Lecture 2 (Revised)

Question 1

Only small and lipophilic molecules can cross?

Answer 1

Plasma membrane readily (Ions and larger polar molecules need help to cross membrane)

Question 2

4 Types of Ions Channels?

Answer 2

1) Leak
2) Stretch-activated
3) Ligand-gated
4) Voltage-gated

Question 3

1) (Ion Channel) Leak?

Answer 3

Constitutively active channels

Question 4

2) (Ion Channel) Stretch-activated?

Answer 4

When plasma membrane is stretched, channel is activated

Question 5

3) (Ion Channel) Ligand-gated?

Answer 5

A molecule (ex. neurotransmitter) binds to the protein to activate a channel

Question 6

4) (Ion Channel) Voltage-gated?

Answer 6

Channel activates following a change in membrane potential

Question 7

Action Potential?

Answer 7

Transient changes in membrane potential caused by orchestrated opening and closing of ion channels

Question 8

(AP) From - to +?

Answer 8

Depolarization

Question 9

(AP) From + to -?

Answer 9

Repolarization

Question 10

When it repolarizes and it goes past -70 mV, that is?

Answer 10

Hyperpolarization

Question 11

Resting Potential of AP?

Answer 11

-70 mV

Question 12

Membrane Potential?

Answer 12

(Em)
-Voltage difference across lipid bilayer
-Created by varying concentrations of ions on either side of plasma membrane

Question 13

What is the charge at a specific moment?

Answer 13

Membrane Potential (Em)

Question 14

Equilibrium (Nernst) Potential?

Answer 14

(Eeq)
Reflects a balance (at equilibrium) between chemical and electrical gradients for a single permeable ion

Question 15

Equilibrium (Nernst) Potential Equation?

Answer 15

Eeq = 58/z * log (Co/Ci)
(z = ion charge)
(Ci = internal conc.)
(Co = external conc.)

Question 16

Direction of Ion Movement?

Answer 16

Determined by knowing Equilibrium and Membrane Potential for that ion
(Membrane Potential will always wants to go towards Equilibrium)

Question 17

Membrane Potential will always want to go towards?

Answer 17

Equilibrium

Question 18

(Cation (+))
Em < Eeq?

Answer 18

Moves IN

Question 19

(Cation (+))
Em > Eeq?

Answer 19

Moves OUT

Question 20

(Anion (-))
Em < Eeq?

Answer 20

Moves OUT

Question 21

(Anion (-))
Em > Eeq?

Answer 21

Moves IN

Question 22

Ena?

Answer 22

+67 mV

Question 23

Ecl?

Answer 23

-33 mV

Question 24

Ek?

Answer 24

-84 mV

Question 25

Goldman Equation describes?

Answer 25

Resting membrane potential, accounting for relative permeabilities, and concentration gradients of 3 primary permeable ions

Question 26

Goldman Equation?

Answer 26

Question 27

(Goldman Equation)
Can change resting membrane potential (Em) of a cell by?

Answer 27

1) Changing relative permeability of a specific ion (primarily by K+)
2) Concentration of an internal/external concentration

Question 28

1) (Goldman Equation) (Em shifts with changing [K+])
As external [K+] increases, Em becomes?

Answer 28

Less negative (depolarization)

Question 29

1) (Goldman Equation) (Em shifts with changing [K+])
As external [K+] decreases, Em becomes?

Answer 29

More negative (hyperpolarization)

Question 30

2) (Goldman Equation)
Em shifts with changes in relative permeability?

Answer 30

Em moves toward equilibrium potential of ion of increased permeability