Transmitters and excitability

Question 1

How does the resting potential change as development progresses

Answer 1

Becomes more negative - result of expression and insertion of new channels and pumps

Question 2

What work to glia do in order to change the resting potential

Answer 2

Removal of extracellular potassium - from 35mM to 4.5

Question 3

What happens to input resistance as development continues

Answer 3

Goes down - more current can flow across the membrane due to the increased number of ion channels

Question 4

What causes the depolarization in an immature neuron

Answer 4

Calcium - action potentials are infrequent and last longer as a result - their delayed action results from the delayed expression of K channels for repolarization

Question 5

What are delayed rectifiers

Answer 5

A rectifier is a channel that only allows current through one way
Delayed - opens sometime after its voltage threshold has been reached
Outward delayed K rectifiers allow positive charge out of neurons after an action potential
Appearance of these channels shortens the action potential

Question 6

How do neurons refine the way they respond to activity

Answer 6

By incorporation of different channel types

Question 7

How do calcium channels change as the neuron develops

Answer 7

Initially are low voltage activated Tcurrents and are rapidly inactivated
Mature channels are high voltage activated N and L currents and remain open for much longer

Question 8

Where is N-current found

Answer 8

Axon terminals and travel down - control neurotransmitter release

Question 9

How do GABA receptors change during development

Answer 9

Initially receptors are excitatory - Cl concentrations are higher inside the cell sue to NKCC1 - when the cell depolarizes the Cl moves out instead of in - depolarizing the cell - activates calcium ans sodium channels