A&P homework (11.1-11.14)

During depolarization, which gradient(s) move(s) Na+ into the cell? A) only the electrical gradient B) Na+ does not move into the cell. Na+ moves out of the cell. C) both the electrical and chemical gradients D) only the chemical gradient

both the electrical and chemical gradients

The sodium-potassium ion exchange pump A) is not involved in producing the resting membrane potential. B) transports sodium ions into the cell during depolarization. C) depends on a hydrogen gradient for energy. transports potassium ions out of the cell during repolarization. D) moves sodium and potassium opposite to the direction of their electrochemical gradients

moves sodium and potassium opposite to the direction of their electrochemical gradients

What is the value for the resting membrane potential for most neurons? A) -90 mV B) -70 mV C) +30 mV

-70 mV

What type of conduction takes place in unmyelinated axons? A) Saltatory conduction B) Electrical conduction C) Continuous conduction D) Synaptic transmission

Continuous conduction

Which of the following is defined as a graded hyperpolarization of the postsynaptic membrane? A) IPSP B) resting potential C) equilibrium potential D) EPSP

IPSP

What changes occur to voltage-gated Na+ and K+ channels at the peak of depolarization? A) Activation gates of voltage-gated Na+‎ channels close, while activation gates of voltage-gated K+‎ channels open. B) Inactivation gates of voltage-gated Na+‎ channels close, while activation gates of voltage-gated K+‎ channels open. C) Activation gates of voltage-gated Na+‎ channels close, while inactivation gates of voltage-gated K+‎ channels open. D) Inactivation gates of voltage-gated Na+‎ channels close, while inactivation gates of voltage-gated K+‎ channels open.

Inactivation gates of voltage-gated Na+‎ channels close, while activation gates of voltage-gated K+‎ channels open

The membranes of neurons at rest are very permeable to _____ but only slightly permeable to _____. A) Na+; K+ B) Na+; Cl- C) K+; Na+ D) K+; Cl-

K+; Na+

In which type of axon will velocity of action potential conduction be the fastest? A) Unmyelinated axons with the largest diameter B) Myelinated axons with the smallest diameters C) Myelinated axons with the largest diameter D) Unmyelinated axons of the shortest length

Myelinated axons with the largest diameter

The concentrations of which two ions are highest outside the cell. A) Na+ and A- (negatively charged proteins) B) Na+ and Cl- C) K+ and A- (negatively charged proteins) D) K+ and Cl-

Na+ and Cl-

The Na+-K+ pump actively transports both sodium and potassium ions across the membrane to compensate for their constant leakage. In which direction is each ion pumped? A) Na+ is pumped out of the cell and K+ is pumped into the cell. B) K+ is pumped out of the cell and Na+ is pumped into the cell. C) Both Na+ and K+ are pumped out of the cell. D) Both Na+ and K+ are pumped into the cell

Na+ is pumped out of the cell and K+ is pumped into the cell

Clusters of RER and free ribosomes in neurons are called A) neurofibrils. B) Nissel bodies. C) microglia. D) neurofilaments. E) perikaryon

Nissel bodies

In the formation of an action potential at the initial segment of an axon, what produces the brief hyperpolarization during the step in which the potassium channels begin closing? A) The stimulus that initiates the action potential causes voltage-gated sodium channels to open. B) Sodium ions rush into the cell. C) Potassium ions enter the cell until all of the potassium channels have closed. D) Potassium ions continue to leave the cell until all of the potassium channels have closed.

Potassium ions continue to leave the cell until all of the potassium channels have closed

Which glial cells are found only in the PNS? A) Schwann cells B) oligodendrocytes C) ependymal cells D) microglia

Schwann cells

Which of the following definitions or descriptions is correct? A) An inhibitory postsynaptic potential (IPSP) is a graded depolarization of the postsynaptic membrane. B) An excitatory postsynaptic potential (EPSP) is a graded hyperpolarization of the postsynaptic membrane. C) Temporal summation occurs when a single synapse depolarizes once. D) Spatial summation involves multiple synapses that are active simultaneously.

Spatial summation involves multiple synapses that are active simultaneously.

What is the first step in Wallerian degeneration? A) The Schwann cells wrap around the axon as it elongates. B) The Schwann cells proliferate along the path of the original axon. C) The axon regrows into the site of injury. D) The axon and myelin degenerate and fragment.

The axon and myelin degenerate and fragment

Puffer fish poison blocks voltage-gated sodium channels like a cork. What effect would this neurotoxin have on the function of neurons? A) The absolute refractory period would be shorter than normal. B) Neurons would depolarize more rapidly. C) Action potentials would lack a repolarization phase. D) The axon would be unable to generate action potentials. E) None, because the chemically gated sodium channels would still function.

The axon would be unable to generate action potentials.

Why does regeneration of the action potential occur in one direction, rather than in two directions? A) The inactivation gates of voltage-gated K+‎ channels close in the node, or segment, that has just fired an action potential. B) The inactivation gates of voltage-gated Na+‎ channels close in the node, or segment, that has just fired an action potential. C) The activation gates of voltage-gated K+‎ channels open in the node, or segment, that has just depolarized. D) The activation gates of voltage-gated Na+‎ channels close in the node, or segment, that has just depolarized.

