Lecture 19 - Synaptic transmission

Question 1

How is information transferred between cells?

Answer 1

Chemically- via synaptic interactions

Question 2

What are the features of a synapse? (7)

Answer 2

Pre-synaptic nerve terminal, synaptic cleft, post-synaptic cell, receptors, voltage gated Ca2+ channels, synaptic vesicles, neurotransmitter inactivation enzyme.

Question 3

When an action potential arrives at an axon terminal, what are triggered?

Answer 3

Voltage gated calcium channels, allowing Ca2+ to enter the terminal

Question 4

When calcium ions diffuse into the axon terminal during a synapse, what does this trigger?

Answer 4

Trigger synaptic vesicles to release neurotransmitters via exocytosis

Question 5

What is the fundamental process in which synaptic vesicles release neurotransmitters?

Answer 5

Exocytosis

Question 6

When neurotransmitters diffuse across the synaptic cleft, what occurs at the post-synaptic cell?

Answer 6

Neurotransmitters bind to chemically gated sodium ion channels, allowing them to open and release sodium into the cell, creating a graded depolarisation (local potential).

Question 7

When chemically gated sodium channels close after depolarisation in the post-synaptic cell, what happens to the neurotransmitters that were bound to the channel?

Answer 7

They are released and broken down by enzymes.

Question 8

When Acetylcholine is broken down after release from chemically gated sodium channels, what is formed?

Answer 8

AChE enzyme breaks it down into Acetate and Choline, which is reabsorbed by the axon terminal.

Question 9

What is the enzyme used to break acetylcholine down into acetate and choline after it is release from the post-synaptic chemically gated sodium channels?

Answer 9

AChE

Question 10

How does the axon terminal ‘recycle’ the neurotransmitter ACh?

Answer 10

The axon terminal reabsorbs choline from the synaptic cleft and combines it with Acetyl-CoA (from the mitochondria) to form acetylcholine which can then be released again via synaptic vesicles.

Question 11

Which term describes the resting membrane potential (RMP)?

Answer 11

Polarised

Question 12

Which phase of the action potential occurs when voltage gated sodium channels open?

Answer 12

Depolarisation

Question 13

Dramatically increases how fast propogation happens

Answer 13

Myelin

Question 14

What is the myelin sheath made of in the PNS?

Answer 14

Schwann cells

Question 15

What is the myelin sheath made of in the CNS?

Answer 15

Oligodendrocytes

Question 16

Narrow gaps with no myelin
High density of voltage gated ion channels

Answer 16

Nodes of ranvier