CHAPTER 8

27) Opening of voltage-gated sodium channels in the membrane of a neuron results in A) depolarization. B) repolarization. C) hyperpolarization. D) increased negative charge inside the membrane. E) myelination.

A

11) The largest and most numerous of the glial cells in the central nervous system are the A) astrocytes. B) Schwann cells. C) oligodendrocytes. D) microglia. E) ependymal cells.

A

14) The neurilemma of axons in the peripheral nervous system is the outer layer of A) astrocytes. B) Schwann cells. C) oligodendrocytes. D) microglia. E) ependymal cells.

B

10) The branching structures that, together with the cell body, are sensitive to chemical, mechanical, or electrical stimulation are called A) axons. B) Nissl bodies. C) synapses. D) dendrites. E) neurofibrils.

D

13) Small phagocytic glial cells, which are derived from white blood cells, are called A) astrocytes. B) Schwann cells. C) oligodendrocytes. D) microglia. E) ependymal cells.

D

18) Neurons that have two or more dendrites and a single axon extending away from the cell body are called A) polypolar. B) unipolar. C) bipolar. D) tripolar. E) multipolar.

E

28) Which statement is trueregarding action potential propagation? A) In salutatory conduction, the myelin is composed of fat, which insulates the axon membrane against sodium ion flow across the membrane. B) Continuous propagation results in one graded potential producing multiple action potentials. C) The action potential will die out along the axon if another graded potential does not occur. D) All voltage-gated channels along the axon open at the same time, allowing sodium to flow in simultaneously. E) The active transport of sodium and potassium through sodium-potassium ion pumps causes depolarization of the axon membrane.

A

33) A few spiders produce a venom that is a calcium-channel blocker. Where would this venom have on nerve impulse transmission? A) at the axon terminal B) at the axon hillock C) along the dendrite D) along the cell body membrane E) at the postsynaptic membrane

A

39) The ________ is the layer of the meninges that is in direct contact with the surface of the brain. A) pia mater B) subarachnoid space C) dura mater D) epidural space E) arachnoid

A

47) Which spinal cord structure(s) contains the axons of CNS motor neurons that control muscles and glands? A) anterior gray commissure B) white column C) ventral roots D) dorsal roots E) ventral horns

C

48) When a cerebrospinal fluid specimen is needed for testing, the specimen is removed by needle from the L3-L4 interspace area of the vertebral column. Why? A) There are no spaces between the other areas of the vertebral column. B) There is a higher pressure within the subarachnoid space at that point, so it is easier to obtain a specimen. C) There are no spinal nerves located in that area. D) There would be no possible damage to the spinal cord itself when the needle is inserted into the space. E) The space where the needle is inserted is larger than anywhere else along the vertebral column.

D

8) Most neurons in the brain are A) bipolar. B) unipolar. C) anaxonic. D) multipolar. E) tripolar.

D

12) The myelin sheaths that surround the axons of some of the neurons in the CNS are formed by A) astrocytes. B) Schwann cells. C) oligodendrocytes. D) microglia. E) ependymal cells.

A

21) Interneurons A) are found only in the central nervous system. B) carry only sensory impulses. C) carry only motor impulses. D) only connect motor neurons to other motor neurons. E) are found between neurons and their effectors.

A

37) You have been diagnosed with the demyelinating disease called multiple sclerosis. The areas of damage seem to be centered within the spinal cord. The demyelinated areas are most probablywithin the A) ascending and/or descending tracts. B) dorsal or ventral horns. C) central canal. D) dorsal root ganglia. E) gray commissure.

A

6) The ________ division of the nervous system brings sensory information to the central nervous system. A) afferent B) descending C) efferent D) motor E) spinal

A

9) The glial cells responsible for maintaining the blood-brain barrier are the A) astrocytes. B) Schwann cells. C) microglia. D) ependymal cells. E) satellite cells.

A

22) Most neurons lack centrioles. This observation explains A) why neurons grow such long axons. B) why such neurons cannot divide through mitosis. C) the conducting ability of neurons. D) the ability of neurons to communicate with each other. E) the longevity of neurons.

B

23) The all-or-none principle states that A) all stimuli will produce identical action potentials. B) all stimuli great enough to bring the membrane to threshold will produce identical action potentials. C) the greater the magnitude of the stimuli, the greater the intensity of the action potential. D) only sensory stimuli can activate action potentials. E) only motor stimuli can activate action potentials.

B

25) Changes in the membrane potential that cannot spread far from the site of stimulation are called A) threshold. B) graded potentials. C) refractories. D) hyperpolarizations. E) action potentials.

B

30) A stimulus that opens gated potassium ion channels, moving the membrane voltage value below the resting potential value, results in which of the following? A) repolarization B) hyperpolarization C) depolarization D) refraction E) summation

B

31) Identify the correctsequence of steps in the generation of an action potential. 1. Activation of sodium channels and rapid depolarization 2. Inactivation of sodium channels and activation of potassium channels 3. Depolarization to threshold 4. Closing of potassium channels A) 1, 3, 4, 2 B) 3, 1, 2, 4 C) 4, 3, 2, 1 D) 1, 3, 2, 4 E) 3, 1, 4, 2

B

32) Adrenergic synapses release the neurotransmitter A) acetylcholine. B) norepinephrine. C) dopamine. D) serotonin. E) GABA.

