2.6 Lundy Ch. 3 (1)

Question 1

presynaptic terminal

Answer 1

• end of the axon

- contains vesicles of NT

Question 2

postsynaptic terminal

Answer 2

• membrane region of receiving cell

- has receptors

Question 3

synaptic cleft

Answer 3

space between presynaptic and postsynaptic terminals

Question 4

steps of synaptic transmission

Answer 4

1. AP arrives at presynaptic terminal
2. membrane depolarizes and Ca2+ channels open
3. Ca2+ flows into presynaptic terminal and triggers movement of vesicles that contain NT toward a release site in the membrane
4. vesicles fuse with membrane and release NT into the cleft
5. NT diffuses across synaptic cleft
6. NT binds to a receptor on postsynaptic membrane
7. receptor changes shape

Question 5

What happens when the receptor on the postsynaptic terminal changes shape?

Answer 5

• opens an ion channel or

- activates intracellular messengers

Question 6

Synaptic transmission can happen in different locations

Answer 6

• axosomatic (on cell body)
• axodendritic (on dendrites)
• axoaxonic (on axon)

Question 7

What influences the amount of NT released into the synaptic cleft?

Answer 7

number and duration of action potentials that reach the terminal

Question 8

What is a neurotransmitter?

Answer 8

• released by presynaptic neuron

- acts either directly on postsynaptic ion channels or activates proteins inside postsynaptic neuron

Question 9

What are the two types of neurotransmitters?

Answer 9

• ionotropic (fast acting)

- metabotropic (slow acting)

Question 10

ionotropic NT

Answer 10

• directly affect postsynaptic membrane by activating ion channels
• short lived effects

Question 11

metabotropic NT

Answer 11

• indirectly affect postsynaptic membrane by activating proteins inside the postsynaptic neuron
• regulate fast transmission by controlling amount of NT released from terminals
• influence actions of ionotropic NT on postsynaptic membrane

Question 12

What is a neuromodulator?

Answer 12

• released into extracellular fluid

- adjust activity of neurons

Question 13

Where do neuromodulators act?

Answer 13

away from the synaptic cleft

Question 14

Depending on where it’s released, the same molecule may be either of these

Answer 14

neurotransmitter or neuromodulator

Question 15

Neuromodulators often act in conjunction with ______

Answer 15

neurotransmitters

Question 16

Timing of neuromodulator actions

Answer 16

effects come on slowly and stay around longer than neurotransmitters