NERVOUS SYSTEM CELLS. a. afferent division CHAPTER 12 ORGANIZATION OF THE NERVOUS SYSTEM. Student Name

Student Name CHAPTER 12 NERVOUS SYSTEM CELLS T he nervous system organizes and coordinates the millions of impulses received each day to make communication with and enjoyment of our environment possible. The functioning unit of the nervous system is the neuron. Three types of neurons exist sensory, motor, and interneurons which are classified according to the direction in which they transmit impulses. Nerve impulses travel over routes made up of neurons and provide the rapid communication necessary for maintaining life. Your study of the nervous system begins with the simplest concept of impulse conduction known as the reflex arc. It then progresses to the more complex pathways such as divergence/convergence. An understanding of the anatomy and physiology of the nervous system cells is necessary before you progress to the complexity of this system and its multiple divisions. I ORGANIZATION OF THE NERVOUS SYSTEM Matching identify each part of the nervous system with its definition. 1. 2. 3. 4. consists of the brain and spinal cord composed of nerves arising from brain and spinal cord PNS subdivision that transmits incoming information from the sensory organs to CNS produces the "fight or flight" response a. afferent division b. autonomic nervous system c. central nervous system d. efferent nervous system e. parasympathetic division f. peripheral nervous system g- somatic nervous system h. sympathetic division 5. 6. 7. 8. subdivision that carries information from the CNS to skeletal muscle subdivision of efferent division that transmits information to smooth muscle, cardiac muscle, and glands consists of all outgoing motor pathways coordinates the body's normal resting activities f If you had difficulty with this section, review pages 342-344 Copyright 2003, Mosby, Inc. All rights reserved. 117

118 Study and Review Guide to accompany Anatomy & Physiology, 5th edition II CELLS OF THE NERVOUS SYSTEM Matching identify each type of cell with its 9. characteristics. has the ability of phagocytosis 10. helps to form the blood-brain barrier 11. produces fatty myelin sheath in PNS a. astrocyte b. microglia c. oligodendrocyte d. Schwann cell largest and most numerous of the neuroglial cells 12. produces myelin sheath in CNS 13. type of neuroglia that forms the neurilemma 14. "star-cell" disorder of this cell associated with multiple 15. sclerosis 16. Multiple Choice select the best answer. 17. Which of the following are classified as nerve fibers? a. axon b. dendrites c. both a and c d. none of the above 18. Which of the following conduct impulses towards the cell body? a. axons b. dendrites c. Nissl bodies d. none of the above 19. A neuron with one axon and several dendrites is a: a. multipolar neuron. b. unipolar neuron. c. bipolar neuron. d. none of the above. 20. Which type of neuron lies entirely within the CNS? a. afferent b. efferent c. interneuron d. none of the above 21. Which sequence best represents the course of an impulse over a reflex arc? a. receptor, synapse, sensory neuron, motor neuron, effector b. effector, sensory neuron, synapse, motor neuron, receptor c. receptor, motor neuron, synapse, sensory neuron, effector d. receptor, sensory neuron, interneuron, motor neuron, effector Copyright 2003, Mosby, Inc. All rights reserved.

120 Study and Review Guide to accompany Anatomy & Physiology, 5th edition Labeling using the terms provided, label the following illustration of a myelinated axon. neurilemma (sheath of Schwann cell) plasma membrane of axon nucleus of Shwann cell myelin sheath node of Ranvier neurofibrils Labeling identify the classification of each type of neuron in the following illustrations. Peripheral process Central process Axon Dendrites

Student Name Labeling using the terms provided, label the following illustration of a reflex arc. 121 gray matter interneuron sensory neuron axon cell body spinal nerve motor neuron axon white matter synapse dendrite To skeletal muscle effector Spinal cord *If you had difficulty with this section, review pages 344-351 III N ERVES AN D TRACTS Multiple Choice select the best answer. 22. A complete nerve, consisting of numerous fascicles and their blood supply, is held together by a fibrous coat called the: a. endoneurium. c. epineurium. b. perineurium. d. fascicle. 23. Small, distinct regions of gray matter within the CNS are usually called: a. white matter. c. ganglia. b. nuclei. d. fascicle. 25. Gray matter in the CNS consists of: a. nerve fibers. c. axons. b. neuroglia. d. cell bodies. 26. Most nerves in the human nervous system are: a. sensory nerves, c. mixed nerves. b. motor nerves. d. reflex nerves. 24. Nerves that contain mostly efferent fibers are called: a. sensory nerves, c. mixed nerves. b. motor nerves. d. Schwann nerves. ^If you had difficulty with this section, review pages 350-352 Copyright 2003, Mosby, Inc. All rights reserved.

