Question

What permeability changes would you expect to occur at the postsynaptic neuron to result in hyperpolarization?    

(P=permeability)

		A. increased P Na+ and/or P K+
		B. increased P K+ and/or P Cl-
		C. increased P Ca++
		D. increase P Na+
		E. none of these answers

Answer 1

The correct answer is B, there is increased Permeability of K and Cl ions.

Explanation:

Hyperpolarization is a change in a cell's membrane potential that makes it more negative. It is the opposite of a depolarization. It inhibits action potentials by increasing the stimulus required to move the membrane potential to the action potential threshold.

It happens during the Postsynaptic Inhibition/Direct Inhibition.

• This occurs due to the release of an inhibitor neurotransmitter instead of an excitatory neurotransmitter substance.
• The most important inhibitory neurotransmitter substance is GABA(Gamma Amino Butyric Acid) the other is glycine.
• The inhibitory neurotransmitter acts on the postsynaptic membrane by binding with the receptor.
• The transmitter receptor opens the ligand-gated K channels instead of Na channels, now the K ions pass out of synapse into the extracellular fluid.
• Cl channels also open followed by an influx of chlorine inside.
• The exit of K and the influx of Cl cause more negativity inside.leading to hyperpolarisation