Biology nephron key vocabulary

Cortex

The outer region of the kidney. It contains the glomerulus, renal capsule, proximal convoluted tubule, and distal convoluted tubule.

Medulla

The middle region of the kidney. It contains the Loop of Henle and the collecting duct.

Nephron

Microscopic filtering units, also known as kidney tubules. They are responsible for filtering substances from the blood and forming urine.

Glomerulus

A ball of capillaries that sits in the renal capsule. Blood passes through larger arterioles into the capillaries and leaves through smaller venules.

Ultrafiltration

The process where substances are filtered from the capillaries of the glomerulus into the capsule under pressure. Only small substances like glucose, urea, salts, and water pass across the basement membrane.

Renal (Bowman's) Capsule

A hollow cup-like structure surrounding the glomerulus. It collects the glomerular filtrate produced by ultrafiltration.

Selective Reabsorption

The process by which useful substances, like glucose and sodium ions, are actively transported from the glomerular filtrate back into the blood.

Urea

A nitrogenous waste product formed in the liver when proteins break down. It is filtered by the kidneys and excreted as part of urine.

Urine

Excretory fluid formed by nephrons in the kidney, stored in the bladder, and passed out through the urethra. It contains water, dissolved urea, and salts, with no glucose in a healthy person.

Excretion

The process by which waste products of metabolism are removed from the body. Examples include urea and carbon dioxide. (Note: undigested food leaving the alimentary canal is egestion, not excretion.)

Kidney

The organ responsible for removing urea from the blood and regulating water and salt concentrations. It filters substances from the blood to maintain homeostasis.

Renal artery

The blood vessel that carries blood to the kidney. The blood is under high pressure and contains relatively high levels of urea.

Renal vein

The blood vessel that carries blood away from the kidney. The blood is under low pressure and contains relatively low levels of urea.

Bladder

A muscular organ that stores urine. It receives urine from the kidneys via the ureters and releases it through the urethra.

Urethra

The tube that carries urine from the bladder to the outside of the body.

Ureter

The tube that transports urine from the kidney to the bladder.