The renin-angiotensin system plays a key role in regulating blood pressure and fluid balance. Renin is synthesized in the kidneys and cleaves angiotensinogen to form angiotensin I, which is then cleaved by ACE to form angiotensin II. Angiotensin II increases blood pressure by constricting blood vessels and stimulating aldosterone release. It also acts in the kidneys, brain, and cells. The renin-angiotensin system is targeted by ACE inhibitors, angiotensin receptor blockers, and renin inhibitors to treat hypertension and related conditions. Substance P is a neurotransmitter involved in various physiological processes throughout the body.

1. 
RENIN ANGIOTENSIN
SYSTEM
sadaqat ali

2. 
 synthesized as a preprohormone (prorenin)
 synthesized and stored in the juxtaglomerular
apparatus of the nephron
 An important modulator of angiotensin production
RENIN

3. 
 Plays a key role in the regulation of
 fluid and electrolyte balance
 arterial blood pressure
 Excessive activity can result in
 hypertension
 disorders of fluid and electrolyte homeostasis
ANGIOTENSIN II

4. 
 Blood Pressure
 Increase BP
 Adrenal Cortex
 stimulate aldosterone synthesis
Actions

5. 
 Kidney
 increase proximal tubular sodium reabsorption
 inhibit the secretion of renin
Actions

6.  Central Nervous System
 increase secretion of vasopressin
 increase secretion of ACTH
 Cell Growth
 mitogenic for vascular and cardiac muscle cells
Actions

7. 
 AT1 receptor → Gq-coupled receptor
 AT2 receptor → nitric oxide mediated
Receptors

8. 
 Angiotensin-Converting Enzyme Inhibitors
 Captopril, enalapril
 Angiotensin Receptor Blockers
 Losartan, valsartan, irbesartan, candesartan,
olmesartan, telmisartan
 Renin Inhibitors
 Aliskiren → Inhibits catalytic activity of renin
Drugs

9. 
 CNS → neurotransmitter
 GIT → transmitter in ENS and as a local hormone
 Involved in behavior, anxiety, depression, nausea, and emesis
 a potent arteriolar vasodilator
 causes contraction of venous, intestinal, and bronchial
smooth muscle
 stimulates secretion by the salivary glands
 causes diuresis and natriuresis by the kidneys
SUBSTANCE P