The document discusses the role of the kidney and the renin-angiotensin-aldosterone system (RAAS) in regulating blood pressure and hypertension. The kidney controls blood pressure by regulating salt, water, and electrolyte balance. The RAAS is activated when blood pressure drops, causing the release of renin and a chain of hormones that ultimately increase water retention and vasoconstriction, raising blood pressure. Dysregulation of the RAAS can lead to chronic high blood pressure.

2. Role of kidney in long term control of artrial
pressure and hypertension,renin angiotensin
system for artrial pressure regulation
Submitted to: Sir Tajamul
Submitted by: Muhammad Zain (386-2110-239)
Basit (87)
Usman (91)
Roshan ul Hassan(92)
Usman Sajid (93)
Subject: Physiology

3. INTRODUCTION
What is kidney??
The kidneys are a pair of bean-shaped organs on either side of your spine,
below your ribs and behind your belly. Each kidney is about 4 or 5 inches long,
roughly the size of a large fist.
The kidneys' job is to filter your blood. They remove wastes, control the
body's fluid balance, and keep the right levels of electrolytes.

4. What is artrial pressure??
In general, an individual’s “blood pressure,” or systemic
arterial pressure, refers to the pressure measured within large arteries in
the systemic circulation. This number splits into systolic blood pressure
and diastolic blood pressure.

5. CONTROL OF HYPERTENSION
What is hypertension??
Blood pressure is the force of blood pushing against
blood vessel walls as your heart pumps out blood. High blood pressure also
called hypertension, is an increase in the amount of force that blood places
on blood vessels as it moves through the body.
Normal range of BP:
Normal blood pressure reading is 120/80mmHg.

6. Mechanism:
 The kidneys ensure that the make-up and volume of the fluids in the
body is correct. They help control the chemical balance of the blood
and regulate the bodys level of sodium, potassium and calcium. The
kidneys remove waste products and excess water from the body and
so help to regulate blood pressure.
The kidney has a pivotal role in controlling arterial blood pressure
by regulating salt and water excretion and controlling peripheral
vascular tone via several neurohormonal mechanisms.

7. Stages of hypertension

8. RENAL MECHANISM
There are several mechanisms through which the body regulates
arterial pressure
 Baroreceptor Reflex
 Antidiuretic Hormone
 Renin-Angiotensin-Aldosterone System (RAAS)

9. Renin-Angiotensin-Aldosterone System
(RAAS)

10. Introduction
What is RAAS??
The Renin-Angiotensin-Aldosteorne System (RAAS) is a
multi-hormonal system that coordinates a variety of physiological
processes for proper regulation of blood volume and pressure.
RAAS regulates sodium and water absorption in the kidney thus
directly having an impact on systemic blood pressure.
Typically, RAAS is activated when there is a drop in blood pressure
(reduced blood volume) to increase water and electrolyte reabsorption
in the kidney; which compensates for the drop in blood volume, thus
increasing blood pressure.

11. Renin
 Juxtaglomerular cells in the kidney are abundant in an inactive
precursor protein called prorenin which is constantly secreted.
Decreased blood pressure activates juxtaglomerular cells, which
leads to prorenin being cleaved into its active form – renin, which is
then secreted into the bloodstream.

12. Angiotensin-converting enzyme
 Angiotensin-converting enzyme or ACE, is a central component of
the renin–angiotensin system (RAS), which controls blood pressure
by regulating the volume of fluids in the body. It converts the
hormone angiotensin I to the active vasoconstrictor angiotensin II.
Therefore, ACE indirectly increases blood pressure by causing
blood vessels to constrict. ACE inhibitors are widely used as
pharmaceutical drugs for treatment of cardiovascular diseases.

13. Angiotensin
Renin acts on angiotensin (continuously produced by the liver)
to cleave a 10 amino acid peptide from the N-terminus to form
angiotensin I (inactive). Angiotensin-converting-enzyme
(ACE) further cleaves angiotensin I to form angiotensin II –
which is the primary active peptide of RAAS. ACE is
primarily found in vascular endothelia of the lungs and the
kidneys.

14. Angiotensin II
 Angiotensin II binds to angiotensin type I A (AT1AR) or B (AT1BR),
as well as type II (AT2R) receptors. Angiotensin II is a potent
vasoconstrictor, which leads to increased blood pressure. Normally,
if blood pressure is too high, atrial natriuretic peptide (ANP) –
secreted by cardiac muscle cells – leads to reductions in blood
volume, leading to reduced blood pressure

15. Aldosterone
 Angiotensin II stimulates the secretion of aldosterone is produced by
the zona glomerulosa of the adrenal cortex (adrenal gland) and is
involved in the retention of sodium in the kidney and other glands.
The retention of water and sodium leads to increased blood volume,
and thus blood pressure.

16. Mechanism of RAAS

17. Dysfunctional RAAS
 Primary pathologies of impaired RAAS include chronic
hypertension, kidney, and cardiac failure. Abnormally active RAAS
leads to chronic hypertension and thus the high blood pressure needs
to be counterbalanced.
 ACE inhibitors are commonly used drugs in the treatment and
management of hypertension and heart failure. ACE inhibition
prevents the conversion of angiotensin I to angiotensin II, thus
keeping angiotensin inactive.

18. Summary
 In summary, the renin-angiotensin-aldosterone system (RAAS) is a critical
regulator of blood pressure (blood volume & electrolyte balance) as well as
vascular tone & resistance. Normally, renin is secreted if blood pressure is too low
thus activating angiotensin II to increase blood pressure and vascular resistance.
 Abnormal activation of RAAS leads to chronic hypertension, cardiac failure, and
kidney conditions, and may be a predictor for risk of complication in COVID-19.
Drugs inhibiting the RAAS pathway such as ACE inhibitors and ARBs are
effective treatments for hypertension and cardiac failure.