Adrenal Gland Flashcards
In order what are the layers of the adrenal gland?
- Capsule
- Cortex
- Adrenal medulla
What are the three layers of the adrenal cortex (in order)?
- Zona glomerulosa
- Zona fasciculata
- Zona reticularis
What does the zona glomerulosa produce?
Mineralcorticoids e.g aldosterone
What does the zona fasciculata produce?
Glucocorticoids e.g cortisol
What does the zona reticularis produce?
Androgens e.g DHEA
What does the adrenal medulla produce?
Norepinephrine and epinephrine
What are the functions of aldosterone?
- Aldosterone increases uptake of sodium by the kidneys so less is lost in the urine. This leads to more water staying in the body.
- –> increasing blood volume therefore increasing blood pressure. - Aldosterone promotes the loss of H+ in the urine, therefore helping to prevent acidosis.
What controls aldosterone secretion?
The RAAS pathway
Where is renin secreted from?
JGA in the kidneys
Where is angiotensinogen produced?
The liver
Explain the RAAS system.
- Renin is produced by the kidneys in response to decreased blood pressure.
- Renin travels to the liver where it converts angiotensinogen into angiotensin 1.
- Angiotensin 1 travels in the blood to the lungs.
- ACE is present in the lungs and converts angiotensin 1 into angiotensin 2.
- Angiotensin 2 causes vasoconstriction and stimulates aldosterone production in the adrenal gland.
Where does angiotensin II act?
The smooth muscle in the walls of arterioles.
Where are glucocorticoids produced?
The zona fasciculata in the adrenal gland
What are the effects of glucocorticoids?
- Protein breakdown
- Gluconeogenesis
- Lipolysis
- Resistance to stress
- Increased blood pressure
- Anti-inflammatory effects
- Depression of immune responses
What is the function of protein breakdown by cortisol?
Cortisol breaks down the proteins in muscle fibres increasing the number of amino acids in the blood, allowing new protein production.
How does cortisol combat stress?
Increases blood glucose levels therefore there is more ATP available to combat stress.
How does cortisol increase blood pressure?
Cortisol makes blood vessels more sensitive to hormones that cause vasoconstriction, thus increasing blood pressure.
—> Important in cases of severe blood loss.
How do glucocorticoids have an anti-inflammatory effect?
Glucocorticoids inhibit white blood cells that participate in the inflammatory response.
However this also delays tissue repair slowing wound healing.
—> Useful in treating chronic inflammatory conditions such as rheumatoid arthritis.
What is the importance of depressed immune response induced by glucocorticoids?
Glucocorticoids are prescribed after organ transplant to delay tissue rejection.
Explain the control of cortisol secretion.
- CRH produced by hypothalamus
- Goes to AP through HPS
- Corticotrophs in AP secrete ACTH
- ACTH acts on the adrenal cortex stimulating cortisol production.