Lecture 15- Autonomic Nervous System

Question 1

What are the 3 divisions of the autonomic nervous system?

Answer 1

parasympathetic
sympathetic
enteric

Question 2

What are the two parts of the peripheral nervous system?

Answer 2

Autonomic

Somatic

Question 3

What are three differences between the autonomic and somatic nervous system?

Answer 3

Autonomic

• 2 neurons b/t CNS and effector organ
• innervates smooth, cardiac muscle and glands
• either excitatory or inhibitory

Somatic

• single neuron between CNS and skeletal muscle
• innervates skeletal muscle
• leads only to muscle contraction

Question 4

What levels do the preganglionic sympathetic fibers exit the spinal cord?

Answer 4

T1-L3- thoracolumbar

Question 5

Where are the cell bodies of the preganglionic sympathetic neurons found?

Answer 5

Intermediolateral column of the thoracic and upper lumbar spinal cord

Question 6

Where are the cell bodies of the preganglionic parasympathetic neurons found?

Answer 6

brainstem and s2-4

Question 7

Where do the preganglionic sympathetic neurons project to?

Answer 7

the sympathetic chain and prevertebral ganglia before projecting to their targets

Question 8

Where are the cell bodies of the postganglionic parasympathetic neurons found?

Answer 8

in the walls of the target organs or in ganglia very close

Question 9

Which cranial nerves carry parasympathetic fibers?

Answer 9

3, 7, 9, 10

III, VII, IX, X

Occulomotor, Facial, Glossopharyngeal

Question 10

Where do the preganglionic fibers of the oculomotor nerve (CN III) project?

Answer 10

ciiary ganglion

Question 11

Where do the preganglionic fibers of the facial nerver (CN VII) project?

Answer 11

PPG/submaxillary (submandibular) ganglion

Question 12

Where do the preganglionic fibers of the glossopharyngeal (CN IX) project?

Answer 12

otic ganglia

Question 13

Where do the preganglionic fibers from the vagus (CN X) project?

Answer 13

innervate viscera in thoracic and abdominal cavities

Question 14

Where do preganglionic fibers from S2-4 project?

Answer 14

pelvic viscera such as the colon bladder and genitalia

Question 15

Which 3 organs have only sympathetic innervation compared to most organs that receive dual innervation from both sympathetic and parasympathetic systems?

Answer 15

• sweat glands
• adrenal medulla
• peripheral blood vessels

Question 16

What are the two most important neurotransmitters in the autonomic nervous system?

Answer 16

Acetylcholine

Norepinephrine

Question 17

What neurotransmitters is released by neurons in the somatic nervous system to innervate skeletal muscle? What receptor do they bind to on the skeletal muscle?

Answer 17

Acetylcholine

Binds to N1 receptors

Question 18

Where are N1 receptors found? What neurotransmitter binds to them?

Answer 18

found on skeletal muscle

acetylcholine binds to them

Question 19

What does curare block?

Answer 19

N1 receptors on skeletal muscle-prevents acetylcholine binding thus inhibiting muscle contraction

Question 20

What substance blocks N1 receptors on skeletal muscle?

Answer 20

curare

Question 21

What neurotransmitter is released between preganglionic and postganglionic neurons in both the sympathetic and parasympathetic nervous systems?

Answer 21

N2 receptors- bind to acetylcholine

Question 22

Where are N2 receptors found? What substance blocks them?

Answer 22

Found on postganglionic parasympathetic and sympathetic neurons…blocked by hexamethonium

Question 23

What substance blocks N2 receptors?

Answer 23

hexamethonium

Question 24

What does hexamethonium block?

Answer 24

N2 receptors found on the postganglionic parasympathetic and sympathetic cells…blocks communication between pre and post ganglionic cells

Question 25

What type of receptors are found in the adrenal medulla?

Answer 25

N2 receptors that bind to acetylcholine

Question 26

What does the adrenal medulla secrete?

