Urinary System: Kidneys Functions and Anatomy

Urinary System: Kidneys Functions and Anatomy

Kidneys

Responsible for maintaining stable volume, electrolyte composition, and osmolarity of ECF.

Homeostasis

Maintaining stable internal conditions in the body.

ECF

Extracellular fluid; fluid outside the cells.

Urine

Liquid waste product excreted by the kidneys.

Toxic metabolic wastes

Wastes produced by the body's metabolism that are harmful if not eliminated.

Renin

Enzymatic hormone produced by the kidneys that helps regulate salt conservation.

Erythropoietin

Hormone produced by the kidneys that stimulates red blood cell production.

Nephron

Microscopic functional unit of the kidney that forms urine.

Glomerulus

Tuft of capillaries in the nephron where filtration of blood occurs.

Bowman's Capsule

Double-walled cup that surrounds the glomerulus and collects filtered fluid.

Proximal Tubule

Part of the nephron where uncontrolled reabsorption and secretion of substances occur.

Loop of Henle

U-shaped tube in the nephron that establishes an osmotic gradient in the kidney.

Juxtaglomerular Apparatus

Specialized tubular and vascular cells next to the glomerulus that help regulate kidney function.

Distal Tubule

Part of the nephron where controlled reabsorption and secretion of substances occur.

Collecting Duct

Tube that carries fluid from multiple nephrons to the renal pelvis.

Cortical Nephrons

Type of nephron located in the outer layer of the renal cortex.

Juxtamedullary Nephrons

Type of nephron located in the inner layer of the renal cortex, with longer loops of Henle.

Glomerular Filtration

Process of filtering a protein-free plasma from the glomerulus into Bowman's Capsule.

Tubular Reabsorption

Selective movement of filtered substances from the tubular lumen into the peritubular capillaries.

Tubular Secretion

Selective movement of nonfiltered substances from the peritubular capillaries into the tubular lumen.

Urine Excretion

Elimination of substances from the body in urine.

Glomerular membrane

Structure that substances must pass through to be filtered, including pores, basement membrane, and filtration slits.