Cellular Neurophysiology - Turko

Question 1

What is the difference between the absolute and relative refractory periods following an AP?

Answer 1

Absolute - No Generation of a further AP possible within this time span as voltage gated Na+ channels are inactivated

Relative - increased depolarisation required for AP generation due to K+ channel mediated afterpolarization

Question 2

What protein is primarily responsible for actively generating the electrochemical gradient between the inside and outside of cells and what ions does it transport?

Answer 2

Na+/K+ ATPase (sodium potassium pump), transports 3 Na+ out of cell and 2 K+ into the cell (per ATP converted to ADP)

Question 3

Thickness of cellular membrane

Answer 3

5nm

Question 4

Cell membranes are more permeable to
A) hydrophilic
B) hydrophobic
Molecules

Answer 4

B

Question 5

What is the membrane time constant (tau)?

Answer 5

The time required for the membrane potential to reach 63% of its maximal change following application of a fixed current.

Question 6

The membrane time constant (tau) is calculated by…

Answer 6

Multiplying membrane capacitance and membrane resistance

Question 7

Why does the the hyperpolarization following an AP allow for increased AP firing frequency?

Answer 7

Because Na+ channels de-inactivate more rapidly at more negative membrane voltages

Question 8

Resting membrane potential is most determined by the intracellular /extracellular balance of _, but closest to the equilibrium potential of _.
Full in appropriate ions.

Answer 8

A: potassium
B: chloride

Question 9

2 approaches to modelling the spread of electrical signals along the neuron

Answer 9

Cable theory

Compartmental models

Question 10

Equilibrium potentials of 4 main ions :

Answer 10

Ca 2+: 150mv
Na +: 60mv
Cl-: - 70mv
K+: - 90mv

Question 11

What is the difference between a closed and inactivated channel?

Answer 11

A closed channel will own and permit ion flow when it’s open consortia are met (ligand binding or voltage threshold), inactivated must first de - inactivate (“relatively” slow process, sped up by more negative membrane potentials for voltage gated channels), entering the courses state, before they can be opened.

Question 12

To simply model the flow of current across a membrane containing ion channels what two features in electrical circuits are required?

Answer 12

A circuit with a resistor (ion channels) and a capacitor (membrane capacitance)

Question 13

Die of ions through voltage gated channels is an
A) Active
B) Passive
Process

Answer 13

B

Question 14

Nernst equation

Answer 14

Eq=(RT)/(ZF)log([ion extracellular]/[ion intracellular])

R - gas constant
T - temperature in kelvin
Z - Valence of ion
F - Faradys constant

Question 15

Perineuronal nets

Answer 15

A type of extracellular matrix that surrounds a sub set of neurons in the brain and spinal cord;Type of extracellular matrix particularly associated with PV+ (parvalbumin expressing) interneurons