Chapter Two — Electrical Signals of Neurons

Question 1

Resting membrane potential

Answer 1

The relatively static membrane potential of quiescent cells is called the resting membrane potential (or resting voltage), as opposed to the specific dynamic electrochemical phenomena called action potential and graded membrane potential.

Question 2

receptor potential

Answer 2

A change in potential produced by sensory transduction

Question 3

synaptic potential

Answer 3

an alteration in the membrane potential of a cell resulting from activation of a synaptic input

Question 4

Innervate

Answer 4

Supply (an organ or other body part) with nerves

Question 5

action potential

Answer 5

The change in electrical potential associated with the passage of an impulse along the membrane of a muscle cell or nerve cell

Question 6

hyperpolarization

Answer 6

Hyperpolarization is a change in a cell’s membrane potential that makes it more negative. It is the opposite of a depolarization.

Nothing very dramatic happens, so it’s called a passive electrical response.

Question 7

Depolarization

Answer 7

In biology, depolarization is a change in a cell’s membrane potential, making it more positive, or less negative. In neurons and some other cells, a large enough depolarization may result in an action potential.

Question 8

Threshold potential

Answer 8

The threshold potential is the membrane potential to which a membrane must be depolarized to initiate an action potential.

Question 9

All-or-none law

Answer 9

the principle that the strength by which a nerve or muscle fiber responds to a stimulus is not dependent on the strength of the stimulus. If the stimulus is any strength above threshold, the nerve or muscle fiber will give a complete response or otherwise no response at all.

Question 10

Why are electrical potentials generated across the membranes of neurons.

Answer 10

1. There are differences in concentration of certain ions across nerve cell membranes.
2. Membranes are selectively permeable to some of these ions.

Question 11

Active transport

Answer 11

the movement of a substance against its concentration gradient (from low to high concentration)

Question 12

ion channel

Answer 12

(ion channel) Protein channel in a cell membrane that allows passage of a specific ion down its concentration gradient.

Question 13

electrochemical equilibrium

Answer 13

A balance between chemical and electrical driving forces such that there is no net movement of ions across the cell membrane.

Question 14

equilibrium potential

Answer 14

In a biological membrane, the reversal potential (also known as the Nernst potential) of an ion is the membrane potential at which there is no net (overall) flow of ions from one side of the membrane to the other.

Question 15

nernst equation definition

Answer 15

In electrochemistry, the Nernst equation is an equation that can be used (in conjunction with other information) to determine the equilibrium reduction potential of a half-cell in an electrochemical cell. It can also be used to determine the total voltage (electromotive force) for a full electrochemical cell.

Question 16

Nernst equation (content)

Answer 16

Equilibrium potential(x) = [(gas constant) x (absolute temperature)]/[(electrical charge) x (Faraday constant)] x ln ([X]1/[X]2)

Question 17

Nernst equation (simplified)

Answer 17

Equilibrium potential(x) = 58/(valence) x log ([X]1/[X]2)

Question 18

Relationship between membrane potential and K+ concentration gradient

Answer 18

a linear relationship with logarithm of conentration gradient with a slope of 58mV (actually 58/(valence)) per tenfold change in gradient

Question 19

Goldman equation

Answer 19

V = 58 log (PK[K]2 + PNA[Na]2 +PCl[Cl]1) / (PK[K]1…+PCl[Cl]2)

Question 20

Why does an inside-negative potential arise in neurons?

Answer 20

1. membrane of resting neuron is more permeable to K+ ions than anything else
2. There is more K+ inside the membrane than out

Question 21

What causes the membrane potential of a neuron to depolarize during an action potential?

Answer 21

Mechanisms increase the permeability of Na+ into the neuron by opening Na+ channels during the rising and overshoot phase of action potential

Question 22

Rising phase

Answer 22

The earliest positive-going portion of the nerve or muscle action potential, syn. Hypopolarization phase, Upstroke.

The initial, depolarizing, phase of an action potential, caused by the regenerative, voltage-dependent influx of a cation such as Na^+ or Ca^2+.

Question 23

Overshoot phase

Answer 23

The peak, positive-going phase of an action potential, caused by high membrane permeability to a cation such as Na+ or Ca2+.

Question 24

Undershoot

Answer 24

The final, hyperpolarizing phase of an action potential, typically caused by the voltage-dependent efflux of a cation such as K^+.