Branches of Human Physiology

Physiology is the study of a living organism's biological functioning. Human physiology, therefore, is the study of the biological functions and mechanisms of human beings.

A sub-discipline of biology, the field is comprised of numerous branches and systems of study. These branches may vary by approach, by process, by subsystem, and even by the organism, such as animal physiology, plant physiology, and so on and so forth. However, when individuals typically consider the branches of human physiology, they're usually referring to the body's various subsystems.

The major subsystems of human physiology include:

•             Circulatory

•             Digestive/Excretory

•             Endocrine

•             Immune

•             Integumentary

•             Musculoskeletal

•             Nervous

•             Renal/Urinary

•             Reproductive

•             Respiratory

Let's learn about some of these subsystems in greater detail.

Circulatory System

The circulatory system, also referred to as the cardiovascular system, refers to the organ system which circulates blood and transports nutrients, oxygen, carbon dioxide, blood cells, and hormones to and from cells in the body. Through this system, the body is able to fight pathogens and maintain homeostasis, a steady-state of internal conditions conducive to normal functioning. The parts of the circulatory system include the heart, blood, and blood vessels.

Digestive/Excretory System

The digestive system processes nutrition and the excretory system removes waste. These two systems work for hand and hand and are therefore often spoken of together. The digestive system includes the mouth, esophagus, stomach, small intestine, and large intestine. The excretory system removes waste in the forming of urine and feces, but also in the forms of sweat (removing excess salts) and exhalation (releasing carbon dioxide). 

Endocrine System

The endocrine system is a network of glands in the body that secrete hormones. These hormones are responsible for growth and development, metabolism, organ function, reproduction, and mood regulation. In fact, almost every cell, organ, and system in the body relies on these hormones in order to function.

The parts of the endocrine system include the hypothalamus, pituitary gland, pineal gland, thyroid gland, parathyroid, thymus, adrenals, pancreas, ovaries, and testes. The hypothalamus, pituitary gland, and pineal gland are located in the brain.

Immune System

The immune system, one of the most well-known physiological subsystems, is what allows the human body to fight disease and infection. It's a complex network of cells and proteins that is incredibly able to "remember," or recognize, every single microbe it has ever encountered and neutralized. By doing so, if you get sick because of one type of germ, the body will remember how it defeated it and thus protect you against becoming sick again. In fact, this is how vaccines work.

The main parts of the immune system include white blood cells, antibodies, the complement system, the lymphatic system, spleen, bone marrow, and the thymus. 

Integumentary System

The integumentary system is the largest organ of the body and includes the skin or the outermost layer of the human body. It includes all layers of the skin—the epidermis, dermis, and hypodermis—as well as hair, nails, and associated glands. This system is responsible for keeping pathogens out of the body, by functioning as a physical barrier, and for regulating temperature, synthesizing vitamin D, detecting external stimuli, and more.

To learn more about human physiology, visit human physiology labs online.