Lecture 4

Question 1

In neurons: Conductance refers to the amount of (open/closed) ion channels

Answer 1

OPEN

Question 2

In neurons: Current refers to the ability of (ions/electrons) flowing through channels

Answer 2

IONS

Question 3

Ohm’s Law is when two areas are _____ _____ to voltage. Therefore, ______ is conducted between them.

Answer 3

directly proportional ; current

Question 4

The equation for Ohm’s Law, the current flow across a membrane, is ___=__*__

Answer 4

I= gV

Question 5

If g=0 in a membrane’s current, this means (few/no) ions flow through the channels. Therefore, (small/no) amounts of current occur.

Answer 5

NO ; NO

Question 6

If g > 0 in a membrane’s current, this means V = (0/>/<). Therefore, some ions flow through channels. However, if V = (0/>/<), then no current will flow.

Answer 6

> ; 0

Question 7

Name the two things ion forces create when paired together.

*hint: refer to the Nernst equation

Answer 7

membrane potential and current flow

Question 8

Name the most important factor for neuronal communication:

Answer 8

the phospholipid bilayer

Question 9

The (tail/head) of lipids are hydrophilic:

Answer 9

Head

Question 10

The (tail/head) of lipids are hydrophobic:

Answer 10

Tail

Question 11

The _______ protein structure forms amino acids

Answer 11

Primary

Question 12

The ______ protein structure forms 3D structures of the protein

Answer 12

Tertiary

Question 13

The ______ protein structure is inside of a 3D formation (alpha helix, beta, sheet)

Answer 13

Secondary

Question 14

The ________ protein structure is composed of multiple units from different genes

Answer 14

Quaternary

Question 15

When a charge builds up, membrane capacitance will have an external (+/-) charge at the outside, attracting (+/-) to the inside.

Answer 15

when a charge builds up, the external (+) charge increases at the membrane, attracting (-) to the inside of the membrane

Question 16

When Na+ is high outside with a COUNTERbalance ion (-) charge, this means Na+ flows (in/out/no)side:

Answer 16

No flow (no open channels)

Question 17

When Na+ is high outside and there is a selectively open channel, the Eion for Na+ is _____

Answer 17

+62mV

Question 18

The equilibrium potential for any ion is calculated the ______ equation

Answer 18

the Nernst Equation

Question 19

If the ionic charge (z) is positive. The ion is high on the inside, low outside so log is less than 1. Given this info, Eion will be (+/-)

Answer 19

Negative.

Positive (+ charge) * negative (log < 1= -) = negative.

Question 20

If the ionic charge (z) is positive. The ion is high on the outside, low inside so log is greater than 1. Given this info, Eion will be (+/-)

Answer 20

Positive.

Positive (+ charge) * positive (log > 1= +) = positive.

Question 21

If the ionic charge (z) is negative. The ion is high on the inside, low outside so log is less than 1. Given this info, Eion will be (+/-)

Answer 21

Positive

Negative (- charge) * negative (log < 1 = -) = positive

Question 22

If the ionic charge (z) is negative. The ion is high on the outside, low inside so log is greater than 1. Given this info, Eion will be (+/-)

Answer 22

Negative.

Negative (- charge) * positive (log > 1 = +) = negative.

Question 23

With resting potential, the inside is (+/-) and the outside is (+/-)

Answer 23

• ; +

Question 24

With resting potential, Vm cannot be Ek+ due to ______ ______

Answer 24

leak channels

Na+ is 1/40th of K+ conductance so it aims to make it more (+) than -80mV.

Question 25

When ions move through specific channels, each ion is always trying to make Vm (=/) than Eion.

Answer 25

= Leak channels cause large driving force = conductance

Question 26

The driving force equation = ____(+/-)_____

Answer 26

Vm - Eion

Question 27

Driving force is a measure of how (close/far) the cell is relative to Eion.

Answer 27

far

Question 28

The further a cell is from Eion, the greater the ______ _____

Answer 28

driving force

Question 29

If Vm is close to Eion, there is no _____ _____

Answer 29

driving force

Question 30

Current (I) = _____ * _____ _____

Answer 30

conductance * driving force

Question 31

Permeability is the (property/ability) of a charge moving through a channel and is related to ______

Answer 31

property ; conductance

Question 32

Conductance is the (property/ability) of a charge moving through a channel

Answer 32

ability

Question 33

Na-KATPase uses ____ to keep K+ high (in/out)side and Na+ low (in/out)side.

