resting potential

Question 1

Neuron communication

Answer 1

• conduct info using electrical signals called action potentials

Question 2

flow of ions

Answer 2

• ions flow in and out of the membrane in waves
• not like free electrons flowing down

Question 3

Potential

Answer 3

possibility to do something
- caused by separation of electrical charges across the membrane

Question 4

electrical potential

Answer 4

difference in electrical charge
- voltage

Question 5

Neuron at rest

Answer 5

• has no inputs
• the ions are not evenly distrubuted across the membrane
• inside is more negative

Question 6

main ions at play

Answer 6

1. Na+
2. K+
3. Cl-
4. Ca2+

Question 7

Ions inside the cell

Answer 7

• k+ is more prevalen inside
• also anions present

Question 8

ions outside the cell

Answer 8

• Cl-
• Na+
• Ca2+

Question 9

How does the RMp state arise?

Answer 9

because of the semi permeable membrane

Question 10

what makes up the mebrane

Answer 10

• phospholipid bilayer
• polar hydrophilic heads
• nonpolar hydrophobic tails

Question 11

Semi permeable membrane

Answer 11

• only small, uncharged lipid soluble molecules can pass
• charged ions cant cross without the use of pores or pumps because of their size and hydration

Question 12

Channels

Answer 12

• proteins make up channels that are very selective to certain ions
• thay can be gated and open and close

Question 13

selecting ions in channels

Answer 13

1. select based on charge (+/-)
2. based on size (diameter of hydration)

Question 14

main ingredient of fluid (in and out)

Answer 14

• polar water
• covalent bonds

Question 15

factor affecting RMP

Answer 15

1. diffusional force
2. electrical force

Question 16

diffusional force

Answer 16

• ions flow from area of high concentration to low concentration
• acts until they are balanced

Question 17

Electrical force

Answer 17

• ions of similar charges repel, and opposite attract
• depends on resistance

Question 18

1 mV

Answer 18

= 0.001 V
- voltage (read by voltmeter)

Question 19

Equilibrium potential

Answer 19

reached when the diffusional and electrical forces are equal and opposite
- net movement across membrane will cease

Question 20

generating electrical potential

Answer 20

1. ionic concentration gradient
2. selective permeability

Question 21

Nernst equation

Answer 21

• calculated equilibirum of one ion
• need to know concentration in and out

Question 22

E of RMP

Answer 22

-65 mV

Question 23

E of Na+

Answer 23

+58 mV

Question 24

E of K+

Answer 24

• 80mV

Question 25

E of Ca2+

Answer 25

+123 mV

Question 26

E of Cl-

Answer 26

- 65 mV

Question 27

why does K contribute the most

Answer 27

1. there is a lot in the neuron 2. some channels are always open 3. diffuses out until voltage balance concentration - k has 40:1 more channels - it leaks

Question 28

Goldman equation

Answer 28

- extension of nerst - caluculates eq of all ions acting together

Question 29

goldman depends on what

Answer 29

- permeability of ion - concentration of ions

Question 30

Forces on K+

Answer 30

concentration pushes outward - electrical psuhes inward - wants to get to -80 but concentrational wins

Question 31

forces on Na+

Answer 31

- diffusion and electrical push it inwards

Question 32

Ion pumps

Answer 32

- leakage woul reduce concentration gradient if it werent for pumps - they use 70% of the brain ATP - not a pore - always going

Question 33

Sodium potassium pump

Answer 33

- bring in 2 K+ - takes out 3 Na+

Question 34

Important considerations

Answer 34

1. very small changes in concentration of an ion can cause large changes in RMP 2. this happens on the surfaces of the membranes (edges)

Question 35

Astrocytes and K+

Answer 35

- diffuse it over a large area - regulate external concntration - store it - remove it through pumps and channels - a little change in it could really mess things up - BBB