Transport of Sodium and Chloride

Flashcards covering key concepts related to the transport of Sodium and Chloride in the kidneys.

Na⁺ balance

Most of the body’s Na⁺ is in the ECF, regulating ECF volume by Na⁺ and Cl⁻ excretion.

Filtered Na⁺ load

The kidney’s daily filtered Na⁺ load is equivalent to 9-times the body’s entire Na⁺ content.

Reabsorption percentages

Proximal tubule (67%), Loop of Henle (25%), Distal tubule (5%), Collecting duct (3%).

Paracellular route

Reabsorption of Na⁺ through junctions between cells.

Transcellular route

Reabsorption of Na⁺ across the apical and basolateral surfaces of the cell.

Na-K pump

A pump that actively transports Na⁺ out of the cell and K⁺ into the cell, requiring ATP.

Transcellular Na⁺ transport

Involves facilitated diffusion and active transport across nephron segments.

Transepithelial potential (Vte)

The luminal potential relative to the basolateral potential created by transcellular Na⁺ reabsorption.

Apical Na⁺ cotransporters

Transporters that couple Na⁺ uptake to the uptake of another solute.

NHE (Na/H exchanger)

An exchanger that extrudes H⁺ into the lumen, participating in acid-base balance.

Basolateral K⁺ channel

Allows K⁺ to be recycled, facilitating net Na⁺ reabsorption.

Diuretics

Drugs that reduce Na⁺ reabsorption, including thiazides and loop diuretics.

Water reabsorption in PT

Passive process that occurs secondary to solute transport through aquaporin channels.

AVP (antidiuretic hormone)

Increases water permeability in the collecting duct and affects Na⁺ reabsorption.

Cl⁻ reabsorption

Occurs via paracellular and transcellular routes, driven by electrochemical gradients.

Renin-angiotensin-aldosterone axis

A pathway that stimulates Na⁺ reabsorption through various mechanisms.

Sympathetic nervous system

Increases Na⁺ reabsorption by reducing renal blood flow and stimulating transport mechanisms.

Atrial natriuretic peptide (ANP)

Hormone that causes renal vasodilation and increases Na⁺ excretion.