Phys Ch 8 Neurons

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

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.

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.

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.

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.

The portions of a neuron that extend off of the roughly spherical cell body are usually collectively called ANSWER: processes. projections. protrusions. prostheses.

Neurotransmitter is stored and released from ANSWER: axon terminals and axon varicosities. axon terminals only. cell bodies only. axon varicosities only. dendritic spines only.

Information coming into the central nervous system is transmitted along ________ neurons. ANSWER: afferent sensory and efferent efferent afferent and sensory sensory

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.

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

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.

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.

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.

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.

The region where the axon terminal meets its target cell is called the ANSWER: dendrites. nerve. synapse. collateral. hillock.

The axon is connected to the cell body by the ANSWER: collaterals. axon hillock. synapse. axon terminal. myelin sheath.

Branches that sometimes occur along the length of an axon are called ANSWER: collaterals. dendrites. axon terminals. axon hillocks. synapses.

Neurotransmitters are released from the ANSWER: dendrites. synapse. axon terminals. collaterals. axon hillock.

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.

Anterograde and retrograde axonal transport are forms of ________ transport. ANSWER: slow fast Neither of these

Clusters of nerve cell bodies in the peripheral nervous system are called ANSWER: glia. ganglia. nodes. neuroglia. microglia.

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.

Glial cells communicate primarily using ANSWER: chemical signals only. neurotransmitters only. electrical signals only. neuromodulators only. electrical signals and chemical signals.

Myelin is formed by ANSWER: Schwann cells and oligodendrocytes. axons only. oligodendrocytes only. Schwann cells only.

These glial cells act as scavengers. ANSWER: microglia Schwann cells astrocytes oligodendrocytes ependymal cells

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.

These glial cells may contribute to Lou Gehrig's disease. ANSWER: Schwann cells microglia ependymal cells oligodendrocytes astrocytes

Which of the following is the most common location where action potentials originate? ANSWER: synaptic cleft axon hillock cell body synaptic bouton dendrites

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.

Which is the correctly written Nernst equation? ANSWER: log 61/z × [ion]out / [ion]in 61/z × log [ion]in / [ion]out log 61/z × [ion]in / [ion]out 61/z × log [ion]out / [ion]in

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

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.

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.

The channelopathy known as QT syndrome is a result of mutation in ________ channels. ANSWER: sodium chloride potassium sodium, potassium, or calcium calcium

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

Action potentials are primarily associated with the membranes of ANSWER: axons only. dendrites only. cell bodies and axons. cell bodies only. dendrites and axons.

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

Ion concentrations are first significantly affected after ________ action potential(s). ANSWER: a few thousand one a few hundred a few million a few dozen

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.