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Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins Memmler’s The Human Body in Health and Disease 11 th edition Chapter 9 The Nervous.

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Presentation on theme: "Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins Memmler’s The Human Body in Health and Disease 11 th edition Chapter 9 The Nervous."— Presentation transcript:

1 Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins Memmler’s The Human Body in Health and Disease 11 th edition Chapter 9 The Nervous System: The Spinal Cord and Spinal Nerves

2 Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins Role of the Nervous System Nervous system coordinates all body systems Detects and responds to stimuli Brain and spinal cord act as switching centers Nerves carry messages to and from centers

3 Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins Structural Divisions Central nervous system (CNS) –Brain –Spinal cord Peripheral nervous system (PNS) –Cranial nerves –Spinal nerves

4 Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins Anatomic divisions of the nervous system.

5 Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins Functional Divisions Somatic nervous system Controlled voluntarily Effectors are skeletal muscles No further subdivisions Autonomic (or visceral) nervous system (ANS) Controlled involuntarily Effectors are smooth muscle, cardiac muscle, and glands Subdivided into –Sympathetic nervous system –Parasympathetic nervous system

6 Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins Brain SomaticAutonomic Skeletal; Voluntary control Glands; Cardiac & Smooth Muscle; Involuntary Sympathetic “Fight/ flight” Parasympathetic “Rest/ digest”

7 Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins Checkpoint 9-1: What are the two divisions of the nervous system based on structure? Checkpoint 9-2: The nervous system can be divided functionally into two divisions based on type of control and effectors. What division is voluntary and controls skeletal muscle, and what division is involuntary and controls involuntary muscles and glands?

8 Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins Neurons and Their Functions Neurons Functional cells of nervous system Highly specialized Unique structure

9 Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins Diagram of a motor neuron. The break in the axon denotes length. The arrows show the direction of the nerve impulse. Is the neuron shown here a sensory or a motor neuron?

10 Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins Structure of a Neuron Cell body Nucleus Other organelles Cell fibers Dendrites Axons –Some are protected by myelin sheath

11 Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins a. b. c What is a dendrite? a. A neuron fiber that conducts impulses away from the cell body b. A neuron fiber that conducts impulses to the cell body c. A gap between myelin-covered axons

12 Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins Answer: b. A neuron fiber that conducts impulses to the cell body

13 Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins Formation of a myelin sheath. (A)Schwann cells wrap around the axon, creating a myelin coating. (B) The outermost layer of the Schwann cell forms the neurilemma. Spaces between the cells are the nodes (of Ranvier).

14 Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins ACTIVITY Make your own myelin covered nerve

15 Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins Checkpoint 9-3: The neuron, the functional unit of the nervous system, has long fibers extending from the cell body. What is the name of the fiber that carries impulses toward the cell body and what is the name of the fiber that carries impulses away from the cell body? Checkpoint 9-4: Myelin is a substance that covers and protects some axons. What color describes myelinated fibers, and what color describes unmyelinated tissue of the nervous system?

16 Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins Types of Neurons Sensory neurons (afferent neurons) –Conduct impulses to spinal cord, brain Motor neurons (efferent neurons) –Conduct impulses to muscles, glands Interneurons (central or association neurons) –Conduct information within CNS

17 Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins Nerves and Tracts Nerve: fiber bundle within PNS Tract: fiber bundle within CNS Organized into fascicles Connective tissue layers –Endoneurium –Perineurium –Epineurium

18 Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins Checkpoint 9-5: Nerves are bundles of neuron fibers in the PNS. These nerves may be carrying impulses either toward or away from the CNS. What name is given to nerves that convey impulses toward the CNS, and what name is given to nerves that transport away from the CNS?

19 Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins Neuroglia Neuroglia (glial cells) Protect and nourish nervous tissue Support nervous tissue Aid in cell repair Remove pathogens and impurities Regulation composition of fluids around and between cells

20 Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins Checkpoint 9-6: The nervous system’s nonconducting cells protect, nourish and support the neurons. What are these cells called?

21 Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins The Nervous System at Work Electrical impulses sent along neuron fibers and transmitted between cells at junctions

22 Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins The Nerve Impulse Plasma membrane carries electrical charge (potential) Plasma membrane is polarized (negative charge) Membrane potential reverses, generates electrical charge (action potential) –Resting state –Depolarization –Repolarization Sodium/potassium (Na+/K+) pump Myelin sheath speeds conduction

23 Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins Question: Which ions are involved in the action potential? a. Potassium and calcium b. Sodium and oxygen c. Sodium and potassium

24 Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins Answer: c. Sodium and potassium

25 Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins Checkpoint 9-7: An action potential occurs in two stages. In the first stage, the charge on the membrane reverses, and in the second stage, it returns to the resting state. What are the names of these two stages? Checkpoint 9-8: What ions are involved in generating an action potential?

26 Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins The Synapse Junction point for transmitting nerve impulse Axon (presynaptic cell) Dendrite (postsynaptic cell) Synaptic cleft Neurotransmitters –Epinephrine (adrenaline) –Norepinephrine (noradrenaline) –Acetylcholine Receptors

27 Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins Neurotransmitters and Psychoactive Drugs Psychoactive drugs affect neurotransmitter activity in the brain Used to treat depression, anxiety, obsessive-compulsive disorder (OCD) Selective serotonin reuptake inhibitors (Example: Prozac) –Block serotonin uptake Others block norepinephrine, dopamine.

28 Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins A synapse. (A)The end-bulb of the presynaptic (transmitting) axon has vesicles containing neurotransmitter, which is released into the synaptic cleft to the membrane of the postsynaptic (receiving) cell. (B) Close-up of a synapse showing receptors for neurotransmitter in the postsynaptic cell membrane.

