Lecture 4 Exam Part 3

Front 1

What nervous system does regeneration of neurons only occur in?

Back 1

Peripheral Nervous System

Front 2

What happens to the muscle fibers when you lose innervation to the muscle fibers: an axon is severed and the muscle continues to get smaller and smaller (degeneration)?

Back 2

Denervation atrophy

Front 3

What is formed when the distal part of an axon begins to degenerate, along with some of the schwann cells that surrounded it, leaving only a few reminents of schwann cells left along with their endoneurium (outside covering), which produces a hallway like passageway that can potentially guide a regrowing axon back to the muscle fiber?

Back 3

Regeneration tube

Front 4

True/False: You only get a regeneration tube from schwann cells, their endoneurium, and their basal lamina.

Back 4

True

Front 5

What begins to occur once one of the newly formed axon branches from the part of the neuron that is still alive, reaches the regeneration tube?

Back 5

It begins to secrete growth hormone, causing the one that found the tube to grow faster than the other branches that were formed outside the tube, which causes a breakdown of the ones that did not enter the regeneration tube, and the newly formed axon branch finds its way back to where it needs to reside through the regeneration tube.

Front 6

What is a negatively charged particle that is too large to escape the cell: ATP, RNA, proteins with amino acids containing negative charges, and inorganic phosphates?

Back 6

Fixed anions

Front 7

True/False: The inside of the cell is negative.

Back 7

True

Front 8

What are the three forces that cause cells to either move in or out of the cell?

Back 8

1. Simple diffusion (moves along its concentration gradient - more outside than in so the particles will move to the outside)

2. Electrical gradient (move positive particles into the cell because it's negative)

3. Permeability

Front 9

What happens to the distribution of potassium in the cell?

Back 9

Because there is a lot of potassium inside the cell than there is outside, potassium will want to leave the cell (diffusion). Because the charge of potassium is positive and the inside of the cell is negative, potassium wants to move into the cell (electrochemical gradient). Potassium has many channels it can move through (high permeability). The result would be a large amount of potassium inside the cell and a little amount of potassium outside the cell.

Front 10

What is the resting membrane potential of a cell?

Back 10

-90 millivolts

Front 11

What is the term for the cell sitting at -90 millivolts if only potassium is involved?

Back 11

Potassium equilibrium potential (only one ion affecting the charge of the cell)

Front 12

What happens to the distribution of sodium inside the cell?

Back 12

Because there is a high concentration of sodium outside the cell and a low concentration of sodium inside the cell, sodium will want to move into the cell (diffusion). Because sodium is positively charged and the inside of the cell is negatively charged sodium will want to move into the cell (electrochemical gradient). There are only a few channels that allow sodium in and out of the cell (low permeability).

Front 13

What happens to the charge of the cell if we add sodium in with potassium, changing the voltage of the cell as a whole?

Back 13

The resting membrane potential of the cell changes from -90 millivolts to -70 millivolts.

Front 14

Which ion is the most important in setting the resting membrane potential of the cell?

Back 14

Potassium, because it made the resting membrane potential -90 millivolts, whereas sodium only made the resting membrane potential -70 millivolts.

Front 15

What allows sodium to leak into the cell all the time, as long as it brings something else along with it?

Back 15

Secondary active transport

Front 16

Since sodium is constantly leaking in, what causes the resting membrane potential to remain the same at -70 millivolts?

Back 16

Sodium potassium pump (pumps 3 sodium out and pumps 2 potassium in)

Front 17

What percentage of energy expenditure of a neuron is going towards keeping the sodium potassium pumps going?

Back 17

70%

Front 18

What type of ion channel prtein is a hollow tube that is always open (can never close) but is very ion specific, so not just anything can go through it?

Back 18

Leakage channel (aka non gated channels)

Front 19

What type of ion channel protein can change shape, allowing it to open and close, and is very ion specific, only opening and/or closing to a variety of different stimuli?

Back 19

Gated channel

Front 20

What can cause a gated channel to open?

