2.4 - Cell to Cell Communication

Question 1

How do electrical synapses occur?

Answer 1

• through gap junctions that allow direct electrical signalling between cells

Question 2

TRUE OR FALSE

Electrical synapses are slow

Answer 2

FALSE

they are fast

Question 3

Where do electrical synapses occur mainly?

Answer 3

uncommon, occur mainly in the CNS

Question 4

Where are electrical synapses important?

Answer 4

in nervous system development and transmission in adult brain

Question 5

Which neurons use chemical synapses?

Answer 5

peripheral neurons

Question 6

TRUE OR FALSE:

Chemical synapses are the majority of synapses

Answer 6

TRUE

Question 7

What is the neuroeffector junction?

Answer 7

synapse between neurons and effector cells

Question 8

What is a neuromuscular junction?

Answer 8

synapse between neuron and muscle

Question 9

List the 2 types of responses caused by neurotransmitters in the post synaptic cell

Answer 9

1. Direct response: fast synaptic potential
   - does not last long
2. Indirect response: slow synaptic potential
   - longer lasting response
   - uses G proteins, via 2nd messenger response system

Question 10

What are the major types of neurotransmitters?

Answer 10

• acetylcholine
• biogenic amines
• amino acids
• neuropeptides
• purines
• gases

Question 11

what are cholinergic neurons?

Answer 11

neurons that secrete or have receptors for ACh

Question 12

Where does the synthesis of ACh occur and how?

Answer 12

HOW:

• synthesized from choline and acetyl CoA
• catalyzed by enzyme choline acetyl transferase CAT

WHERE:
- axon terminal

Question 13

What are the 2 types of cholinergic receptors?

Answer 13

• muscarinic: coupled to G proteins = slower

- nicotinic: receptor operated channels = faster

Question 14

Biogenic amines contain an amine group (NH2). They are derived from single amino acids. Give some examples:

Answer 14

• serotonin
• histamine
• dopamine
• NE
• E

Question 15

What is the most abundant group of neurotransmitters in the CNS?

Answer 15

amino acids

Question 16

Name the 4 amino acids that function as neurotransmitters in CNS

Answer 16

• Glutamate, aspartate = released at excitatory synapses to depolarize post synaptic cell
• glycine, GABA = released at inhibitory synapses

Question 17

Purines are nucleotides that act as NTs. Where do they bind? Give some examples

Answer 17

• bind to purinergic receptors in CNS and other excitable tissues
• e.g. adenosine, AMP, ATP

Question 18

How is Nitric Oxide synthesized?

Answer 18

from O2 and arginine, catalyzed by enzyme Nitric oxide synthase

Question 19

Nitric Oxide needs the assistance of enzymes to degrade. TRUE OR FALSE?

Answer 19

false, CAN DEGRADE ON ITS OWN

Question 20

What enzyme degrades ACh from the synaptic cleft?

Answer 20

acetylcholineesterase found on presynaptic of postsynaptic membrane or both

Question 21

What happens when ACh is degraded?

Answer 21

choline is transported back into the presynaptic axon terminal to be used again

Question 22

What are the 2 principle types of neurotransmitters in the PNS?

Answer 22

• ACh

- NE and E

Question 23

the PNS is divided in what branches?

Answer 23

afferent (sensory)

efferent (motor)