122 Study and Review Guide to accompany Anatomy & Physiology, 5th edition IV REPAIR OF NERVE FIBERS True or false 27. 28. Neurons have a vast ability to repair themselves. Regeneration of nerve fibers will occur if the cell body is intact and the fibers have a neurilemma. There are no differences between the CNS and PNS concerning the repair of damaged fibers. 29. *If you had difficulty with this section, review pages 352-353 V NERVE IMPULSES Multiple Choice select the best answer. 30. Compared with the inside of the cell, the outside of most cell membranes is: a. positive. b. negative. c. equal. d. none of the above. 31. The difference in electrical charge across a plasma membrane is called: a. depolarization. b. membrane potential. c. both a and b. d. none of the above. 32. A neuron's resting membrane potential is: a. 70 mv. c. 30 mv. b. -70 mv. d. -30 mv. 33. Which of the following statements is true concerning the sodium-potassium pump? a. Three sodium ions are pumped out of the neuron for every two potassium ions pumped into the neuron. b. Two sodium ions are pumped out of the neuron for every three potassium ions pumped into the neuron. c. Three sodium ions are pumped out of the neuron for every three chloride ions pumped into the neuron. d. Three sodium ions are pumped out of the neuron for every three potassium ions pumped into the neuron. True or false 34. 35. A membrane that exhibits a membrane potential is said to be polarized. A slight shift away from the resting membrane potential in a specific region of the plasma membrane is often called a stimulus-gated channel. Chlorine ions (C1-) are the dominant extracellular cations. 36. *If you had difficulty with this section, review pages 353-355

Student Name. VI ACTION POTENTIAL 123 Multiple Choice select the best answer. 37. During a relative refractory period: a. an action potential is impossible. b. an action potential is possible only in response to a very strong stimuli. c. an action potential is occurring. d. none of the above. 38. Voltage-gated channels are: a. membrane channels that close during voltage fluctuations. b. membrane channels that open in response to voltage fluctuations. c. membrane channels that are altered from an extremely high stimulus. d. none of the above. 39. When current leaps across an insulating myelin sheath from node of Ranvier to node of Ranvier, the type of impulse conduction is: a. repolarization. b. refraction. c. saltatory conduction. d. diffusion. 40. The larger the diameter of a nerve fiber: a. the slower the speed of conduction. b. the faster the speed of conduction. c. Fiber diameter does not influence speed of conduction. d. the more the speed fluctuates. True or false 41. 42. Action potential and nerve impulse are synonymous. When repolarization has occurred, an impulse cannot be conducted. The action potential is an all-or-none response. Many anesthetics function by inhibiting the opening of sodium channels and thus blocking the initiation and conduction of nerve impulses. f If you had difficulty with this section, review pages 355-359 VII SYNAPTIC TRANSMISSION Multiple Choice select the best answer. 45. Which of the following structures is NOT a component of a chemical synapse? a. synaptic knob b. synaptic cleft c. neurotransmitter d. plasma membrane of postsynaptic neuron 46. A synaptic knob is located on the: a. synaptic cleft. c. dendrite. b. axon. d. cell body. 47. Which of the following is true of spatial summation? a. Neurotransmitters released simulta neously from several presynaptic knobs converge on one postsynaptic neuron. b. Simultaneous stimulation of more than one postsynaptic neuron occurs. c. Impulses are fired in a rapid succession by the same neuron. d. Speed of impulse transmission is increased when several neurotransmitters are released.

124 Study and Review Guide to accompany Anatomy & Physiology, 5th edition True or false 48. 49. 50. In an adult, the nervous system is replete with both electrical synapses and chemical synapses. Rapid succession stimulation of a postsynaptic neuron by a synaptic knob can have a cumulative effect over time that can result in an action potential. Ca ++ ions cause the release of neurotransmitters across the synaptic cleft. Labeling using the terms provided, label the following illustration of a chemical synapse. synaptic knob stimulus-gated Na + channels presynaptic cell synaptic cleft postsynaptic cell action potential voltage-gated K + channels voltage-gated Ca ++ channels ^If you had difficulty with this section, review pages 359-362 Copyright 2003, Mosby, Inc. All rights reserved.

