3: Resting and Action Potentials

Question 1

What ions have the most influence on plasma the membrane?

Answer 1

K+, Na+, Cl-

Question 2

Leak channels

Answer 2

always open and work when cell is at rest

Question 3

What ion has the most leak channels?

Answer 3

K+

Question 4

Gated ion channels

Answer 4

open and close because of stimulus

Question 5

Voltage gated ion channel

Answer 5

channels open or close due to voltage changes

Question 6

Inactive state of voltage gated channels

Answer 6

forced rest, only some cells have

Question 7

What ions are the most common voltage gated channels?

Answer 7

Na+, K+, Ca+2

Question 8

Ligand gated ion channels

Answer 8

open due to a NT or hormone binding to receptor

Question 9

Mechanoreceptors

Answer 9

respond to a mechanical stimulus (pressure, stretch)

Question 10

Thermoreceptors

Answer 10

respond to temperature changes

Question 11

Chemoreceptors

Answer 11

respond to chemical changes

Question 12

Na+/K+ pump

Answer 12

pumps out 3 Na+ and pumps in 2 K+, creating a positive charge outside the cell

Question 13

What ion have the most influence of RMP?

Answer 13

K+

Question 14

Depolarization

Answer 14

change in membrane potential in the positive direction

Question 15

Repolarization

Answer 15

return of the membrane potential toward RMP

Question 16

Hyperpolarization

Answer 16

the membrane potential become more negative than RMP

Question 17

Graded potentials

Answer 17

small local changes in membrane potential

Question 18

What causes the decrease in magnitude over time of GPs?

Answer 18

electrotonic conduction

Question 19

Excitatory postsynaptic potentials

Answer 19

GPs that bring the membrane potential closer to threshold and more likely to fire an AP

Question 20

Inhibitory postsynaptic potentials

Answer 20

GPs that take the membrane potential away from threshold and make the cell less likely to fire an AP

Question 21

End-plate potential

Answer 21

GPs in skeletal muscle cells caused by ACh binding onto poststynaptic membrane ion channels

Question 22

Receptor potential

Answer 22

GPs in sensory receptor cells caused by mechanical or chemical stimuli from internal or external environment

Question 23

Steps of AP

Answer 23

1. At RMP, high Na+ outside cell and high K+ inside cell
2. large enough GP causes Na+ channels to open and Na+ rushes inside cell, depolarizing cell to a more + voltage
3. Na+ channels slowly close, K+ channels open and K+ rushes out of cell, repolarizing MP
4. K+ continue to leave cell via leak and voltage gated channels and return to RMP once voltage gated K+ channels close

Question 24

Refractory period

Answer 24

excitable cells cannot produce APs

Question 25

Absolute refractory period

Answer 25

cannot generate AP no matter now large the stimulus

Question 26

Relative refractory period

Answer 26

a stronger than threshold (suprathreshold) can generate an AP

Question 27

Ionophore toxicity

Answer 27

make cell membrane permeable to ions, usually feed additives for cattle, nor suitable for horses

Question 28

Channelopathies

Answer 28

genetic mutations altering ion channel function