Adrenal medulla Flashcards
ß2 target tissues
vascular smooth muscle of
SKELETAL Muscle
GI tract, wall
Bladder, wall Bronchioles
catecholamine storage
storage vesicles of chromaffin cells
Conversion of Tyr to DOPA takes place in —— and is regulated by——.
Cytosol ( TYR → DOPA).
ACh released from preganglionic sysmpathetic neurons (nicotinic receptor).
ß1 target tissues
Heart
Salivary glands
adipose tissue
kidneys
Control the stimulation of catecholamine release
hypothalamus and the brain stem
À receptors are more sensitive to (EPi or NE)
Norepinephrine (NE)
ANEEE
a2 mechanism of action
Inhibition of adenylyl cyclase, dec. cAMP
Compate the effects of medullary hormones vs NTs
medullary hormones- Global
NT’s - Local
COMT and it’s function
Catechol-O-methyl transfrase – inactivates catecholamines
Adrenal medulla action during an exercise:
How simoultaneously increase CO and bld flow to skeletal muscle:
B2 adrenergic receptors of skeletal muscle vasculature is coupled to AC which cause an inc. cAMP.
In cardiac muscle, an inc. in cAMP, inhibits phosphorylation of MLC (myosin light chain).
The combination of the two results in an increase in O2 availibility. (B2 is also a bronchiodialator)
Stimulates NE ⇒ Epi
Cortisol (adrenal cortex)
The modulator of the following synthetic step (catecholamine synthesis):
NE –> Epi
Cortisol released by adrenal cortex
The adrenergic receptor(s) with higer affinity for NE (NE>E):
All the ones + B3
a1, B1
what are the cells capable of storing catecholamines:
catecholamine cells
80% release NE
20% Epi
à1 target tissues
vascular smooth muscle skin renal, splanchnic, GI tract SPINCTERS bladder, sphincters radial muscles, iris
cells responsible for synthesis and release of catecholamines
chromaffin- adrenal medula
Adrenal medulla action on
1- veind and lymphatics
2- skeletal muscle arterioles
3- splanchnic arterioles
1- veins and lymphatic-
à vasocistriction ⇒ inc. venus return
2- skeletal muscle arterioles-
ß2 vasodialation ⇒ inc. blood flow
3- Splanchnic arterioles
à vasoconstriction ⇒ red. blood flow to GI
ß receptors are more sensitive to (Epi or NE).
EPI BEEPEE
Parent compound of catecholamines:
Tyr
Hormonal reinforcement of adrenal medulla during exercise
1- ß cells- à2 Receptors.
2- à cells- ß2 Receptors.
1- dec. insulin
2- inc glucagon
physiological effect of medullary hormones
Global
Inc, HR and contractile force
Skeletal mucles blood vessels DIALATED
blood vessel constriction
Bronciole dialation
lipolysis stimulation
Inc metabolic rate-
Increase O2 consumption and heat production
breakdown glycogen in skeletal muscle
pupil dialation
Cortex secrets steroids, while medulla secret ——
catecholamines- epinephrine, norepinephrine
à2 target tissues
GI tract, wall
How the followings are acheived by adrenal medula during exercise in order to conserve energy:
Inc Blood glusoce
Inc Blood ketone bodies (KB)
Inc Blood FFA
Inc Blood Lactate
Inc Blood Glycerol
GI and urinary tracts - B2- dec motility Adipose- B2-B3- inc lipolysis- dec. glucose uptake liver B2- Increased ( glycogenolysis, gluconeogenesis, and ketogenesis) Skeletal muscle B2- inc glycogenolysis, decreased Glucose uptake
The recptor with equal affinity for E and NE (E=NE)
a2
mechanism of action inhibition of AC (The only inhibitory)
Catecholamine
a- transport
b- inactivation
c- excretion
a- transported in blood: FREE or SULFATE conj with short half life
b- Inactivation-
- target tissue uptake,
- MAO
- COMT inactive metabolites
c- Excrete in urine
Rate determining step of catecholamine synthesis
dopa conversion to norepinephrine (NE)
DOPA → NE
Both postganglionic sympathetic neurons and chromaffin cells are derived from:
neuronal crest
The main regulator of the catecholamine synthesis and release:
Hypothalamus and brain stem
The adrenergic receptor with higher affinity for E ( E>NE):
B2
B (1 and 2) adrenergic mechanism of action
Stimulation of AC, Inc. cAMP
ACh released from preganglionic sysmpathetic neurons (nicotinic receptor) modulates these two synthetic steps of catecholamine synthesis:
Tyrosine –> XDopa
Dopa –> NE
What are the stimuli for catecholamine release:
What is the mechanism of release:
Stress is the stimuli for release (catecholamines are stress hormones)
Mode of release: exocytosis
Stimuli for catecholamine release and its mechanism
Stress as stimuli- stimulation - ACh binding to nicotinic receptors
Mechanism: exocytosis
