Chapter 12 Practice Questions

6 September 2022
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question
The nervous system employs exclusively electrical means to send messages, whereas the endocrine system communicates by means of chemical messengers.
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False
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Most neurons have multiple dendrites.
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True
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Neurons move material away from the soma by retrograde transport.
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False
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Unipolar neurons have only a single process leading away from the soma.
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True
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Oligodendrocytes serve the same purpose in the CNS that satellite cells do in the PNS.
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False
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Ependymal cells line the inner cavities of the CNS.
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True
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In the brain, neurons are more abundant than neuroglia.
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False
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An action potential never occurs in dendrites.
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True
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When a neuron is stimulated, Na+ gates open and allow Na+ to exit the cell.
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False
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In a myelinated fiber, only the initial segment in the trigger zone has voltage-regulated channels.
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False
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Norepinephrine is a monoamine.
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True
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Acetylcholine triggers the synthesis of the second messenger cAMP only in neurons of the PNS.
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False
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Nitric oxide (NO) acts as a neuromodulator by altering synaptic function.
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True
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Any two EPSPs will override one IPSP.
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False
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Memories are formed by neural pathways of modified synapses.
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True
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The __________ division carries signals to the smooth muscle in the large intestine.
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visceral motor
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The __________ division tends to prepare the body for action.
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sympathetic
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Which of the following are effectors?
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Glands
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What is another name for the autonomic nervous system?
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Visceral motor division
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Nerves are __________ of the nervous system.
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organs
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Some __________ neurons are specialized to detect stimuli, whereas __________ neurons send signals to the effectors of the nervous system.
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afferent; efferent
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About 90% of the neurons in the nervous system are __________ neurons.
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association
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What is the most common type of neuron?
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Multipolar
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The term "nerve fiber" refers to a(n) __________.
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axon
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Most metabolic and regulatory functions in a neuron happen where?
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The soma
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Which glial cell is found wrapped around nerve fibers in the PNS?
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Schwann cells
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In which part of a neuron is the postsynaptic membrane usually found?
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Dendrite
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What is the primary site on a neuron for receiving signals from other neurons?
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The dendrites
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Which cells form myelin in the spinal cord?
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Oligodendrocytes
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A myelin sheath is composed primarily of __________.
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lipids
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Conduction of a nerve impulse would be the fastest in which of the following?
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A large diameter myelinated fiber
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In order to regenerate, a peripheral nerve fiber must have which of the following?
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The soma and at least some neurilemma intact
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Which of the following ions has the greatest influence on the resting membrane potential?
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Potassium
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Where do most local potentials form in a neuron?
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The dendrites
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In a neuron, the opening of sodium gates typically leads to __________.
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depolarization of the plasma membrane
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Which of the following will cause the plasma membrane to hyperpolarize when at its RMP?
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An inflow of chloride
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Local potentials are __________, meaning they vary in magnitude according to the strength of the stimulus.
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graded
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An inhibitory local potential causes which of the following?
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Hyperpolarization of the plasma membrane
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While a neuron membrane is depolarizing its __________.
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sodium gates are fully open
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A neuron receives a stimulus. Which of the following events happens next?
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A local potential develops
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In an action potential, which event directly follows repolarization?
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Hyperpolarization of the membrane
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Local potentials are __________, whereas action potentials are __________.
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graded; all or none
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What occurs during hyperpolarization of a neuron membrane?
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Potassium ions are leaving the cell
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When the voltage of a plasma membrane shifts from +35mV towards 0 mV, the cell is __________.
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repolarizing
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During the absolute refractory period which of the following is true?
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No stimulus of any strength will trigger a new action potential.
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A traveling wave of excitation is known as a(n) __________.
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nerve signal
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What would be the best explanation for why myelinated fibers conduct signals faster than unmyelinated fibers?
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Diffusion of ions along the axoplasm is faster.
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All of the following are typical characteristics of neurotransmitters except __________.
