A. receiving, storing, and processing information on the internal and external environments
B. bringing about changes in physiology and/or behavior to ensure optimal functions of homeostatic mechanisms
C. secretion of hormones
D. coordination of movement
E. All of the choices are correct.
A. It is a fatty membranous sheath.
B. It is formed by glial cells.
C. It influences the velocity of conduction of an electrical signal down an axon.
D. It covers all parts of the neuron, including the axon, cell body, and dendrites.
A. It refers to the passage of materials from the cell body of a neuron to the axon terminals.
B. It refers to the passage of materials from axon terminals to the cell body of a neuron.
C. It refers to the transport of materials from the inside to the outside across the axonal membrane.
D. It is especially important for maintaining the integrity of neurons with long axons.
A. A given neuron can be either a presynaptic neuron or a postsynaptic neuron.
B. An individual neuron can receive information from multiple other neurons.
C. An individual neuron can transmit information to multiple other neurons.
D. A neuron can simultaneously release more than one type of neurotransmitter.
E. A neuron receives information on its axons and delivers it to other neurons through its dendrites.
A. They form the myelin for axons.
B. Neurons outnumber glial cells 10 to 1 in the nervous system.
C. They deliver fuel molecules to neurons and remove the waste products of metabolism.
D. They are important for the growth and development of the nervous system.
E. They regulate the composition of the extracellular fluid in the CNS.
A. is called the potential difference between those points.
B. is called the diffusion potential between those points.
C. is called the the current, and is expressed in the units of millimoles.
D. is the same for all ions.
A. doubling both voltage and resistance
B. reducing both voltage and resistance by half
C. doubling voltage and reducing resistance by half
D. reducing voltage by half and doubling resistance
E. quadrupling both voltage and resistance
A. The concentration of Na+ in A will be higher than it was at time zero.
B. Diffusion of K+ from A to B will be greater than the diffusion of K+ from B to A.
C. There will be a potential difference across the membrane, with side B negative relative to side A.
D. The electrical and diffusion potentials for K+ will be equal in magnitude and opposite in direction.
E. The concentration of Cl- will be higher in B than it was at time zero.
A. It requires very few ions to be distributed unevenly.
B. It has the same value in all cells.
C. It is oriented so that the cell's interior is positive with respect to the extracellular fluid.
D. Only nerve and muscle cells have a potential difference across the membrane at rest.
E. It is not altered by changing concentration gradients of permeating ions.
A. The plasma membrane is most permeable to sodium ions.
B. The concentration of sodium ion is greater inside the cell than outside.
C. The permeability of the plasma membrane to potassium ions is much greater than its permeability to sodium ions.
D. The plasma membrane is completely impermeable to sodium ions.
E. The plasma membrane is completely impermeable to potassium ions.
A. equal to the equilibrium potential for potassium.
B. equal to the equilibrium potential for sodium.
C. slightly more negative than the equilibrium potential of potassium ion.
D. more positive than the equilibrium potential for potassium.
E. more positive than the equilibrium potential for sodium.
A. favors its movement into the cell at the resting membrane potential.
B. favors its movement out of the cell at the resting membrane potential.
C. is equal and opposite to the electrical potential acting on Na+ at the resting membrane potential.
D. Is in the same direction as the diffusion potential due to the concentration gradient for K+.
E. favors movement of Na+ in the opposite direction as the electrical potential acting on Na+ at the resting membrane potential.
A. depolarization of resting nerve cells
B. hyperpolarization of resting nerve cells
C. The potassium equilibrium potential of nerve cells would become more negative.
D. The sodium equilibrium potential would become less positive.
A. It generates a small electrical potential such that the inside is made negative with respect to the outside.
B. It maintains a concentration gradient for K+ such that diffusion forces favor movement of K+ into the cell.
C. It maintains an electrical gradient at the equilibrium potential of K+.
D. It transports equal numbers of sodium and potassium ions with each pump cycle.
E. It pumps 3 Na+ ions into the cell for every 2 K+ ions it pumps out.
A. Resting membrane potential would become more negative.
B. Resting membrane potential would become less negative.
C. The concentration gradient for Na+ would remain the same.
D. The resting membrane potential would eventually become positive inside with respect to outside.
E. There would be no change in the resting membrane potential.
A. It is a function of the concentration of that ion on both sides of the membrane.
B. It is the potential at which there is no net movement of that ion across the membrane.
C. It is the potential difference across the membrane at which an electric force favoring movement of the ion in one direction is equal in magnitude and opposite in direction to the diffusion force provided by the concentration difference of the ion across the membrane.
D. A permeable ion will move in the direction that will tend to bring the membrane potential toward that ion's equilibrium potential.
E. An anion that is in higher concentration inside the cell than outside the cell will have a negative eqilibrium potential.
A. Increasing the permeability of a resting neuronal membrane to K+ will make the membrane potential more negative inside with respect to outside.
B. In resting neurons, there is a net diffusion of K+ into the cell.
C. changing the resting membrane potential of a neuron to -80 mV would increase K+ diffusion rate out of the cell.
D. potassium is the only permanent ion at rest.
E. there must be another permanent ion with an equilibrium potential more negative than -90 mV.
A. The permeability to Na+ is much greater than the permeability to K+.
B. All of the K+ channels in the membrane are open.
C. The voltage-gated Na+ channels are in the inactivated state.
D. Most of the voltage-gated Na+ channels are in the closed state.
E. There is equal permeability to Na+ and K+.
A. a receptor potential in a sensory receptor cell
B. a depolarizing excitatory postsynaptic potential (EPSP)
C. a hyperpolarizing inhibitory postsynaptic potential (IPSP)
D. a depolarizing pacemaker potential
E. a depolarizing action potential
A. an action potential requires the opening of Ca2+ channels, whereas a graded potential does not.
B. an action potential is propagated without decrement, whereas a graded potential decrements with distance.
C. an action potential has a threshold, whereas a graded potential is an all-or-none phenomenon.
D. movement of Na+ and K+ across cell membranes mediate action potentials, while graded potentials do not involve movement of Na+ and K+.
E. action potentials vary in size with the size of a stimulus, while graded potentials do not.
A. trigger an excitatory postsynaptic potential.
B. cause a change in membrane potential.
C. trigger an action potential.
D. be conducted to the axon hillock.
E. depolarize a dendrite.
A. The membrane potential must be at the Na+ equilibrium potential.
B. Na+ influx must exceed K+ efflux.
C. The membrane must be out of the relative refractory period.
D. Na+ channels must all be inactivated.
E. Multiple inhibitory postsynaptic potentials (IPSPs) must summate.
A. K+ channels open before the Na+ channels.
B. Na+ channels are activated and then inactivated.
C. K+ channels open at the same time as the Na+ channels.
D. K+ channels are opened when Na+ binds to the channel.
E. K+ influx causes Na+ channels to inactivate.
A. PK+ becomes much greater than PNa+.
B. PNa+ becomes much greater than PK+.
C. PK+ is the same as PNa+.
D. Na+ efflux (flow out of the cell) occurs.
E. K+ flows rapidly into the cell.
A. The electrical gradient is in a direction that would tend to move K+ out of the cell.
B. The concentration gradient for K+ is in a direction that would tend to move it into the cell.
C. The concentration gradient for K+ greatly increases compared to at rest.
D. The concentration gradient for Na+ is in a direction that would tend to move it out of the cell.
E. The electrical gradient for Na+ is in a direction that would tend to move it into the cell.