Nervous System Ms. Bowman

Nervous System Master controlling and communicating system of the body 1-Information that is gathered and sent to the brain is sensory 2-The brain processes and interprets the information and decides what action should be taken 3-Brain sends a response called a motor output

Nervous System Central Nervous System BrainSpinal Cord Peripheral Nervous System Motor SomaticAutonomic SympatheticParasympathetic Sensory

Central Nervous System (CNS) Consists of brain and spinal cord The integrating and command center of the nervous system Interprets sensory input and dictates motor responses based on past experience, reflexes, and current conditions

Peripheral Nervous System (PNS) The part of the nervous system outside of the CNS Consists mainly of nerves that extend from the brain (cranial nerves) and spinal cord (spinal nerves) These nerves serve as the communicating lines that link all parts of the body to the CNS 2 divisions-Sensory and Motor

Sensory Division of PNS “carrying toward” Consists of nerve fibers that convey impulses to the CNS from sensory receptors located throughout the body Keeps the CNS constantly informed of events going on inside and outside the body

Motor Division of PNS “carrying away” Transmits impulses from the CNS to effector organs (muscles and glands) Impulses activate muscles to contract and glands to secrete They bring about a motor response 2 parts: Somatic and Autonomic

Somatic Nervous System Voluntary nervous system Composed of nerve fibers that conduct impulses from CNS to skeletal muscles Allows us to consciously control our skeletal muscles

Autonomic Nervous System Involuntary nervous system Consists of visceral (pertaining to your gut) motor fibers that regulate the activity of smooth muscles, cardiac muscles, and glands 2 subdivisions: Sympathetic and Parasympathetic

Sympathetic Division of ANS Mobilizes involuntary body systems during activity

Parasympathetic Division of ANS Conserves energy Promotes housekeeping functions during rest

Neurons Nerve cells The structural units of the nervous system Highly specialized cells that conduct messages in the form of nerve impulses from one part of the body to another Special characteristics ▫Extreme longevity-can function for a lifetime ▫Amitotic-lose ability to divide; most cannot be replaced if they are damaged or destroyed ▫High metabolic rate-require continuous and abundant supplies of oxygen and glucose

Neurons Typically large, complex cells Vary in structure, but all have a nucleus and one or more processes that project Processes ▫Axons-conducting region; generate nerve impulses and transmit them ▫Dendrites-receptive or input region; information collector

Classification of Neurons Multipolar-3 or more processes; most common neuron type in humans and major type in CNS Bipolar-2 processes; one axon and dendrite; rare neurons found in some special sense organs Unipolar-1 single short process that divides T-like

Brain Protected by the meninges ▫Comprised of 3 layers of connective membranes  Dura Mater-strongest; outermost  Arachnoid Mater- middle; forms a loose brain covering; web-like projections anchor it to pia mater  Pia Mater-composed of delicate connective tissue; lots of blood vessels; innermost; clings tightly to brain Cerebrospinal Fluid (CSF)-watery “broth” that forms a liquid cushion and protects the brain and spinal cord; helps to nourish the brain Ventricles-canals that carry the CSF within brain and brain stem

Brain Divided into 3 components ▫Cerebrum ▫Cerebellum ▫Brain Stem

Cerebral Hemispheres Form the superior part of the brain Entire surface marked by gyri (elevated ridges of tissue) that are separated by sulci (shallow grooves) Fissures (deep grooves) separate large regions of the brain Where our conscious mind is found; enables us to be aware of ourselves and sensations, to communicate, remember, understand, and initiate voluntary movements

Cerebellum Processes inputs received from the cerebrum, brain stem, and sensory receptors Provides the precise timing and appropriate patterns of skeletal muscle contraction for smooth, coordinated movements and agility needed for our daily living Activity occurs subconsciously so we are not aware of it

Brain Stem Produce the rigidly programmed, automatic behaviors necessary for survival Origin of 10 of the 12 pairs of cranial nerves