FUNCTION OF KIDNEY IN CONTROL OF BLOOD PRESSURE


The kidneys provide a hormonal mechanism for the regulation of blood pressure via dealing with blood extent.


1- Renin‐angiotensin‐aldosterone system  of the kidneys regulates blood quantity. In reaction to growing blood strain, the juxtaglomerular cells within the kidneys secrete renin into the blood. 

  • Renin converts the plasma protein angiotensinogen to angiotensin I, 

which in flip is transformed to angiotensin II via enzymes from the lungs.

  • Angiotensin II activates  mechanisms that increase blood strain:







  • Angiotensin II constricts blood vessels throughout the body (elevating blood stress with the aid of growing resistance to blood float). 

Constricted blood vessels lessen the quantity of blood added to the kidneys, which decreases the kidneys' ability to excrete water (raising blood pressure by increasing blood volume).


  • Angiotensin II stimulates the adrenal cortex to secrete aldosterone, a hormone that reduces urine output via growing retention of H 2O and Na + by means of the kidneys (raising blood stress through growing blood quantity).


Numerous substances influence blood stress. Some critical examples follow:


  • Epinephrine and norepinephrine

hormones secreted by way of the adrenal medulla, raise blood stress by means of increasing coronary heart fee and the contractility of the coronary heart muscle tissues and with the aid of causing vasoconstriction of arteries and veins. Those hormones are secreted as a part of the fight‐or‐flight reaction.





  • Antidiuretic hormone (ADH),

a hormone produced by means of the hypothalamus and released with the aid of the posterior pituitary, raises blood stress by stimulating the kidneys to preserve H 2O (raising blood stress via growing blood volume).





  • Atrial natriuretic peptide (ANP),

a hormone secreted by the atria of the coronary heart, lowers blood stress by way of inflicting vasodilation and by stimulating the kidneys to excrete more water and Na +(decreasing blood pressure through decreasing blood quantity).





  • Nitric oxide (NO), secreted via endothelial cells, causes vasodilation.


  • Nicotine in tobacco raises blood strain with the aid of stimulating sympathetic neurons to increase vasoconstriction and with the aid of stimulating the adrenal medulla to growth secretion of epinephrine and norepinephrine.






  • Alcohol lowers blood pressure via inhibiting the vasomotor center (causing vasodilation) and by inhibiting the release of ADH (growing H 2O output, which decreases blood extent).