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  • 1. Chapter 23 A&P The Nervous System
  • 2. Introduction
    • The nervous system is the body’s information gather, storage center and control system.
    • It controls, directs and coordinates body functions.
    • The nervous system is divided into the central nervous system and the peripheral nervous system.
  • 3. Objectives
    • Identify the structures that make up the nervous system.
    • Explain how nerve impulses are transmitted.
    • State the functions of the central nervous system, the peripheral nervous system and the autonomic nervous system.
    • Identify disorders associated with the nervous system.
    • Lifespan considerations.
  • 4. Neurons, Nerve Fibers, Nerves and Tracts
  • 5. Neurons / Nerve Cell
    • All nervous system tissue is made up of nerve cells, called neurons, and their supporting tissues called neuroglia.
    • These cells allow the body to interacts with its internal and external environments.
    • There are 3 types of neurons: motor (doers), sensory (sensors) and interneurons (communicators).
  • 6. Motor Neurons
    • Motor neurons cause muscles to contract and glands to secrete, and organs to perform their functions.
    • They can also inhibit these actions.
    • Motor neurons are also known as efferent meaning they carry messages away from the cell body to the muscles and organs.
  • 7. Motor neuron
    • Motor neurons have a nucleated cell body with process extending away from the cell body.
    • These nerve fibers are called axons and dendrites.
    • Dendrites carry impulses to the cell body and the axon carries impulses away from it.
  • 8. Motor neurons
    • Most axons are covered with a fatty insulating substance called the myelin sheath.
    • Axons with myelin sheath transmit impulses faster than those without.
    • Damage to unmyelinated cells is usually permanent.
    • The axon and dendrites allow neurons to communicate.
  • 9. What does this mean?
    • Hit your thumb with a hammer and the motor neurons allow you to pull back you hand.
    • Smell fresh baked bread and your mouth waters.
    • Dust in your eye causes you to blink.
  • 10. Sensory neurons
    • The second types of nerve cell is known as the sensory neuron or afferent neurons.
    • Sensory neurons have sensor receptors that allow transmission or impulses, or messages, to the central nervous system.
    • Therefore our ability to feel the hammer, smell the bread or feel the discomfort from the dust.
  • 11. Interneurons
    • Third type of nerve cell.
    • Found in the central nervous system and mediate impulses between the motor and sensory neurons.
  • 12. Nerve fibers, Nerves and Tracts
    • A nerve is a bundle of nerve fibers, located outside the brain and spinal cord, that connect various parts of the body.
    • Sensory nerves carry messages to the CNS (brain) and the motor nerves carry messages away from the CNS.
    • Groups of nerve fibers within the CNS are known as tracts.
  • 13. Nerve Impulses
    • Chemical neurotransmitters are stored in the axon terminals.
    • The space between neurons is called a synapse.
    • Information is received in the dendrite, passed through the cell body, travels down the axon and over the synapse to the next dendrite.
  • 14. The Central Nervous System Brain Cerebrum Largest part of the brain Thought intelligence Cerebellum Regulates & Coordinates Body movement Brainstem Connects Cerebrum To spinal cord Spinal Cord Conducts info To & from the brain. Protected by Meninges Dura Matter Arachnoid Pia Matter
  • 15. The Peripheral Nervous System
    • The peripheral nervous system has 12 pairs of cranial nerves and 31 pairs of spinal nerves.
    • Peripheral nerves with special functions for the autonomic nervous system.
  • 16. Cranial Nerves
    • The cranial nerves conduct impulses between the brain and the head, neck, chest and abdomen.
    • Impulses for smell, vision, hearing, pain, touch, temperature and pressure, voluntary and involuntary muscles control.
  • 17. Peripheral Nervous Stsyem
    • Spinal nerves carry impulses from skin, extremities and internal body structure not supplied by cranial nerves.
  • 18. Autonomic Nervous System
    • Controls involuntary muscles and functions including heartbeat, blood pressure, intestinal contractions and glandular secretions.
  • 19. Autonomic Nervous System
    • Sympathetic
    • Speeds up functions
    • Stimulated with exercise
    • Stimulated with anger, excitement or fear.
    • Parasympathetic
    • Slows down functions
    • Activated with relaxation
    • Activated when under stimulated for too long
  • 20. What happens with fear?
  • 21. The Sensory System