week 2 - resting potential and action potential

Question 1

What is the main component of a cell that drives in neuron communication?

Answer 1

cell membrane

Question 2

cell membrane

Answer 2

• phospholipid bilayer
• semi-permeable

Question 3

semi-permeable

Answer 3

very small structures, such as oxygen and other gases, can pass; ions (charged particles) cannot

Question 4

What do neurons use to communicate with each other?

Answer 4

ions (charged particles)

Question 5

cations

Answer 5

• positive charge
• ex.) Na+, Ca+ K+

Question 6

anions

Answer 6

• negative charge
• ex.) CI-

Question 7

What is one way that ions cross the cell membrane?

Answer 7

They use ion selective channels made of transmembrane protein pores.

Question 8

Why are some ion channels gated?

Answer 8

to prevent ions from going through

Question 9

What forces will push an ion across an open ion channel?

Answer 9

diffusion and electrostatic forces

Question 10

diffusion

Answer 10

molecules move from high concentration to low concentration

Question 11

electrostatic force

Answer 11

• electrical gradient
• opposites attract, likes repel

Question 12

What is potential?

Answer 12

the difference in charge between the inside and outside of a cell membrane

Question 13

What is the resting membrane potential of a neuron?

Answer 13

-70mV

Question 14

Why is the resting membrane potential negative?

Answer 14

due to the unequal distribution of ions; there are more anions inside compared to outside

Question 15

During diffusion, which way to ions go?

Answer 15

• K+: outside
• CI-: inside
• Na+: inside

Question 16

During electrostatic forces, which way do ions go?

Answer 16

• K+: inside
• CI-: outside
• Na+: inside

Question 17

Why is there an unequal distribution of ions?

Answer 17

selective permeability and sodium-potassium pump

Question 18

selective permeability

Answer 18

• membrane is moderately permeable to K+ and CI- but relative permeable to Na+
• Na+ is impermeable

Question 19

sodium-potassium pump

Answer 19

• makes up for Na+ impermeability
• active transporter (must use ATP)
• pumps 3 Na+ out for every 2 K+ pumped in

Question 20

What is the direction of neuronal conduction?

Answer 20

• soma to axon
• then presynaptic to postsynaptic

Question 21

What is action potential?

Answer 21

rapid changes in cell membrane potential

Question 22

depolarization

Answer 22

• inside of cell becomes less negative/more positive
• cations enter and anions exit

Question 23

hyperpolarization

Answer 23

• inside of cell becomes more negative/less positive
• anions enter and cations exit

Question 24

axon hillock

Answer 24

• spike initiation zone
• stimulus can be applied once or multiple times

Question 25

What happens when stimulus reaches threshold?

Answer 25

• action potential occurs
• may cause ion channels to open/close

Question 26

What is the movement of Na+ channels when action potential occurs?

Answer 26

• Na+ ion channels will open and Na+ ion rush in (causes depolarization
• channels close at peak of action potential (Na+ cannot enter)

Question 27

What happens during action potential?

Answer 27

• when cell membrane threshold is met, voltage-gated Na+ channels open up, Na+ enters the cell
• Na+ channels close in 1 msec
• In the meantime, voltage-gated K+ channels open, K+ leaves cell, repolarizing it
• “all-or-none”

Question 28

How is information coded by the nervous system?

Answer 28

based on changes in pattern frequency

Question 29

What would happen if you were given a drug that blocked Na+ channels?

Answer 29

action potential does not occur

Question 30

What happens if you are given a drug that blocks K+ channels?

Answer 30

repolarization would not occur (constant depolarization)