Chapter 4

Question 1

What causes resting potential?

Answer 1

Caused by an unequal distribution of ions on either side of the membrane. Outside contains mostly Na+ and Cl- while inside contains mostly K+ and organic anions A-.

More negative inside and more positive outside the cell.

Question 2

What is the charge of a polarized neuron.

Answer 2

-70 mV

Question 3

Action Potential

Answer 3

A chain reaction that is caused by a brief charge in mV (electrical voltage). -70mV to +50mV

Question 4

What happens in action potential?

Answer 4

A stimulus causes the cell membrane to open and allow Na+ ions inside and K+ ions outside. A voltage charge speeds down the axon to the next neuron.

Question 5

An action potential is a ________response.

Answer 5

All or nothing

Question 6

Action potentials are nondecremental, meaning…

Answer 6

They do not grow weaker as they travel.

Question 7

What must sodium-potassium pumps do in order to maintain polarization?

Answer 7

Allow 3 Na+ out for ever 2 K+ in.

Question 8

What does concentrate gradient do?

Answer 8

Ions move from more concentrated areas to less concentrated areas.

Question 9

Absolute period

Answer 9

The time after an action potential when the neuron is unable to fire again.

Question 10

Refractory period

Answer 10

The time following the absolute period when a neuron is able to fire again.

Question 11

What determines the number of absolute and refractory periods?

Answer 11

The intensity of the stimulus.

Question 12

Effect of an excitatory stimulus

Answer 12

Increases the chance that the neuron will fire

Question 13

Effect of an inhibitory stimulus

Answer 13

Decreases the chance the the neuron will fire

Question 14

Reputake and why it happens

Answer 14

Neurotransmitters are drawn back into buttons by transporter mechanisms immediately after they are released. Happens when an extra neurotransmitter is released into the synapse.

Question 15

Saltatory conduction

Answer 15

When the action potential jumps along the action because of the myelin.

Question 16

Spaces between myelin sheaths are called…

Answer 16

Nodes of Ranevier.

Question 17

Chemicals that either inhibit or excite activity

Answer 17

Neurotransmitters

Question 18

Electrostatic pressure

Answer 18

Ions are repelled from die of membrane with same charge and attracted to sides with opposite charge.

Question 19

Why are sodium-potassium pumps needed?

Answer 19

Some ions leak through. Concentration gradient allows for too much Na+ to enter.

Question 20

EPSP’s and IPSP’s are ___________potentials

Answer 20

Graded

Question 21

Temporal summation

Answer 21

The event referring to EPSP and IPSP biliary to accumulate over a short time.

Question 22

Spatial summation

Answer 22

Inputs can arrive at different locations on the dendrites and cell body.

Question 23

What determines whether an EPSP or IPSP will fire?

Answer 23

The algebraic balance between them.

Question 24

What forces regulate synaptic activity?

Answer 24

Presynaptic inhibition and exhibition, autoreceptors, and glial cells

Question 25

Presynaptic inhibition

Answer 25

Decreases the release of a neurotransmitter

Question 26

Presynaptic exhibition

Answer 26

Increases the release of a neurotransmitter

Question 27

How do autoreceptors work?

Answer 27

Sense the amount of a neurotransmitter in the cleft so the neuron can reduce excessive output

Question 28

resting potential

Answer 28

The difference in charge between the inside and outside of the neuron's membrane when the neuron is at rest.