ADRENAL GLAND Flashcards
What are the 3 types of hormones produced in the adrenal cortex?
- Glucocorticoids - eg. cortisol
- Mineralocorticoids - eg. aldosterone
- Adrenal androgens - adrenal androgen precursors
What is produced in the adrenal medulla?
Catecholamines - adrenaline and noradrenaline
How are steroid hormones formed and what molecule do they originate from?
- All derived from cholesterol
- Go through a series of metabolic processes in order to become specific hormone in the adrenal gland
- Each step is mediated by an enzyme primarily responsible for the glomerulus
Give 3 facts about corticosteroids:
- solubility
- binding
- what does it affect
- Lipid soluble and so can pass through the bilayer
- Bind to intracellular receptors and bind depending on their structure
- They alter gene transcription either directly or indirectly
Give 3 things glucocorticoids control
- Homeostasis
- Dampens immune response
- Gluconeogenesis
Give 5 effects of excess glucocorticoids
- Promote glycogen breakdown
- promotes central visceral adiposity and central fat build up
- Increases insulin resistance
- Decreases bone formation
- Depression and psychosis
How are glucocorticoids transported? (3)
- 90% glucocorticoids bind to proteins called CBP (corticosteroid binding globulin)
- 5% bind to albumin
- 5% are free and so can pass through the plasma membrane and are active
Is there more or less CBG bound corticosteroids in inflammation?
less
What effect does stress have on CBG?
This stress promotes the breakdown of CBG and reduce its synthesis and so there is more free, bioavailable cortisol which has a bigger impact on tissues
Give two mineralocorticoids
- Aldosterone
- DOC
Where do mineralocorticoids effect?
- Pancreas
- Kidneys - reabsorption of sodium
- Promote deposition of collagen in the heart, high levels of aldosterone can result in fibrosis of the heart
- Maintain water balance/ osmotic balance
Explain the RAAS system
- Lower circulating blood means that less blood goes into the kidneys
- Juxtaglomerular cells in the renal corpuscle detect this and release enzymes called renin
- Renin results in activation of protein in liver called angiotensinogen which is then activated to angiotensin I
- Angiotensin I I is not active and needs to be converted into active II by ACE enzyme produced in the lung
- II binds to aldosterone receptors in the cortex and this results in aldosterone release
Aldosterone reabsorbs sodium and water from the kidneys and excretes potassium and this increases circulating blood volume
Explain the competition between cortisol and aldosterone (5)
Aldosterone and cortisol bind to same receptor
Cortisol levels higher than aldosterone
Body has tissues sensitive to aldosterone
Cortisol can be deactivated into cortisone
Cortisol therefore doesn’t bind to the receptor which allows aldosterone to bind
Does high blood volume result in more or less aldosterone production?
lower aldosterone production
What is the main androgen produced by the adrenals?
DHEA
Other common one is Androstenedione
