CH 13 Practice Problems

the sympathetic and parasympathetic divisions belong to the _____ nervous system

autonomic

a neuron never has more than one ______

axon

where does the axon originate?

axon hillock

the cytoplasm of a neuron is called the ______ and the membrane is the _____

axoplams; axolemma

16. A/an _____ synapse is formed when a presynaptic neuron synapses with the cell body of a postsynaptic neuron

axosomatic

10. which of the following appears earlier than all the rest in prenatal development of the nervous system? a. neural groove b. pair of primary vesicles c. neural plate d. neural crest e. neural tube

c. neural plate

6. Neurotransmitters are found in a. the cell bodies of neurons b. the dendrites c. the axon hillock d. the axon terminal e. the postsynaptic plasma membrane

d. axon terminal

3. the soma of a mature neuron lacks a. a nucleus b. endoplasmic reticulum c. lipofuscin d. centrioles e. ribosomes

d. centrioles

8. nerves that directly control the motility of the stomach or rate of the heartbeat would belong to a. central nervous system b. somatic sensory division c. somatic motor division d. visceral motor division e. visceral sensory division

d. visceral motor division

the myelin sheath is ______ to the neurilemma

deep

14. neurons receive incoming signals by way of specialized processes called

dendrites

2. Neurons arise from embryonic a. endoderm b. epidermis c. mesoderm d. mesenchyme e. ectoderm

e. ectdoderm

1. The integrative functions of the nervous system are performed mainly by a. afferent neurons b. efferent neurons c. neuroglia d. sensory neurons e. interneurons

e. interneurons

5. A friends takes a flash photograph of you, and you continue to see an image of the flash for several seconds afterward. This phenomenon is the result of a _____ circuit a. diverging b. converging c. presynaptic d. reverberating e. parallel after discharge

e. parallel after discharge

myelination in the CNS

each oligodendrocyte reaches out to myelinate several nerve fibers in its immediate vicinity

17. all of the nervous system except the brain and spinal cord is called the ___

peripheral nervous system

20. at a given synapse, the _____ neuron has neurotransmitter receptors

postsynaptic

neurotransmitters bind to surface _____ on the ______ neuron to stimulate or inhibit it

receptors; postsynaptic

12. motor effects that depend on repetitive output from a neural pool are most likely to use the _____ type of neural circuit

reverberating

_____ cells surround somas of neurons in the ganglia; insulate them and regulate their chemical environment (PNS)

satellite

____ ______ connect sense organs to the CNS

sensory (afferent) neurons

at the distal end, an axon usually has a ____ _____ - an extensive complex of fine branches

terminal arborization

the more dendrites a neuron has =

the more information it can receive from other cells and incorporate into its decision making

Why do nodes (gaps) between segments in the myelin sheath of nerve fibers occurs during myelination?

-in both the PNS and CNS, a nerve fiber is much longer than the reach of a single glial cell, so it requires many Schwann cells or oligodendrocytes to cover one fiber -internodal segments = the myelin-covered segments from one gap to the next

Milder form of spina bifida

-occulta = involves only one to a few vertebra with no functional problems -more severe = cystica: sac protrudes from spine and may contain parts of the spinal cord and nerve roots, meninges, and CSF

What the two factors that determine the speed at which a signal travels along a nerve fiber?

1. diameter of the fiber 2. presence/absence of myelin **large fibers = greater surface area = more rapid signal conduction **myelinated = faster

glial cells of the PNS include

Schwann cells and satellite cells

_____ cells form neurilemma around all PNS nerve fibers and myelin around them; aid in regeneration of damaged nerve fibers

Schwann

T or F: the unmyelinated fibers in the PNS are enveloped in Schwann cells

T: one Schwann cell harbors form 1 to 12 small nerve fibers in grooves in its surface

myelination in the PNS

a Schwann cell spirals repeatedly around a single nerve fiber, laying down as many as a hundred compact layers of its own membrane with almost no cytoplasm between the membranes = myelin sheath *finally end with a thick outermost coil called the neurilemma

9. the glial cells that guide migrating neurons in the developing fetal brain are a. astrocytes b. oligodendrocytes c. satellite cells d. ependymal cells e. microglia

a. astrocytes

4. the glial cells that destroy microorganisms in the CNS are a. microglia b. satellite cells c. ependymal cells d. oligodendrocytes e. astrocytes

a. microglia

7. another name for the axon of a neuron is a. nerve fiber b. neruofibril c. neurilemma d. axoplasm e. endoneurium

a. nerve fiber

11. neurons that convey information to the CNS are called sensory, or ____ neurons

afferent

13. prenatal degeneration of the forebrain results in a birth defect called _____

anencephaly

19. In the PNS, the somas of the neurons are concentrated in enlarged, knotlike structures called ______ connected to the nerves

ganglia

myelin sheath ______ exist in both the CNS and PNS

gaps

_______ _______ greatly outnumber neurons in the brain

glial cells

_______ are contained entirely within the CNS

interneurons

the trigger zone of a neuron is at the ______ of the _______ and the axon

junction; neurosoma

What is the first structure of the central nervous system?

neural plate - gives rise to most neurons and to all glial cells except microglia (come from mesoderm)

Development of the Nervous System

neural plate ---> neural groove with raised neural fold on each side --> neural tube ---> closure of neural tube ---> neural crest

18. the ___ and ____ are necessary for regeneration of damaged nerve fibers in the PNS

neurilemma and endoneurium

15. in the CNS, cells called _____ perform one of the same functions that Schwann cells do in the PNS

oligodendrocytes

myelin is produced by ____ in the CNS

oligodendrocytes

glial cells of the CNS include

oligodendrocytes, microglia, astrocytes, ependymal cells

_____ _____ have an axon and produce action potentials

unipolar neurons