PE CH 4

Sodium ions: Na+

Diffusion.: In Electrostatic: In From higher to lower concentration Thru electrostatic, opposite attracts thus Na+ go inside However, membrane keeps it out

Chloride ions: Cl- (highest concentration outside the neuron)

Diffusion: In Electrostatic: out From higher to lower concentration Because of electrostatic(negative charge) chloride wants to stay outside

Potassium ions: K+

Diffusion: out Electrostatic: In From higher to lower concentration

Characteristics of an action potential

Discrete event:All or none ( it has to go up more than -50 or above 0) Time Scale:Thousands of Action potential in second Rate coding: Hippocampal place cells

electricity is what making CNS move the body

Galvani

The neurotransmitter-sensitive ion channels on muscle end plates differ from other ion channels in that: A) they have a different resting membrane potential. B) they allow only K+ to leave the neuronal membrane. C) they allow only Cl- to leave the neuronal membrane. D) K+ and Na+ enter and leave through the same channels.

K+ and Na+ enter and leave through the same channels.

Hyperpolarization

Membrane: - 100mV K+ channels open K+ channels close

Depolarization

Membrane: -50mV Na+ channels open (it will open above -50mv)

Resting potential

Membrane: -70mV Na+ & K+ channels are closed

Repolarization

Membrane: 30mV K+ channels open (it will open above 0) Na+ channels close ( no longer balance)

When the neuron is at rest, ______ channels are normally closed, whereas ______ is free to enter and leave the cell. A) K+; Na+ B) Cl-; Na+ C) Na+; K+ D) K+; Cl-

Na+; K+

______ channels are more sensitive than ______ channels, so they open first during the action potential. A) Calcium; potassium B) Potassium; calcium C) Sodium; potassium D) All channels are equally sensitive.

Sodium; potassium

Which of the following is NOT true? A) The cell membrane is semipermeable, so it keeps in large negatively charged protein molecules. B) The membrane keeps out Na+ and allows K+ and C1- to pass more freely. C) The membrane has a sodium-potassium pump that removes potassium from inside the cell and replaces it with sodium. D) The summed charges of the unequally distributed ions leave the inside of the membrane at-70 mV relative to the outside. This is the cell's resting potential.

The membrane has a sodium-potassium pump that removes potassium from inside the cell. and replaces it with sodium

Which of the following is not involved in producing the resting potential? A) potassium ions B) chloride ions C) calcium ions D) sodium ions

calcium ions

The resting potential: A) is -70 mV in all species. B) can vary from -40 mV to -90 mV within a species. C) can vary from -40 mV to -90 mV between species. D) None of the answers is correct.

can vary from -40 mV to -90 mV between species.

When a substance moves from an area of high concentration to an area of low concentration, it is an example of a(n): A) concentration gradient. B) voltage gradient. C) ionic translocation. D) None of the answers is correct

concentration gradient

A change in the resting potential from -70 mV to -65 mV is called: A) an excitatory postsynaptic potential. B) repolarization. C) depolarization. D) hyperpolarization.

depolarization.

A cell cannot produce an action potential: A) during the relative refractory period. B) during the absolute refractory period. C) during the intermediate refractory period. D) None of the answers is correct.

during the absolute refractory period

Small voltage fluctuations in the cell membrane that occur near the vicinity of the axon are called: A) action potentials. B) graded potentials. C) ion fluctuations. D) nerve impulses.

graded potentials.

A change in the resting potential from -70 mV to -73 mV is called: A) depolarization. B) hyperpolarization. C) graded excitatory potential. D) nothing, as these changes occur spontaneously

hyperpolarization

The action potential normally consists of the summed current changes caused by the ______ andthe ______. A) inflow of sodium; outflow of potassium B) outflow of sodium; inflow of potassium C) inflow of calcium; outflow of potassium D) inflow of sodium; outflow of chloride

inflow of sodium; outflow of potassium

Sodium/Potassium pump

it keeps sodium out and bringing in potassium in 3 Na+ out 2 K+ in

The repolarization of the neuronal membrane is largely due to the: A) closing of calcium channels, stopping the influx of calcium. B) opening of potassium channels, allowing the outflow of potassium. C) closing of potassium channels, stopping the influx of potassium. D) closing of sodium channels, stopping the outflow of sodium.

opening of potassium channels, allowing the outflow of potassium.

Channels in the cell membrane are formed by: A) sodium ions. B) potassium ions. C) protein molecules D) lipids.

protein molecules

During the ______ it is more difficult, but not impossible, for another action potential to be initiated. A) absolute refractory period B) rebound period C) relative refractory period D) action potential

relative refractory period

Nerve impulse describes: A) an action potential crossing the synaptic cleft. B) input at the dendrites of a cell. C) the movement of an action potential along the axon. D) an action potential along the combined axons, which are called nerves.

the movement of an action potential along the axon

An action potential usually goes only in one direction in an axon because: A) the ions can flow only in one direction. B) the refractory periods force the impulse to go in one direction. C) the ion flow is attracted to chemicals in the synaptic knob. D) autoreceptors inhibit backward flow of ions.

the refractory periods force the impulse to go in one direction

During an action potential: A) the voltage of the cell membrane drops to 0 and then returns to -70 mV. B) the voltage of the cell membrane drops to 0, returns to about -100 mV, and then goes to 70mV. C) the voltage of the cell membrane goes to about +30 mV and then drops to -70 mV. D) the voltage of the cell membrane goes to about +30 mV, drops to -100 mV, and then goes to-70 mV.

the voltage of the cell membrane goes to about +30 mV and then drops to -70 mV.

Refractory periods are due to: A) voltage-sensitive sodium and potassium channels. B) voltage-sensitive chloride channels. C) the time constraint on the sodium-potassium pump.D) inhibitory postsynaptic potentials

voltage-sensitive sodium and potassium channels.