Back 20

A change in the electrical distribution across the membrane (voltage - a change from -90 millivolts to -70 millivolts)

Front 21

What is the term for the ability of a cell to respond to a stimulus with an electrical signal, and occurs only in muscle cells and neurons?

Back 21

Excitability

Front 22

What are the four types of gated channels?

Back 22

1. Voltage

2. Chemical

3. Mechanical

4. Light

Front 23

True/False: Some chemicals can cause the gated channel to open or close.

Back 23

True: Hormones cause the channel to open or close.

Front 24

True/False: Some proteins will open or close in response to physical pressure.

Back 24

True: When something is pushed against the skin, the membrane is deformed, causing a channel to pop open allowing ions to move in, which generates an electrical signal.

Front 25

What is the term for a cell having a membrane potential that is not 0?

Back 25

Polarized (resting cells and neurons)

Front 26

What is the term for taking the resting membrane potential and making it more negative?

Back 26

Hyperpolarization

Front 27

What type of ion would we want to add to a cell to hyperpolarize it?

Back 27

Negative ions (chloride)

Front 28

What type of ion would we want to remove from a cell to hyperpolarize it?

Back 28

Positive ions (potassium)

Front 29

What is the term for making the membrane potential of the cell less negative?

Back 29

Depolarization

Front 30

What type of ion would we want to add to the cell to depolarize it?

Back 30

Positive ion (sodium)

Front 31

What type of ion would we want to remove from the cell to depolarize it?

Back 31

Negative ion

Front 32

What is the term for the small changes in membrane potential (-90 millivolts to -80 millivolts)?

Back 32

Local potentials

Front 33

True/False: Local potentials effect the entire cell.

Back 33

False: They only effect the area where they are taking place.

Front 34

What are local potentials considered, because you can have a small local potential (-5 millivolt change) or you can have a large local potential (-20 millivolt change)?

Back 34

Graded

Front 35

What are local potentials considered, because they decline with distance?

Back 35

Decremental

Front 36

What are local potentials considered, because they can negate changes if one area has a depolarization occurring while the area next to it has a hyperpolarization occurring?

Back 36

Reversible

Front 37

What are the two types of changes that occur in a local potential?

Back 37

1. Excitatory

2. Inhibitory

Front 38

Anything that hyperpolarizes the membrane (taking it further away from 0) is referred to as what type of change?

Back 38

Inhibitory

Front 39

Anything that depolarizes the membrane (taking it closer to 0) is referred to as what type of change?

Back 39

Excitatory

Front 40

What is a change in an electrical potential associated with the passage of an impulse along the membrane of a muscle cell or nerve cell?

Back 40

Action potential

Front 41

True/False: Depolarization leads to an action potential.

Back 41

True

Front 42

Where does an action potential begin?

Back 42

Trigger zone

Front 43

What starts the beginning of an action potential?

Back 43

A local potential causing depolarization

Front 44

What is the voltage for threshold, which, once reached, triggers an action potential?

Back 44

-55 millivolts

Front 45

What is the term for the very high upstroke after threshold has been reached in an action potential?

Back 45

Depolarization (which can increase to +35 millivolts)

Front 46

What is the term for the immediate turn around (coming back down of the action potential to past the normal resting membrane potential)?

Back 46

Repolarization

Front 47

What is the term for the overshooting of the repolarization stage resulting in the inside of the cell being slightly more negative?

Back 47

Hyperpolarization

Front 48

True/False: You can only get an action potential on an axon where there are voltage sodium and potassium channels present.

Back 48

True: Starts at the trigger zone

Front 49

What are the steps in an action potential?

Back 49

1. Depolarization occurs

2. Threshold is reached (-55 millivolts)

3. Voltage gated sodium channels begin to open quickly (fast sodium channels)

4. Voltage gated potassium channels begin to open slowly (slow potassium channels)

5. Sodium pours into the cell which depolarizes the cell, opening up more sodium channels leading to more depolarization

6. The voltage is now +35 millivolts inside the cell

7. When the voltage passes 0 the sodium channels begin to close, sodium stops

8.

Front 50

What type of feedback loop occurs during an action potential?

Back 50

Positive feedback loop