Answer 26

epinephrine (80%) | norepinephrine (20%)

Question 27

Where are muscarinc receptors found?

Answer 27

``` blood vessels smooth muscle cardiac muscle glands sweat glands ```

Question 28

What neurotransmitter stimulates muscarinic receptors?

Answer 28

acetycholine

Question 29

Which type of fibers used Ach to stimulate the muscarinic receptors on blood vessels and sweat glands?

Answer 29

sympathetic

Question 30

Which type of fibers use Ach to stimulate muscarinic receptors on smooth muscle, cardiac muscle and glands?

Answer 30

parasympathetic

Question 31

Which type of fibers use norepinephrine to stimulate smooth muscle, cardiac muscle and glands?

Answer 31

sympathetic

Question 32

What does atopine block?

Answer 32

muscarinic receptors on smooth muscle, cardiac muscle and glands that receive parasympatheic input via Ach

Question 33

What blocks the muscarinic receptors on smooth muscle, cardiac muscle and glands?

Answer 33

atropine

Question 34

The adrenal medulla receives direct input from the preganglionic nerve fibers of the ____________ nervous system via ACh binding to _____ receptors.

Answer 34

sympathetic | N2

Question 35

Which type of ACh receptors are associated with the autonomic NS? somatic NS?

Answer 35

autonomic (Para and Synm)- N2, M | somatic- N1

Question 36

Would blocking N1 receptors with curare affect skeletal muscle activity? Would it affect smooth muscle activity?

Answer 36

It would affect skeletal muscle activity but not smooth muscle because they use N2 and M receptors

Question 37

What are the 4 types of NE receptors?

Answer 37

alpha 1 and 2, beta 1 and 2

Question 38

What is the role of the alpha 1 NE receptor?

Answer 38

activation leads to contraction of smooth muscles and glands, stimulated by release of NE from postganglionic sympathetic fibers

Question 39

What is the role of the alpha 2 NE receptor?

Answer 39

autoreceptor that inhibits NE release

Question 40

What is the role of the adrenergic beta 1 receptor?

Answer 40

activation by release of NE from the postganglionic sympathetic cell causes increased heart rate and force of contraction

Question 41

What is the role of the adrenergic beta 2 receptor?

Answer 41

activation by release of NE from the postganglionic sympathetic cell causes relaxes GI tract smooth muscle

Question 42

What ANS division uses varicosties to release NT from postganglionic neurons?

Answer 42

sympathetic

Question 43

What enzyme converts dopamine to NE?

Answer 43

dopamine beta-hydroxylase (DBH)

Question 44

How is DBH (dopamine beta-hydroxylase used as a measure of sympathetic activity?

Answer 44

It is often released in vesicles from postganglionic neurons along with NE and can be used to show how much NE is being release (i.e. how much sympathetic activity)

Question 45

Which receptors on the preganglionic memebrane acts to inhibit further release of NE from preganglionic sympathetic neurons?

Answer 45

alpha-2 receptors

Question 46

What four factors regulate release of NE from varicosities on the postganglionic sympathetic neuron?

Answer 46

1. The flux of Calcium (determined by the rate of firing) 2. Amount of NE available (DBH enzyme need for synthesis) 3. Receptors of other NTs 4. Autoreceptors- alpha 2 receptors

Question 47

What enzyme breaks down NE?

Answer 47

Monoamine oxidase in mitochondria (MAO)

Question 48

What are the three mechanisms of termination of NE action?

Answer 48

1. re-uptake and MAO predown inside pre-synaptic cell 2. diffusion 3. Extra neuronal uptake and breakdown my MAO enzymes

Question 49

Which enzyme synthesizes NE? Which enzyme breaks it down?

Answer 49

synthesize- Dopamine Beta Hydroxalase (DBH) breakdown- Monoamine oxidase (MAO)

Question 50

Can somatic neurons be inhibitory?

Answer 50

no- they are only excitatory