Urinary system part IV

Reabsorption

The process by which the renal tubule recovers useful materials from the tubular fluid and returns them to the bloodstream.

Secretion

The process of adding substances from blood to tubular fluid to be excreted with urine.

Renal threshold

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

Glucosuria

The presence of glucose in the urine, often due to high blood glucose levels.

Osmotic concentration

The total number of solute particles per liter, expressed in osmoles or milliosmoles.

Proximal convoluted tubule (PCT)

The part of the nephron where the majority of nutrient reabsorption occurs, including glucose and amino acids.

Nephron loop

The part of the nephron with a descending limb permeable to water and an ascending limb impermeable to water.

Distal convoluted tubule (DCT)

The part of the nephron involved in selective reabsorption of sodium and calcium ions and active secretion of wastes.

Collecting duct

The structure that collects filtrate from multiple nephrons and regulates water and solute reabsorption.

Antidiuretic Hormone (ADH)

A hormone that increases water reabsorption in the collecting ducts, released by the posterior pituitary in response to high blood osmolarity.

Aldosterone

A hormone produced by the adrenal cortex that promotes sodium reabsorption and potassium excretion.

Atrial Natriuretic Peptide (ANP)

A hormone that promotes sodium and water excretion, opposing the effects of aldosterone and ADH.

Renin-Angiotensin-Aldosterone System (RAAS)

A hormone system that regulates blood pressure and fluid balance through action of renin and angiotensin II.

Urinalysis

A chemical and physical analysis of urine used as an important diagnostic tool.

Detrusor muscle

The muscular layer of the urinary bladder that contracts to expel urine.

Urethral sphincter

A circular band of muscle that acts as a valve to control urine discharge.

Urine voiding reflex

A spinal reflex that initiates urination when the bladder's stretch receptors signal fullness.