Nerve transmission

Question 1

What is patch clamping used for?

Answer 1

Measure current across membrane
-Flow of ions creates current

-Gives map of current against time, where current can be seen to give an idea of how many channels are open

Question 2

What geometries can be studied with patch clamping?

Answer 2

Inside-out geometry
-internal membrane surface
Whole-cell geometry
-all ion channels in cell
Outside-out geometry
-external membrane surface

Question 3

What does the Na+/K+ pump do?

Answer 3

Pumps 3Na+ out for every 2K+ in
-dependent on ATP
-maintains Na+/K+ concs

Question 4

What does the resting K + channel do?

Answer 4

Open all the time, allowing K+ to leak out (creating -ve membrane pot)

Question 5

What does the voltage-gated Na+ channel do?

Answer 5

Open to let Na+ move in when action potential comes along
-Gates controlled by voltage-sensing α-helices (more up towards +ve charge when action potential comes)
-Have a plug which blocks hole after 1ms of being open

Question 6

What does the voltage-gated K+ channel do?

Answer 6

Opens to let K+ move out
-Delayed but still respond to action potential
-Have a plug

Question 7

What is the myelin sheaf?

Answer 7

Insulating membrane layer made of Schwann cells around neurones
-Prevent ions crossing membrane so that nerve impulses can travel faster

Nodes = gaps between

Loss of myelin in areas of brain and spinal cord leads to multiple sclerosis (MS)