Lecture 5 - Action Potential Propagation and Synaptic Transmission

Question 1

What is it called when voltage drops below -65 and potassium is at its highest

Answer 1

Hyperpolarization

Question 2

What direction does sodium move

Answer 2

Since sodium works by diffusion it works in both directions

Question 3

Process of inactivated to closed to open

Answer 3

Sodium channels are inactive meaning they cannot be opened, during this action potential (AP) can’t propagate back in the direction

When sodium channels eventually close, they can be opened. As a result, the surge of sodium that spreads through the axon causes another action potential as it travels down axon

Question 4

What is faster passive or active diffusion in currents?

Answer 4

Passive is very fast compared to active flow generated during an AP

Question 5

Passive Diffusion

Answer 5

Charges diffuse passively along an axon. It experiences exponential decay of charge as it gets away from exertion point.

Question 6

How is action potential regenerated?

Answer 6

Voltage- gated Na + and K+ are ONLY at the Nodes of Ranvier. Therefore, the action potential is re- generated at each node. It then spreads passively down the axon under he myelinated portion

Question 7

Why does action potential jump through axon

Answer 7

Because as you move along the axon, things are faster under myline so the action potential goes fast, slow, fast, slow. AP drops from node to node

Question 8

Key rule about mylinated axons

Answer 8

they conduct much faster

Question 9

What are the nodes of Ranvier?

Answer 9

The nodes of ranvier are sodium channels

Question 10

What is the very small space in between neurons called?

Answer 10

Synaptic cleft

Question 11

Pre vs Post synaptic neurons

Answer 11

Pre synaptic neruons= axon
post = dendritic spines

Question 12

Complex important protein

Answer 12

SNARE complex which find vesicles, bind and open them releasing a neurotransmitter

Question 13

Budding process

Answer 13

Budding then
Docking then
Priming then
Fusion then
Budding which creates a new vesicle

Question 14

Calcium and SNARE proteins

Answer 14

Calcium triggers snare proteins. snare complexes are activated by calcium ay pre synaptic vesicle which undergoes budding process to realize more neurotransmitter molecules

Calcium entering neurons = release of neurotransmitter

Question 15

Quantal release of neurotransmitters

Answer 15

When calcium enters synaptic vesicles fuse to realize content into synaptic cleft. 1 Quantal =1 vesicle

Number of vesicles fusing directly correlates to amount of NT in synapse 1:1 ratio

Question 16

11 steps of synapse

Answer 16

1. Transmitter is synthesized and then stored in vesicles
2. An AP invade the presynaptic terminal
3. Depolarization of presynaptic thermal causes opening of voltage gated calcium channels
4. Influx of calcium through channels
5. calcium causes vesicles to fuse with presynaptic membrane
6. transmitter is realized into synaptic cleft via exocytosis

6.5 Neuro transmitters diffuse across post synaptic membrane

7. transmitter binds to receptor molecule in postsynaptic membrane
8. Opening or closing of post synaptic channels
9. Postsynaptic current causes excitatory or inhibitory postsynaptic potential to occur which changes the excitability of the postsynaptic cell
10. Removal of neurotransmitters by glial cells or enzymes
11. Vesicles are recycled or budding process

Question 17

How many neurotransmitters can you receive vs send

Answer 17

receive infinite but can only send one