pituitary adrenal axis Flashcards
what class of hormone is cortisol
glucocorticoid
where is cortisol synthesised
in the zona fasciculata of the adrenal cortex
What stimulates cortisol production?
ACTH released from the pituitary gland
what hormone class is aldosterone
mineralocorticoid
what is the primary product of chromatin cells in the medulla
epinephrine
where are androgens synthesised
zona reticularis
where are mineralocorticoids synthesised
zona glomerulosa
when hormones are released into the cortex where do they go
flow down into medulla vein
what is the difference in short-term and long-term stress response to adrenal medulla
in short-term the adrenal medulla releases epi and norepi
in long-term the adrenal medulla releases glucocorticoids and mineralocorticoids
effects of mineralocorticoids
retention of Na and water by kidneys
increased blood volume and pressure
effects of glucocorticoids
proteins and fats broken down into glucose => increased blood glucose
suppression of immune system
anti-inflammatory
what are all steroid hormones derived from
cholesterol
where is ACTH produced
anterior pituitary
How is ACTH release regulated by the hypothalamus?
The hypothalamus releases CRH which stimulates the anterior pituitary to secrete ACTH
How does negative feedback regulate ACTH release?
Cortisol exerts negative feedback on both the hypothalamus and the anterior pituitary, inhibiting the release of CRH and ACTH when cortisol levels are high.
How does ACTH stimulate cortisol production?
ACTH activates the MC2R on adrenal cells, which triggers the production of cAMP, leading to activation of enzymes involved in cortisol biosynthesis.
what transports cortisol
Corticosteroid binding globulin
where are the enzymes that produce steroid hormones from cholesterol located
mitochondria and SeER
How does cortisol affect the liver?
stimulates gluconeogenesis
What is cortisol’s effect on muscle tissue?
protein catabolism
How does cortisol act on adipose tissue?
stimulates lipolysis
How does cortisol exert its effects at the cellular level?
Cortisol binds to intracellular glucocorticoid receptors (GR), which then translocate to the nucleus and regulate the expression of specific genes
What happens after cortisol binds to its receptor?
The cortisol-receptor complex binds to glucocorticoid response elements (GREs) in the DNA, either enhancing or repressing transcription of target genes.
What is cortisol excess, and what condition is it associated with?
associated with Cushing’s syndrome, where the body produces or is exposed to abnormally high levels of cortisol.
What is cortisol deficiency, and what condition is it associated with?
linked to Addison’s disease, where the adrenal glands fail to produce adequate cortisol, leading to a range of symptoms.
What are the main causes of Cushing’s syndrome?
Exogenous administration of glucocorticoids
Endogenous causes such as pituitary adenomas
What are the main causes of Addison’s disease?
autoimmune disease where adrenal cortex attacking antibodies destruct cortex
What metabolic effects are seen in Cushing’s syndrome?
hyperglycaemia
symptoms of crushing syndrome
moon face
weight gain
hypertension
osteoporosis
symptoms of addisons disease
fatigue
weight loss
hypotension
hypoglycaemia
what does aldosterone promote
Na retention and K excretion
what does prolonged use of glucocorticoids cause
irreversible atrophy of cortisol secreting cells
body can no longer produce its own cortisol
explain the pituitary adrenal axis leading to insulin secretion
corticotropin releasing hormone (CRH) from hypothalamus stimulates adrenocorticotropic hormone (ACTH) from anterior pituitary
this targets the adrenal cortex (zona fassiculata) to secrete cortisol
when are cortisol levels highest
morning
when might the activity of CRH-ACTH-cotrisol system be enhanced
during stress
what role does DHEA have in females
regulates androgen dependent process such as growth of pubic and axillary hair enhancement of pubical growth
what controls androgen secretion?
what does DHEA inhibit
ACTH
gonadotropin releasing hormone
what is conns syndrome
hyper secreting adrenal tumour made of aldosterone secreting cells
hyper secretion of aldosterone causes
excessive Na retention (hypernatermia)
hypokalaemia
hypertension
what causes the main symptoms in Cushing syndrome
excessive gluconeogenesis
too many amino acids converted into glucose
what does adrenal androgen hyper secretion cause
adrenogenital syndrome
in females causes masculin characteristics
in newborn females causes male external genitalia to form
where are catecholamines stored and how are they release
stored in chromaffin cells and secreted into blood by exocytosis
describe the stress response in relation to catecholamines
hypothalamus stimulates sympathetic nervous system to stimulate epinephrine release from chromaffin cells in adrenal medulla
the sympathetic nervous system can also cause vasoconstriction
