Princeton Review: Chapter 3 Biological Foundations of Behavior

Question 1

What are neurons?

Answer 1

They are specialized cells that can transmit and process information from one part of the body to another in the form of electrochemical impulses.

Question 2

What is an action potential?

Answer 2

It is a short lasting event that is started by a stimuli that causes the electrical membrane potential across the membrane to rise and fall due to ions movement.

Question 3

What is the purpose of the action potential?

Answer 3

To spread the message to the next axon and/or different target cell.

Question 4

Give a simplified view of the pathway of an action potential from the beginning to the end

Answer 4

A stimuli causes ion channels to be open/close this leads to an action potential that is transported down the axon at the end where then this signal is converted into a chemical signal at the synapse by the release of neurotransmitters into the synaptic cleft.

Question 5

When an action potential is converted into a chemical signal via the release of a neurotransmitter at the synaptic cleft that is called?

Answer 5

synaptic transmission

Question 6

What are the main structural parts of a neuron?

Answer 6

1. Body called the soma
2. dendrites take signals coming in
3. axon takes signal away
4. Axon hillock which connects the body to the axon
5. node of Ravier the gaps between myelin sheaths
6. myelin the insulating envelope that surrounds axons and serves to transmit the signal across an axon.

Question 7

The body of a neuron is called?

Answer 7

The soma

Question 8

How many axons can a neuron have?

Answer 8

Only one

Question 9

How many dendrites can a neuron have?

Answer 9

From one to many

Question 10

A neuron with one dendrite is called?

Answer 10

a bipolar neuron

Question 11

A neuron with many dendrites is called?

Answer 11

multipolar

Question 12

What happens to an axon at the end?

Answer 12

The axon branches off and terminate in synaptic knobs

Question 13

What are synaptic knobs?

Answer 13

They are the ends of the branched axons that connect with target cells.

Question 14

What protein is important for vesicle and organalle movement along microtubules in axons?

Answer 14

Kinesin

Question 15

What type of movement does kinesin drive?

Answer 15

Anterograde movement which is movement from the soma to the axon terminus

Question 16

What is the resting membrane potential?

Answer 16

-70 mV (miliVolts)

Question 17

What is responsible for the resting membrane potential?

Answer 17

Two primary membrane protein; Na/K ATPase pump and the potassium leak channels

Question 18

Describe the charge distribution during resting membrane potential?

Answer 18

Negative on the inside of the cell and positive outside

Question 19

What does the Na/K ATPase pump do?

Answer 19

It pumps 3 Na out/ 2 K in using 1 ATP

Question 20

What type of transporter is the Na/K ATPase pump?

Answer 20

Primary Active transporter since it is moving sodium against its concentration gradient and using ATP to do this.

Question 21

What is a leak channel?

Answer 21

A channel that is open and allows for ions to move freely down their concentration gradient

Question 22

What are potassium channels?

Answer 22

They are channels that allow only potassium to pass through

Question 23

Why is the resting membrane potential negative?

Answer 23

The Na/K ATPase channel is effectively pumping out 3 + charges and bringing in only 2+ leaving a net negative inside the cell. In addition, the K leak channels keep removing the K that is pumped inside the cell back out taking out more positive ions. This leaves the inside of the cell to have a net negative charge.

Question 24

Are there sodium leak channels?

Answer 24

There are few of them making the membrane virtually impermeable to sodium.

Question 25

If potassium leak channels are blocked what happens to membrane potential?

Answer 25

The inside of the cell will be less negative since K ions will not be removed from the inside keeping some of the positive charge inside.

Question 26

If sodium ions were allowed to flow down their concentration gradient what would happen to membrane potential?

Answer 26

Make the interior less negative since the sodium ions pumped out by the Na/K ATPase pump would be countered by sodium ions pumped out to be pumped back in.

Question 27

There is a difference in charge between the inside and outside of the cell making the cell _________

Answer 27

polarized

Question 28

What happens when the cell is depolarized?

Answer 28

Becomes less polar as there is a change in membrane potential bringing the -70mV to a less negative number and even positive.

Question 29

After depolarization what is the process that returns the cell to resting membrane potential called?

Answer 29

Repolarization

Question 30

What type of protein is responsible for the propagation of action potentials?

Answer 30

Voltage gated sodium channels

Question 31

When are voltage gated sodium channels activated?

Answer 31

When the membrane potential is slight deploraized to a threshold of -50mV the channels are opened and activated.

Question 32

What is the threshold potential for voltage gated sodium channels to be opened?

Answer 32

-50mV

Question 33

What happens when the voltage gated sodium channels are open?

Answer 33

Sodium ions are allowed to moved down their concentration gradient and depolarize the membrane.

Question 34

Voltage gated sodium channels depolarize the membrane to about what electrical potential before being inactivated?

Answer 34

+35mV

Question 35

How does an action potential move down the axon?

Answer 35

The wave gets passed on to the next region of the membrane as sodium ions move down the axon and slightly depolarize neighboring sections of the membrane until the threshold is reached and the voltage gated sodium channels are opened.

Question 36

Is there a difference in amplitude between the action potential that was started in the beginning vs. the one passed on?

Answer 36

No if an action potential is started it will continue to be renewed as it moves down the axon without a change in amplitude.

Question 37

Sodium in resting membrane potential is high _____ and low _____

Answer 37

Higher outside and lower inside

Question 38

Potassium in resting membrane potential is high____ and low _____

Answer 38

K+ is pumped in and is therefore high inside and low outside.

Question 39

Opening K leak channels will have what affect?

Answer 39

Make the cells more negative (K moves out towards the low concentration of K)

Question 40

Opening Voltage gated Na Channels will have what affect?

Answer 40

Make the cells more positive

Question 41

Utilizing the Na/K ATPase makes the cell more?

Answer 41

Negative on the inside

Question 42

After the membrane is depolarized and reach +35 mV what happens?

Answer 42

1. K+ voltage gated channels open
2. Na+ voltage gated channels become inactivated
   effectively repolarizing the membrane.

Question 43

Compare the rates by which the Voltage gated Na channels close and K open/close?

Answer 43

Na channels are quick to close for the purpose of shutting off the flow of Na into the cell. While K channels stay open longer but are slow to open

Question 44

In an attempt to repolarize the membrane potential _____ channels are open and ______ channels are closed.

Answer 44

Sodium CLOSED

K OPEN

Question 45

What happens during the process by which Na channels are close and K are open?

Answer 45

The membrane potential is overshot and too many K are let out of the cell making the membrane potential more negative than at resting potential -90 mV.