Nervous System

Biology 3201 1. Unit 1- Maintaining Dynamic Equilibrium II Ch. 12 – The Nervous System (pp. 390-419) 12.1 – Structure of the Nervous System nervous system: a high-speed communication system which delivers information to and from the brain and spinal cord and all over the body. In any nervous system, there are 4 main components: (1) sensors: gather information from the external environment (sense organs) (2) conductors: carry information from sensors to modulators or from modulators to effectors (nerves) (3) modulators: interpret sensory information and send information to effectors (brain, spinal cord) (4) effectors: part of the body that responds because of information from a modulator (muscles, glands) The Human Nervous System Two main components of the human nervous system: (1) central nervous system (CNS): the brain and spinal cord (2) peripheral nervous system (PNS): the nerves that enter and leave the brain and spinal cord CNS 6 receives sensory information and initiates control 6 protected by several things: (1) skull – hard casing that protects the brain (2) vertebrae – protects spinal cord (3) meninges – three protective membranes surrounding the brain and spinal cord. They are filled with cerebrospinal fluid to help cushion. (4) Ventricles (cavities) in the brain which are filled with cerebrospinal fluid 6 grey matter: brownish-grey nerve tissue consisting of mainly cell bodies within the brain and spinal cord 6 white matter: the white nerve tissue of the brain and spinal cord, consisting of mostly

myelinated neurons. PNS 6 two parts: (1) autonomic nervous system: the part of the nervous system that relays information to the internal organs that are not under the conscious control of the individual. This system is made up of the sympathetic and the parasympathetic nervous systems. - sympathetic: speeds up muscle activity and activates in times of stress; “fight or flight response” ex. Increases heart rate, breathing rate, nervousness -