The inactivation gates of voltage-gated Na+‎ channels close in the node, or segment, that has just fired an action potential.

What is the function of the myelin sheath? A) The myelin sheath increases the speed of action potential conduction from the initial segment to the axon terminals. B) The myelin sheath increases the insulation along the entire length of the axon. C) The myelin sheath decreases the resistance of the axonal membrane to the flow of charge. D) The myelin sheath decreases the speed of action potential conduction from the initial segment to the axon terminals.

The myelin sheath increases the speed of action potential conduction from the initial segment to the axon terminals.

Oligodendrocytes: A) assist in producing, circulating, and monitoring the CSF. B) are the myelin-producing glial cells in the CNS. C) maintain the blood-brain barrier. D) are the myelin-producing glial cells in the PNS.

are the myelin-producing glial cells in the CNS

The axon is connected to the cell body at the A) axon hillock. B) synaptic knobs. C) synapse. D) collateral branches. E) telodendria

axon hillock

Branches that may occur along an axon are called A) synaptic knobs. B) collateral branches. C) dendrites. D) hillocks. E) synapses

collateral branches

Functions of astrocytes include all of the following except A) responding to neural tissue damage. B) conducting action potentials. C) maintaining the blood-brain barrier. D) absorbing excess neurotransmitter. E) forming a three-dimensional framework for the CNS

conducting action potentials

A shift of the resting transmembrane potential toward 0 mV is called A) hyperpolarization. B) depolarization. C) repolarization. D) non-polarization. E) hypopolarization

depolarization.

An action potential is self-regenerating because __________. A) repolarizing currents established by the efflux of K+‎ flow down the axon and trigger an action potential at the next segment B) depolarizing currents established by the influx of K+‎ flow down the axon and trigger an action potential at the next segment C) repolarizing currents established by the efflux of Na+‎ flow down the axon and trigger an action potential at the next segment D) depolarizing currents established by the influx of Na+‎ flow down the axon and trigger an action potential at the next segment

depolarizing currents established by the influx of Na+‎ flow down the axon and trigger an action potential at the next segment

The sum of the electrical and chemical forces acting on an ion is known as its ________ gradient. A) electrochemical B) chemiosmotic C) concentration D) osmotic E) potential

electrochemical

EPSPs (excitatory postsynaptic potentials) occur when A) more potassium ions than usual leak out of a cell. B) more calcium ions than usual leak out of a cell. C) extra sodium ions enter a cell. D) hyperpolarizations occur. E) chloride ions enter a cell.

extra sodium ions enter a cell.

In saltatory propagation, a local current produces a(n): A)repolarization. B) hyperpolarization. C) resting potential. D) graded depolarization.

graded depolarization

Ion channels that are always open are called ________ channels. A) gated B) local C) leak D) regulated E) active

leak

Graded potentials A) are often all-or-none. B) may be either a depolarization or a hyperpolarization. C) produce an effect that increases with distance from the point of stimulation. D) produce an effect that spreads actively across the membrane surface without diminishing. E) always cause repolarization.

may be either a depolarization or a hyperpolarization

Small, wandering cells that engulf cell debris and pathogens in the CNS are called A) satellite cells. B) oligodendrocytes. C) astrocytes. D) microglia. E) ependymal cells

microglia

The most common neurons in the CNS, including the motor neurons that control skeletal muscles, are: A) multipolar neurons. B) bipolar neurons. C) unipolar neurons. D) anaxonic neurons.

multipolar neurons

The separation of plus and negative charges across the membrane creates a ________ difference, or voltage A) graded B) potential C) concentration D) gradient E) kinetic

potential

The same ________ can have different effects depending on the properties of the ________. A) hormone; neurotransmitter B) substrate; receptor C) receptor; neurotransmitter D) neurotransmitter; receptor E) propagation; neurotransmitter

receptor; neurotransmitter

The buildup of depolarization when EPSPs arrive in rapid succession is called ________ summation. A) temporal B)chemical C) spatial D) threshold E) electrical

temporal

A characteristic of graded potentials is: A) the stronger the stimulus, the smaller and more concentrated is the area affected. B) the nature of the graded change in membrane potential is determined by the properties of the Nissel bodies of the neuronal cell involved. C) the effect spreads passively through local currents. D) the effect of the transmembrane potential increases with distance from the site of stimulation

the effect spreads passively through local currents.

A gated channel that responds to changes in transmembrane potential is called a(n) ________ channel. A) voltage-gated B) leak-gated C) chemically gated D) mechanically gated E) ATP

voltage-gated

Which type of membrane channels are found in axons? A) voltage-gated Na+ and K+ channels B) voltage-gated Ca2+ channels C) voltage-gated K+ channels D) chemically gated Na+ and K+ channels E) voltage-gated Na+ channels

voltage-gated Na+ and K+ channels

The generation of an action potential in a neuron requires the presence what type of membrane channels? A) leakage channels B) voltage-gated channels C) chemically gated channels D) membrane channels are not required

voltage-gated channels

Most CNS neurons lack centrioles. This observation explains A) why CNS neurons grow such long axons. B) why CNS neurons cannot regenerate. C) the ability of neurons to generate an action potential. D) the ability of neurons to produce a resting potential. E) the ability of neurons to communicate with each other.

why CNS neurons cannot regenerate