1. Why are depolarizations referred to as excitatory postsynaptic potentials and hyperpolarizations as inhibitory postsynaptic potentials?

2. What are the differences between absolute and relative refractory periods?

3. Compare the synthesis pathways of catecholamine neurotransmitters.

4. Compare the functions of ionotropic and metabotropic neurotransmitter receptors.

5. Contrast the ways in which neurotransmitters and hormones are used as chemical messengers.