Kidney Function and Regulation

These flashcards cover key vocabulary related to kidney function and regulation, including definitions of important terms and concepts.

Nephron

The functional unit of the kidney, with about one million in each kidney.

Bowman's capsule

Structure where a protein-free ultrafiltrate of plasma is formed.

Proximal convoluted tubule

Main site for reabsorption of water and solutes into the interstitial fluid and peritubular capillaries.

Loop of Henle

Part of the nephron that creates a highly concentrated interstitial fluid in the medulla.

Distal tubule/Collecting duct

Regulates solute reabsorption and secretion, with water content regulation in the medullary collecting duct.

GFR (glomerular filtration rate)

The amount of plasma that enters Bowman's capsules per minute, with urine output being about 1% of the GFR.

Podocytes

Cells that form the inner layer of Bowman's capsule, featuring filtration slits that allow water and ions to pass but not proteins.

Tubular maximum (Tm)

The maximum transport capacity of carrier proteins in the nephron.

Filtered load

The amount of substance entering the tubules per minute.

Countercurrent mechanism

The process where fluid flows down the descending limb and up the ascending limb of the Loop of Henle, establishing an osmotic gradient.

ECF [Na+]

Extracellular fluid sodium concentration, which is directly related to plasma volume regulation.

Renin

An enzyme released by the kidneys that is stimulated by low arterial pressure, low GFR, or increased renal sympathetic nerve activity.

Angiotensin II (AT II)

A hormone that increases plasma renin levels and has multiple effects on fluid balance and blood pressure.

Acidosis

A condition characterized by increased H+ secretion in the kidneys and increased CO2 removal by the lungs.

Alkalosis

A condition characterized by decreased H+ secretion in the kidneys and decreased CO2 removal by the lungs.

Parathyroid hormone (PTH)

A hormone that regulates plasma calcium levels by increasing gut absorption, bone resorption, and kidney reabsorption.

Normal plasma osmolarity

290-300 mOsm/L, the concentration of solutes in plasma.

Normal plasma pH range

7.35-7.45, the normal acidity or alkalinity of the plasma.