LEC EXAM #2 CHP 7

Question 1

3 types of excitable cells:

Answer 1

• neurons
• muscles (skeletal, smooth, and heart)
• secretory cells (pituitary, insulin producing cells of the pancreas)

Question 2

How is the electrochemical gradient “established”?

Answer 2

Na/K ATPase pump

Question 3

How is the RMP “maintained”?

Answer 3

• Na/K ATP ase pump
• Na leak channels
• K leak channels

Question 4

What contributes to resting membrane potential?

Answer 4

• Electrochemical gradients (charge + concentration)

- amount of leak channels present for each ion

Question 5

Has the most leak channels:

Answer 5

K+

Question 6

What are the 4 phases for excitable cells?

Answer 6

1. RMP (-70 mv)
2. depolarization -> threshold (-55 mv)-> action potential
3. repolarization
4. hyperpolarization-> back to RMP

Question 7

Na/K ATPase pump pumps:

Answer 7

3 Na+ out and 2 K+ in per ATP

Question 8

Conc. of K+ inside/outside:

Answer 8

Inside: 150
Outside: 5

Question 9

Conc. of Na+ inside/outside:

Answer 9

Inside: 15
Outside: 150

Question 10

K+ wants to go:

Answer 10

Outside

Question 11

Na+ wants to go:

Answer 11

Inside

Question 12

Why does the RMP never reach -90 mv?

Answer 12

Due to the Na/K ATPase pump

Question 13

K+ equilibrium:

Answer 13

-90 mv

Question 14

What resets RMP?

Answer 14

Na v.g.c. pump + leak channels

Question 15

Which voltage gated channel is used during depolarization?

Answer 15

Na+ v.g.c.

Question 16

Which voltage gated channel closes and which is used during repolarization?

Answer 16

Na+ v.g.c closes

K+ v.g.c opens

Question 17

Na equilibrium:

Answer 17

+60

Question 18

Na+ voltage gated channel phases:

Answer 18

Open, inactive, closed

Question 19

In Na v.g.c, if you don’t hit threshold of ___, you don’t get:

Answer 19

-55 mv

an action potential

Question 20

T or F

Once an AP has been generated, the amplitude of the depolarization wave will be the same for all action potentials generated:

Answer 20

True

Question 21

V.G.C won’t pop open if _______, once reset to _____ is when you will get a stimulus and it’ll respond

Answer 21

inactive

closed

Question 22

Repolarization makes the inside more:

Answer 22

Negative

Question 23

2 types of refractory periods:

Answer 23

• Absolute

- Relative

Question 24

Absolute refractory period:

Answer 24

Na+ v.g.c. are inactive-> no AP possible

Question 25

Depolarization makes the inside more:

Answer 25

Positive

Question 26

Low potassium affects:

Answer 26

Coordination and skeletal muscles

Question 27

Relative refractory period:

Answer 27

Some Na+ v.g.c. closed and some inactive-> can have an AP with a stimulus greater than -55 mv

Question 28

What happens if you block K+ v.g.c.?

Answer 28

Makes depolarization last longer

Question 29

Develops when there is a charge difference:

Answer 29

Electrical gradient

Question 30

Develops when there is a concentration of ion difference:

Answer 30

Chemical gradient

Question 31

Ions tend to move from an area of ____ conc. to an area of ___ conc.

Answer 31

High to low

Question 32

What measures the inside of the cell?

Answer 32

RMP

Question 33

The presence of ____ ______ in the cytosol adds to the negativity of the cytosolic side of the membrane:

Answer 33

Anionic proteins (A-)

Question 34

AP operate on:

Answer 34

an all-or-none principle

Question 35

Once Na v.g.c. become inactive…

Answer 35

K+ v.g.c. open

Question 36

Propagation down a nerve axon occurs in ____ direction because Na v.g.c. are inactive for a certain length of time:

Answer 36

one

Question 37

Purpose of lidocaine and tetracaine:

Answer 37

Blocks Na v.g.c. so there is no depolarization

Question 38

The hyperpolarization phase of the action potential is due to:

Answer 38

the prolonged opening of the K+ v.g.c.

Question 39

In the nervous system, the strength of the stimulus is coded into:

Answer 39

The frequency of the action potentials generated

Question 40

Which area of the neuron generate signals that open the voltage-gated channels in the first part of the axon, thus causing an action potential?

Answer 40

Dendrites and cell body

Question 41

The fastest conduction of an action potential would occur in an axon with which of the following characteristics?

Answer 41

Large diameter and myelinated

Question 42

A cation is a:

Answer 42

Positively charged ion