Phys Ch 8 Neurons

24 July 2022
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Detailed understanding of the cellular basis of signaling in the nervous system has led to good understanding of consciousness, intelligence, and emotion. ANSWER: True False
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False
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The brain and spinal cord together compose the ANSWER: peripheral nervous system. somatic motor division of the nervous system. autonomic division system. central nervous system. visceral nervous system.
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central nervous system.
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Exocrine glands, smooth muscles, and cardiac muscles are controlled by the ANSWER: central nervous system. enteric nervous system. peripheral nervous system. autonomic nervous system. somatic motor division.
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autonomic nervous system.
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Autonomic motor neurons are subdivided into the ANSWER: sympathetic and parasympathetic divisions. somatic and enteric divisions. visceral and enteric divisions. visceral and somatic divisions. central and peripheral divisions.
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sympathetic and parasympathetic divisions.
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The enteric nervous system is a network of neurons that function in controlling ANSWER: excretion, particularly urination. reproduction. the endocrine system. the skeletal system. digestion.
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digestion.
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The portions of a neuron that extend off of the roughly spherical cell body are usually collectively called ANSWER: processes. projections. protrusions. prostheses.
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processes.
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Neurotransmitter is stored and released from ANSWER: axon terminals and axon varicosities. axon terminals only. cell bodies only. axon varicosities only. dendritic spines only.
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axon terminals and axon varicosities.
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Information coming into the central nervous system is transmitted along ________ neurons. ANSWER: afferent sensory and efferent efferent afferent and sensory sensory
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afferent and sensory
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The afferent and efferent axons together form the ANSWER: autonomic division system. peripheral nervous system. visceral nervous system. somatic motor division of the nervous system. central nervous system.
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peripheral nervous system.
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In general, the nervous system is composed of which two types of cells? 1. motor 2. neurons 3. sensory 4. glial 5. associative ANSWER: 1 and 2 3 and 5 1 and 3 3 and 4 2 and 4
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2 and 4
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The cell body of neurons is generally ANSWER: 90% of the cell volume. 10% of the cell volume. 50% of the cell volume. found in the same position on every neuron.
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10% of the cell volume.
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Interneurons are found ANSWER: throughout the nervous system. only in spinal nerves. only in the spinal cord. only in the brain. only in the CNS.
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only in the CNS.
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The multiple thin, branched structures on a neuron whose main function is to receive incoming signals are the ANSWER: dendrites. somata. cell bodies. axons. None of the answers are correct.
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dendrites.
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The collection of axons that carries information between the central nervous system and the peripheral effectors is called the ANSWER: dendrite. axon hillock. axon. varicosity. nerve.
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nerve.
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The region where the axon terminal meets its target cell is called the ANSWER: dendrites. nerve. synapse. collateral. hillock.
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synapse.
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The axon is connected to the cell body by the ANSWER: collaterals. axon hillock. synapse. axon terminal. myelin sheath.
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axon hillock.
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Branches that sometimes occur along the length of an axon are called ANSWER: collaterals. dendrites. axon terminals. axon hillocks. synapses.
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collaterals.
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Neurotransmitters are released from the ANSWER: dendrites. synapse. axon terminals. collaterals. axon hillock.
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axon terminals.
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The term axonal transport refers to ANSWER: -the transport of microtubules to the axon for structural support. -the movement of the axon terminal to synapse with a new postsynaptic cell. -the release of neurotransmitter molecules from the axon. -vesicle transport of proteins and organelles down the axon. -None of the answers are correct.
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vesicle transport of proteins and organelles down the axon.
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Anterograde and retrograde axonal transport are forms of ________ transport. ANSWER: slow fast Neither of these
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fast
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Clusters of nerve cell bodies in the peripheral nervous system are called ANSWER: glia. ganglia. nodes. neuroglia. microglia.
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ganglia.
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Glial cells ANSWER: -provide structural and metabolic support and help maintain homeostasis of the brain's extracellular fluid. -only help maintain homeostasis of the brain's extracellular fluid. -only guide neurons during growth and repair. -only provide structural and metabolic support. -All of the answers are correct.
