BIOL 273 - Unit 2.4

Question 1

Information communicated via synapses: what are the 3 components and where are they located

Answer 1

1. Presynaptic cell at the axon terminal
2. Synaptic cleft in the space between cells
3. Postsynaptic cell in the membrane

Question 2

What are the two types of synapses that vary based on the signal passed bw cells

Answer 2

1. Electrical synapses
2. Chemical synapses

Question 3

Describe electrical synapses

Answer 3

• signalling done in gap junctions
• rapid conduction in both directions
• common in the CNS
• between neurons and between neurons+glial cells

Question 4

Describe chemical synapses

Answer 4

• make up the vast majority of synapses
• information carried via neurotransmitter
• used by peripheral neurons
• between neurons and between neuron +effector
• neuroeffector junction
• neuromuscular junction

Question 5

What does the presynaptic cell contain

Answer 5

many vesicles (small packages of neurotransmitter)

Question 6

Where do vesicles of the presynaptic cell fuse to and release into

Answer 6

fuse to presynaptic membrane
- release contents and diffuse through the synaptic cleft
- they bind to receptors on the postsynaptic cell membrane

Question 7

Describe the events at the synapse

Answer 7

1. action potential travels down the axon and depolarizes the axon terminal in the presynaptic cell
2. depolarization wave triggers opening of voltage gated Ca+2 channels in the presynaptic cell membrane
3. Calcium entry signals the synpatic vessels in the presynaptic cell to release the neurotransmitters
4. Neurotransmitters diffuse across synaptic cleft and binds with specific receptors on postsynaptic cell membrane
5. Binding of the neurotransmitter intiates a response in the postsynaptic cell

Question 8

What are the two types of response neurotransmitters create in the postsynaptic cell

Answer 8

1. Direct response
2. Indirect response

Question 9

describe the effect of DIRECT RESPONSE when neurotransmitters are released onto the post synaptic cell

Answer 9

(aka fast synaptic potential)
- quick response that does not last long , done via interaction with an ion channel

Question 10

describe the effect of INDIRECT RESPONSE when neurotransmitters are released onto the post synaptic cell

Answer 10

(aka slow synaptic potential)
- take longer to create the response
- longer lasting response
- signal transduction mechanisms uses G proteins and 2nd messenger signals

Question 11

What are the two types of neurotransmitters

Answer 11

1. Acetylcholine
2. Amines

Question 12

What is acetylcholine catalyzed by and where is it synthesized

Answer 12

enzyme choline acetyl transferase (CAT)
- synthesized in axon terminal and packaged into vesicles

Question 13

What do you call neurons that secrete or have receptors for ACh

Answer 13

cholinergic

Question 14

What are the two subtypes of cholinergic receptors, where they respond to the binding of ACh

Answer 14

1. Muscarinic (coupled to G proteins)
   - slower/indirect response
2. Nicotinic (receptor operated channels)
   - faster/direct response

Question 15

Describe what the neurotransmitter amine can be converted to

Answer 15

dopamine, norepinephrine, epinephrine

Question 16

Where is the neurotransmitter amine synthesized

Answer 16

in axon terminal and packaged into vesicles

Question 17

What do you call a neuron that secrete norepinephrine (a type of amine transmitter) ?

Answer 17

adrenergic

Question 18

What are the two classes of adrenergic receptors

Answer 18

alpha and beta , and subtypes of each

Question 19

How does the neurotransmitter ACh be inactivated at the synaptic cleft

Answer 19

can be degraded via enzymes clled acetylcholinesterase .
- found on presynaptic/postsynaptic membrane

Question 20

Describe the two ways synaptic transmission occur in the peripheral nervous system

Answer 20

• Afferent branch
• Efferent branch