X Renin is an enzyme that plays a crucial role in the renin-angiotensin-aldosterone system (RAAS), which regulates blood pressure, fluid balance, and electrolyte balance in the body.
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Activation of Angiotensinogen: Renin acts on its substrate, angiotensinogen, which is produced by the liver, to convert it into angiotensin I.
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Formation of Angiotensin I: Angiotensin I is an inactive precursor peptide formed by the cleavage of angiotensinogen. Renin catalyzes this conversion.
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Activation of Angiotensin II: Angiotensin I is further converted into angiotensin II by the angiotensin-converting enzyme (ACE), mainly in the lungs. However, the initial step of converting angiotensinogen to angiotensin I by renin is a crucial step in this process.
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Vasoconstriction: Angiotensin II is a potent vasoconstrictor, causing the narrowing of blood vessels, which increases blood pressure.
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Stimulation of Aldosterone Release: Angiotensin II stimulates the adrenal cortex to release aldosterone. Aldosterone acts on the kidneys to increase sodium reabsorption, which leads to increased water retention and expansion of blood volume. This also contributes to an increase in blood pressure.
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Thirst Stimulation: Angiotensin II stimulates thirst, leading to increased fluid intake. This helps in replenishing fluid volume in the body.
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Sympathetic Nervous System Activation: Angiotensin II stimulates the sympathetic nervous system, leading to increased heart rate and cardiac output, which also contributes to elevating blood pressure.