Renal Endocrinology Flashcards
Outline the renin-angiotensin-aldosterone system.
Liver releases angiotensinogen
Renin from kidney converts angiotensinogen to angiotensin 1
ACE from lungs converts angiotensin I to angiotensin II
Angiotensin II does stuff including stimulating aldosterone secretion
What does angiotensin II do?
WATER & SALT RETENTION
Increased sympathetic activity
Tubular Na+ Cl- reabsorption and K+ excretion. water retention
Aldosterone secretion which also helps with the above point
Arteriolar vasoconstriction = increase in BP
ADH secretion from pituitary gland - increased absorption of H20 into blood (retention)
What triggers the RAAS to start?
Low blood pressure, low renal perfusion of blood triggers release of renin
What happens after RAAS has happened?
BP increases, renal perfusion increases which inhibits further release of renin
Does RAAS increase or decrease blood pressure?
Increases it!
What type of hormone is cortisol?
Steroid
Where is cortisol made?
In the zona fasciculata of the adrenal cortex
When is cortisol released?
Stress
Low blood sugar
What does cortisol do?
Increases blood sugar by gluconeogenesis
Supresses immune system
Aids metabolism of fat, proteins & carbs
What is gluconeogenesis?
Generating glucose from non carbohydrate sources, like lactate, glycerol, amino acids
Another name for adrenaline and noradrenaline?
Epinephrine and norepinephrine
Where are adrenaline & noradrenaline released from?
Medulla of adrenals
Act as chemical mediators at the ends of sympathetic nerve fibres. They convey nerve impulses to the target organs
Difference between noradrenaline and adrenaline?
Not a lot
Similar structure
Similar actions in the body
Norad - constricts all blood vessels in the body
Ad - constricts small blood vessels, but dilates blood vessels in liver and skeletal muscle
What does adrenaline and noradrenaline do?
Increase heart contraction rate and force
Increasing cardiac output
Increases blood glucose
More blood & glucose available to muscles
When are adrenaline and noradrenaline released?
Stress
What is the name for the receptor that receives noradrenaline & adrenaline?
Adrenergic receptors
Name the two group of adrenergic receptors?
Alpha and beta
What do alpha receptors do?
Vasoconstriction of veins
Decrease in motility of smooth muscle in GI tract
What do beta receptors do?
Increase cardiac output by increasing HR
Increase renin release
Smooth muscle relaxation in bronchi, GI tract
Vasodilation
What type of hormone is erythropoietin (EPO)?
A glycoprotein hormone
What does EPO do?
Essential for erythropoiesis - red cell production
Where is EPO produced?
By interstitial fibroblasts in kidney, near PCT
Also in liver
Which organ makes most of the EPO in adulthood? And what about as a foetus?
Adulthood - kidney
Foetus - liver
When is EPO released?
In hypoxic conditions - low oxygen
To increase production of rbcs
Where are hormone receptors for peptide hormones found?
On the plasma membrane
Where are hormone receptors for lipid-soluble (steroid) hormones found?
In cytoplasm of cell
What happens when a hormone binds to a hormone receptor?
The receptor initiates multiple signalling pathways leading to change in behaviour of target cell
What is the secondary messenger system?
Intracellular signalling molecules released by the cell after a hormone has bound to the cell’s receptor
2ndary messengers trigger physiological changes in the cell
What type of hormone is aldosterone?
Steroid hormone
Where is aldosterone produced?
Zona glomerulosa of adrenals
What does aldosterone do?
Acts on DCTs and collecting ducts increasing reabsorption of ions and salts into blood
Conserves water & sodium
Excretes potassium
Increases blood volume & pressure
What type of hormone is atrial natriuretic peptide?
Peptide hormone
Where is atrial natriuretic peptide secreted from?
Heart muscle cells (atrial)
What does atrial natriuretic peptide do?
Homeostasis of body water, sodium, potassium and fat
Lowers water, sodium & adipose loads on circulation - lowers blood volume
Opposite to aldosterone!
When is aldosterone released?
Low blood volume and pressure
Secretion stimulated by angiotensin II
When is atrial natriuretic peptide released?
High blood volume and pressure
What is another name for vasopressin?
ADH - antidiuretic hormone
What type of hormone is vasopressin?
Peptide
Where is vasopressin released?
Formed in hypothalamus, transported by axons to posterior pituitary
Released by posterior pituitary into blood
What does vasopressin do?
Increases water permeability of kidneys collecting duct and DCT
Does this by inducing translocation of aquaporin channels (more of them appear)
So more water is reabsorbed into blood
Water retention
