2.6 Lundy Ch. 3 (1) Flashcards Preview

7303 Neuroanatomy > 2.6 Lundy Ch. 3 (1) > Flashcards

Flashcards in 2.6 Lundy Ch. 3 (1) Deck (16):
1

presynaptic terminal

- end of the axon
- contains vesicles of NT

2

postsynaptic terminal

- membrane region of receiving cell
- has receptors

3

synaptic cleft

space between presynaptic and postsynaptic terminals

4

steps of synaptic transmission

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

5

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

- opens an ion channel or
- activates intracellular messengers

6

Synaptic transmission can happen in different locations

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

7

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

number and duration of action potentials that reach the terminal

8

What is a neurotransmitter?

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

9

What are the two types of neurotransmitters?

- ionotropic (fast acting)
- metabotropic (slow acting)

10

ionotropic NT

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

11

metabotropic NT

- 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

12

What is a neuromodulator?

- released into extracellular fluid
- adjust activity of neurons

13

Where do neuromodulators act?

away from the synaptic cleft

14

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

neurotransmitter or neuromodulator

15

Neuromodulators often act in conjunction with ______

neurotransmitters

16

Timing of neuromodulator actions

effects come on slowly and stay around longer than neurotransmitters