Neurotransmitters

Question 1

About how many neurotransmitters are in the body?

Answer 1

100 chemical substances.

Question 2

What are the 2 classes of neurotransmitters?

Answer 2

1. Small molecules.
2. Neuropeptides.

Question 3

What are the characteristics of small molecules?

Answer 3

1. Rapid acting.
2. Acute responses of the nervous system.
   ex: ACH, Dopamine.

Question 4

What are the characteristics of neuropeptide molecules?

Answer 4

Slow/prolonged acting.
ex: CCK, GnRH.

Question 5

Where are small molecules synthesized?

Answer 5

In the cytosol of presynaptic neurons.

Question 6

What are small molecules absorbed by?

Answer 6

Active transport into vesicles.

Question 7

What effect do small molecules normally have on post-synaptic neurons?

Answer 7

Increase or decrease conductance through ion channels.

Question 8

What are the 2 types of neurons?

Answer 8

1. Adrenergic.
2. Cholinergic.

Question 9

What 3 places are cholinergic neurons found?

Answer 9

1. Sympathetic and parasympathetic preganglionic.
2. Sympathetic postganglionic neurons that innervate sweat glands.
3. All postganglionic parasympathetic glands.

Question 10

What type of neurons secrete acetylcholine?

Answer 10

Cholinergic neurons.

Question 11

What type of neuron are most postganglionic sympathetic neurons?

Answer 11

Adrenergic.

Question 12

What are the 2 groups of neurons on the autonomic motor pathway?

Answer 12

1. Preganglionic.
2. Postganglionic.

Question 13

Where are the cell bodies of preganglionic neurons?

Answer 13

In the brain or spinal cord.

Question 14

How do the axons of preganglionic nerves exits the CNS?

Answer 14

Via cranial and spinal nerves.

Question 15

What type of fibers compose preganglionic neurons?

Answer 15

Type B fibers.

Question 16

Where to the synaptic end buttons of preganglionic neurons end?

Answer 16

Autonomic ganglia.

Question 17

Where are the cell bodies of postganglionic neurons?

Answer 17

In the autonomic ganglion.

Question 18

How many preganglionic axons is a postganglionic neuron cell body synapsing with?

Answer 18

1 or more.

Question 19

What type of fibers compose postganglionic axons?

Answer 19

Type C fibers.

Question 20

Where do the synaptic end bulbs of postganglionic neurons terminate?

Answer 20

In the visceral effector.

Question 21

Where does the sympathetic division of the ANS originate?

Answer 21

The 12 thoracic segments and first 3 lumbar spinal segments.
*Thoracolumbar division.

Question 22

Where does the parasympathetic division of the ANS originate?

Answer 22

The 4 cranial nerves and sacral segments 2-4.
*Craniosacral division.

Question 23

What are the two types of cholinergic receptors?

Answer 23

1. Nicotinic.
2. Muscarinic.

Question 24

Where are nicotinic receptors found?

Answer 24

1. Dendrites and cell bodies of the sympathetic and parasympathetic postganglionic neurons.
2. Motor end plate at neuromuscular junction.

Question 25

What substance mimics the action of Ach by binding these receptors?

Answer 25

Nicotine.

Question 26

Where are muscarinic receptors found?

Answer 26

1. Effectors innervated by parasympathetic postganglionic neurons. 2. Sweat glands.

Question 27

What poison mimics the action of Ach binding?

Answer 27

Muscarine, a mushroom poison.

Question 28

Are nicotinic receptors used for activation, inhibition, or both?

Answer 28

Activation.

Question 29

What kind of action do nicotinic receptors stimulate in the nerve fiber?

Answer 29

Depolarization through increased Na+ permeability that leads to excitation of the postsynaptic cell.

Question 30

Are muscarinic receptors used for activation, inhibition, or both?

Answer 30

Both.

Question 31

What is an example of an excitatory muscarinic receptor?

Answer 31

Smooth, circular muscles of the iris to contract due to decreased K+ conductance.

Question 32

What is an example of an inhibitory muscarinic receptor?

Answer 32

Inhibits/relaxes smooth muscles of GIT sphincters through increased K+ conductance.

Question 33

Where is Ach synthesized?

Answer 33

In the presynaptic terminal.

Question 34

What is Ach a combination of?

Answer 34

Acetyl-CoA and Choline.

Question 35

What enzyme is key in the synthesis of Ach?

Answer 35

Choline acetyltransferase.

Question 36

Where is norepinephrine released from?

Answer 36

Adrenergic neurons.

Question 37

Where is norepinephrine synthesized and stored?

Answer 37

In synaptic vesicles.

Question 38

What 2 neurotransmitters bind to adrenergic receptors?

Answer 38

1. Epinephrine. 2. Norepinephrine. *Are both also hormones when released from the adrenal medulla.

Question 39

What are the two main types of adrenergic receptors?

Answer 39

1. a. 2. B.

Question 40

Where are adrenergic receptors found?

Answer 40

On visceral effectors.

Question 41

What do a1 receptors stimulate?

Answer 41

Ca2+ release.

Question 42

What do a2 receptors stimulate?

Answer 42

Decreased cAMP.

Question 43

What do B1 and B2 receptors stimulate?

Answer 43

Increased cAMP.

Question 44

Which type of receptor is stimulated more strongly by norepinephrine?

Answer 44

Alpha receptors.

Question 45

What terminates norepinephrine activity?

Answer 45

1. Reuptake by the axon that released it. 2. Catechol-O-methyltransferase or Monoamine oxidase enzymatically degrades it.

Question 46

What type of receptor is stimulated more strongly by epinephrine?

Answer 46

Both alpha and beta receptors are strongly stimulated.