Lesson 14 Synapse, Neurotransmitters, Neural Circuits

Question 1

what is a synapse?

Answer 1

a point where an axon terminal meets the next cell (another neuron, gland cell, muscle cell)

Question 2

what happens at a neuron to neuron synapse?

Answer 2

the action potential arrives at the end of the presynaptic neuron, where it releases a neurotransmitter that the postsynaptic neuron will respond to.

Question 3

what are the 2 types of synapses?

Answer 3

electrical synapses - direct physical contact between cells (links the cytoplasm of adjacent cells

chemical synapses - signal transmitted across a gap by chemical neurotransmitters (two cells do NOT touch)

Question 4

what are some characteristics of electrical synapses?

Answer 4

• they are locked together at gap junctions
• they allow ions to pass between cells
• produce continuous local current and action potential propagation (spread)

Question 5

how were neurotransmitters discovered?

Question 6

what is the synaptic cleft?

Answer 6

the gap between the presynaptic neuron and postsynaptic neuron

Question 7

what are electrical synapses?

Answer 7

a gap junction that join adjacent cells where electrical signals spread directly from cell to cell

Question 8

where are neurotransmitters released?

Answer 8

at chemical synapses

Question 9

what is an advantage and disadvantage to electrical synapses?

Answer 9

advantage: occur much faster, no delay for release, diffusion, and binding of neurotransmitter

disadvantage: they can’t integrate information

Question 10

where are synaptic vesicles contained?

Answer 10

the axon terminal of presynaptic neurons. the synaptic vesicles contain neurotransmitters.

Question 11

what do postsynaptic neurons contain?

Answer 11

they contain a postsynaptic density of neurotransmitter receptors and ions channels.

Question 12

why does a synaptic delay occur?

Answer 12

it occurs since chemical synapses are not directly in contact with the postsynaptic cell and require the release of a neurotransmitter to stimulate/inhibit the target cell

Question 13

when does the synaptic delay occur?

Answer 13

between the arrival of the action potential at the synaptic terminal

Question 14

what reflexes have the fastest responses?

Answer 14

monosynaptic reflexes have the fastest responses because the fewer the synapses found between the transmission of the information, the less synaptic delay. this is in comparison to polysynaptic reflexes.

Question 15

what is synaptic fatigue?

Answer 15

this occurs when a neurotransmitter cannot recycle fast enough to meet the demands of intense stimuli

Question 16

state an example of synaptic fatigue with a cholinergic synapse.

Answer 16

a cholinergic synapse uses acetylcholine (ACh). the formation of new ACh from recycled choline is not fast enough to meet demand. if too many action potentials are reaching the axon terminals, there will not be enough neurotransmitters produced for exocytosis and released into the synaptic cleft.

Question 17

what are the 2 classifications of neurotransmitters?

Answer 17

1. excitatory (depolarizing)
2. inhibitory (hyperpolarizing)

Question 18

name 5 neurotransmitters (major chemical categories)

Answer 18

1. acetylcholine
2. amino acids
3. monoamines (biogenic amines)
4. gases
5. neuropeptides

Question 19

what are the 3 kinds of synapses?

Answer 19

1. excitatory cholinergic synapse (ACh)
2. inhibitory GABA-ergic synapse (GABA)
3. excitatory adrenergic synapse (NE)