Nervous System ( Synapse)

Question 1

What happens at the Synapse of the neuron?

Answer 1

• where signals molecules are secreted by neurons
• is the target cell receptors for signal molecules
• is the anatomical connection between neurons and their targets

Question 2

What are the 2 parts of a synapse?

Answer 2

1) presynaptic neuron

2) postsynaptic neuron

Question 3

What are the types of Neurotransmitters? (5)

Answer 3

1) acetylcholine (ACh)
2) Serotonin (5-HT)
3) Dopamine
4) Norepinephrine (NE)
5) epinephrine (E)

Question 4

What is acetylcholine synthesized from?

Answer 4

• choline (found in the membrane phospholipids)

- Acetyl Coenzyme A/ acetyl CoA (metabolic intermediate that links glycolysis to the citric acid cycle)

Question 5

Neurons that secrete acetylcholine and receptors that bind to ACh are described as?

Answer 5

Cholinergic

Question 6

Cholinergic receptors are divided into what 2 main subtypes?

Answer 6

1) Cholinergic Nicotinic receptors

2) Cholinergic muscarinic receptors

Question 7

Where are Cholinergic nicotinic receptors found?

Answer 7

• skeletal muscles
• ANS
• CNS

Question 8

Where are Cholinergic Muscarinic receptors found?

Answer 8

• smooth and cardiac muscles
• endocrine and exocrine glands
• CNS

Question 9

Which neurotransmitters are amine acid derived?

Answer 9

• serotonin
• dopamine
• norepinephrine/epinephrine

Question 10

Serotonin is derived from what amino acid?

Answer 10

Tryptophan

Question 11

Where is serotonin found?

and what are the neurons that secrete serotonin called?

Answer 11

• CNS

- serotonergic receptors

Question 12

Dopamine is derived from what amino acid?

Answer 12

Tyrosine

Question 13

Neurons that secrete dopamine are called?

Answer 13

Dopamine receptors

Question 14

Norepinephrine (NE)/Epinephine (E) is derived from what amino acid?

Answer 14

-tyrosine

Question 15

Neurons that secrete norepinephrine and epinephrine are called?

Answer 15

-adrenergic (alpha,beta)

Question 16

Where are adrenergic (epinephrine,norepinephrine) receptors found?

Answer 16

• smooth and cardiac muscles
• CNS
• exocrine and endocrine glands

Question 17

Summarize the release of neurotransimitters to the synaptic cleft

Answer 17

-neurotransimitters in the axon terminal are stored in vesicles, so their release in the synaptic cleft takes place by exocytosis

Question 18

Explain the release steps of neurotransmitters into the postsynaptic cleft in detail (5 steps)

Answer 18

1) action potential depolarizes the axon terminal
2) the depolarization opens the Ca2+ channels and Ca2+ enters the cell
3) Calcium entry triggers exocytosis of synaptic vesicle contents
4) Neurotransmitter diffuses across the synaptic cleft and binds with receptors on the postsynaptic cleft
5) Neurotransmitter binding initiates response in the postsynaptic cleft

Question 19

Summarize the neurotransmitter termination process

Answer 19

1) Neurotransmitters can be returned to axon terminals for reuse or transported into glial cells
2) Enzymes inactivated neurotransmitters (degradation)
3) Neurotransmitters can diffuse out of the synaptic cleft

Question 20

Summarize the degradation process of neurotransmitters

Answer 20

-neurotransmitters that didn’t diffuse away from the synapse are inactivated by enzymes in the synaptic cleft

Question 21

Describe the step by step degradation process of Acetylcholine (ACh)

Answer 21

1) acetylcholine is made of choline and acetyl CoA
2) In the synaptic cleft, ACh is rapidly broken down by the enzyme acetylcholinesterase
3) Choline is transported back into the axon terminal by cotransport with Na+
4) Recycled choline is used to make more ACh

Question 22

What are the 2 post synaptic responses

Answer 22

1) excitatory postsynaptic potential

2) inhibitory postsynaptic potential

Question 23

What happens to the postsynaptic cell when it receives an Excitatory postsynaptic potential (EPSP)?

Answer 23

-depolarizes the postsynaptic cell

Question 24

What happens to the postsynaptic cell when it receives an Inhibitory postsynaptic potential (IPSP)?

Answer 24

-hyperpolarizes postsynaptic cell

Question 25

Describe Spatial Summation

Answer 25

-summation of several subthreshold signals results in an action potential

Question 26

Summarize the process of Synaptic Inhibition

Answer 26

-One inhibitory postsynaptic potential (IPSP) sums with two excitatory postsynaptic potentials (EPSPs) to prevent an action potential in the postsynaptic cell

Question 27

Steps of a synaptic inhibition

Answer 27

1) One inhibitory and two excitatory neurons fire

2) The summed potentials are below threshold, so no action potential is generatede

Question 28

Summarize a global presynaptic inhibition

Answer 28

-all targets of the postsynaptic neuron are inhibited equally

Question 29

What are the steps of global presynaptic inhibition

Answer 29

1) Excitatory and inhibitory presynaptic neurons fire
2) Summed signal in postsynaptic neuron is below threshold
3) No action potential initiated at trigger zone
4) No response occurs in any target cell

Question 30

Describe temporal summation

Answer 30

-occurs when two graded potentials from one presynaptic neuron occur close together in time

Question 31

In a temporal summation, describe what happens when their is no summation

Answer 31

-two subthreshold graded potentials will not initiate an action potential if there are far apart in time

Question 32

In a temporal summation, describe what happens during a summation that causes an action potential

Answer 32

-two subthreshold potentials arrive at the trigger zone within a shower period of time, they may sum and initiate an action potential