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Acid-base map and compensatory mechanisms
Buffering and Henderson-Hasselbalch equation
Physiologic pH and buffers
The role of the kidney in acid-base balance
Plasma anion gap
Renal system anatomy and physiology
Body fluid compartments
Movement of water between body compartments
Measuring renal plasma flow and renal blood flow
Regulation of renal blood flow
TF/Px ratio and TF/Pinulin
Phosphate, calcium and magnesium homeostasis
Free water clearance
Kidney countercurrent multiplication
Distal convoluted tubule
Loop of Henle
Proximal convoluted tubule
Tubular reabsorption and secretion
Tubular reabsorption and secretion of weak acids and bases
Tubular reabsorption of glucose
Tubular secretion of PAH
0 / 7 complete
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erythropoietin in p. 609
erythropoietin and p. 609
high altitude p. 688
with pheochromacytoma p. 343
polycythemia and p. 219, 727
release of p. 609
in renal failure p. 623
signaling pathways for p. 351
anemia of chronic disease p. 427
aplastic anemia p. 427
with polycythemias p. 438
With erythropoietin, ‘-poietin’ means ‘to make’ and ‘erythro-’ refers to red blood cells, so erythropoietin is a hormone that stimulates the production of erythrocytes or red blood cells in the bone marrow. Erythropoietin, or EPO, is produced in the kidneys, and to a lesser extent in the liver, and travels through the blood to the bone marrow where it stimulates immature cells to transform into mature red blood cells.
Every cell in the body uses oxygen for cellular respiration. As we breathe, oxygen diffuses into the bloodstream where it binds hemoglobin within the red blood cells and gets carried off to various parts of the body. Red blood cells live for about 120 days, so there is a constant need to produce new red blood cells.
Now, in the bone marrow, there are proerythroblasts, which are primitive or immature red blood cells. The kidneys produce a constant level of erythropoietin, which gets released into the blood and makes its way to the bone marrow, where it binds to erythropoietin receptors on the immature red blood cells and causes them to erythrocytes, or mature into red blood cells, usually this production of erythropoietin is constant, so the production of mature red blood cells is constant. If there’s ever decreased oxygen delivery to the tissues, then one thing the body can do is ramp up production of oxygen delivery vehicles, in other words red blood cells. In this situation, the kidney cells ramp up production of erythropoietin, therefore ramping up production of mature red blood cells. Interestingly, erythropoietin prevents immature red blood cells from killing themselves by apoptosis, meaning that without erythropoietin, developing red blood cells die via apoptosis.
Fundamentally, decreased oxygen delivery to the tissues can be due to a decrease in blood flow or a decrease in blood oxygen content. If there’s a decrease in blood flow, then increasing the number of red blood cells is not effective, however, if there’s a decreased oxygen content, then increasing the number of red blood cells is effective and will help with oxygen delivery.
Erythropoietin (EPO) is a hormone that regulates the production of red blood cells. EPO is produced by kidney cells, and can be deficient in individuals with chronic kidney diseases, resulting in reduced production of red blood cells, thus anemia.
EPO is made in response to low oxygen levels in the tissues. It signals the bone marrow to produce more red blood cells, which helps to increase oxygen delivery to tissues. EPO is also used as a doping agent in endurance sports because it can improve performance by increasing the amount of oxygen that is delivered to muscles. EPO doping has been reported to have negative health effects, including an increased risk of heart attack and stroke.
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