PSL201 – Feb 26 – Endocrine 4 Adrenal Hormones.docx

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11 Apr 2012

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PSL201 Feb 26 Endocrine 4: Adrenal Hormones
Adrenal Glands (suprarenal glands)
- located above the kidneys
- outer cortex and inner medulla
- adrenal cortex:
o zona glomerulosa, outer layer
o zona fasciculate, middle layer
o zona reticularis, inner layer
- adrenocorticords: hormones secreted by adrenal cortex (steroids)
o mineralocorticoids: (primarily sldosterone) secreted by cells in the
zona glomerulosa and regulate sodium reabsorbtion and potassium
secretion by the kidneys
o glucocorticoids: (primarily cortisol) are secreted by cells in the zona
fasciculate and regulate the bodies response to stress
o sex hormones: (primarily sndrogens) secreted by cells in the zona
reticularis (and gonads) and regulate reproductive function
- adrenal medulla: contains chromaffin cells and secretes catecholamines
The effects of Aldosterone
- steroid hormone released from the adrenal cortex that regulates sodium
reabsorbtion and potassium seretion
- binds to cytosolic receptors in the DT and collecting ducts
o increases the number of open K and Na channels
o also causes synthesis of new channels
o also stimulates Na+/K+ pumps
- release controlled By the (RAAS) system
The Renin-Angiotensin-Aldosterone System:
- walls of afferent arteriole are granular cells that secrete renin
- macula densa cells in the walls of the DT detect changes in sodium and
chloride levels in tubular fluid
o Na+ decreases, renin release increases
- Renin then acts on angiotensinogen which is secreted by the liver
o Cleaves some AA’s converting it to angiotensin I
- Angiotensin converting enzyme (ACE) then cleaves off AA’s from
angiotensin I converting it to angiotensin II
- Angiotensin II acts as a vasoconstrictor, is important in regulation of MAP
and stimulates aldosterone release form the adrenal cortex.
o Also acts on hypothalamus where it stimulates ADH and thirst
- secreted by the adrenal cortex
- at high [] they play a role in stress adaptation
Factors Affecting Secretion of Glucocorticoids
- secretion stimulated by adrenocorticotrophic hormone (ACTH) from the
anterior pituitary which is stimulated by corticotrophin releasing
hormone (CRH) from the hypothalamus
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