B

4) The part of the peripheral nervous system that brings information to the central nervous system is the A) motor division. B) afferent division. C) efferent division. D) autonomic division. E) somatic division.

B

40) Head injuries that damage cerebral blood vessels are serious conditions because A) they could cause severe pain. B) the blood could compress and distort the relatively soft tissues of the brain. C) epicardial tissue will be affected. D) the venous sinus will not drain. E) pathways will be blocked.

B

41) The projections of gray matter extending through the white matter toward the outer surface of the spinal cord are called A) wings. B) horns. C) pyramids. D) fibers. E) tracts.

B

7) The ________ nervous system provides involuntary regulation of smooth muscle, cardiac muscle, and glandular activity. A) central B) autonomic C) somatic D) collateral E) ganglionic

B

16) Branches that sometimes occur along the length of an axon are called A) action potentials. B) synaptic knobs. C) collaterals. D) hillocks. E) synapse.

C

17) Neurons that have one axon and one dendrite with the cell body between them are called A) polypolar. B) unipolar. C) bipolar. D) tripolar. E) multipolar.

C

19) Which neuroglial cells produce CSF in some regions of the brain? A) microglia B) Schwann cells C) ependymal cells D) oligodendrocytes E) astrocytes

C

24) The resting potential of a neuron is A) 0 mV. B) +10 mV. C) -70 mV. D) -10 mV. E) +70 mV.

C

26) Saltatory conduction A) occurs only if the myelin sheath is continuous. B) occurs only if nodes of Ranvier are lacking. C) is faster than conduction on an unmyelinated axon. D) produces a stronger action potential. E) occurs at the synapse.

C

29) During continuous conduction, A) action potentials move in all directions along an axon. B) action potentials occur at successive nodes along the length of the stimulated axon. C) local currents depolarize adjacent areas of membrane so that action potentials continue along the membrane. D) the action potential starts at the beginning of the neuronal pathway and continues form neuron to neuron. E) local potentials produce a continuous outward flow of potassium ions.

C

43) Enlargements of the spinal cord occur A) near the posterior median sulcus. B) adjacent to the anterior median fissure. C) in the cervical and lumbar regions. D) in the thoracic region of the spinal cord. E) in the cervical and thoracic regions.

C

15) Clusters of rough endoplasmic reticulum and free ribosomes are known as A) neurofilaments. B) neurofibrils. C) synapses. D) Nissl bodies. E) microglia.

D

20) Bundles of CNS axons that share a common origin, destination, and function are called A) the cortex. B) centers. C) nuclei. D) tracts. E) ganglia.

D

34) Multiple areas of the brain can regulate breathing at the same time by stimulating the diaphragm for contraction. This activity is best explained by A) saltatory conduction. B) divergent neuronal pools. C) linear neuronal pools. D) convergent neuronal pools. E) the all-or-none principle.

D

35) Which of the following neurotransmitters usually depolarizes postsynaptic neurons? A) serotonin B) dopamine C) GABA D) acetylcholine E) monoamine oxidase

D

38) Which of the following contains a delicate network of collagen and elastin fibers through which cerebrospinal fluid circulates? A) epidural space B) dural sinus C) arachnoid villi D) subarachnoid space E) pia mater

D

42) Axons that cross from one side of the spinal cord to the other are found in the A) anterior white columns. B) lateral gray horns. C) posterior gray horns. D) gray commissures. E) posterior white columns.

D

44) The entire spinal cord is divided into ________ segments. A) 5 B) 12 C) 25 D) 31 E) 35

D

45) The gray matter of the spinal cord is dominated by A) tracts. B) columns. C) meninges. D) cell bodies of neurons and glial cells. E) blood vessels.

D

36) Which of the following is the correctorder of events that occur at a cholinergic synapse? 1. Extracellular calcium enters the axon terminal, triggering the exocytosis of acetylcholine. 2. Acetylcholine is removed by acetylcholinesterase. 3. Acetylcholine binds to receptors and depolarizes the postsynaptic membrane. 4. Axon terminal depolarizes. A) 2, 3, 1, 4 B) 1, 4, 3, 2 C) 4, 1, 2, 3 D) 3, 4, 1, 2 E) 4, 1, 3, 2

E

46) In adults, the spinal cord usually extends to which level? A) tenth thoracic vertebra B) first sacral vertebra C) seventh cervical vertebra D) fourth or fifth lumbar vertebra E) first or second lumbar vertebra

E

49) If the dorsal root of a spinal nerve is severed, A) motor control of skeletal muscles would be impaired. B) motor control of visceral organs would be impaired. C) the spinal cord would not be able to process information at that level. D) the brain would not be able to communicate with that level of the spinal cord. E) incoming sensory information would be disrupted.

E

5) All of the nervous tissue outside of the central nervous system comprises the ________ nervous system. A) somatic B) autonomic C) sympathetic D) central E) peripheral

E