Flashcards in Adrenal Gland Phys Deck (52)
Adrenal Gland composed of what two areas?
Cortex and Medulla
Adrenal cortex is located where in relation to the medulla
What types of hormones does the adrenal cortex make?
Three regions of the adrenal cortex
zona glomerulosa (15%)
zone fasiculata (75%)
zona reticularis (10%)
What does the zona glomerulosa make?
What do the zona fasiculates and zona reticularis make?
Glucocorticoids (cortisol), SAndrogens and Estrogens
Adrenal Medulla makes?
Catecholamines (Epinephrine and Norepinephrine)
See slides and hormone table bs for function of the hormones
Transport of adrenocortical hormones in blood is facilitated by what?
steroid hormone-binding serum proteins called GLOBULINS
-partially by albumin which has low affinity
90% of Cortisol exists in what form
BOUND, moslty to transcortin and partially to albumin
10% of cortisol in plasma is :
60% of aldosterone is bound to?
Purposes of hormone binding protein:
- suppress the biological activity of steroid hormones
- protect the hormone from structural alteration
- Extend the half-life of hormones
- Provide an active hormone to the target tissue when needed
What is teh source of all steroid hormones
What provides the cholesterol
LDL (80% cholesterol for steroid synthesis)
How cholesterol get into adrenal cells for steroid synthesis
LDL binds to LDL receptors (clathrin coated pits) on the plasma membranes of adrenal cortical cells
LDL is transported into the cells by what process
endocytosis (endosomal membrane trafficking)
In lysosomes cholesterol is released from the receptors
Cholesterol is then esterified and stored in cytoplasmic vesicles until it is needed for steroid synthesis
Key enzyme in steroid synthesis
cholesterol desmolase (cyp11A1) part of the P450 superfamily
- facilitates the conversion of cholesterol to pregnenolone
What controls steroidogenesis
ACTH stimulates CYP11A1
- also stimulates cholesterol uptake by upregulating LDL receptors
Besides Desmolase, what is the other key enzyme in mineralocorticoid biosynthesis
What upregulates desmolase activity?
ACTH...you know this
What upregulates aldosterone synthase
What is the final step of mineralocorticoid biosynthesis?
corticosterone to aldosterone
Target organs for aldosterone
kidneys, brain, lungs, heart, vascular
What is the mechanism of mineralocorticoid effect?
Upregulates gene expression:
1) binds to MR's in the cytoplasm
2) The hormone receptor complex translocates to the nucleus
3) Binding to the promoter area of specific genes
4) Upregulation of gene expression (Na/K ATPase, Na, K transporters
Genes that are upregulated by the mineralocorticoids?
- Na/K ATPase...ATP dependent transport of Na and K
- Epithelial sodium channel (ENaC
- Serum and Glucocortocoid regulated kinase 1 (SGK1)
- Renal outer medullary K channel
---Important to note that SGK1 activates Na/K ATPase, ENac, and ROMK)
GLucocorticoids are produced where?
Zona Reticularis and Zona Fasiculata (main site of synthesis)