Membrane Potentials

Question 1

What is voltage difference?

Answer 1

Difference in charge between inside + outside of cell

Question 2

What is membrane potential?

Answer 2

Voltage across plasma membrane=> gives ions the potential to move from one side to other

Question 3

What is definition of resting potential?

Answer 3

Membrane potential of cell not sending signals

Question 4

What is resting potential in neuronal cell?

Answer 4

-70mV

Question 5

What is resting potential of cardiac cell?

Answer 5

-90mV

Question 6

What occurs in formation of resting potential?

Answer 6

K+ channels are always open at resting potential
Inside the cell, [K+] is high and [Na+] is low
Outside the cell, [K+] is low and [Na+] is high
Na+ and K+ gradients are maintained by Na-k pump which is ATP driven, pumping 3 Na+ out and pumping 2 K+ ions in.

Question 7

What is Nernst equation?

Answer 7

Considers membrane permeable to single ion 
Equilibrium potential (Eion) = 62mV (log[ion] outside / [ion] inside)

Question 8

What is equilibrium potential of K+ ion?

Answer 8

-90mV

Question 9

What is equilibrium potential of Na+ ion?

Answer 9

+62mV

Question 10

What is Goldman equation?

Answer 10

Takes into account all the ions of the membrane

Question 11

What is hyper polarisation?

Answer 11

Membrane potential becomes more negative

Gated potassium channels open, K+ ions diffuses our making the inside of cell more negative

Question 12

What is depolarisation?

Answer 12

When gated sodium channels open, Na+ ions diffuses into cell, making inside of the cell more +ve

Question 13

What are 5 stages of generation of action potential in neurones?

Answer 13

Resting state
Depolarisation 
Rising phase of Action potential 
Falling phase of action potential 
Undershoot

Question 14

What are 6 stages of generation of action potential in cardiac cell?

Answer 14

Diastole= voltage gated Na+ and K+ channels are closed 
Depolarisation 
Rapid Na+ inactivation 
Plateau phase 
Rapid repolarisation 
Diastole- closing of K+ channels

Question 15

What are evolutionary adaptations of axon structure?

Answer 15

2 variables that control speed of AP travels is diameter of axon + myelination of axon

Question 16

What are 2 different type of cells that myelin sheath is created depending upon whether axon is in either CNS or PNS?

Answer 16

Oligodendrocytes in CNS

Schwann cells in PNS

Question 17

What is node of Ranvier?

Answer 17

Is where action potentials are formed

They are gaps in myelin sheath where voltage gated sodium channels are found

Question 18

Action potentials in myelinated axons jump between nodes of Ranvier via….

Answer 18

Saltatory conduction

Question 19

What do action potentials do?
In neuronal cell
In cardiac cell

Answer 19

APS can arrive either chemical or electrical synapse
In neuron: electrical signal -> chemical signal in synapse -> electrical signal
Cardiac cell-> don’t release transmitter. They are directly coupled to next cell by gap junction channel

Question 20

What is gap junction channel?

Answer 20

Proteins that directly allow the systole of one cell to be connected to with systole of next cell. As result AP can flow from one cell to another quickly