1/4 Adrenal Glands: Regulation COMPLETE*** Flashcards
Where are the adrenal glands located? 2
on the cranial aspect of the kidneys
within the retroperitoneal space
Describe the structure of the Adrenal Gland 2
the outermost aspect is the cortex
the innermost aspect is the medulla
Adrenal Cortex: State the names of the divisions of the Adrenal cortex from outermost to innermost
zona glomerulosa
zona fasciculata
zona reticularis
Adrenal Cortex: What does the Zona Glomerulosa secrete?
- What about the Zona Fasciculata?
- What about the Zona Reticularis?
mineralocorticoids
glucocorticoids
androgens
Adrenal Cortex: Give an example of a mineralocorticoid
- Give an example of a Glucocorticoid
- Give an example of an Androgen
aldosterone
cortisol
testosterone
Adrenal Medulla: What does the medulla secrete?
- Give 2 examples of these substances
catecholamines
epinephrine and norepinephrine
Adrenal Cortex: What collective term can be given to all substances secreted by the adrenal cortex?
- What substance are all these hormones derived from?
- Describe their synthesis 3
steroid hormones
cholesterol
cholesterol is converted into pregnelone by P450 side chain cleavage enzyme
pregnelone is then converted into different corticoids based on the zone
the rate limiting step is activated by ACTH
HPA Axis: Describe the HPA axis for Glucocorticoids
the hypothalamus secretes ACTH releasing hormone
this stimulates corticotropin cells in the pituitary gland to secrete ACTH
ACTH stimulates the adrenal cortex to secrete glucocorticoids
ACTH has negative feedback on the hypothalamus
glucocorticoids have negative feedback on the hypothalamus and pituitary gland
HPA Axis: How is ACTH releasing hormone passed form the hypothalamus to the anterior pituitary gland?
down axons leading to the portal capillary bed in the anterior pituitary gland
Adrenal Cortex: Which cells in the pituitary gland produce ACTH?
- How is ACTH synthesised? 3
corticotropic cells
ACTH is synthesised from pro-opiomelanocortin (POMC)
POMC undergoes a series of modifications
it is cleaved to yield various polypeptides including ACTH
What is the fate of glucocorticoids after their release form the adrenal cortex? 4
most are bound to plasma proteins and transported in the blood
they bind to specific cell membrane or cytosolic receptors at their target tissue
the receptor-steroid complex is transported to the nucleus of the cell
this results in altered gene expression
Glucocorticoids: What are they essentially?
- State their general role
- how does it achieve this? 9
increasing blood glucose concentration
stimulates glycogenolysis
stimulates gluconeogenesis
stimulates proteolysis
stimulates lipolysis
mobilises fats from peripheral stores
break down muscle
antagonises insulin
increased GFR
blocks ADH action so less water reabsorbed
Glucocorticoids: What are some of the other minor actions of glucocorticoids? 4
reduces calcium concentration
release of neutrophils from marginating pool
down regulates immune response
hunger and thirst
Mineralocorticoids: Give an example of one
- What do they do?
aldosterone
they maintain salt and water balance to maintain blood pressure
Mineralocorticoids: What is the stimulus for aldosterone release?
low blood pressure activating RAAS
