Question 1

primary way nerons communicate:

Accepted Answer

action potentials

Question 2

action potentials:

Accepted Answer

rapid changes in membrane potential that occur when graded potentials summate at trigger zone and reach threshold

Question 3

all or none principle:

Accepted Answer

once threshold is reached an action potential will occur regardless of stimulus strength

Question 4

4 phases of action potentials

Accepted Answer

1) depolarization
2) repolarization
3) afterpotential (hyperpolarization)
4) return to resting membrane potential

Question 5

voltage gated ion channels function in action potentials:

Accepted Answer

regulate ion movement across membrane + essentail for generationing action potentials

Question 6

ex. of voltage gated ion channels in action potentials:

Accepted Answer

sodium channels & potassium channels

Question 7

steps of voltage gated ion channel activity:

Accepted Answer

1) resting membrane potential
2) depolarization
3) repolarization
4) end of repolarization
5) afterpotential (hyperpolarizaiton)
6) return to resting membrane potential

Question 8

resting membrane potential:

Accepted Answer

Na⁺ activation gates are closed; inactivation gates are open
K⁺ channels are closed
Outside of membrane is more positive than inside

Question 9

depolarization:

Accepted Answer

Na⁺ activation gates open → Na⁺ enters cell
K⁺ channels begin to open
Positive-feedback cycle: more Na⁺ entry → more channels open

Question 10

repolarization:

Accepted Answer

Na⁺ inactivation gates close → Na⁺ entry stops
K⁺ channels open → K⁺ exits cell

Question 11

end of repolarization:

Accepted Answer

Na⁺ activation gates close, inactivation gates reopen
Resting configuration restored

Question 12

afterpotential (hyperpolarization):

Accepted Answer

K⁺ channels stay open longer than needed
Extra K⁺ leaves → membrane becomes more negative than resting

Question 13

return to resting membrane potential:

Accepted Answer

K⁺ channels close
Sodium-potassium pump restores resting conditions

Question 14

refractory period:

Accepted Answer

time where a neuron's ability to respond to a stimulus is reduced

Question 15

types of refractory periods:

Accepted Answer

absolute & relative

Question 16

absolute refractory period:

Accepted Answer

- no 2nd action potential can occur
- from beginning of aLP to near end of repolarization

Question 17

relative refractroy period:

Accepted Answer

stronger than threshold stimulus required

Question 18

Action Potential Frequency:

Accepted Answer

The number of action potentials generated per unit time in response to a stimulus.

Question 19

Stimulus Strength Categories:

Accepted Answer

1) Subthreshold
2) Threshold
3) Submaximal
4) Maximal
5) Supramaximal

Question 20

Subthreshold:

Accepted Answer

cannot trigger AP

Question 21

Threshold:

Accepted Answer

just enough to trigger AP

Question 22

Submaximal:

Accepted Answer

between threshold and maximum

Question 23

Maximal:

Accepted Answer

produces highest AP frequency

Question 24

Supramaximal

Accepted Answer

stronger than maximal, no increased frequency

Question 25

Stronger stimuli →

Accepted Answer

higher frequency, not larger AP

Question 26

Maximum frequency limited by...

Accepted Answer

absolute refractory period

Question 27

Higher frequency is interpreted as...

Accepted Answer

a stronger signal

Question 28

Propagation of Action Potentials:

Accepted Answer

The movement of an action potential along an axon

Question 29

Types of Conduction:

Accepted Answer

Continuous conduction (unmyelinated axons) & Saltatory conduction (myelinated axons)

Question 30

Continuous conduction:

Accepted Answer

Local currents depolarize adjacent membrane
One-way conduction due to refractory period

Question 31

Saltatory conduction:

Accepted Answer

Action potentials “jump” between nodes of Ranvier
Faster due to myelin insulation

Question 32

Speed of Conduction:

Accepted Answer

The rate at which an action potential travels along an axon

Question 33

Factors Affecting Speed:

Accepted Answer

Myelination (faster with myelin)
Thickness of myelin sheath
Axon diameter (larger = faster due to more channels and surface area)

Question 34

Nerve Fiber Types:

Accepted Answer

Type A, Type B, Type C

Question 35

Type A

Accepted Answer

large, myelinated (15–120 m/s)
Skeletal motor and most sensory neurons

Question 36

Type B

Accepted Answer

medium, lightly myelinated (3–15 m/s)
Autonomic nervous system (ANS)

Question 37

type C

Accepted Answer

small, unmyelinated (≤ 2 m/s)
ANS

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Action Potentials

Chapter 11 - A & P Lecture