renal system Flashcards
Describe renal hormones
The kidney as an endocrine organ – Renin (RAS) – Erythropoietin – Calcitriol • The kidney as a target organ for hormones – Antidiuretic hormone (AVP, pituitary) – Aldosterone (RAAS, adrenal gland) – Cardiac hormones
renin, where is it produced, what is stumuli for release
• Produced in the cells juxtaglomerular
apparatus (JGA)
• Stimuli for release:
– Low blood pressure (detected by baroreceptors)
– Decrease in Na (detected at the macular densa)
– Stimulation of the renal sympathetic nerves
Erythropoietin
• Kidney is the major site of production –
interstitial cells
• Also produced in the liver - perisinusoidal cells
• Glycoprotein hormone
• Half life ~5 hours
• Binds to EpoR (located in bone marrow, CNS)
and activates JAK2 signalling cascade
Roles of epo?
Classical -> stimulate production of red cells
Wound healing Cardioprotection Angionesesis Neuroprotectnat in premmie baboes Renal and retinal protecion
Simulation and actions of EPo and erthropoiesis
Hypoxia detected (decreased O2 bc low RBC)-> epo prodction -> stimulates erythroppoiesis in bone marrow->erythroppoiesis increase RBC -> blood o2 return to normal
what stimulates epo?
How much oxygen can be delivered to tissue, -> tissue will detect -> will induce HIF and stim epo:
Low tissue oxygenation can be bc not enough hemoglobin -> iron defficient , or hemorrhage
Or if not enough o2 attached to hemo e.g high altitude
epo production baby and adult
In liver as baby and in kidney as adult
how you get rbc from red blood cell?
In bone marrow, stem cells turn into BFU-E then CFU-E then erythroblasts then reticulocytes then red cell mass
EPO acts on BFU-E AND CFU-E
What are the Actions of Epo on the bone marrow
cts on red blood cell progenitors and precursors
(in the bone marrow)
• Protects these cells from apoptosis.
• Targets
– Burst forming units (BFU-E)
– colony forming units (CFU-E)
• cooperates with various other growth factors
(e.g., glucocortioicds, IL-6).
• Precursors of red cells, the proerythroblasts and
basophilic erythroblasts also express Epo-R.
describe Erythropoietin receptor
- Located on erythroid progenitors - Cytokine receptor - Signals through JAK2-STAT pathway - Increased Epo production in people with mutations in the Epo-R –increased hematocrit.
CAN ACTIVATE MULTIPLE SECONDARY MESSENGER SYSTEMS TO HAVE DIFFERENT TARGET
What is gold medal mutation?
- Point mutation in the Epo-R causes Primary familial polycythaemia - Increased hematocrit esp good for endurance sports
Altered Epo production
?
Low Epo production in kidney failure
• Anemia (multiple causes)
• Early sign of renal failure is tiredness due to
lack of Epo production
epo can be therapteutic for aneamia
what are some Non-haemopoietic effects of EPO
Actions of Epo in wound healing:
1) improves mobility of cells and increases migration
rate, particularly in keratinocytes and fibroblasts,
resulting in an overall quicker wound closure.
2)(2) reduces inflammatory reaction.
(3) Increased angiogenic response, accelerated
microvascular network formation, and improved
maturation are associated with improved nutrition and
metabolism of the wound
Epo as a performance enhancing drug
Widely used by endurance athletes, particularly cyclists • Increased hematocrit to >55% • Increased blood viscosity • Strokes! Cardiac events! • Death!!!
summary of Calcitriol
Steroid hormone
• Produced in the cells of the proximal tubule
• 1,25-dihydroxyvitamin D3
• Hormonally active metabolite of vitamin D
• Calcitriol increases the level of calcium (Ca2+)
in the blood by increasing the uptake of
calcium from the gut and stop loss from urine
Calcitriol receptor?
Is in nucleus
Transcriptually regulates does whole range of things