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All of the answers are correct.
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Glial cells communicate primarily using ANSWER: chemical signals only. neurotransmitters only. electrical signals only. neuromodulators only. electrical signals and chemical signals.
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chemical signals only.
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Myelin is formed by ANSWER: Schwann cells and oligodendrocytes. axons only. oligodendrocytes only. Schwann cells only.
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Schwann cells and oligodendrocytes.
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These glial cells act as scavengers. ANSWER: microglia Schwann cells astrocytes oligodendrocytes ependymal cells
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microglia
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During childhood, growth and development of the brain PRIMARILY occurs by increasing ANSWER: -neuron numbers only. -neuron size only. -neuron size and number of dendrites and synapses. -neuron numbers and neuron size. -number of dendrites and synapses only.
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neuron size and number of dendrites and synapses.
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These glial cells may contribute to Lou Gehrig's disease. ANSWER: Schwann cells microglia ependymal cells oligodendrocytes astrocytes
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microglia
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Which of the following is the most common location where action potentials originate? ANSWER: synaptic cleft axon hillock cell body synaptic bouton dendrites
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axon hillock
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The Nernst equation predicts ANSWER: -the membrane potential resulting from all permeable ions. -the threshold membrane potential. -extracellular ion concentrations -the membrane potential resulting from permeability to a single ion. -intracellular ion concentrations.
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the membrane potential resulting from permeability to a single ion.
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Which is the correctly written Nernst equation? ANSWER: log 61/z ร— [ion]out / [ion]in 61/z ร— log [ion]in / [ion]out log 61/z ร— [ion]in / [ion]out 61/z ร— log [ion]out / [ion]in
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61/z ร— log [ion]out / [ion]in
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What does the Goldman-Hodgkin-Katz equation take into account that the Nernst equation does NOT? ANSWER: the electrical charges of the ions the solubilities of the ions the permeabilities of the ions the sizes of the ions the temperature
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the permeabilities of the ions
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The resting membrane potential results from ANSWER: -differences in membrane permeability to Na+ and K+ only. -activity of the sodium/potassium pump only. -uneven distribution of ions across the cell membrane and differences in membrane permeability to Na+ and K+. -uneven distribution of ions across the cell membrane only. -None of the answers are correct.
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uneven distribution of ions across the cell membrane and differences in membrane permeability to Na+ and K+.
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Which ion(s) is/are higher in concentration inside the cell compared to outside? ANSWER: potassium chloride calcium sodium More than one of the answers is correct.
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potassium
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The channelopathy known as QT syndrome is a result of mutation in ________ channels. ANSWER: sodium chloride potassium sodium, potassium, or calcium calcium
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sodium, potassium, or calcium
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Ion channel inactivation is ANSWER: -any type of channel closing. -closing of the channel even when the stimulus continues. -closing of the channel in response to decrease in the stimulus. -None of the answers are correct.
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closing of the channel even when the stimulus continues.
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The rising phase of the action potential is due to ANSWER: Na+ flow out of the cell and K+ flow into the cell. K+ flow out of the cell only. Na+ flow out of the cell only. K+ flow into the cell only. Na+ flow into the cell only.
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Na+ flow into the cell only.
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The falling phase of the action potential is due primarily to ANSWER: -Na+ flow out of the cell only. -Na+ flow in the cell only. -Na+ flow out of the cell and K+ flow into the cell. -K+ flow into the cell only. -K+ flow out of the cell only.
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K+ flow out of the cell only.
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The point during an action potential when the inside of the cell has become more positive than the outside is known as the ANSWER: depolarization. peak. falling phase. rising phase. overshoot.
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overshoot.
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The absolute refractory period of an action potential ANSWER: -only allows a neuron to ignore a second signal sent that closely follows the first. -ensures one-way travel down an axon, allows a neuron to ignore a second signal sent that closely follows the first, and prevents summation of action potentials. -ensures one-way travel down an axon and allows a neuron to ignore a second signal sent that closely follows the first. -only ensures one-way travel down an axon. -only prevents summation of action potentials.
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ensures one-way travel down an axon, allows a neuron to ignore a second signal sent that closely follows the first, and prevents summation of action potentials.
