Chapter 2 - Action Potentials

Question 0

Semipermeable membranes

Answer 0

Let some particles through, leave others out because of physical properties

Question 1

Diffusion

Answer 1

Particles move from high concentration to low concentration till it’s evenly distributed

Question 2

Ions

Answer 2

Electrically charged atoms and molecules

Question 3

Ionic interactions

Answer 3

Like charges repel, opposites attract

Question 4

Cations

Answer 4

Positive

Question 5

Anions

Answer 5

Negative

Question 6

Distribution of ions across semipermeable membrane depends on:

Answer 6

Relative permeability, electrical gradient, concentration gradient

Question 7

Outside charge of cell in resting state

Answer 7

Positive

Question 8

Inside charge during resting state

Answer 8

Negative

Question 9

Membrane potential at resting state

Answer 9

-70mV

Question 10

Depolarize

Answer 10

Inside becomes more positive

Question 11

Resting ion channels

Answer 11

Passive channels that are unaffected by voltage

Question 12

Voltage-gated channels

Answer 12

Open or closed depends on the membrane potential. Found on the AXON MEMBRANE

Question 13

Ligand-gated channels

Answer 13

Open or closed depends on a specific molecule binding with receptor site on protein channel. Important in chemical transmission across the synapse

Question 14

Phosphorylated-gated channels

Answer 14

Open or closed depends on phosphate group binding to the intracellular portion of a membrane protein ion channel

Question 15

Action potential

Answer 15

Brief reversal of the polarity of the potential

Question 16

All or none

Answer 16

Amplitude is constant in axon. It is not altered by stimulus intensity. If you reach threshold, you’ll get action potential.

Question 17

Hyper polarization

Answer 17

More negative on inside

Question 18

Graded depolarizing potential

Answer 18

Occurs in response to stimulation. Graded bc magnitude is related to degree of stimulation. Totally dependent on degree of stimulation

Question 19

Refractory period

Answer 19

Immediately after start, membrane resists start of second action potential

Question 20

Absolute refractory period

Answer 20

No way action potential is being fired if other stimulus comes in right after action potential. Membrane absolutely cannot produce action potential regardless of stimulus intensity (~1min)

Question 21

Relative refractory period

Answer 21

After absolute refractory period, k+ is still leaving cell, eventually cell is hyperpolarized making it more difficult to stimulate, but strong enough stimulus can produce an action potential

Question 22

Multiple sclerosis

Answer 22

Demyelination of axons disrupts or prevents conduction of action potentials

Question 23

Local anesthetics

Answer 23

Block voltage-gated na+ channels. Not very permanent. Low potency

Question 24

General anesthetics

Answer 24

Open k+ channels wider so they resist neuron reaching threshold potential when na+ starts to enter cell. Make inside more negative, hyperpolarizing

Question 25

Tetrodotoxin

Answer 25

Highly potent, blocks voltage-gated Na+ channels with very high potency. Naturally occurs in liver of pacific puffer fish

Question 26

Why action potential is necessary?

Answer 26

Allows for signals to be transmitted over long distances with high fidelity and no decay. Graded potentials decay over time and space