excretions and osmo

Osmolarity

Concentration of solutes in a solution, measured in mosm/L. Normal osmolarity of blood is approximately 300 mosm/L.

Bowman's capsule

The initial structure in the nephron where filtration of blood occurs.

Proximal tubule

The segment of the nephron following Bowman's capsule, involved in reabsorbing water and salts.

Descending loop of Henle

Part of the nephron where water is reabsorbed, increasing the osmolarity of the filtrate.

Ascending loop of Henle

Part of the nephron where salt is reabsorbed, leading to a decrease in the osmolarity of the filtrate.

Distal tubule

The segment of the nephron where osmolarity is approximately 100 mosm/L and changes little.

Collecting duct

Final part of the nephron where the filtrate passes back through the medulla and osmolarity increases due to water loss.

Antidiuretic hormone (ADH)

Hormone produced by the hypothalamus that increases water reabsorption in the kidneys.

Juxtaglomerular apparatus (JGA)

Specialized kidney tissue that releases renin in response to decreased blood pressure or Na+ concentration.

Renin

An enzyme released by the JGA that converts angiotensinogen to angiotensin II.

Angiotensin II

A hormone that increases blood pressure and volume by causing arterioles to constrict and stimulating reabsorption of salt and water.

Aldosterone

Hormone released by the adrenal glands that promotes salt and water reabsorption in the distal tubule.

Atrial natriuretic factor (ANF)

A hormone that opposes the renin-angiotensin-aldosterone system (RAAS) by promoting the excretion of salt and water in response to increased blood pressure.