Ch 60 ANS and Adrenal Medulla

Question 1

Briefly, what is the pathway of SNS nerves to the adrenal medulla?

Answer 1

preganglionic sns fibers go without synapsing from the intermediolateral horn cells of the SC, through sympathetic chains, through splanchnic nerves, to the modified neuronal cells secreting epi/norepi into the blood

Question 2

What are the two main SNS abdominal ganglia?

Answer 2

Celiac and hypogastric

Question 3

Which structures have cholinergic postganglionic SNS fibers? (the exceptions)

Answer 3

Sweat glands, piloerector muscles, and a few blood vessels

Question 4

What is secreted by all preganglionic nerve fibers?

Answer 4

Acetylcholine

Question 5

Where are the transmitter vesicles of acetylcholine or norepinephrine synthesized and stored?

Answer 5

The variscosities of many PSNS and all SNS fibers

Question 6

Which ion causes terminals to release their neurotransmitters?

Answer 6

Calcium diffusion into nerve terminal or variscosities

Question 7

How is acetylcholine synthesized and destroyed, and how long does it last?

Answer 7

Made when choline acetyl-transferase catalyzes the combination of acetyl-coA and choline. It persists a few seconds. Then it’s split into acetate and choline by acetylcholinesterase in local connective tissue

Question 8

Briefly, how is norepinephrine synthesized?

Answer 8

Starts in adrenergic nerve terminal endings, and completes in secretory vesicles.
Tyrosine –> Dopa. Dopa –> dopamine.
Dopamine is transported to the vesicles, and then hydroxlyated to NorEpi. Some norepi is methylated into epi

Question 9

By which 3 ways is norEpi removed from the secretory site?

Answer 9

1. Active transport to reuptake into nerve terminals (predominant)
2. Diffusion away
3. Destruction by monoamine oxidase or catechol-o-methly transferase

Question 10

How long is norepi or epi active?

Answer 10

10 to 30 seconds. takes minutes to ‘fade away’

Question 11

Where are muscarinic vs nicotinic receptors found in the body?

Answer 11

Muscarinic: on all effector cells stimulated by postganglionic cholinergic neurons
Nicotinic: At the autonomic ganglia at synapses between pre and postganglionic neurons, or at neuromuscular junctions

*in both PSNS and SNS

Question 12

Stimulation of adrenergic Beta2 receptors results in ______

Answer 12

Vasodilation (including coronaries), intestinal relaxation, uterus relaxation, bronchodilation, calorigenesis, glycogenolysis, and bladder wall relaxation

Question 13

Stimulation of adrenergic Beta1 receptors results in ______

Answer 13

Cardioacceleration, increased myocardial strength, lipolysis

Question 14

Stimulation of adrenergic Beta3 receptors results in ______

Answer 14

thermogenesis

Question 15

Stimulation of adrenergic alpha receptors results in ______…and which is specifically alpha2?

Answer 15

Vasoconstriction, iris dilation, intestinal relaxation, intestinal sphincter contraction, pilomotor contraction, bladder sphincter contraction, and
alpha 2 = inhibiting neurotransmitter release

Question 16

How does SNS stimulation dictate changes in systemic arterioles?

Answer 16

adrenergic alpha: constrict in the muscle
Adren B2 and cholinergic: dilate muscle vessels
Constricts abdominal visceral vessels

Question 17

How do the effects of epinephrine and norepinephrine on blood pressure differ?

Answer 17

Norepinephrine: increases TPR and elevates arterial pressure.
Epinephrine: raises arterial pressure to a lesser extent but increases cardiac output

Question 18

Briefly, what are the three main differences between epinephrine and norepinephrine?

Answer 18

1. Epi stimulates beta receptors more strongly
2. Norepinephrine has a stronger effect on blood vessel constriction
3. Epi has 5-10x the metabolic effect as norepi

Question 19

How does the PSNS vs SNS control the pupillary opening?

Answer 19

SNS: contracts meridonal fibers of the iris to dilate the pupil
PSNS: contracts the circular muscle of the iris to constrict the pupil

Question 20

How does the SNS vs PSNS control the shape of the lens?

Answer 20

PSNS: contracts the ciliary muscle to release tension on the ligaments and allow the lens to become convex, so the eye focuses on objects near at hand
SNS: Slight relaxation of the ciliary muscle to flatten the lens further and see far objects more clearly

Question 21

What is meant by SNS or PSNS “tone”? What is its purpose

Answer 21

Tone allows a single nervous system to both increase and decrease the activity of a stimulated organ … so a decrease OR increase in activity of the SNS or PSNS can enact a change.

Question 22

What is denervation supersensitivity?

Answer 22

An enhanced reaction of an organ or tissue to hormonal stimulation after the organ has been denervated, to enable that organ/tissue to respond to SNS or PSNS stimulation. Thought to occur due to receptor upregulation in the postsynaptic membrane

Question 23

Briefly, what is the baroreceptor reflex?

Answer 23

When stretch receptors located in the walls of the internal carotid arteries and the aortic arch are stretched by high pressure, signals transmit to the brainstem to inhibit SNS impulses to the heart and blood vessels and excite the PSNS.
Result: arterial pressure falls (normalize)

Question 24

What is mass discharge? How does this occur?

Answer 24

When large portions of the SNS discharge at the same time.
1. Increased arterial pressure
2. Increased blood flow to active muscles and decreased to abdominal viscera
3. Increased cellular metabolic rate
4. Increased blood glucose [ ]
5. Increased glycolysis
6. Increased muscle strength
7. Increased mental activity
8. Increased rate of blood coagulation

Question 25

Which receptors do the following drugs stimulate?
Phenylephrine, albuterol, isoproterenol?

Answer 25

Phenylephrine: alpha
Albuterol: Beta2
Isoproterenol: beta

Question 26

What do ephedrine, tyramine, and amphetamine have in common?

Answer 26

They all cause the release of NorEpi from storage vesicles in the SNS nerve endings

Question 27

What receptors do methacholine and pilocarpine act upon?

Answer 27

muscarinic cholinergic receptors

Question 28

What do neostigmine, pyridostigmine, and ambenonium have in common?

Answer 28

They all inhibit acetylcholinesterase to potentiate the effect of acetylcholine at the NMJ

Question 29

What do atropine, homatropine, and scopolamine have in common?

Answer 29

They block the action of acetylcholine at the muscarinic type of cholinergic effector organs