Nerves Part 4

Question 1

Discuss the presynaptic events during signal transmission.

Answer 1

1. Axon terminal membrane depolarized.
2. Voltage gated calcium channels open
3. Calcium flows into axon terminal cytoplasm.
4. Exocytosis of neurotransmiter.

Question 2

Discuss the postsynaptic events during signal transmission.

Answer 2

1. Neurotransmitter binds and activates receptors (integral membrane proteins)
2. Opening or closing of particular ion channels.
3. Depolarization (EPSP) or hyperpolarization (IPSP) in post synaptic CM.

Question 3

Describe an excitatory neurotransmitter.

Answer 3

Activates a receptor that causes depolarization of the post synaptic membrane; EPSP

1. Either opens membrane channel through which cations enter OR
2. Closes membrane channel through which cations are leaving the post synaptic cell.

Question 4

Describe an inhibitory neurotransmitter.

Answer 4

Activates a receptor that causes hyperpolarization of the post synaptic membrane; IPSP. Opens a membrane channel through which cations will leave the post synaptic cell.

Question 5

Discuss Temporal summation

Answer 5

Summation of post synaptic membrane potentials produced when post synaptic effects of multiple pre synaptic action potentials in a single presynaptic axon are added up.

Question 6

Can dendrites or soma form an action potential?

Answer 6

NO, they dont have voltage gated sodium channels; Action potentials form in the axon hillock if the summation of EPSPs depolarizes the axon hillock to threshold.

Question 7

Discuss Spatial summation.

Answer 7

Summation of post synaptic membrane potentials produced when the post synaptic effects of presynaptic action potentials in multiple axon terminals are added up.

Question 8

Name some excitatory neurotransmitters.

Answer 8

Glutamate, Aspartate

Question 9

Name some inhibitory neurotransmitters.

Answer 9

Glycine, GABA

Question 10

What is the fate of Ach?

Answer 10

1. Hydrolyzed to choline and acetate by acetylcholinesterase; On both pre and postsynaptic cells.
2. Reuptake of choline into presynaptic cell via secondary active transport; Symport with sodium.

Question 11

What are the two types of cholinergic receptors?

Answer 11

1. Nicotinic: Activated by Ach and nicotine

2. Muscarinic: Activated by Ach and Muscarine.

Question 12

Discuss the effects of acetylcholinesterase inhibitors.

Answer 12

1. Muscarinic effects: Tearing, constriction of pupils, salivation
2. Nicotinic effects on skeletal muscle: Twitching
3. CNS effects (both muscarinic and nicotinic): Convulsions, coma, death.