The balanced internal state of organisms is known as homeostasis, which describes the processes by which organisms maintain their optimal internal conditions.
Physiology is the study of the normal functions and mechanisms of the different systems in the body. Humans and many other animals attain homeostasis through distinct physiological processes in specialized cells.
One or more cell types with supporting functions form tissues, which in turn make up organs with specialized bodily functions. Organ systems consist of two or more organs that work together to provide a common function. The vertebrate physiological system contains 11 major organ systems. While all of the organ systems are interconnected, they do function somewhat independently of one another.
The respiratory system controls gas exchange to supply the body with oxygen as it removes carbon dioxide in the lungs after passage through the nasal cavity, pharynx, larynx, trachea, and bronchus. The circulatory system consists of the heart, blood vessels and blood, and delivers oxygen and nutrients to the tissues, while removing carbon dioxide and waste products throughout the body.
Blood pressure is generated by the contraction of the heart ventricles. Elevated blood pressure levels over extended periods of time can strain and damage the blood vessels and is associated with cardiovascular disease and stroke.
