Lecture 3/4

Question 1

Electrical impulse is initiated in the ________, travels thru cell body down the axon to presynaptic terminal

Answer 1

dendrite

Question 2

Impulses/Action potentials are the result of coordinated opening and closing of multiple _______ that are permeable to Na, K, Cl,Ca

Answer 2

ion channels

Question 3

Name the 3 electrical signals of nerve cells.

Answer 3

Receptor potential (graded)
Synaptic potential (graded)
Action potential (all or none)

Question 4

Resting membrane potential is a ___________

Answer 4

intrinsic property of the cell

Question 5

Define current

Answer 5

movement of charge in a given time period

Question 6

What 2 factors determine amplitude (size) of a current?

Answer 6

potential difference between electrodes and electrical conductance of the medium between them.

Question 7

Electrical potential is…?

Answer 7

amount of potential energy per unit of charge at given location

Question 8

Potential difference is…?

Answer 8

difference in potential between 2 locations

Question 9

What is the term for ease of flow between 2 points?

Answer 9

conductance

Question 10

Resistance is…?

Answer 10

inverse of conductanceand measured in ohms

Question 11

What is Ohm’s law

Answer 11

V=IR

V=voltage, I=current, R=resistance

Question 12

Girls transform into drag kings? https://www.youtube.com/watch?v=uK98jrF_0Og

Answer 12

…

Question 13

What is a capacitor?

Answer 13

2 conductors (solution inside and outside the cell) separated by an insulator.

Question 14

A seperation of charge occurs when?

Answer 14

charge is introduced onto one of the conductors and it pushes similar charges away from the other conductor since they repel.

Question 15

Capacitance is measures of what?

Answer 15

how much charge needs to be transferred from 1 conductor to another to set up a given potential difference

Question 16

____________ across membranes drives ion flux.

Answer 16

Charge seperation.

once it occurs, potential difference drives ions from one point to another

Question 17

Flow of ions creates _________

Answer 17

current.

no ion gradient means no voltage difference and no current flow

Question 18

What are the 3 main ions involved in neuron excitability?

Answer 18

Na+
K+
Cl-

Question 19

Membrane proteins regulate _______ into and out of cell.

Answer 19

ion flux

Question 20

Name 2 characteristics of ion transporters

Answer 20

Actively move ions against concentration gradient.

Create ion concentration gradients

Question 21

Name 2 characteristics of Ion channels

Answer 21

Allows ions to diffuse down concentration gradient

Cause selective permeability to certain ions

Question 22

What are 2 factors that cause the resting membrane potential

Answer 22

the separation of ions across the cell membrane

the permeability of the membrane itself to those ions

Question 23

What does the Nernst equation predict?

Answer 23

Voltage created by diffusion of a single ion type.

Question 24

For a positively charged ion, if the membrane potential is more _______ than the equilibrium potential then the direction of flux is ________

Answer 24

positive, out of the cell

Question 25

For a positively charged ion, if the membrane potential is more negative than the equilibrium potential than the direction of flux is ________.

Answer 25

into the cell.

Question 26

The farther away from the equilibrium potential the membrane voltage is, the ________

Answer 26

larger the current

Question 27

Resting membrane voltage depends primarily on ________.

Answer 27

K+ concentration gradient

Question 28

What do we calculate using the Goldman equation?

Answer 28

Relative permeabilities of each ion in addition to voltage created by diffusion

Question 29

T/F: The value of the resting membrane potential calculated by the Goldman equation cannot fall between Nernst potentials.

Answer 29

False

Question 30

T/F: membrane voltage is determined by K+ distribution at rest.

Answer 30

True

Question 31

For any ion, its distribution across the membrane is determined by...?

Answer 31

Chemical gradient Electrical gradient Permeability (conductance)

Question 32

Maintaining the resting membrane potential is an ________ process

Answer 32

active

Question 33

The resting membrane potential is NOT an equilibrium potential. Why?

Answer 33

It relies on expenditure of ATP by ion pumps for maintenence.

Question 34

Membrane potential can be changed by altering ion gradients or _______.

Answer 34

permeability

Question 35

What is the action potential a result of?

Answer 35

increasing permeability to Na+ and K+