Synapses

Question 1

What is the site where information is transmitted from one cell to another?

Answer 1

Synapse

Question 2

True/False: Electrical synapses allow current to flow from an excitable cell to the next via gap junctions.

Answer 2

True

Question 3

Where are electrical synapses found?

Answer 3

Cardiac muscle and some smooth muscle

Question 4

True/False: Chemical synapses transmit information via synaptic cleft by use of a hormone.

Answer 4

False, by use of a neurotransmitter.

Question 5

True/False: A neurotransmitter is released by endocytosis.

Answer 5

False. By exocytosis

Question 6

Give a brief summary of the Neuromuscular Junction event sequence. (Seven steps)

Answer 6

1. Ap -> motorneuron. Local currents depolarize adj regions to threshold. Presynaptic terminal is depolarized. Ca2+ channels are open. 2. Ca2 flows into terminal 3. Ca2+ uptake releases Ach, fuse to PM and exocytosis occurs. 4. Ach diffuses across the synaptic cleft to motor end plate. Ach binds to nicotinic receptors, opening the channels and permeability of motor end plates to Na+ and K+ increases. 5. Na+ an dK+ channels open and flow down gradients. 6. Depolarization of motor end plate causes AP to generate on muscle. 7. End plate potential is terminated as ACh degrade to choline and acetate (by AchE) and half is recycles and 1/2 is discarded.

Question 7

A man diagnosed with myostenia gravis notes increased muscle strength when he is treated with an AchE inhibitor, What is the basis for this improvement?

Answer 7

Levels of Ach at the muscle end plate

Question 8

What substance blocks Ach release eventually leading to death by respiratory failure?

Answer 8

Botulinus toxin

Question 9

What substance competes w. Ach for the nicotinic receptors on the end plate?

Answer 9

Curare

Question 10

Neostigmine is a type of what inhibitor that causes prolonged AP in treatment of myastheinia gravis?

Answer 10

AchE inhibitor

Question 11

What substance blocks choline reuptake, depleting the stores therefore decreasing Ach synthesis?

Answer 11

Hemicholinum

Question 12

What type of receptors are on the motor end plate of the NMC junction?

Answer 12

Nicotinic receptors

Question 13

What type of synapse is a single AP in presynaptic cell causes a single AP in the postsynaptic cell.

Answer 13

One to one

Question 14

What type of synapse has many presynaptic cells converging to the postsynaptic cell?

Answer 14

Many to one

Question 15

What type of synapse fires an AP in the presynaptic cell creating a burst of APs in the postsynaptic cell?

Answer 15

One to many

Question 16

What type of synapse is least common?

Answer 16

One to many

Question 17

Where is an example of one to many synapse?

Answer 17

Motorneurons on Renshaw cells of SC

Question 18

What type summation of presynaptic inputs arrive at the postsynaptic cell simultaneously?

Answer 18

Spatial summation

Question 19

What type of summation of presynaptic inputs arrive at postsynaptic cell in rapid succession?

Answer 19

Temporal

Question 20

In spatial summation, What happens if both inputs are excitatory?

Answer 20

They combine and increase depolarization

Question 21

In spatial summation, What happens if one input is excitatory and one is inhibitory?

Answer 21

They cancel out

Question 22

In temporal summation, what happen when the overlap in time?

Answer 22

They combine

Question 23

What does TEA inhibit?

Answer 23

K+ channels