Renal endocrinology

Question 1

What starts the RAAS system?

Answer 1

• Macula densa cells in the DCT detect an decrease in Na+ ions and secreted prostaglandins
• they cause the secretion of Renin from the juxtagolmerular apparatus

Question 2

What is the action of rennin?

Answer 2

cleaves inactive angiotensinogen (produced in the liver and freely circulates) into angiotensin 1

Question 3

what happens to angiotensin ?

Answer 3

ACE in the lungs converts it into angiotensin 2

Question 4

what is the action of angiotensin 2?

Answer 4

• systemic and intra-renal efferent vasoconstrictor

- stimulates the release of ADH and aldosterone by acting on the hypothalamus

Question 5

describe the structure of the adrenal cortex?

Answer 5

3 zones

• zona glomerolsa
• zona fascicular
• zona reticulosa

Question 6

what are secreted from each zone of the adrenal cortex? what is the main one of each?

Answer 6

• zona glomerolsa - mineralcorticoids - aldosterone
• zona fascicular - glucocorticoids - cortisol
• zona reticulosa - androgens

Question 7

what is the function of cortisol?

Answer 7

allows the body to deal with stress

• increases blood glucose levels
• dampens immune system
• increases amino acid generation
• increases lipolysis
• has a permissive effect on catecholamines

Question 8

How is cortisol negatively fed back?

Answer 8

• cortisol has to bind to a protein in the blood - cortisol binding globin
• presence of this in the blood has a negative feedback effect on the hypothalamus so less CRH is released

Question 9

what is produced by the adrenal medulla?

Answer 9

catecholamines

• 80% adrenaline
• 20% noradrenaline

Question 10

what is the purpose of catecholamines?

Answer 10

• they are part of the sympathetic nervous system

- used to bring about a fight or flight response

Question 11

What effects do adrenaline and nor-adrenaline have?

Answer 11

• increase lypolysis
• increase gluconeogenesis
• increase cardiac contractility
• causes tachycardia
• causes the redistribution of circulation

Question 12

where would you find alpha adrenaline receptors? what does activation of these cause?

Answer 12

• found in arteries not in skeletal muscle

- causes vasoconstriction for the redistribution of blood to skeletal muscles

Question 13

where would you find beta 1 adrenaline receptors? what does activation of these cause?

Answer 13

-found in the heart

• causes increased contractility
• causes an increase in heart rate

Question 14

where would you find beta 2 adrenaline receptors? what does activation of these cause?

Answer 14

• found in vascular and non vascular smooth muscles
• mainly in bronchioles and skeletal muscle arteries
• causes skeletal arteries to vasodilate - increasing blood flow
• causes bronchioles to dilate to inrease the flow of air to the alveoli

Question 15

what are the shapes of the adrenal glands?

Answer 15

L = crescent 
R = pyRamidal

Question 16

what is EPO? where is it produced? what action does it have?

Answer 16

Erythropoietin

• causes the increase in RBC production
• produced in the kidneys interstitial cells