Question

1)

In a neuron, a depolarizing graded potential can directly cause:

	a.	opening of voltage-gated Na+ channels
	b.	inactivation of voltage-gated Na+ channels
	c.	opening of ligand-gated cation channels
	d.	both a) and b) are correct, and c) is incorrect
	e.	a), b) and c) are all correct

2)

Which of the following type(s) of ion channels is/are localized in the synaptic bouton and is/are required for chemical synaptic transmission?

	a.	Voltage-gated Na+ channel
	b.	Ligand-gated ACh Receptor
	c.	Voltage-gated Ca++ channel
	d.	both a) and b) are correct, and c) is incorrect
	e.	a), b) and c) are all correct

Answer 1

Ans

1. C is correct

A. The voltage gated channels will open in response to voltage. The voltage-gated sodium channels open when membrane potential reaches -55mV and sodium influx occurs increasing the voltage

B. They close in response to the membrane potential.

C. The graded potential is caused by a ligand which causes opening of the ligand gated channels. So, the depolarizing graded potential can directly cause opening of ligand gated cation channels.

D c is correct

E. A,b wrong

2. c is correct

A. Voltage gated Sodium ion channels are located in many tissues in nerve , muscles,heart etc.

B. Ligand gated ACH receptors are located on the postsynaptic neuron where the neurotransmitter acetyl choline will bind to.

C. Voltage gated calcium channel are located on the synaptic bouton.

D. C is correct

E. A and B wrong.