The human body is made up of several organ systems that work together as one unit. In the pyramid of life that organizes all of the elements of life into categories, organ systems are nested between an organism and its organs. Organ systems are the groups of organs that are within an organism.
Ten major organ systems of the human body are listed below along with the major organs or structures that are associated with each system. Each system depends on the others, either directly or indirectly, to keep the body functioning normally.
Once you a feeling confident in your knowledge of the organ system, try a simple quiz to test yourself.
Circulatory SystemDorling Kindersley / Getty Images
The main function of the circulatory system is to transport nutrients and gasses to cells and tissues throughout the body. This is accomplished by the circulation of blood. Two components of this system are the cardiovascular and lymphatic systems.
The cardiovascular system is comprised of the heart, blood, and blood vessels. The beating of the heart drives the cardiac cycle which pumps blood throughout the body.
The lymphatic system is a vascular network of tubules and ducts that collect, filter and return lymph to blood circulation. As a component of the immune system, the lymphatic system produces and circulates immune cells called lymphocytes. The lymphatic organs include the lymph vessels, lymph nodes, thymus, spleen, and tonsils.
Digestive Systemcomotion_design / Getty Images
The digestive system breaks down food polymers into smaller molecules to provide energy for the body. Digestive juices and enzymes are secreted to break down the carbohydrates, fat, and protein in food. The primary organs are the mouth, stomach, intestines, and rectum. Other accessory structures include the teeth, tongue, liver, and pancreas.
Endocrine SystemCHRISTIAN DARKIN / SCIENCE PHOTO LIBRARY / Getty Images
The endocrine system regulates vital processes in the body including growth, homeostasis, metabolism, and sexual development. Endocrine organs secrete hormones to regulate body processes. Major endocrine structures include the pituitary gland, pineal gland, thymus, ovaries, testes, and thyroid gland.
The integumentary system protects the internal structures of the body from damage, prevents dehydration, stores fat, and produces vitamins and hormones. The structures that support the integumentary system include skin, nails, hair, and sweat glands.
Muscular SystemOliver Burston / Getty Images
The muscular system enables movement through the contraction of muscles. Humans have three types of muscles: heart muscle, smooth muscle, and skeletal muscles. Skeletal muscle is made up of thousands of cylindrical muscle fibers. The fibers are bound together by connective tissue that is made up of blood vessels and nerves.
Nervous SystemScience Picture Co / Getty Images
The nervous system monitors and coordinates internal organ function and responds to changes in the external environment. The major structures of the nervous system include the brain, spinal cord, and nerves.
Reproductive SystemDEA PICTURE LIBRARY / Getty Images
The reproductive system enables the production of offspring through sexual reproduction between a male and female. The system is comprised of male and female reproductive organs and structures which produce sex cells and ensure the growth and development of offspring. The major male structures include the testes, scrotum, penis, vas deferens, and prostate. The major female structures include the ovaries, uterus, vagina, and mammary glands.
Respiratory SystemLEONELLO CALVETTI / Getty Images
The respiratory system provides the body with oxygen via a gas exchange between air from the outside environment and gases in the blood. The major respiratory structures include the lungs, nose, trachea, and bronchi.
Skeletal SystemSCIEPRO / Getty Images
The skeletal system supports and protects the body while giving it shape and form. The major structures include 206 bones, joints, ligaments, tendons, and cartilage. This system works closely with the muscular system to enable movement.
Urinary Excretory SystemStocktrek Images / Getty Images
The urinary excretory System removes wastes and maintains water balance in the body. Other aspects of its function include regulating electrolytes in body fluids and maintaining normal pH of the blood. The major structures of the urinary excretory system include the kidneys, urinary bladder, urethra, and ureters.