TIM STUFF

Question 1

why is the inside of a cell negative?

Answer 1

because the proteins that allow the cell to do everything are present inside and absent outside the cell, so there is a net negative charge causes a skewed distribution of the major ions

Question 2

which ion is the most permeable? least permeable?

Answer 2

potassium

sodium

Question 3

what are the two forces that cause an ion to move?

Answer 3

electrical and concentration

Question 4

sodium has a tendency to move in or out of a cell?what about potassium?

Answer 4

into the cell

out of the cell

Question 5

what is the equation for total diffusion?

Answer 5

permeability x driving force

Question 6

what is diffusion like for potassium?

Answer 6

high permeability, low driving force

Question 7

what is diffusion like for sodium?

Answer 7

low permeability, high driving force

Question 8

T/F, the membrane potential of a cell will always most closely resemble the Nernst potential of the most permeable ion? what accounts for the difference

Answer 8

T

the contribution of the sodium potassium pump to the resting membrane potential

Question 9

the sodium potassium can be affected by what substance, causing an immediate 5 mV depolarization to -65?

Answer 9

ouabain

Question 10

term used to describe the beginning of the action potential when the charge separation across the membrane is being lost and so the membrane potential moves from -50mV up to +30 mV?

Answer 10

depolarization phase

Question 11

this is the phase of the action potential where the membrane potential returns back to its resting value of -70 mV?

Answer 11

repolarization phase

Question 12

this is the phase of the membrane potential when It continues to become more negative than the rest at rest?

Answer 12

afterhyperpolarization phase

Question 13

during the afterhyperpolarization phase, this is the name of the period when threshold will likely be reached again any time soon making it less likely for another action potential?

Answer 13

relative refractory period

Question 14

how many gates do sodium channels have?

Answer 14

two gates

Question 15

how many gates do potassium channels have?

Answer 15

one gate

Question 16

how many gates do non gated potassium channels have?

Answer 16

none, its open all the time

Question 17

what are the components of the voltage gated sodium channels?

Answer 17

activation gates (outside)
inactivation gates (inside)
conductance pore
selectivity filter
voltage sensor

Question 18

name this part of the voltage gated sodium channel:

only allows sodium to enter the channel? Also a toxin can bind here and block the channel?

Answer 18

selectivity filter

tetrodotoxin

Question 19

name this part of the voltage gated sodium channel:

not a specific structure of the protein, but recognizes that charges within the protein will shift as the inside of the cell becomes less negative? this leads to the opening of the activation gate

Answer 19

voltage sensor, only about 6 positive charges need to shift in order to open the gate

Question 20

name this part of the voltage gated sodium channel:

located on the intracellular end of the channel and is open at rest. The inactivation gate closes after the activation gate opens causing sodium conductance through the channel to return to zero, and what period is this?

Answer 20

inactivation gate

absolute refractory period

Question 21

name this part of the voltage gated sodium channel:

located near the selectivity filter and is closed until threshold is reached. Once opened, both the activation and inactivation gates are open and sodium can pass through the conductance pores

Answer 21

activation gate

Question 22

what is unique about the voltage gate potassium channels?

Answer 22

similar to sodium but remember:

there is only one gate, which is either open or closed

the charges in the conductance pore are arrange such that they stabilize potassium rather than sodium

Question 23

name the pharmacological agent that acts o voltage gated channels:

stabilizes the membrane and increases threshold

Answer 23

calcium

Question 24

name the pharmacological agent that acts o voltage gated channels:

blocks sodium channels from the extracellular side

Answer 24

tetrodotoxin

Question 25

name the pharmacological agent that acts o voltage gated channels:

lidocaine, procaine and inserts in the conductance pore and block sodium permeability increases

Answer 25

local anesthetic

Question 26

name the pharmacological agent that acts o voltage gated channels:

from the skin of poisonous frogs, irreversibly opens sodium channels

Answer 26

batrachtotoxin

Question 27

name the pharmacological agent that acts o voltage gated channels:

block potassium channel opening leading to larger repolarizations

Answer 27

scorpion toxin

Question 28

name the pharmacological agent that acts o voltage gated channels:

blocks voltage gated potassium channels, but only from the intracellular fluid side of the channel

Answer 28

TEA (tetraethylammonium) same affect like scorpion toxin

Question 29

T/F, the more action potentials a neuron has, the more ion pumping that it does? what is the affect

Answer 29

T

increase demand of glucose leading to analog 2-deoxyglucose and the development of PET scan