READ: Introduction to Animals
4. Organ Systems
Groups of Organs Form Organ Systems
Your heart pumps blood around your body. But how does your heart get blood to and from every cell in your body? Your heart is connected to blood vessels such as veins and arteries. Organs that work together form an organ system. Together, your heart, blood, and blood vessels form your cardiovascular system.
What other organ systems can you think of?
Organ Systems Work Together
Your body’s 12 organ systems are shown in Table below. Your organ systems do not work alone in your body. They must all be able to work together to maintain homeostasis.
For example, when the men in Figure above jumped into the cold water, their integumentary system (skin), cardiovascular system, muscular system, and nervous system worked quickly together to ensure the icy water did not cause harm to their bodies.
For example, the nervous system sent nerve messages from the skin to tell the cardiovascular system to reduce the blood flow to the skin. Blood flow is then increased to the internal organs and large muscles to help keep them warm and supply them with oxygen. The nervous system also sent messages to the respiratory system to breathe faster. This allows for more oxygen to be delivered by the blood to the muscular system.
One of the most important functions of organ systems is to provide cells with oxygen and nutrients and to remove toxic waste products such as carbon dioxide. A number of organ systems, including the cardiovascular and respiratory systems, all work together to do this.
| Organ System | Major Tissues and Organs | Function |
| Cardiovascular | Heart; blood vessels; blood | Transports oxygen, hormones and nutrients to the body cells. Moves wastes and carbon dioxide away from cells |
| Lymphatic | Lymph nodes; lymph vessels | Defense against infection and disease, moves lymph between tissues and the blood stream |
| Digestive | Esophagus; stomach; small intestine; large intestine | Digests foods and absorbs nutrients, minerals, vitamins, and water |
| Endocrine | Pituitary gland, hypothalamus; adrenal glands; Islets of Langerhans; ovaries; testes | Hormones communicate between cells to maintain homeostasis |
| Integumentary | Skin, hair, nails | Protection from injury and water loss; physical defense against infection by microorganisms; temperature control |
| Muscular | Cardiac (heart) muscle; skeletal muscle; smooth muscle; tendons | Movement, support, heat production |
| Nervous | Brain, spinal cord; nerves | Collects, transfers and processes information |
| Reproductive | Female: uterus; vagina; fallopian tubes; ovaries Male: penis; testes; seminal vesicles | Production of gametes (sex cells) and sex hormones; production of offspring |
| Respiratory | Trachea, larynx, pharynx, lungs | Brings air to sites where gas exchange can occur between the blood and cells (around body) or blood and air (lungs) |
| Skeletal | Bones, cartilage; ligaments | Supports and protects soft tissues of body; movement at joints; produces blood cells; stores minerals |
| Urinary | Kidneys; urinary bladder | Removes extra water, salts, and waste products from blood and body; control of pH; controls water and salt balance |
| Immune | Skin; bone marrow; spleen; white blood cells | Defense against diseases |
CK-12 Foundation, Biology. http://creativecommons.org/licenses/by-nc-sa/3.0/