions to in turn increase blood volume which will further increase blood pressure. This is