Neurophysiology

Question 0

What underlie electrical signaling?

Answer 0

Ionic forces!

Question 1

What’s the big picture in order?

Answer 1

Nerve cells, parts of neuron, synapse, synaptic cleft, neuronal membrane, ion channel

Question 2

What kind of membrane do we have?

Answer 2

Semipermeable

Question 3

What’s diffusion

Answer 3

Causes ions to flow from areas of high to low concentration, alone their concentration gradient

Question 4

Define electrostatic pressure

Answer 4

Causes ions to flow towards oppositely charges areas (electrical gradient)

Question 5

What are ion channels?

Answer 5

Proteins that down the membrane and allow ions to pass in and out

Question 6

What do gated channels open and close to?

Answer 6

Voltage changes, chemical, mechanical action

Question 7

What do neuronal cell membranes repel?

Answer 7

Water!

Question 8

What surround ions? And what does that allow?

Answer 8

Ions are surrounded by water and therefor they can enter the cell only through w channel

Question 9

What are neuronal membranes not permeable to?

Answer 9

Neuronal membranes are not permeable to big negatively charged proteins (anions)

Question 10

What are neurons selectively permeable to?

Answer 10

Neurons are selectively permeable to k+ . It an enter or leave the cell freely

Question 11

What does k+ do at rest?

Answer 11

At rest, k+ ions move into the negative interior of the cell because of electrostatic pressure

Question 12

What happens as k+ ions build up inside the cell?

Answer 12

As k+ ions build up inside the cell, they also diffuse out alone the concentration gradient

Question 13

When does k+ reach equilibrium?

Answer 13

K+ reaches equilibrium is hen ion movement out is balanced by ion movement in

Question 14

What is the membrane slightly permeable to?

Answer 14

The membrane is slightly permeable to sodium ions (Na+) so they slowly leak in

Question 15

What does the sodium potassium pump do?

Answer 15

The sodium potassium pump puns Na+ out and k+ in, to maintain the resting potential

Question 16

How much of the brain spends running out he sodium potassium pump?

Answer 16

40 percent

Question 17

The pump is good for leakage but not good for what?

Answer 17

Influx of sodium

Question 18

What’s does tetrodotoxin do?

Answer 18

Blocks nerve action by binding to/blocking pores of voltage gated, sodium channels in neuron membranes

Question 19

Why did the man who ate fugu feel like he was dying?

Answer 19

Because he was. His respiratory system was failing. The fish ovaries must be cleaned

Question 20

Where do graded potential take place?

Answer 20

Dendrites

Question 21

What happens as graded potential spread across the membrane?

Answer 21

They diminish. (“Ripples in a pond”)

Question 22

What occurs when the membrane reaches threshold?

Answer 22

It triggers an action potential, & inside of the cell briefly becomes positive

Question 23

T or F: neurons fire at full amplitude or not at all.

Answer 23

True. Thus, they cannot reflect increased stimulus strength

Question 24

Action potentials increase in frequency with what?

Answer 24

Action potentials increase in frequency with increase stimulus strength

Question 25

Where do action potentials start?

Answer 25

The axon hillock

Don’t give up! We are getting an a!

Question 26

What do voltage gated na+ channels open in response to?

Answer 26

Initial depolarization

Question 27

Once more voltage gated channels open what happens?

Answer 27

More Na+ ions enter until membrane potential reaches +40 mV

Question 28

After membrane potential reaches +40, what’s the third step?

Answer 28

Voltage gated na+ channels close