29 Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins Question: The point of junction for transmitting a nerve impulse is called what? a. axon b. synapse c. vesicle

30 Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins Answer: b. synapse

31 Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins Checkpoint 9-9: Chemicals are needed to carry information across the synaptic cleft at a synapse. As a group, what are all these chemicals called?

32 Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins The Spinal Cord Links PNS and brain Helps coordinate impulses within CNS Contained in and protected by vertebrae

33 Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins Spinal cord and spinal nerves. Nerve plexuses (networks) are shown. (A) Lateral view. (B) Posterior view. Is the spinal cord the same length as the spinal column? How does the number of cervical vertebrae compare with the number of cervical spinal nerves?

34 Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins Structure of the Spinal Cord Unmyelinated tissue (gray matter) –Dorsal horn –Ventral horn –Gray commissure –Central canal Myelinated axons (white matter) –Posterior median sulcus –Anterior median fissure –Ascending and descending tracts

35 Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins Checkpoint 9-10: The spinal cord contains both gray and white matter. How is this tissue arranged in the spinal cord? Checkpoint 9-11: What is the purpose of the tracts in the white matter of the spinal cord?

36 Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins The spinal cord. (A) Cross-section of the spinal cord showing the organization of the gray and white matter. The roots of the spinal nerves are also shown. (B) Microscopic view of the spinal cord in cross-section (x5).

37 Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins The Reflex Arc Receptor detects stimulus Sensory neuron transmits impulses to CNS CNS coordinates impulses and organizes response Motor neuron carries impulses away from CNS Effector carries out response

38 Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins Typical reflex arc. Numbers show the sequence of impulses through the spinal cord (solid arrows). Contraction of the biceps brachii results in flexion of the arm at the elbow. Is this a somatic or an autonomic reflex arc? What type of neuron is located between the sensory and motor neuron in the CNS?

39 Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins Checkpoint 9-12: What name is given to a pathway through the nervous system from a stimulus to an effector?

40 Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins Reflex Activities Simple reflex –Rapid –Uncomplicated –Automatic Spinal reflex –Stretch reflex

41 Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins Medical Procedures Involving the Spinal Cord Lumbar puncture (spinal tap) –Cerebrospinal fluid (CSF) removed for testing Drug administration –Anesthetic (an epidural or spinal anesthesia) –Pain medication

42 Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins Diseases and Other Disorders of the Spinal Cord Multiple sclerosis (MS) Amyotrophic lateral sclerosis Poliomyelitis Tumors Injuries –Monoplegia –Diplegia –Paraplegia –Hemiplegia –Tetraplegia (Quadriplegia)

43 Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins Question: In a lumbar tap, what is removed from the body for testing? a. cerebrospinal fluid b. lymph c. bone marrow

44 Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins Answer: a. cerebrospinal fluid

45 Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins The Spinal Nerves 31 pairs Each nerve attached to spinal cord by two roots –Dorsal root Dorsal root ganglion –Ventral root Nerves near end of cord travel together in the cord until each exits from its respective intervertebral foramen Mixed nerves

46 Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins Branches of the Spinal Nerves Cervical plexus –Phrenic nerve Brachial plexus –Radial nerve Lumbosacral plexus –Sciatic nerve Dermatomes

47 Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins Dermatomes. A dermatome is a region of the skin supplied by a single spinal nerve. Which spinal nerves carry impulses from the skin of the toes? From the anterior hand and fingers?

48 Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins Checkpoint 9-13: How many pairs of spinal nerves are there?

49 Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins Disorders of the Spinal Nerves Peripheral neuritis Sciatica Herpes zoster Guillain-Barré syndrome

50 Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins The Autonomic Nervous System (ANS) Regulates the action of glands, smooth muscles of hollow organs and vessels, and heart muscle Preganglionic neuron connects spinal cord to ganglion Postganglionic neuron connects ganglion to effector

51 Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins Checkpoint 9-14: How many neurons are there in each motor pathway of the ANS?

52 Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins Divisions of the Autonomic Nervous System Sympathetic nervous system Parasympathetic nervous system

53 Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins Sympathetic nervous system Thoracolumbar area Collateral ganglia –Celiac ganglion –Superior mesenteric ganglion –Inferior mesenteric ganglion Adrenergic system Activated in the four E’s: excitement, emergency, embarassment, exercise

54 Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins Parasympathetic nervous system Arise in craniosacral areas Terminal ganglia Cholinergic system

55 Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins Question: Any group of nerve cell bodies located outside the central nervous system is known as what? a. a ganglion b. a plexus c. a horn

56 Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins Answer: a. a ganglion

57 Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins Autonomic nervous system. The diagram shows only one side of the body for each division. Which division of the autonomic nervous system has ganglia closer to the effector organ?

58 Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins Cellular Receptors “Docking sites” on postsynaptic cell membranes Two types: Cholinergic receptors –Nicotinic (bind nicotine) on skeletal muscle cells –Muscarinic (bind muscarine, a poison) on effector cells of PNS Adrenergic receptors –Found on receptor cells of sympathetic nervous system –Bind norepinephrine, epinephrine

59 Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins Functions of the Autonomic Nervous System Sympathetic nervous system –Fight-or-flight response Parasympathetic nervous system –Returns body to normal Systems generally have opposite effects on organ

60 Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins Checkpoint 9-15: Which division of the ANS stimulates a stress response, and which division reverses the stress response?

61 Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins Question: What is the technical name of a “docking site” on a postsynaptic cell membrane? a. neurotransmitter b. cellular receptor c. dendrite

62 Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins Answer: b. cellular receptor

63 Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins QUESTIONS?


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