Adrenal Medulla: Catecholamines and Adrenergic Receptors

Question 1

True or False
The Adrenal medulla is part of the autonomic nervous system which is composed of sympathetic and parasympathetic systems

Answer 1

True

Question 2

Sympathetic

Answer 2

preganglionic nerves exit the central nervous system via the thoracic and lumbar spinal nerves
- secrete norepinephrine as neurotransmitter at synaptic junctions

Question 3

Parasympathetic

Answer 3

Preganglionic nerves exit the central nervous system by the cranial nerves and sacral spinal nerves

Question 4

Adrenal Medulla

Answer 4

lack axons and secrete their neurotransmitter (epinephrine) directly into the blood)
- Blood acts as synapse carrying epinephrine to receptors throughout the body

Question 5

Adrenal Medulla is under the control of ….

Answer 5

Autonomic sympathetic system

Question 6

Chromaffin cells

Answer 6

• produce EPI and NEP
• released into the blood (acts as a synapse but instead of a post ganglionic neuron)

Question 7

Catecholamine Biosynthesis

Answer 7

Tyrosine
Dopamine
Norepinephrine
(PNMT) –> epinephrine

Question 8

Tyrosine, Dopamine, Norepinephrine happen …

Answer 8

Outside the Adrenal medulla b/c post ganglionic neurons&raquo_space; produce catecholamine

Question 9

Local Cortisol

Answer 9

• diffused cortisol into the medulla stimulating PNMT to produce epinephrine from norepinephrine

Question 10

PNMT

Answer 10

Limiting step for the conversion of norepinephrine into Epinephrine

Question 11

Epinephrine: 80-85% of the catecholamine secreted by the …

Answer 11

adrenal medullar cells
- cells bathed by blood coming from the adrenal cortex

Question 12

Norepinephrine 15-20& of most NE in circulation originates from

Answer 12

leakages of adrenergic neurons

Question 13

Catecholamines originate from 2 sources

Answer 13

Chromaffin cells and sympathetic neurons

Question 14

primary source of circulating norepinephrine is

Answer 14

spillover from sympathetic nerves innervating blood vessels

Question 15

high sympathetic nerve activation

Answer 15

small amount of norepinephrine that is diffused into the blood and circulates throughout the body increases dramatically

Question 16

Common stimuli for catecholamine release

Answer 16

• exercise
• hypoglycemia
• hypotension
• hypoxia
• hemorrhage
• heart failure
• exposure to cold
• pain
• emotional distress

Question 17

Actions of catecholamines

Answer 17

Flight or flight response
- fast response mediated by nervous reflex
- epinephrine release from the adrenal medulla
- norepinephrine release in adrenergic synapse

Question 18

EPI (fight or flight response)

Answer 18

• breakdown of hepatic glycogen (stored glu)
• increase heart rate (chronotropic effect)
• increase stroke volume (strength of heart contraction- inotropic effect)
• increase peripheral vasoconstriction
• increase blood pressure
• dilation of coronary arteries & dilation of muscle vessels

Question 19

Epinephrine and Norepinephrine in the bloodstream has a

Answer 19

improves response

Question 20

EPI in the adipose tissue in response to hypoglycemia

Answer 20

EPI (in the bloodstream) binds to receptor on adipocyte to stimulate (HSL), which breaks down triglycerides into FA and glycerol
FFA and glycerol in the blood are taken up bby hepatocyte where FFA are made into ketones and Glycerol is broken down to glucose by (PEPCK and G-6-P) and input of cortisol