Metabolic reactions in the body produce nonvolatile acids, such as sulfuric acid, which generate an acid load of approximately 1 mEq of H+ per kilogram of body weight daily. Excreting H+ in the urine is essential to balance this acid load.

In the kidneys, cells within the proximal convoluted tubules (PCT) and the collecting ducts secrete hydrogen ions (H+) into the tubular fluid. Specifically, in the PCT, Na+/H+ antiporters secrete H+ while reabsorbing Na+.

However, the intercalated cells in the collecting duct play a more prominent role in regulating the pH of body fluids. Type A intercalated cells contain proton pumps (H+/ATPases) in their apical membranes that secrete H+ into the tubular fluid.

Interestingly, another type of intercalated cell called type B intercalated cells houses proton pumps in its basolateral membrane and Cl/HCO3 antiporters in its apical membrane. These cells have a dual function: secreting HCO3 and reabsorbing H+. Type A intercalated cells help maintain the pH of body fluids by excreting excess H+ when the pH is too low, while type B intercalated cells excrete excess HCO3⁻ when the pH is too high.

Some of the secreted H+ is buffered in the collecting duct by mono-hydrogen phosphate ions and a small amount of ammonia. Both of these combine with the H+ in the tubular fluid. The resulting dihydrogen phosphate and ammonium ions cannot diffuse back into tubule cells and are excreted in the urine.

The body ensures precise pH regulation through these coordinated mechanisms in the kidneys, safeguarding critical physiological processes.

Dal capitolo 30:

article

Now Playing

30.17 : Renal Regulation of Acid-Base Balance

Fluid, Electrolyte, and Acid-Base Balance

56 Visualizzazioni

article

30.1 : Body Water Content and Fluid Compartments

Fluid, Electrolyte, and Acid-Base Balance

201 Visualizzazioni

article

30.2 : Composition of Body Fluids

Fluid, Electrolyte, and Acid-Base Balance

153 Visualizzazioni

article

30.3 : Fluid Movement Between Compartments

Fluid, Electrolyte, and Acid-Base Balance

174 Visualizzazioni

article

30.4 : Regulation of Water Intake

Fluid, Electrolyte, and Acid-Base Balance

162 Visualizzazioni

article

30.5 : Regulation of Water Output

Fluid, Electrolyte, and Acid-Base Balance

117 Visualizzazioni

article

30.6 : Disorder of Water Balance

Fluid, Electrolyte, and Acid-Base Balance

128 Visualizzazioni

article

30.7 : Roles of Electrolytes: Sodium and Potassium

Fluid, Electrolyte, and Acid-Base Balance

53 Visualizzazioni

article

30.8 : Roles of Electrolytes: Chloride and Bicarbonate

Fluid, Electrolyte, and Acid-Base Balance

36 Visualizzazioni

article

30.9 : Roles of Electrolytes: Calcium and Phosphate

Fluid, Electrolyte, and Acid-Base Balance

44 Visualizzazioni

article

30.10 : Regulation of Sodium and Potassium

Fluid, Electrolyte, and Acid-Base Balance

48 Visualizzazioni

article

30.11 : Acid-Base Balance

Fluid, Electrolyte, and Acid-Base Balance

117 Visualizzazioni

article

30.12 : Buffer Systems in the Body

Fluid, Electrolyte, and Acid-Base Balance

165 Visualizzazioni

article

30.13 : Protein Buffers in Blood Plasma and Cells

Fluid, Electrolyte, and Acid-Base Balance

147 Visualizzazioni

article

30.14 : Phosphate Buffer

Fluid, Electrolyte, and Acid-Base Balance

155 Visualizzazioni

See More

JoVE Logo

Riservatezza

Condizioni di utilizzo

Politiche

Ricerca

Didattica

CHI SIAMO

Copyright © 2025 MyJoVE Corporation. Tutti i diritti riservati