Regulation of sodium excretion. Renin Let’s write!
Antinatriuretic system provides a delay of Na and reduces its excretion. Its humoral link is associated with the renin-angiotensin- aldosterone system (RAAS).
•Renin is a proteolytic enzyme secreted by the juxtaglomerular apparatus (JGA) of the kidney. Renin-producing cells are sensitive to volume reduction, blood pressure differences in the arterioles, and changes in the concentration of Na in the tubular fluid.
Regulation of sodium excretion. Renin
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•Renin acts on angiotensinogen and cleaves a peptide of ten amino acids from it, forming angiotensin-I.
•Under the influence of the angiotensin-converting enzyme (ACE), inactive angiotensin-I passes into angiotensin-II, which is a physiologically highly active substance with multiple effects, among which the most significant are stimulation of the synthesis and secretion of aldosterone by the adrenal cortex and a powerful vasoconstrictor effect.
Antinatriuretic system
Aldosterone is a major component of the antinatriuretic system. It enhances the reabsorption of sodium in the renal tubules, which leads to a delay in this ion in the body. In addition, aldosterone reduces potassium reabsorption in the tubules of the kidney.
•Aldosterone penetrates the cell and interacts with a specific protein receptor. The resulting hormone-receptor complex penetrates the nucleus and induces the process of gene transcription, as a result, the synthesis of 3 functional tubular proteins is included:
1)channel proteins that facilitate the penetration of Na + into the cell through the apical membrane,
2)protein pumps Na -K -ATPase, directly providing the active transfer of Na from the tubules into the blood
3)enzyme proteins in mitochondria that provide cells with the energy necessary for sodium transport.
Natriuretic system |
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The natriuretic system provides excretion of sodium by the kidney (natriuresis) and is activated with an increase in fluid volume.
•The natriuretic system is represented by a family of substances, the common name of which is NUP (natriuretic peptides). These include, first of all, atrial natriuretic peptide (ANP).
•PNP has a strong natriuretic, diuretic and antihypertensive effect. Its natriuretic effect is realized through the effect on hemodynamics, GFR and a decrease in sodium reabsorption in the renal tubules.