The NERVOUS SYSTEM has two main subdivisions: the somatic, or voluntary, component; and the autonomic, or involuntary, component. The autonomic nervous system regulates certain body processes, such as blood pressure and the rate of breathing, that work without conscious effort. The somatic system consists of nerves that connect the brain and spinal cord with muscles and sensory receptors in the skin.

The skeletal system gives the body its basic framework, providing structure, protection, and movement. The 206 bones in the body also produce blood cells, store important minerals, and release hormones necessary to life.  

The muscular system is comprised of the sum total of muscles throughout the body that move the skeleton, maintain posture through steady contraction, and generate heat through cell metabolism. Humans have three types of muscle.  

The circulatory system is a body-wide network of blood, blood vessels, and lymph. Powered by the heart, it is the body’s distribution system to organs with oxygen, hormones and essential nutrients that helps it function properly. 

The respiratory system, which includes air passages, pulmonary vessels, the lungs, and breathing muscles, provides oxygenated blood to the body tissues and removes waste gases.