Parts of the Nervous System
Central Nervous System
Your central nervous system is made up of your brain and spinal cord. The central nervous system is the control center for all incoming and outgoing messages. It receives all information about your body, evaluates it, and integrates a response that is passed along to other organ systems. The central nervous system is the place where memories, knowledge, thoughts, and emotions are formed. It is also responsible for coordinating the movements of your muscles.
The job of your brain is to send outgoing messages to your body and interpret incoming messages from your body. It is protected by a bony case, your skull, and is divided into three main parts: the cerebrum, the cerebellum, and the brain stem.
Your cerebrum is located above your cerebellum and is the largest part of your brain. It consists of two halves (also known as hemispheres) that are in charge of different bodily functions. The left hemisphere is responsible for speech, language, and hand movements while the right hemisphere is responsible for hearing, touch, and balance. Both hemispheres communicate with each other to accomplish all of these functions, along with memory, emotions, and eyesight. The large size and interpretation capacity of the cerebrum is what gives humans their intelligence and ability to think critically.
Your cerebellum is a fist-sized structure located at the rear base of your cerebrum. Its main function is to regulate coordination and balance by directing groups of muscles during fine motor movements, and controlling larger muscles to maintain stability and posture. The cerebellum functions to make movements smooth, not jerky.
Your brain stem lies at the base of your brain, connecting the two hemispheres of the cerebrum and attaching your brain to your spinal cord. Your brain stem is a relay center for incoming messages and it controls unconscious bodily functions that you do not have to think about, such as your heart rate and breathing. Messages from sensory organs, like your eyes, ears, heart and lungs travel to the brain stem, where the information is integrated into a response and then sent to other parts of your brain.
Your spinal cord is the main pathway for signals to enter and exit your brain. It is essentially a cord of neurons that runs down from the base of your skull to your tail bone. To protect this important structure, a series of bones called vertebrae surround your spinal cord and make up your backbone. Nerves moving from this system out to your body are not part of the central nervous system, but instead belong to your peripheral nervous system.
Peripheral Nervous System
Your peripheral nervous system consists of the nerves that extend out from your spinal cord to your arms, legs and trunk, like a two-way street traveling to and from your central nervous system. This allows information to be passed to all parts of your body.
The peripheral nervous system is subdivided into the somatic nervous system and the autonomic nervous system.
Somatic Nervous System
Your somatic nervous system consists of all the nerves connecting the central nervous system to other parts of your body, such as skeletal muscle and skin. This system is in charge of all voluntary movement. It also controls your senses, including vision, taste and touch. Different sensory receptors detect sensations and send their information to your spinal cord and brain. The central nervous system then interprets the stimuli and generates a response. Each type of sensory receptor can send only one type of sensation.
Autonomic Nervous System
Your autonomic nervous system consists of all nerve pathways that extend to organs made of smooth muscle, cardiac muscle, and glands. This system regulates unconscious functions that you do not think about, such as heart rate, sweating, and gastrointestinal system.