[Durgical](https://durgical.com/en/) › [DurgiPedia](https://durgical.com/en/durgipedia/) › [Physiology](https://durgical.com/en/physiology/) › [Cardiovascular](https://durgical.com/en/physiology/#s-cardio) › Long-term blood pressure control by the kidney [Physiology](https://durgical.com/en/physiology/) · [Cardiovascular](https://durgical.com/en/physiology/#s-cardio) # Long-term blood pressure control by the kidney - Regulation - Exam priority: medium In the long run, blood pressure is set by the kidneys: if pressure rises, they excrete more salt and water until it comes back down. Updated 2026-11-01 Also called: Pressure natriuresis **See it in 3D:** [Kidneys](https://durgical.com/en/anatomy/kidney/) · [Left renal artery](https://durgical.com/en/anatomy/renal-artery/) · [Right renal artery](https://durgical.com/en/anatomy/renal-artery-abdomen/) · [Left adrenal gland](https://durgical.com/en/anatomy/suprarenal-gland/) ## Key points - Pressure natriuresis: higher renal perfusion pressure → more sodium and water excretion → less volume → pressure falls. - The equilibrium point is where the renal function curve (excretion versus pressure) crosses the salt and water intake line. - It is a "near-infinite gain" control: it corrects the whole error, though it takes hours to days. - Only two things move long-term pressure: shifting the renal curve or changing salt intake. - Angiotensin II makes the curve steeper (pressure changes little with salt); if it is blocked, pressure becomes salt-sensitive. - Baroreceptors reset over days: they do not set long-term pressure. ## What it is When arterial pressure rises, the kidney excretes more sodium and water (pressure natriuresis and diuresis); extracellular volume falls and pressure comes back. The equilibrium pressure is the one at which salt excretion equals intake. So for hypertension to persist, the kidney must need a higher pressure to excrete the salt being eaten. ## How it works, step by step - Arterial pressure rises for any reason. - Peritubular capillary and renal interstitial pressure rise, and less sodium is reabsorbed in the proximal tubule. - Renin is suppressed: angiotensin II and aldosterone fall, and the tubule keeps even less sodium. - More sodium and water are excreted than are taken in. - Extracellular volume, mean filling pressure and venous return fall. - Cardiac output drops and, over time, tissue autoregulation lowers peripheral resistance too. - Pressure settles back where excretion equals intake. ## Equations **Mean arterial pressure**MAP = CO × SVR **CO** cardiac output **SVR** systemic vascular resistance The kidney does not change the formula; it changes volume, which moves output, and autoregulation then adjusts resistance. ## Regulation - *+* **Angiotensin II**: Constricts the efferent arteriole, boosts proximal sodium reabsorption and stimulates aldosterone: shifts the renal curve to higher pressures. - *+* **Aldosterone**: Retains sodium in the collecting duct. - *+* **Renal sympathetic nerves**: Release renin and increase sodium reabsorption. - *−* **Atrial natriuretic peptides**: Raise filtration and sodium excretion when the atria are stretched. - *−* **Pressure natriuresis**: Removes excess salt and water while pressure sits above the equilibrium point. ## Clinical notes - In chronic kidney disease nephrons are lost: more pressure is needed to excrete the same salt, and hypertension is almost the rule. - Renal artery stenosis lowers the pressure the kidney "sees" and forces systemic pressure up so the salt gets excreted. - Diuretics and salt restriction lower pressure because they work on this same volume balance. ## Memory aid "The kidney keeps the books": pressure does not stay up unless the kidney signs off. ## Test yourself Think of the answer, then tap the question to see it. ## If a person with healthy kidneys is given a large volume load, why does pressure return to baseline within days? High pressure raises sodium and water excretion (pressure natriuresis) until the extra volume is gone; balance returns to where excretion equals intake. ## What must happen in the kidney for hypertension to persist? The renal function curve must shift right: the kidney needs a higher pressure to excrete the salt being eaten. ## Why does a person taking an ACE inhibitor become more salt-sensitive? Without angiotensin II the kidney cannot tune sodium reabsorption to intake; the renal curve flattens and each change in salt moves pressure more. ## Why do baroreceptors not set arterial pressure in the long term? They reset within a day or two to the new pressure and stop opposing it; the lasting adjustment comes from the renal salt and water balance. [Add to my cards (4)](https://durgical.app/estudiar/?add=/en/physiology/long-term-blood-pressure-control-by-the-kidney/) ## See it in 3D The structures of Durgical's 3D anatomy where it happens. - [Kidneys](https://durgical.com/en/anatomy/kidney/) - [Left renal artery](https://durgical.com/en/anatomy/renal-artery/) - [Right renal artery](https://durgical.com/en/anatomy/renal-artery-abdomen/) - [Left adrenal gland](https://durgical.com/en/anatomy/suprarenal-gland/) ## Related topics - [The renin–angiotensin–aldosterone system](https://durgical.com/en/physiology/the-renin-angiotensin-aldosterone-system/) - [Physiology of hypertension](https://durgical.com/en/physiology/physiology-of-hypertension/) - [The baroreceptor reflex](https://durgical.com/en/physiology/the-baroreceptor-reflex/) - [Nervous control of the circulation and the CNS ischemic response](https://durgical.com/en/physiology/nervous-control-of-the-circulation-and-the-cns-ischemic-response/) - [Venous return and the Guyton curves](https://durgical.com/en/physiology/venous-return-and-the-guyton-curves/) ## Related conditions - [Arterial hypertension](https://durgical.com/en/conditions/arterial-hypertension/) - [Chronic kidney disease](https://durgical.com/en/conditions/chronic-kidney-disease/) - [Heart failure](https://durgical.com/en/conditions/heart-failure/) ## In Biochemistry - [Aldosterone](https://durgical.com/en/biochemistry/molecules/aldosterone/) - [Angiotensin-converting enzyme (ACE)](https://durgical.com/en/biochemistry/enzymes/angiotensin-converting-enzyme/) ## In Pharmacology - [ACE inhibitors](https://durgical.com/en/pharmacology/classes/ace-inhibitors/) - [Angiotensin II receptor blockers (ARBs)](https://durgical.com/en/pharmacology/classes/angiotensin-ii-receptor-blockers/) [← All of physiology](https://durgical.com/en/physiology/) Educational physiology content; not a diagnostic or treatment guide and no substitute for a health professional's advice. Values are approximate references. No doses are given. Sources: [20.4 Homeostatic Regulation of the Vascular System](https://openstax.org/books/anatomy-and-physiology-2e/pages/20-4-homeostatic-regulation-of-the-vascular-system) (OpenStax (Rice University), 2022); [Chronic Kidney Disease](https://www.ncbi.nlm.nih.gov/books/NBK535404/) (StatPearls (NCBI Bookshelf), 2024); [Essential Hypertension](https://www.ncbi.nlm.nih.gov/books/NBK539859/) (StatPearls (NCBI Bookshelf), 2023); Hall JE. Guyton and Hall Textbook of Medical Physiology, 13th ed. (ch. 19). Reference book used to check facts; its text and figures are not reproduced (Elsevier, 2016). ## **Spotted a mistake?** We are always improving for the community. Tell us what is wrong and our team will review it. Report a mistake Representative model, for educational purposes only. --- Source: https://durgical.com/en/physiology/long-term-blood-pressure-control-by-the-kidney/ License: CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). Cite as: DurgiPedia (durgical.com), https://durgical.com/en/physiology/long-term-blood-pressure-control-by-the-kidney/