adrenal gland and stress Flashcards
what is downstream of the hypothalamic and anterior pituitary stimuolation
adrenal gland
embryonic orgins of the edulla and the adrenal cortex
they have different embryonic origins
medulla arises from neural ectoderm. modified sympathetic ganglion
the cortex arises from mesoderm
how does nerual tissue get encased by mesoderm
during fetal developemnt, the cortex engulfs the medulla
what are cortisol and androgens secreted by
fasiculata and retucularis zones ZFR
what are adrenal cortex hormones and what are they derived from
steroids derived from cholestrol (dietary source or de novo synthesis)
how is cholestrol transported in the blood
as LDL- low density lipoprotein
how does LDL get inside a cell. what happens when it does
LDL surface receptors bind LDL which is endocytosed by a cell to provide cholestrol and then it is modified by enzymatic action by a different set of enzymes in each zone
what happens at the target cells of the body of adrenal cortex hormones
androgens bind to androgen receptors
cortisol binds to gycocorticoid receptors
aldosterone binds the mineralocorticoid receptor
SCC
side chain cleavage
what is the SCC induced by
angiotensin II which is a peptide hormone or elevated K in the outer zone ZG
ACTH in the middle and inner zones ZF, ZR
which regulate the amount of adrenal cortex hormone produced
what does ACTH do in all 3 zones
stimulates and miantains cellular growth bc it is a trophic hormone
-too much ACTH= hypertrophy and too little= atrophy
it also upregulates LDL receptors
how much andorgen is produced in men in differnent places
adrenal cortex produces an indisgnificant amount of androgens compared to the testes
how much androgens is produced in women and where
adrenal cortex produces a significant source
what actions do androgens have
anabolic actions- muscle building
stanozolol
dihydrotestosterone derivative
cortisol
catabolic steroid
biological effects of cortisol
- carb, protein and fat intermediary metabolism
- protects during acute stress
- anti imflamatory and immunosupressive
- premissive actions for other hormones
metabolic effects of cortisol
raises blood glucose
-stimulates liver gluconeogenesis and inhibits glucose uptake
raises blood amino acid level by incrasing muscle catabolism
raises blood fatty acid level by stimulating lipid breakdown in fat cells
cortisol protection during acute stress
stress stimulates CRH/ACTH/cortisol secretion
metabolic actions increase raw materials needed to respond to stress
anti inflamatory and immunosupressive effects of cortisol
limits immune responses
supresses all steps in inflamation
destroys lymphocytes and reduces antibody production
effects are evident at high pharmacological levels
what inhibits CRH, ACTH, and endogenous cotrisol secreiton
exogenous corticosteroids
cortisols permissive actions and example
in the absence of it, many other homrones are less effective
ex, its necessary for epinepherine and norepenepherine to adequately constrict blood vessels. without cortisol hemmorage is more likely to be lethal
cushings syndrome
disorder of adrenocortical fucntion
cortisol hypersecretion bc of
excess CRH/ ACTH production from hypothalamus or anterior piruitary respectivelly
ACTH secreting tumors that arise elsewhere in the body such as the lung
adrenal cortex tumors that secrete cortisol independantyl from ACTH control
symptoms of cushings
high blood glucose, and protein catabolism used for gluconeogenesis, fat redistribuition to the thorax and abdomen and facial edema or moon face
adrenogenetal syndrome
sex steroid hypersecretion most often andorgenic hypersecretion and rarely estrogenic hypersecretion
how is steroid production connected to ACTH control
it is independant
symptoms of androgenital syndrome
depend on timing of excess secretion
if newborn F, undergo sex reversal
mature F, undergo masculanization (hirtuism)
young M, undergo prevovious puberty
adrenocortical insufficiency/ addisons disease
has two insuficciencies;
- adrenal cortex destroyed by autoimmune action= aldosterone and cortisol deficiency is life threatening.
gonads contribute to sex steroid production - lack of adrenal hormone production due to reduced hormone production at level of hypothalamus or anteroir pituitary
what is the adrenal medulla
modified component of the sympathetic nervous system SNS
NORE
norepinepherine= noradrenaline
E
epinephrine= adrenaline
synthesis of catecholamines
tyrosine to DOPA to dopamine to nore to e
Happens in adrenal medulla
what is the main nore or e
epinephrine and adrenaline- 80%
bioactivity of catecholamine
not essential but important in stess response by supporting and adding to widespread of the sympathetic response.
where are receptors for catacholamines found
in most cells and some are not innervated by SNS
fight or flight response
inc O2 delivery to skeletal muscle and heart
-inc heart rate and contractility
-dialation of coronary and skeletal mmuscle blood vessels and constriction of others
-relaxation of smooth muscle in airways
inc metabolic fules of glucose and fatty acids
reduced digestion and excretion
-relaxation of bladder and GI tract
-constriction of bladder and intestinal sphincters
what does epinephrine do in fight or flight
-relaxation of smooth muscle in airways
-inc metabolic fules of glucose
-relaxation of bladder (decreased urination) and GI tract
what are some other responses to stress
inc secretion of cortisol, ADH, aldosterone, glucagon from pancrease and GH all coordinateed by hypothalamus and anterior pituitary or SNS
role of cortisol during the stress response
inc metabolic fuels of glucose, FA and AA
permissive for catecholamine stimulated casoconstriction
induces enzyme for production of epinephrine
role of ADH and aldosterone during stress
retention of sodium and water to protect ECF and blood volume and important during hevy swearing and in case of blood loss
role of glucagon during stress
opposes effect of insulin to inc blood glucose concentration
what exhibits the phenomemon of synergism
glucagon, epinepherine and cortisol. a
combined effects to raise glucose levels are greater than the additive
results of prolonged stress
hypertension
hyperglycemia
hyperlipidemia
inc infections and allergies
insomnia
headaches
depression
learning and memory problems
direction of blood flow in adrenal cortex
from the outer capsule to the inner medulla
what is the starting point for production of male and female homrones
DHEA
how does ACTH corerlate to all 3 zones in the adrenal cortex
it is trophic for all three
hypertrophy leads to overproduction of homrons
hypotrophy leads to underproduction of homrones
catecholaimes
epinephrine and norepinephrine
