Renal Endocrinology

Question 1

Outline the renin-angiotensin-aldosterone system.

Answer 1

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

Question 2

What does angiotensin II do?

Answer 2

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)

Question 3

What triggers the RAAS to start?

Answer 3

Low blood pressure, low renal perfusion of blood triggers release of renin

Question 4

What happens after RAAS has happened?

Answer 4

BP increases, renal perfusion increases which inhibits further release of renin

Question 5

Does RAAS increase or decrease blood pressure?

Answer 5

Increases it!

Question 6

What type of hormone is cortisol?

Answer 6

Steroid

Question 7

Where is cortisol made?

Answer 7

In the zona fasciculata of the adrenal cortex

Question 8

When is cortisol released?

Answer 8

Stress

Low blood sugar

Question 9

What does cortisol do?

Answer 9

Increases blood sugar by gluconeogenesis

Supresses immune system

Aids metabolism of fat, proteins & carbs

Question 10

What is gluconeogenesis?

Answer 10

Generating glucose from non carbohydrate sources, like lactate, glycerol, amino acids

Question 11

Another name for adrenaline and noradrenaline?

Answer 11

Epinephrine and norepinephrine

Question 12

Where are adrenaline & noradrenaline released from?

Answer 12

Medulla of adrenals

Act as chemical mediators at the ends of sympathetic nerve fibres. They convey nerve impulses to the target organs

Question 13

Difference between noradrenaline and adrenaline?

Answer 13

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

Question 14

What does adrenaline and noradrenaline do?

Answer 14

Increase heart contraction rate and force
Increasing cardiac output

Increases blood glucose

More blood & glucose available to muscles

Question 15

When are adrenaline and noradrenaline released?

Answer 15

Stress

Question 16

What is the name for the receptor that receives noradrenaline & adrenaline?

Answer 16

Adrenergic receptors

Question 17

Name the two group of adrenergic receptors?

Answer 17

Alpha and beta

Question 18

What do alpha receptors do?

Answer 18

Vasoconstriction of veins

Decrease in motility of smooth muscle in GI tract

Question 19

What do beta receptors do?

Answer 19

Increase cardiac output by increasing HR

Increase renin release

Smooth muscle relaxation in bronchi, GI tract

Vasodilation

Question 20

What type of hormone is erythropoietin (EPO)?

Answer 20

A glycoprotein hormone

Question 21

What does EPO do?

Answer 21

Essential for erythropoiesis - red cell production

Question 22

Where is EPO produced?

Answer 22

By interstitial fibroblasts in kidney, near PCT

Also in liver

Question 23

Which organ makes most of the EPO in adulthood? And what about as a foetus?

Answer 23

Adulthood - kidney

Foetus - liver

Question 24

When is EPO released?

Answer 24

In hypoxic conditions - low oxygen

To increase production of rbcs

Question 25

Where are hormone receptors for peptide hormones found?

Answer 25

On the plasma membrane

Question 26

Where are hormone receptors for lipid-soluble (steroid) hormones found?

Answer 26

In cytoplasm of cell

Question 27

What happens when a hormone binds to a hormone receptor?

Answer 27

The receptor initiates multiple signalling pathways leading to change in behaviour of target cell

Question 28

What is the secondary messenger system?

Answer 28

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

Question 29

What type of hormone is aldosterone?

Answer 29

Steroid hormone

Question 30

Where is aldosterone produced?

Answer 30

Zona glomerulosa of adrenals

Question 31

What does aldosterone do?

Answer 31

Acts on DCTs and collecting ducts increasing reabsorption of ions and salts into blood

Conserves water & sodium
Excretes potassium

Increases blood volume & pressure

Question 32

What type of hormone is atrial natriuretic peptide?

Answer 32

Peptide hormone

Question 33

Where is atrial natriuretic peptide secreted from?

Answer 33

Heart muscle cells (atrial)

Question 34

What does atrial natriuretic peptide do?

Answer 34

Homeostasis of body water, sodium, potassium and fat

Lowers water, sodium & adipose loads on circulation - lowers blood volume

Opposite to aldosterone!

Question 35

When is aldosterone released?

Answer 35

Low blood volume and pressure

Secretion stimulated by angiotensin II

Question 36

When is atrial natriuretic peptide released?

Answer 36

High blood volume and pressure

Question 37

What is another name for vasopressin?

Answer 37

ADH - antidiuretic hormone

Question 38

What type of hormone is vasopressin?

Answer 38

Peptide

Question 39

Where is vasopressin released?

Answer 39

Formed in hypothalamus, transported by axons to posterior pituitary
Released by posterior pituitary into blood

Question 40

What does vasopressin do?

Answer 40

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