The Adrenal Glands Flashcards
Where are the adrenal glands located
Above the Kidneys
Name the 2 types of tissue which makes up adrenal glands
1- medulla (inner)
2 - cortex (outer)
What is the layer on the outside of adrenal glands called and the function
The capsule
It’s a fibrous protective layer
Which cells are located in the adrenal medulla and what 2 hormones do they produce
Chromaffin cells
Produce epinephrine and norepinephrine
(Adrenaline and noradrenaline)
Chromaffin cells in the medulla have the potential to become post synaptic neurones - why don’t they differentiate
Due to cortisol presence in the cortex stops them differentiating
What type of hormones are epinephrine and norepinephrine
Amino acid hormones (like thyroxin)
What 3 steroid hormones (derived from cholesterol) are produced in the adrenal cortex
1- cortisol
2- aldosterone
3- adrenal androgens eg testosterone oestrogen
Name the 3 layers of the cortex
1- zona glomerulosa (most outer)
2- zona fasciculata (outer)
2- zona reticularis (inner)
What type of steroid hormone is produced at the zona glomerulosa
Aldosterone
Why can’t zona glomerulosa produce androgens or cortisol
No 17alpha hydroxylase enzyme present
= can’t modify cholesterol into them
What type of hormone is aldosterone and give its function
It’s a mineralo corticoid
Important for water and mineral reuptake at the Kinsey ,colon and salivary glands
What type of protein binds to aldosterone because it is a steroid hormone and hydrophobic
Albumin
Explain how aldosterone does it’s mineralocorticoid job
Binds to mineralocorticoid receptors on areas such as collecting duct on the kidney
This allows for upregulation of the NA/K pump, and the sodium channel ENAC
Causes Na reabsorption into blood as well as water
Explain how renin is used to control aldosterone when blood pressure drops
Blood pressure drops is sensed by kidney
Renin is released
Acts on angiotensinogen in the liver
Peptides are cleaved from angiotensinogen by renin
Angiotensin 1 then is converted to angiotensin 2 by ACE enzyme
This angiotensin 2 acts on the zona glomerulosa and this releases aldosterone = more Na uptake into blood = increased BP
What protein does renin activate in the liver
Angiotensinogen
Which enzyme cleaved antigeotensin 1 into angiotensin 2
ACE enzyme
Which hormones are produced by zona fasciculata and zona reticularis
Cortisol and adrenal androgens
Why can’t zona fasciculata and reticularis produce aldosterone
Cells don’t have genes for the enzyme P450 aldo enzyme
Why is cortisol released
When hypothalamus detects stress
What happens when hypothalamus recieves stress signals
The parvocellular neurones release corticotropin releasing hormone into the anterior pituitary
This causes release of adrenocorticotropin from corticotroph cells
This adrenocorticotropin binds to adrenocorticotropin receptors (ACTH) on fasciculata and reticularis
= cortisol production and release
What type of hormone is cortisol
A gluco corticoid
What type of receptor does adrenocorticotropin bind to on fasciculata and reticularis
G protein coupled cell surface receptor (because it’s a peptide hormone)
What happens when adrenocorticotropin binds to acth receptor on the fasciculata and reticularis layers at the adrenal cortex
G protein when activated activated adenylate cyclase
Produces cAMP from ATP
Camp then activated PKA
What 3 effects does pKa activation have when adrenocorticotropin binds
1- increased transcription of enzymes for steroid hormone synthesis
2- activate cholesterol ester hydrolase enzyme
3- activate star protein
