Endocrine function of the kidney/ Secretion of hormones by the kidneys

Question 1

EPO - structure

Answer 1

EPO = glycoprotein hormone

Question 2

EPO - locations

Answer 2

liver = foetus
kidney = adults

Question 3

EPO - function

Answer 3

1 - the specialised cells in kidneys detect low levels of o2 (hypoxia)

2 - in response to this, kidney juxtaglomerular cells secrete EPO into bloodstream

3 - EPO travels to bone marrow erythyroid progenitor cells

3 - these cells differentiate + mature into RBCS

Question 4

EPO - REGULATION

Answer 4

hypoxia inducible factors HIFs
- transcription factors
- activate transcription of EPO gene during hypoxia

negative feedback mechanisms
- normal O2 levels = less EPO activity

Question 5

RAAS system

Answer 5

during low blood pressure, kidney cells, juxtaglomerular cells secrete renin into the bloodstream

angiotensinogen II -> angiotensin I (via renin)

angiotensin I -> angiotensin II (via ACE)
- potent vasoconstrictor
- stimulates release of aldosterone from adrenal glands leading to sodium/ water retention leading to increase in blood volume/pressure

Question 6

active vitamin D = calcitriol

Answer 6

calcidiol (inactive vitamin D) -> calcitriol (active vitamin D)

• promotes absorption of calcium/ phosphate in GI / renal system
• promotes calcium release from bones/ blood

Question 7

prostaglandins

Answer 7

• PGE2/PGI2
• control renal blood flow causing vasodilation
• regulate GFR
• regulate sodium excretion