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Chapter 9 Nervous System

Chapter 9 Nervous System. 9.10-9.13. 9.10. Types of Nerves. Types of Nerves. Nerve = bundles of axons Sensory nerves = conduct impulses to the brain or spinal cord Motor nerves = carry impulses to the muscles and glands Mixed nerves = include both sensory and motor fibers. 9.11.

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Chapter 9 Nervous System

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  1. Chapter 9Nervous System 9.10-9.13

  2. 9.10 Types of Nerves

  3. Types of Nerves • Nerve = bundles of axons • Sensory nerves = conduct impulses to the brain or spinal cord • Motor nerves = carry impulses to the muscles and glands • Mixed nerves = include both sensory and motor fibers

  4. 9.11 Nerve Pathways

  5. Reflex Arcs • Reflex arcs = the simplest of nerve pathways with only a few neurons • Reflexes = a rapid, automatic, involuntary response to a stimulus

  6. Reflex Behavior • Control heart rate, breathing rate, blood pressure, and digestion • Carry out swallowing, sneezing, coughing, and vomiting

  7. Reflex Behavior • Patellar reflex = knee-jerk reflex • Only 2 neurons (sensory and motor) • Helps maintain upright posture • Withdrawal reflex = occurs when you touch a body part to something painful (like stepping on a tack) • Skin receptors  sensory nerves  interneuron  motor neuron  muscles contract • Other interneurons carry sensory impulses to the brain (makes you aware of the pain) • Limits tissue damage

  8. 9.12 Meninges

  9. Meninges • Meninges = membranes that cover the brain and spinal cordand offer protection • Three layers • Dura mater • Arachnoid mater • Pia mater

  10. Dura Mater • Outermost layer of the meninges • Tough, white, fibrous connective tissue • Many blood vessels and nerves • Forms periosteum in brain, but is not connected to the vertebrae in the spinal cord (epidural space)

  11. Arachnoid Mater • Thin, weblike membrane without blood vessels • Between the dura and pia mater • Below is the subarachnoid space with clear, watery cerebrospinal fluid (CSF)

  12. Pia Mater • Very thin and contains many nerves and blood vessels • Nourishes the underlying cells of the brain and spinal cord • Hugs the surface of the organs

  13. 9.13 Spinal Cord

  14. Structure of the Spinal Cord • Spinal cord= slender nerve column passing downward from the brain into the vertebral canal • Begins at the foramen magnum • Tapers to a point and terminates in the lumbar region • Spinal nerves = nerves that arise from the spinal cord and connect it to various body parts (31 pairs)

  15. Structure of the Spinal Cord • Cervical enlargement – supplies nerves to the upper limbs • Lumbar enlargement – gives off nerves to the lower limbs • Central canal – contains cerebrospinal fluid • Nerve tracts – myelinated nerve fibers that comprise major nerve pathways

  16. Structure of the Spinal Cord

  17. Functions of the Spinal Cord • Two major functions • Conduct nerve impulses • Center for spinal reflexes • Ascending tracts = carry sensory info to the brain • Descending tracts = conduct motor impulses from the brain to muscles and glands

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