Synaptic transmission I

Question 1

Parasympathetic innervation of the heart through the______ what nerve and is mediated via______?

Answer 1

1. Vagus

2. ACh

Question 2

Electrical synapses (Gap Junction)

Answer 2

20 Connexin genes and 3 pannexin gene code for gap junction

Question 3

Gap junction function

Answer 3

• Allows electrical communication between cells
• Chemical communication between cells (IP3 and Ca2+)
• Metabolic coupling (allows molecules smaller than 1,000 Daltons to pass)

Question 4

Electrical synapses (Gap Junction) allows

Answer 4

• Very fast
• Bidirectional communication
  
  • useful for breathing and oscillation

Question 5

Chemical synapses

Answer 5

Electrical signal into chemical signal and back to electrical

Question 6

chemical synaptic contacts

Answer 6

most common between axon terminal, dendritic, somatic, or axonal domain

Question 7

what defines Neurotransmitters?

Answer 7

• Substance must be present within the presynaptic neuron
• Must be released due to depolarization to presynaptic response
• Must be Ca2+ dependent
• specific receptors must exist on the postsynaptic cell

Question 8

Classical Transmitter (small molecules)

Answer 8

• Locally synthesized in presynaptic terminal
• Enzyme comes from nucleus vis Slow Axonal Transport
• Small clear core vesicles

Question 9

Release of _______ requires high-frequency stimulation

Answer 9

-neuropeptide

important to have high calcium level in presynaptic terminal

Question 10

The Neuromuscular junction (NMJ

Answer 10

• Large postsynaptic cell
• one axon but about 100 synapses per muscle cell
• high reliability
• only one type of ion channel

Question 11

Stimulation of the motor fiber generates a?

Answer 11

synaptic potential in post-synaptic muscle cell EPP (END PLATE POTENTIAL)

Question 12

Even in the absence of stimulation very small potentials occur called?

Answer 12

Miniature End Plate Potentials (MEPPs)

Question 13

Quantal release theory

Answer 13

EPPs are multiples of MEPPs

• Spontaneous neurotransmitters release occurs in quantal packet (MEPPs)
• AP potentials release of many transmitter quanta (EPP)

Question 14

Quantal (vesicular) release variables are?

Answer 14

• The number of release sites (N)
• Active zones/synapses
• The probability of a quantal release (p)
• docked vesicles
• The size of the quantal response (q)
• receptor sensitivity

Question 15

Calcium is required for transmitter release due to?

Answer 15

It influences the probability of release

Question 16

Calcium

Answer 16

• AP opens volage gated Ca2+ channels

- Ca2+ allows vesicles to fuse with membrane

Question 17

The active zone is where Ca2+ current is?

Answer 17

10x larger than elsewhere

Question 18

Synaptotagmin

Answer 18

Calcium sensor

-Binding of 4 Ca2+ ions is needed to trigger release

Question 19

Calcium Sensor - Synaptotagmin (function)

Answer 19

-Early synaptic vesicle docking via interaction with β-neurexin or
SNAP-25
-Late steps of Ca2+ + evoked synaptic vesicle fusion with the presynaptic membrane.

Question 20

Ca2+ affects the _____ of release, not the quantal_____.

Answer 20

1. Probability

2. Size