The kidneys regulate the blood pressure by a hormonal mechanism called the renin angiotensin aldosterone mechanism. This is done by the juxtaglomerular cells in the kidney which produce renin, when the blood pressure falls.
Renin in turn converts plasma protein angiotensin to angiotensin I which in turn is converted to angiotensin II in the lungs. Angiotensin II constricts the blood vessels throughout the body, thus raising the blood pressure.
Angiotensin II also stimulates the adrenal cortex to secrete aldosterone, which retains water and decreases the urine output, thus increasing the blood volume and the blood pressure.
thank you very much Dr. Anitha - another question - first i do have a decent understanding of positive and negative feedback, but am not a doctor or have that kind of advanced education. but given the info you provided is it safe to assume that if the adrenal gland is not working properly and is unable to secrete enough aldosterone to raise the bp when it is necessary then will the bp bottom out. especially the dyastolic bp (do not have a bleed). thank you very much for your help. please do not ask me to go see my doctor. thanks
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