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Nervous System

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

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Nervous System

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  1. Nervous System Ms. Bowman

  2. 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

  3. 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

  4. 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

  5. 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

  6. 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

  7. 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

  8. 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

  9. Sympathetic Division of ANS • Mobilizes involuntary body systems during activity

  10. Parasympathetic Division of ANS • Conserves energy • Promotes housekeeping functions during rest

  11. 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

  12. 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

  13. 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

  14. 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

  15. Brain • Divided into 3 components • Cerebrum • Cerebellum • Brain Stem

  16. 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

  17. 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

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

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