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they are released into the bloodstream before reaching the postsynaptic cell
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A cholinergic synapse uses __________ as its neurotransmitter.
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acetylcholine
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hat is the most common inhibitory neurotransmitter in the brain?
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Ī³-aminobutyric acid (GABA)
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Which of these happens first in an cholinergic synaptic transmission?
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The synaptic vesicles release acetylcholine
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Which of these happens first in an adrenergic synaptic transmission?
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G protein dissociates from the NE recep
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Some antidepressant drugs act by inhibiting monoamine oxidase (MAO). What is the function of this enzyme?
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It breaks down monoamines.
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Which of these does not contribute to the cessation of the signal in a synaptic transmission?
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Synaptic vesicles secrete neurotransmitter by exocytosis.
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Which neurotransmitter excites skeletal muscle and inhibits cardiac muscle?
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Acetylcholine
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Inhibitory postsynaptic potentials (IPSPs) are associated with which of the following?
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Hyperpolarization of the cell membrane
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The opening of __________ gates produces an __________.
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chloride; IPSP
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Which of these is an example of an EPSP in a typical neuron?
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A voltage change from -70 mV to -69.5 mV
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A neuron can receive thousands of EPSPs from different neurons, and responds by triggering or not triggering an action potential. This addition and response to the net effect of postsynaptic potentials is called __________.
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spatial summation
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What is the opposite of presynaptic inhibition?
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Facilitation
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What type of neural circuit is best for producing a prolonged output?
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A reverberating circuit
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Even though all action potentials are the same, the brain can differentiate a variety of stimuli by source and intensity. The mechanism by which the nervous system converts these action potentials into meaningful information is called neural __________.
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coding
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Parkinson disease is a progressive loss of motor function due to the degeneration of specific neurons. These neurons secrete an inhibitory neurotransmitter that prevents excessive activity in motor centers of the brain. What neurotransmitter is this?
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Dopamine
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Accumulation of Ca2+ in the synaptic knob is called __________, and probably plays an important role in __________.
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synaptic facilitation; short-term memory
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While both systems maintain homeostasis, how does the nervous system differ from the endocrine system?
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The nervous system releases neurotransmitters between cells, while the endocrine system releases hormones into the blood.
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Which body system(s) is(are) dedicated to maintaining stable internal conditions by detecting and responding to stimuli?
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Nervous and endocrine
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What property of neurons allows them to respond to changes in the environment?
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Excitablity
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If a neuron is prevented from sending a neurotransmitter across a synapse to another cell, which neuron property is being inhibited?
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Secretion
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How does a neuron transport enzymes produced in the soma to its axon terminals?
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Along microtubules
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Where are unmyelinated nerve fibers surrounded by Schwann cells?
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In the PNS
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Which of the following is true regarding unmyelinated nerve fibers in the PNS?
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A Schwann cell folds its plasma membrane around several fibers .
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In PNS nerve fiber regeneration, how is a growing axon directed to its original destination?
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It grows within a regeneration tube.
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If the potassium leak channels were suddenly blocked in a resting neuron, what would happen to its resting membrane potential?
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It would become more positive.
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Where does saltatory conduction occur?
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From node to node in myelinated fibers
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Place the following events in synaptic transmission at a cholinergic synapse in order: A - A postsynaptic potential is produced; B - Voltage gated calcium channels open and calcium enters the cell; C - ACh is released and diffuses across the synaptic cleft; D - A nerve signal arrives at a synaptic knob; E - Ligand gated sodium channels open and sodium enters the cell.
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D, B, C, E, A
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Place the following events of synaptic transmission at an adrenergic synapse in order: A - ATP is converted to cAMP B - The cell's metabolism is altered C - G protein binds adenylate cylase D - The G protein dissociates E - NE binds the receptor
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E, D, C, A, B
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The respiratory center gathers information from a variety of sources in order to set the rate and depth of breathing. This is an example of what type of neural circuit?
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Convergent