18 Organ Systems, The Whole Body, and Populations

Organ systems are made up of organs that work together to perform a specific function for the body as a whole. The table below describes the organ systems and their primary organs and physiological functions.

Table 1: Organ Systems, Key Organs, Primary Functions
Organ system Key organ(s) Primary function(s)
integumentary skin support; protection; regulation of fluid levels and temperature
skeletal bones, cartilage support; protection; movement; blood cell production
muscular muscles, tendons support; movement
urinary kidneys, bladder, urethra waste removal; regulation of fluid levels
digestive tongue, esophagus, stomach, small intestine, large intestine, gallbladder, rectum digestion of food; waste removal
respiratory trachea, lungs gas exchange; regulation of temperature
cardiovascular heart, blood vessels transport of materials through the body; regulation of temperature
nervous brain, spinal cord control of behavior and body systems; cognition
endocrine glands control of body systems and development
immune thymus, tonsils, spleen defense against infection
lymphatic lymph nodes, lymphatic vessels immunity; regulating fluid balance
reproductive penis, testes, prostate (males); uterus, ovaries, vagina (females) reproduction

The Whole Body

The organ systems of the body all work together to maintain proper physiological functions. Many times in the arena of anatomy and physiology, including in this course, we closely examine the molecules, cells, tissues and organs of the body to learn their forms and functions. However, it is important to consider that every molecule works as part of the entire system. Endocrine disorders such as diabetes affect glucose levels in the body. Altered blood glucose levels can affect many organ systems. For example, the immune system may not heal as well, the urinary system may experience kidney damage, and the cardiovascular system can experience vascular damage, even to the point of causing blindness. In the body, everything is interconnected.


Beyond the body, populations and environment can impact physiology and health. Some diseases and disorders are common to certain populations, most likely because of genetic connections. Also, environmental conditions can impact health. Particulates in the air can impact respiratory function. We are also affected by foods, exercise, sun exposure and other environmental conditions.


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