One of the examples of the action of the autonomous nervous system is

You are watching a horror movie and notice that your heart rate increases and your mouth becomes dry. What is the reason for this?

Feeling of thirst is due to

Give a brief account of
$(a)$ Mechanism of synaptic transmission
$(b)$ Mechanism of vision
$(c)$ Mechanism of hearing

When we move from darkness into bright light,we cannot see for a short time,but after a while,our vision becomes normal. This is an example of ..........

Given below are two statements with respect to the neurotransmitter,dopamine.
Statement-$I$: Degeneration of dopamine-producing neurons causes Parkinson's disease.
Statement-$II$: Dopamine levels increase due to cocaine.
Choose the most appropriate answer from the options given below.