Answer 33

ATP ; in ; in

Question 34

T/F: NA-KATPase is a channel

Answer 34

FALSE. It's a pump, meaning it runs against concentration gradient

Question 35

Even though NA-KATPase plays no direct role in membrane potential, it still has a function of maintaining ____ _____ _____ across the membrane

Answer 35

ion concentration differences

Question 36

T/F: NA-KATPase is very slow compared to channels.

Answer 36

TRUE

Question 37

NA-KATPase pumps (2/3) Na+ ions (in/out) and (2/3) K+ ions (in/out)

Answer 37

3 Na+ out, 2 K+ in

Question 38

In the soma, there is/are (one/many) Na+ leak channels. Name it/them.

Answer 38

One ; NALCN

Question 39

There are ____ different K+ leak channels, all in the _____ gene family

Answer 39

18 ; KCNK 'two pore'

Question 40

Driving force for K+ = Vm-Eion when Vm = Eion gives a value of ____mV

Answer 40

0. -80 (Vm) - (-80 (Ek)) = 0

Question 41

T/F: it is a universal experience for cells to have a negative inside, positive outside.

Answer 41

TRUE

Question 42

Define Current:

Answer 42

amount of charge per unit time

Question 43

Current is measured in _____

Answer 43

Amps (mA in neurons)

Question 44

Describe how you can change current by manipulating conductance and potential:

Answer 44

Current: open or close channels Potential: increase of decrease voltage

Question 45

In neurons: voltage (aka driving force) is the force pushing ____ through channels

Answer 45

ions

Question 46

The higher the conductance, the (higher/lower) the resistance.

Answer 46

lower

Question 47

The lower the conductance, the (higher/lower) the resistance.

Answer 47

higher

Question 48

Current is dependent on _____ and _____

Answer 48

conductance ; voltage

Question 49

Describe how equilibrium potential is calculated for each ion:

Answer 49

assuming it's the only one open and the nernst equation: Each ion ALWAYS wants to bring the cell to E(ion) with ANY open channel.

Question 50

At E(ion), the current for said ion is (0/+/-) because chem and elec potentials and _____ and _____

Answer 50

0 ; equal ; opposite

Question 51

T/F: In a cell with two open ion channels, each cell can get to E(ion).

Answer 51

FALSE. Neither cell!

Question 52

T/F: K+ and Cl- are the only ions that are high inside, low outside

Answer 52

FALSE. Only K+

Question 53

T/F: Hydrophobic (tail) interaction holds the phospholipid bilayer together

Answer 53

TRUE

Question 54

FILL IN FROM PACKET ON EQUILIBRIUM POTENTIAL

Answer 54

yep

Question 55

In resting neurons, the inside of a membrane is (+)/(-)

Answer 55

9-)

Question 56

In resting neurons, the outside of a membrane is (+)/(-)

Answer 56

(+)

Question 57

Describe why there might be a -65mV charge in the membrane at rest?

Answer 57

Resulting leak channels from K+ and Na+. K+ has a membrane potential of -80mv but Na+ is fighting to get it to 62mV so there's a slightly positive increase. Since K+ has the upper hand of having more leak channels open, and membrane potential is relative to the inside than out, it is closer to -80mV than +62mV.

Question 58

Look at slide 16

Answer 58

yeah

Question 59

Driving force for an ion is the measure (mV) of how (close/far) the cell (is/will be) from Eion

Answer 59

FAR ; IS

Question 60

The further the cell is away from Eion, the (weaker/greater) the driving force.

Answer 60

greater

Question 61

If there's no potential across the membrane, the membrane would be _____ so there always has to be....

Answer 61

dead ; ionic differential across the membrane

Question 62

Flow of just a small number of ions is all that is needed to make a huge difference in _____ ______

Answer 62

membrane potential

Question 63

If Vm is already close to or at Eion, there is a (weak/strong) driving force.

Answer 63

WEAK (or no).

Question 64

Ionic driving force are when ions run across the membrane at a rate proportional to the _____ between Vm at any time and Eion.

Answer 64

difference

Question 65

Go back to slied 20

Answer 65

mhmm

Question 66

Permeability is highly related to (driving force/conductance)

Answer 66

conductance

Question 67

Conductance is the _____ of _____ moving through a channel

Answer 67

action. ; charge