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In order to signal a stronger stimulus, action potentials become ANSWER: more frequent only. longer-lasting only. higher in amplitude only. higher in amplitude and longer-lasting. higher in amplitude and more frequent.
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more frequent only.
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All of the following must occur before a second action potential can begin, EXCEPT ANSWER: -the Na+ inactivation gate must open and the Na+ activation gate must close. -the absolute refractory period must occur. -the Na+ and K+ ions that moved in/out of the cell must move back to their original compartments; the Na+ inactivation gate must open; and the Na+ activation gate must close. -the Na+ and K+ ions that moved in/out of the cell must move back to their original compartments. -None of the answers are correct.
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the Na+ and K+ ions that moved in/out of the cell must move back to their original compartments.
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Voltage-regulated channels are located ANSWER: -in the membranes of axons only. -in the membranes of dendrites only. -on the neuron cell body only. -within the cytosol only. -in the membranes of dendrites, in the membranes of axons, and on the neuron cell body.
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in the membranes of dendrites, in the membranes of axons, and on the neuron cell body.
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The sodium-potassium exchange pump ANSWER: -requires ATP to function. -moves sodium and potassium in the direction of their chemical gradients. -must re-establish ion concentrations after each action potential. -transports sodium ions into the cell during depolarization. -transports potassium ions out of the cell during repolarization.
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requires ATP to function.
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The all-or-none principle states that ANSWER: -all stimuli will produce identical action potentials. -the greater the magnitude of the stimuli, the greater the intensity of the action potential. -only sensory stimuli can activate action potentials. -only motor stimuli can activate action potentials. -all stimuli great enough to bring the membrane to threshold will produce action potentials of identical magnitude.
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all stimuli great enough to bring the membrane to threshold will produce action potentials of identical magnitude.
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When voltage-gated Na+ channels of a resting neuron open, ANSWER: -Na+ enters the neuron and the neuron depolarizes. -Na+ leaves the neuron and the neuron depolarizes. -Na+ enters the neuron. -Na+ leaves the neuron. -the neuron depolarizes.
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Na+ enters the neuron and the neuron depolarizes.
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When voltage-gated K+ channels of a resting neuron open, ANSWER: -the neuron depolarizes. -K+ leaves the neuron. -K+ enters the neuron and the neuron depolarizes. -K+ enters the neuron. -K+ leaves the neuron and the neuron depolarizes.
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K+ leaves the neuron.
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In the membrane of a resting nerve cell, when chemically gated Cl- channels open, ANSWER: -Cl- ions leave the cell. -Cl- ions enter the cell. -Cl- ions leave the cell and the cell becomes depolarized. -the cell becomes depolarized. -Cl- ions enter the cell and the cell becomes depolarized.
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Cl- ions enter the cell.
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Which of the following will best increase the conduction rate of action potentials? ANSWER: -Decrease the diameter of the axon, decrease the resistance of the axon membrane to ion leakage. -Decrease the diameter of the axon, increase the resistance of the axon membrane to ion leakage. -Increase the diameter of the axon, decrease the resistance of the axon membrane to ion leakage. -Increase the diameter of the axon, increase the resistance of the axon membrane to ion leakage.
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Increase the diameter of the axon, increase the resistance of the axon membrane to ion leakage.
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Action potentials are primarily associated with the membranes of ANSWER: axons only. dendrites only. cell bodies and axons. cell bodies only. dendrites and axons.
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axons only.
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Which of the following does NOT influence the time necessary for a nerve impulse to be conveyed by a particular neuron? ANSWER: length of the axon whether axon is sensory or motor diameter of the axon presence or absence of nodes of Ranvier presence or absence of a myelin sheath
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whether axon is sensory or motor
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Ion concentrations are first significantly affected after ________ action potential(s). ANSWER: a few thousand one a few hundred a few million a few dozen
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a few thousand
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The total amount of neurotransmitter released at the axon terminal is directly related to ANSWER: the amplitude of the graded potential. the amplitude of the action potential. the length of the axon. the total number of action potentials.
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the total number of action potentials.