Student Name VII NEUROTRANSMITTERS Multiple Choice select the best answer. 51. Neurotransmitters are released in a synapse 54. Severe depression can be caused by a deficit in and bind to: which of the following neurotransmitters? a. presynaptic terminals. a. acetylcholine c. amines b. the synaptic cleft. b. amino acids d. neuropeptides c. the base of the axon. d. receptors on the postsynaptic terminal. 55. Which of the following is NOT a catecholamine? 52. The main chemical classes of neurotransmit- a. epinephrine c. dopamine ters include all of the following EXCEPT: b. norepinephrine d. serotonin a. acetylcholine. c. amino acids. b. norepinephrine. d. neuropeptides. 53. Which of the following is NOT an example of an amine neurotransmitter? a. serotonin c. glycine b. histamine d. dopamine True or false 56. Many biologists now believe that neuropeptides are the most common neurotransmit ters in the CNS. 57. Cocaine produces a temporary feeling of well-being by blocking the uptake of dopamine. ******If you had difficulty with this section, review pages 363-367 125 VIM MECHANISMS OF DISEASE Fill in the blanks. 58. is a disorder of the nervous system that in volves the glia rather than neurons. 59. is a common type of brain tumor that is usually benign but may still be life-threatening. 60. A highly malignant form of astrocytic tumor is known as 61. Joseph Merrick, the so-called Elephant Man, suffered from. 62. Most disorders of the nervous system cells involve rather than neurons. ****** if y OU h ac [ difficulty with this section, review page 368 Copyright 2003, Mosby, Inc. All rights reserved.

126 Study and Review Guide to accompany Anatomy & Physiology, 5th edition Crossword Puzzle Across 6. Bundle of peripheral nerve fibers 7. Membrane potential of an active neuron (two words) 10. Place where signals are transmitted from one to another neuron 12. Transmits impulses toward the cell body Down 1. Consists of a cell body, an axon, and one or more dendrites 2. potential or difference in electrical charge across the plasma membrane 3. White, fatty substance 4. Supporting cell of the nervous system 5. Signal conduction route to and from the CNS (two words) 8. Center of entire nervous system (abbrev.) 9. Nerves that lie in the "periphery" (abbrev.) 11. Transmits impulses away from the cell body Copyright 2003, Mosby, Inc. All rights reserved.

Student Name 127 APPLYING WHAT YOU KNOW 63. Jim is experiencing muscular weakness, loss of coordination, visual impairment, and speech distur bances. Which disease of the CNS could he be experiencing? Which nervous tissue cells are most likely involved? What specifically occurs to both the neurons and neuroglia of the CNS? What are the possible treatments and what are the theories as to the cause of this disease? 64. John is a professional football player who, upon a severe compressing blow to the head, lost the ability to move his lower body. He was rushed to the hospital where the doctors suspected crushing and bruising to the spinal cord. What are the chances of the damaged nervous tissue repairing itself? DIDYOUKNOW? In the adult human body, there are 46 miles of nerves. ONE LAST QUICK CHECK 1 Circle the correct answer. 65. A synaptic knob is a tiny bulge at the end of the (presynaptic or postsynaptic) neuron's axon. 66. Acetylcholine is an example of a (neurotransmitter or protein molecule receptor). 67. Neurotransmitters are chemicals that allow neurons to (communicate or reproduce) with one another. 68. Neurotransmitters are distributed (randomly or specifically) into groups of neurons. 69. Endorphins and enkephalins are neurotransmitters that inhibit conduction of (fear or pain). 70. Unipolar neurons are always (sensory or motor) neurons. 71. In the peripheral nervous system, small regions of gray matter are known as (nuclei or ganglion). 72. The distal tips of axons form branches called (telodendria or axon hillock). Copyright 2003, Mosby, Inc. All rights reserved.

128 Study and Review Guide to accompany Anatomy & Physiology, 5th edition Matching select the best choice for the following words and insert the correct letter in the blanks. 73. axon a. neurons b. neuroglia 74. supporting cells 75. astrocytes 76. sensory 77. conduct impulses 78. forms the myelin sheath 79. phagocytosis 80. efferent around central nerve fibers 81. multiple sclerosis 82. multipolar