Equipping People To Make Sense Of What They Are Told
Kidneys secrete a variety of hormones.
Erythropoietin - also called hematopoietin or hemopoietin - is released in response
to low levels of oxygen - hypoxia - in the renal circulation. It stimulates the production
of red blood cells - erythropoiesis - in the bone marrow and it is produced by the
peritubular capillary endothelial cells in the kidney. It also has other known biological
functions. For example, erythropoietin plays an important role in the brain's response
to neuronal injury 1 and is involved in the wound healing process.2
Calcitriol - the activated form of vitamin D.
Promotes intestinal absorption of calcium and the renal excretion of phosphate. It
increases the level of calcium in the blood by;
Increasing the uptake of calcium from the gut into the blood.
Decreasing the transfer of calcium from blood to the urine by the kidney.
Increasing the release of calcium into the blood from bone.
Renin - an enzyme involved in the regulation of aldosterone levels as part of the
renin-angiotensin-aldosterone system which regulates the body's mean arterial blood
pressure.
It acts in response to:
A decrease in arterial blood pressure (that could be related to a decrease in blood
volume) as detected by baroreceptors (pressure sensitive cells). This is the most
causal link between blood pressure and renin secretion (the other two methods operate
via longer pathways).
A decrease in sodium chloride levels in the ultra-filtrate of the nephron. This flow
is measured by the macula densa of the juxtaglomerular apparatus.
Sympathetic nervous system activity, that also controls blood pressure, acting through
the β1 adrenergic receptors.
Siren AL et al. (2001). "Erythropoietin prevents neuronal apoptosis after cerebral
ischemia and metabolic stress". Proc Natl Acad Sci USA 98: 4044–4049. doi:10.1073/pnas.051606598.
PMID 11259643.
Haroon ZA, Amin K, Jiang X, Arcasoy MO (September 2003). "A novel role for erythropoietin
during fibrin-induced wound-healing response". Am. J. Pathol. 163 (3): 993–1000.
PMID 12937140.
