Adrenal Glands Flashcards
(28 cards)
What are the functions of the adrenal cortex?
Salt and fluid volume homeostasis, adjust metabolism, immune modulation, minor sex steroids production
What is the function of the adrenal medulla?
“Fight of flight” junction between CNS and rest of tissue
Name pathway of glucocorticoid production.
Hypothalamus –> CRH –> Corticotrophic cells in Ant. Pit. –> ACTH –> Adrenal cortex –> Glucocorticoids
What is the only peptide hormone that activates the hypothalamus-adrenal axis?
CRH
What large peptide is ACTH cleaved off of?
POMC
What type of signaling pathway does CRH work through?
Gs – CAMP – PKA – synthesis of POMC mRNA
Does the adrenal cortex store pre-formed glucocorticoids and mineralocorticoids like the corticotrophic cells of the anterior pituitary?
No - the entire process of hormone (cortisol) synthesis is de novo
What molecule is the adrenal cortex rich in? (makes it yellow)
Lipid droplets that are filled with cholesterol
What is significance of cholesterol in adrenal cortex?
ACTH stimulus results in cholesterol release, which allows steroidogenic enzymes to be translated and sent to mitochondria so SER can make them a hormone
What hormone provides the main negative feedback for the adrenal cortex?
Cortisol
What are the three zones of the adrenal cortex?
zona glomerulosa, zona fasciculata, zona reticularis
What hormones does the zona glomerulosa make? What enzyme does it use to do so?
Mineralocorticoids (Aldosterone)
18-hydroxylase
What hormones do the zona fasciculata make? What enzyme do they use?
Glucocorticoids (cortisol), sex steroids
17-hydroxylase
What regulates aldosterone production in zona glomerulosa?
RAAS system, rise in potassium, ACTH (but minor effect)
What hormones do the zona reticulate make?
What enzymes does it use?
Sex hormones
17,20 lyase
What happens to ACTH levels if cortisol decreases?
ACTH levels increase (b/c there is no negative feedback)
How are steroid hormones transported in the blood?
bound to cortisol binding globulin (CBG) and albumin
What is the end product of sex steroids that is excreted?
17-hydroxysteroids
What is the end product of glucocorticoids that is excreted?
17-ketosteroids
What defines glucocorticoid activity?
Ability to mobilize glucose
What defines mineralocorticoid activity?
Ability to reabsorb sodium
How do renal tubular cells deal with high cortisol levels?
Since aldosterone and cortisol normally have opposite effects, but share the same receptor, renal tubular cells convert cortisol to cortisone (less potent) so that sodium reabsorption stays dependent on aldosterone levels, not cortisol levels
How do glucocorticoids exert their effects on cells? (hint: what type of hormone are they?) How long is the response?
Steroid hormones - bind to nuclear receptors and induce gene transcription; response can last over hours
What effects do glucocorticoids have?
- Metabolic - primes body for fasts, so proteolysis, gluconeogenic enzyme expression, lipolysis
- Anti-inflammatory - inhibits phospholipase-A2, kills immature T and B cells
- Stress
