Regulation of Urine

A set of flashcards covering key terms and concepts related to the regulation of urine, nephron function, and hormonal influences.

Proximal Convoluted Tubule (PCT)

The segment of the nephron where 99% of filtered organic nutrients and 60-70% of filtered water are reabsorbed.

Loop of Henle

A nephron segment responsible for the obligatory reabsorption of water and NaCl, vital for the counter-current multiplication mechanism.

Counter-current multiplication

A mechanism occurring in the Loop of Henle that enhances overall reabsorption due to differing permeabilities of the limbs.

Facultative reabsorption

Water reabsorption regulated by hormonal signals, occurring primarily in the distal convoluted tubule (DCT) and collecting duct (CD).

ADH (Antidiuretic hormone)

A hormone that increases water reabsorption in the kidneys by enhancing the number of aquaporins in DCT and CD cells.

Aldosterone

A hormone that regulates Na+ reabsorption and K+ excretion in the DCT and collecting duct, affecting urine volume and composition.

Diuretic

Any drug that causes diuresis or increased urine production by inhibiting specific renal transporter proteins.

Collecting Duct (CD)

The nephron segment responsible for the facultative reabsorption of water and ions, modulated by ADH and aldosterone.

Thin limb of the Loop of Henle

Permeable to water but impermeable to solutes, facilitating water reabsorption.

Thick limb of the Loop of Henle

Impermeable to water, can pump Na+ and Cl- out of the tubular fluid into the interstitium.

Diabetes Insipidus

A condition caused by deficiency or resistance to ADH, leading to polyuria (excessive urination) and polydipsia (excessive thirst).

Osmolarity gradient

A difference in concentration of solutes in distinct regions, critical for the kidney's ability to concentrate urine.

Aquaporin

Water channels in cell membranes that facilitate transmembrane water transport, activated by ADH.

Renin-Angiotensin-Aldosterone System (RAAS)

A hormone system that regulates blood pressure and water balance primarily through aldosterone secretion.

Paracellular transport

Movement of substances between epithelial cells, playing a minor role in the nephron due to tight junctions in some segments.

Juxtamedullary nephron

A type of nephron with a long Loop of Henle that extends deep into the renal medulla, crucial for the concentration of urine.

Epithelial Na+ Channels (ENaC)

Channels added to the apical surface of DCT and CD cells by aldosterone to enhance sodium reabsorption.

Vasa recta

The capillary network surrounding the nephron that helps maintain the osmotic gradient through counter-current exchange.

Principal cells

Cell types in the collecting duct that are involved in Na+ reabsorption and water permeability regulation.

Polyuria

Excessive urination, commonly associated with diabetes insipidus due to impaired ADH function.