Lecture 6 - Resting membrane potential part 1

Question 1

How do neurones transmit information?

Answer 1

• The nervous system captures, transforms and transmits information.
• The ability to transmit an electric signal is a defining feature of neurons.
The action potential is a very rapid (2 ms) of the resting membrane potential.

Question 2

what’s a defining feature of neruones?

Answer 2

The ability to transmit an electric signal is a defining feature of neurones.

Question 3

what are some key components to resting membrane potential?

Answer 3

• charged atoms/molecules that are dissolved in the intra- and extracellular fluid.
• neuronal memrbane
• proteins
• forces

Question 4

How is an action potential generated?

Answer 4

Movement of ions with different electric charges across the membrane through specialised proteins

Question 5

is water a polar molecule?

Answer 5

yes

Question 6

what an ion?

Answer 6

atoms with a net electric charge + or -

Question 7

whats a positive ion called?

Answer 7

cation

Question 8

whats a negative ion called?

Answer 8

anion

Question 9

ho w is a sphere of hydration formed?

Answer 9

Water molecule stick electrostatically to ions

Question 10

what ions are dissolved in the brain?

Answer 10

calcium, sodium, potassium and chloride.

Question 11

The cell membrane is self ______.

Answer 11

organising

Question 12

the polar heads are?

Answer 12

hydrophilic

Question 13

the lipid tail is?

Answer 13

hydrophobic

Question 14

what are ion channels made from?

Answer 14

multiple subunits (protein in tertiary structure)

Question 15

what are the two states of a neurone?

Answer 15

resting and action

Question 16

what does a neurone do at resting state?

Answer 16

A neuron is integrating incoming signals and is not generating an action potential

Question 17

what does a neurone do in action state?

Answer 17

A neuron has been excited past threshold and fires an action potential.

Question 18

what is membrane potential?

Answer 18

the voltage across the membrane at any moment

Question 19

membrane potential is represented by?

Answer 19

Voltage in millivolts (Vm)

Question 20

at rest what is the voltage?

Answer 20

-65

Question 21

The inside of a cell is more _______ relative to the outside.

Answer 21

negative

Question 22

Resting membrane potential is determined by which two forces?

Answer 22

• Concentration (diffusion)

- Electrostatic pressure (voltage)

Question 23

what does voltage do to ions?

Answer 23

pushes and pulls them around

Question 24

Ions have an electric charge and moved by _____ ______.

Answer 24

electrostatic

pressure

Question 25

define current?

Answer 25

movement of electric charge

Question 26

whats the current conductance and voltage equation? (ohms law)

Answer 26

I = gV

Question 27

what happens when voltage and diffusion interact?

Answer 27

- membrane impermeable to K+ and A- - big concentration gradient - no electrical gradient - charged particles trapped inside in equal amounts - No potential difference between inside and outside of cell

Question 28

How is a balance met?

Answer 28

- diffusion of K+ down concentration gradient - cell becomes more negative - electric potential difference pulls K+ back in - equilibrium reached, no net K+ leaves

Question 29

what happens to forces at equilibrium?

Answer 29

they are equal and opposite

Question 30

what happens to potassium during equilibrium?

Answer 30

No net movement of potassium | still a lot of potassium inside

Question 31

what is equilibrium potential?

Answer 31

- The electrical potential difference that exactly balances an ionic concentration gradient, if the membrane were permeable only to that ion.

Question 32

what are Large changes in membrane potential caused by?

Answer 32

minuscule changes in ionic concentrations

Question 33

The net difference in electric charge occurs at the ____ and ____ surfaces of the membrane.

Answer 33

inside | outside

Question 34

whats the equilibrium potential for potassium?

Answer 34

-80mV

Question 35

whats the ion driving force?

Answer 35

EK = –80 mV; Vm = –65 mV; difference = 15 mV ENa = 62 mV; Vm = –65 mV; difference = –127 mV

Question 36

whats the equilibrium potential for sodium?

Answer 36

62mV

Question 37

If the concentration difference across the membrane is known for an ion, what can be calculated for that ion?

Answer 37

equilibrium potential

Question 38

what is the Nernst equation?

Answer 38

(RT/zF)

Question 39

If you know what the _________ of an ion is inside and outside of a neuron, you can use the _____ equation to calculate the equilibrium potential for that ion

Answer 39

1. concentration | 2. Nernst