9: Adrenal Hormones - Schmidt Flashcards
function of adrenal glands
coordinating response to short and long term stress
three stress response pathways
humoral
neuronal
renin-angiostensin pathway
activated in response to long term stress
humoral pathway –> glucocorticoids –> conserve glucose
short term stress –>
neuronal pathway –> epi and NE–> heart output, respiration and glycogen mobilization
activated by stress through elevated levels of NE –>
renin angiotensin pathway –> production of aldosterone –> increased sodium uptake and rise in blood pressure
glucocorticoids are released from
zona fasiculata
glucocorticoid levels are naturally high …
in the morning due to rhythmic pattern generated by serotonergic neurons (circadian)
CRH –> ACTH –>
ACTH binds to a Gs –> pregenolone and progesterone are generated; cortisol released into bloodstream
cortisol travels through the blood stream
bound to CBG
general effects of glucocorticoids
conservation of glucose
- inhibits glucose uptake by adipose tissue
- induced catabolism of prtns into aa that can be converted into glucose by the liver
prolonged effects of high levels of glucocorticoids
muscle waste
immunodeficiency
cell death
where is renin produced?
macula densa of kidneys
renin is necessary for angiotensinogen –> angiotensin I
Angiotensin II and angiotensin III stimulate…
aldosterone production in the andrenal cortex
ACTH provides additional stimulus for aldosterone production
overproduction of cortisol manifests as
cushings disease
caused by pituitary tumor that leads to elevated secretion of ACTH
overproduction of mineralocorticoids in cushing’s disease leads to…
- reduced potassium levels
- causes weakness
- sodium retention
- high blood pressure
underproduction of cortisol and aldosterone causes …
Addison’s disease
caused by adrenal destruction
addisonian shock
person with long-standing adrenal insufficiency is exposed to stress, leading to acute onset of addison’s disease
treatment addisonian shock
large intravenous doses of cortisol
fluid replacement and antibiotics
potential cause of adrenal hyperplasia
decreased levels of cortisol due to enzymatic gene defects –> no inhibitory feedback –> high ACTH –> adrenal cortex grows!
hormone levels of cushings v. addisons
C: high glucocorticoids and mineralocorticoids caused by high ACTH
A: low glucocorticoids and low mineralocorticoids, high ACTH and MSH due to loss of feedback
moon face, DM, thin skin, poor wound healing, etc.
cushing’s disease
pigmentation of the skin
addision’s disease
a-adrenergic receptors cause…
b-adrenegic receptors cause..
influx of calcium ions into cytoplasm
stimulate adenylate cyclase, causing rise in cytoplasmic cAMP
**effects of epi on muscle, heart, salivary glands, adipose tissue and liver
muscle - lgycolysis and glycogenolysis
heart - increases contraction force
salivary gland - amylase secretion
adipose tissue - breakdown of storage triglycerides
liver - glycogen degradation and glucose export
episodes of epi hypersecretion by pheochromocytomas –>
hypertension
zona glomeruloas –>
aldosterone
zona fasciculata –>
cortisol, DHEA
zona reticularis –>
DHEA (precursor for sex hormones)
medulla –>
epi (and NE, but mostly epi)
pregenolone and progesterone are both precursors to…
cortisol
see slide 8 for pathway
synthesis of cortisol and aldosterone are ____ and ______ pathways
parallel
linked
see slide 10
how are steroids antiinflammatory?
- synthesis of lipocrticin or annexin 1 –> inhibits production of arachidonic acid
- repression of COX –> inhibits synthesis of prostaglandins
ACTH stimulation test would be administer for what?
addison’s disease
administration of ACTH should increase cortisol, will not in addison’s
review slide 15
differences between cushings and addisons
