Lecture 17

Question 1

Which are the three main parts of the autonomic nervous system (ANS)

Answer 1

Sympathetic, Parasympatheic, and Enteric

Question 2

Which part of the ANS is the “rest and digest” branch?

Answer 2

Parasympathetic

Question 3

Why is the rest and digest branch also described as “craniosacral”?

Answer 3

Because the cell bodies of the preganglionic nerve fibers are located in the brain stem and the sacral portion of the spinal cord.

Question 4

Where are the postganglionic fibers located in the parasympathetic nervous system?

Answer 4

In the wall of the target organ.

Question 5

Name 5 examples of organs innervated by the parasympathetic NS?

Answer 5

Heart, lungs, small intestine, stomach, kidneys

Question 6

Which part of the ANS is the “fight or flight” branch?

Answer 6

Sympathetic

Question 7

Anatomically, how can the “fight or flight” branch also be described?

Answer 7

Thoracolumbar

Question 8

Name 5 organs innervated by the sympathetic nervous system

Answer 8

Adrenal gland, pancreas, heart, lungs, liver

Question 9

Where are the preganglionic and postganglionic cell bodies of the sympathetic NS located?

Answer 9

Preganglionic: in the lateral horn of the thoracolumbar spinal cord.
Postganglionic: cell bodies are located in the ganglia of the sympathetic chain that runs parallel to the spinal cord. They are also located in the celiac ganglia and hypogastic ganglia.

Question 10

What are the two main parts of the enteric nervous system?

Answer 10

Myenteric plexus and submucosal plexus

Question 11

What si the function of the Myenteric (Auerbach’s) plexus?

Answer 11

Muscle tone, rhythmic contraction, peristaltic movements of the GI tract

Question 12

What is the function of the Submucosal (Meissner’s) plexus?

Answer 12

Secretion, Absorption, localized contractions

Question 13

What is the main neurotransmitter in the enteric NS?

Answer 13

Seratonin

Question 14

What is the neurotransmitter in all preganglionic neurons of the ANS?

Answer 14

Acetycholine

Question 15

Which receptor activates all postganglionic neurons?

Answer 15

Nicotinic Acetycholine Receptor

Question 16

Which neurotransmitter is used in postganglionic neurons of the parasympathetic nervous system?

Answer 16

Acetycholine

Question 17

What kind of neurotransmitter receptors are found on target tissues of the parasympathetic nervous system?

Answer 17

Muscarinic acetycholine receptors

Question 18

How are the receptors of the parasympathetic nervous system target tissues numbered and what does it tell you?

Answer 18

M1, M2, M3, M4, M5
Odd-numbers muscarinic receptors are excitatory and are located in M1: neuronal; M3: glands and smooth muscle
Even-numbered are inhibitory and M2 is located in cardiac muscles.

Question 19

In contrast to the parasympathetic nervous system, what is the neurotransmitter used by postganglionic neurons of the sympathetic nervous system?

Answer 19

Norepinephrine

Question 20

Name the neurotransmitter receptors on sympathetic nervous system target tissues, and what is one exception?

Answer 20

Adrenergic receptors (Alpha 1, alpha 2, beta 1 and beta 2). 
The exception is sweat glands which have mACHR and are stimulated by acetycholine rather than norepinephrine.

Question 21

Which receptors does epinephrine activate and what are its effects in target tissues?

Answer 21

Epinephrine non-selectively activates adrenergic receptors but the beta-2 receptors on postganglionic neurons/cells are selective for EPI.
It’s effects on target tissues are: increased cardiac output, dilate bronchi, constrict blood vessels to skin and viscera, dilate blood vessels to skeletal muscles, increase fatty-acid mobilization, increase glycogenolysis in liver, increase release of ACTH and TSH, and decrease intestinal motility. It will also relax bladder muscles and constrict bladdder sphincter.

Question 22

What are “NANCs”?

Answer 22

They are non-adrenergic, non-cholinergic transmitters that can be released by the ANS.
Examples: Serotonin, ATP, and nitric oxide (NO)

Question 23

Which body functions are controlled by the ANS?

Answer 23

All homeostatic body functions.

Question 24

What are examples of the opposing effects of the sympathetic and parasympathetic nervous systems?

Answer 24

Bladder: PNS constricts bladder muscles and relaxes urinary sphincter. SNS has the opposite effects.
Bronchi: SNS dilates bronchi, PNS constricts bronchi
Intestines: SNS decreases intestinal motility, PNS increases it.

Question 25

Which end-organs are only predominatly affected by one branch of the ANS?

Answer 25

Adrenal glands are predominatly affected by the sympathetic nervous system. Blood vessels only have sympathetic innervation, however they do contain cholinergic receptors.

Question 26

Why/how are blood vessels an exception with regard to ANS control?

Answer 26

They are only innervated by the sympathetic nervous system, however, blood vessels have cholinergic receptors and can respond to ACh.

Question 27

Provide an example for an end-organ that responds to the PNS and SNS in the same way.

Answer 27

Salivary glands produce saliva regardless of PNS or SNS stimulation.

Question 28

What is the neurotransmitter used by motor neurons (somatic efferent nervous system)?

Answer 28

Motor neurons use acetylcholine (via muscle type nACHR)