Filtration, reabsorption, secretion flashcards

What are the three filtration barriers of the glomerular membrane?

The fenestrated endothelium, the basal membrane, and the surrounding epithelial cell layer.

What is the composition of the filtrate formed during glomerular filtration?

Filtrate is plasma minus most of the plasma proteins.

Where does most tubular reabsorption occur in the kidney?

Most reabsorption occurs in the proximal convoluted tubule.

What substances are reabsorbed by the peritubular capillaries during tubular reabsorption?

Water, glucose, amino acids, and ions.

How does water reabsorption occur in the renal tubules?

Water diffusion is based on differences in osmolarity, moving from areas of low to high concentration.

What is the transport maximum (Tm)?

The concentration of a substance when carriers are saturated, reflecting the number of available carriers.

What is the renal threshold?

The plasma concentration at which a specific substance or ion begins to appear in urine.

How is glucose normally handled in the renal tubules?

Glucose is freely filtered at the glomerulus and is normally 100% actively reabsorbed in the proximal tubule.

What is the main purpose of tubular secretion?

To move molecules from the plasma or peritubular capillaries into the renal tubules, increasing the quantity of solute excreted in urine.

What is the simple rule of excretion regarding substances in renal tubules?

Material that enters the lumen of the renal tubules is excreted unless it is reabsorbed.

What is the equation for the quantity of a substance excreted in urine?

Amount excreted = Amount filtered + Amount secreted - Amount reabsorbed (E = F + S - R).