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THE KIDNEYS'S ROLE IN HOMEOSTASIS - Coggle Diagram
THE KIDNEYS'S ROLE IN HOMEOSTASIS
BLOOD PRESSURE CONTROL
Renin Angiotension system:
when blood volume is low or decreased(dehydration/sodium deficiency) it stimulated the kidney to produce renin which produce angiotensin I and converted to Angiotenssin II.
Angiotensin II stimulates the adrenal cortex to produce aldosterone, and more sodium and water are reabsorbed, which eliminates more potassium and increase blood volume and blood pressure.
WASTE EXCRETION IN URINE
All excess ions, sodium , potassium , calcium, magnesium, chloride, bicarbonate, phosphate and ammonium
Metabolic waste Urea, creatinine, uric acid and nitrogenious waste.
Drug metabolites pharmacological agents are detoxified in liver and excreted through kidney.
Metabolites of Hormones are also excreted in urine for example human chronic gonadotropin in early pregnancy.
FLUID VOLUME BALANCE
Increase in plasma Osmolality, water is reabsorbed int o blood by diluting the plasma and reducing osmolality to normal.
A decrease in plasma osmolality leads to (anti diuretic hormone) ADH secretion by negative feedback. ADH receptors are found in collecting ducts.
ADH- pituitary glands secrets the hormone and receptors in collecting ducts of kidney tubules stimulates the secretion.
Aldosterone is a steroid hormone secreted from the adrenal cortex of the kidney and effects the distal tubules of the nephron. it is regulated by peptide and Angiotensin II
sodium reabsorption is increased when aldosterone is released and water is reabsorbed as well.
Atrial Natriuretic peptide (ANP)- release from cardiac atrial cell in response to stretch in atrium from fluid overload.
ANP inhibits aldosterone secretion by adrenal cortex, reduce renin release by kidney and reduction of ADH from the posterior pituitary to reduce the fluid volume by excreting sodium and water.
pH BALANCE
Alkalosis- is corrected by reducing hydrogen ion secretion in urine.
Acidosis- is corrected by secreting excess hydrogen ion into the urine and increasing bicarbonate reabsorption into plasma.
Normal pH of the body is 7.35-7.45. it is very sensitive and important for normal body function. level of hydrogen ion determines the pH.
kidney controls the acid-base balance by controlling the bicarbonate ions in the body,
Bicarb ions are reabsorbed in the proximal tubule and distal tubule. when higher than normal is detected then excess it is lost in the urine, or trapped / reserved in the blood and excretes hydrogen ions.
ELECTROLYTES BALANCE
MAGNESIUM
Magnesium is a very important intracellular cation involved in energy storage and production.
PHOSPHATE
phosphate is reabsorb in the early proximal tubules when the plasma level is low and excreted in urine when the level is high.
phosphate and calcium exist in equilibrium and phosphate is a very important buffer system to maintain plasma pH.
CALCIUM
level of parathyroid hormone (PTH) in the system effects calcium reabsorption.
SODIUM
65%sodium is actively reabsorbed in proximal tubules and 25% in loop of henle. Aldosterone control reabsorption sodium and water, excrete potassium when blood volume and pressure is low.
POTASSIUM
Small increase in potassium level in extracellular stimulates adrenal cortex to produce aldosterone and effects distal tubules to secrete potassium in urine
fall in aldosterone level has the reverse effect as less potassium is secrete into the urine via negative feedback system.
Aldosterone controls the potassium level in the body and potassium, sodium are inversely proportional to each other.
ERYTHROPOIETIN PRODUCTION
Erythropoietin producing cells produce the hormone to maintain normal red blood cel count and prevention of anemia. for example in CKD patients hemoglobin level is very important to be check regularly.
The negative feedback principle drives Erythropoietin production. it is stimulated by hypoxia and stopped when it is corrected.