Please enable JavaScript.

Coggle requires JavaScript to display documents.

The Roles of the Kidneys in Homeostasis, - Coggle Diagram

- - - - Sodium levels, and hence fluid volume, are regulated by three hormones:
        
        ADH
        
        Secreted by the posterior pituitary gland in response to a rise in plasma osmolality.
        
        ADH receptors are found in the collecting ducts of kidney tubules
        
        ADH acts to open water channels in the walls of the collecting ducts and water is reabsorbed into the blood, diluting the plasma and reducing the osmolality to normal
        
        Aldosterone ( by RAAS pathway in response to decrease in blood volume)
        
        not directly triggered by by extracellular osmolality, but by angiotensin II
        
        It has its effect on the distal tubule of the nephron: the more aldosterone is secreted, the more sodium is reabsorbed and the more water return to the blood
        
        Atrial Natriuretic peptide
        
        released from cardiac atrial cells in response to an increased atrial stretch
        
        ✦ inhibition of aldosterone secretion by the adrenal cortex
        ✦ reduction of renin release by the kidney
        ✦ reduction of ADH release from the posterior pituitary
        ✦ vasodilation
        ✦ natriuresis and diuresis
        
        these effects result in the excretion of sodium and water through the kidney, reducing the extracellular fluid back to normal
  - - - Potasium
        
        65% of reabsorption takes place in the proximal tubule
        
        Aldosterone is the only hormone involved in the control of potasium content
        
        ✦small increase of potassium = aldosterone in the distal tubule of the nephron increases the secretion of potassium in the urine
        
        aldosterone increases sodium reabsorption in exchange for potassium
        
        Potassium is important in maintaining the mebrane potential of nerve and muscle cells and hence affects their excitability
      - Calcium
        
        approximately 65% of reabsorption takes place in the proximal tubule
        
        Calcium ions play an important role in the regulation of nerve and muscle function and in blood clotting
      - Magnesium
        
        magnesium is reabsorbed in the proximal tubule, the thick ascending limb of the loop of Henle, and the distal convoluted tubu
        
        Magnesium's most important role is in the release of chemical energy.
      - Sodium
  - - - In response to acidosis, the tubular cells reabsorb more bicarbonate from the tubular fluid, and the collecting duct cells secrete more hydrogen and generate more bicarbonate and ammoniagenesis leads to an increase in the formation of the NH3 buffer.
      - In response to alkalosis, the kidneys may excrete more bicarbonate by decreasing hydrogen ion secretion from the tubular epithelial cells, and lowering the rates of glutamine metabolism and ammonium excretion.
  - - - Kidneys release enzyme called renin that converts angiotensinogen (a precursor made in the liver) to angiotensin I
        
        angiotensin I (a precursor hormone) is converted to an active hormone called angiotensin II by an enzyme known as angiotensin-converting enzyme (ACE) in the lungs
        
        ✦ Causes vasoconstriction = ⬆️ systemic blood pressure
        ✦ ⬆️ renal perfusion pressure
        ✦ ⬆️ glomerular filtration rate
        
        causes release of a hormone called aldosterone from the adrenal gland
        
        In kidneys, more sodium and water return to blood and more potassium eliminated in urine
        
        ⬆️ Blood volume and blood pressure