CH 1.2 Key Terms

Question 1

Absolute Refractory Period

Answer 1

a time when the membrane is unable to produce an action potential

Question 2

Action Potentials

Answer 2

all-or-none message sent by an axon

Question 3

All-or-None Law

Answer 3

principle that the amplitude and velocity of an action potential are independent of the stimulus that initiated it

Question 4

Concentration Gradient

Answer 4

difference in distribution of ions across the neuron’s membrane

Question 5

Depolarize (depolarization)

Answer 5

To reduce polarization toward zero across a membrane Depression.

Question 6

Electrical Gradient

Answer 6

difference in electrical charges between the inside and outside of the cell

Question 7

Graded Potential

Answer 7

a membrane potential that varies in magnitude in proportion to the intensity of the stimulus

Question 8

Hyperpolarization

Answer 8

increased polarization across a membrane

Question 9

Local Anesthetic

Answer 9

drug that attaches to the sodium channels of the membrane, stopping action potentials

Question 10

Local Neurons

Answer 10

neurons without an axon

Question 11

Myelin

Answer 11

an insulating material composed of fats and proteins

Question 12

Myelinated Axons

Answer 12

axons covered with myelin sheaths

Question 13

Polarization

Answer 13

difference in electrical charges between the inside and outside of the cell

Question 14

Propagation of the Action Potential

Answer 14

transmission of an action potential down an axon

Question 15

Refractory Period

Answer 15

time when the cell resists the production of further action potentials

Question 16

Relative Refractory Period

Answer 16

time after the absolute refractory period that requires a stronger stimulus to initiate an action potential

Question 17

Resting Potential

Answer 17

condition of a neuron’s membrane when it has not been stimulated or inhibited

Question 18

Saltatory Conduction

Answer 18

the jumping of action potentials from node to node

Question 19

Selective Permeability

Answer 19

ability of some chemicals to pass more freely than others through a membrane

Question 20

Sodium–Potassium Pump

Answer 20

mechanism that actively transports sodium ions out of the cell while drawing in two potassium ions

Question 21

Threshold

Answer 21

minimum amount of membrane depolarization necessary to trigger an action potential

Question 22

Voltage-Gated Channels

Answer 22

membrane channel whose permeability to sodium (or some other ion) depends on the voltage difference across the membrane