Anatomy and Functions of the Kidneys

Kidneys

Location and Structure

• Located in the upper abdominal cavity, one on each side of the spine
• Bean-shaped organs, approximately 4-5 inches long and 2-3 inches wide
• Protected by the rib cage and surrounded by a layer of fat
• Each kidney has a distinct outer layer (cortex) and inner layer (medulla)

Functions

• Filtration: remove waste and excess substances from the blood
• Regulation: maintain electrolyte balance, pH balance, and blood pressure
• Endocrine: produce hormones that help regulate blood pressure, produce red blood cells, and maintain strong bones

Nephrons

• Functional units of the kidney, approximately 1 million per kidney
• Consist of:
  • Glomerulus: a cluster of capillaries that filter the blood
  • Bowman's capsule: a double-layered epithelial sac that surrounds the glomerulus
  • Proximal convoluted tubule: reabsorbs water and nutrients back into the bloodstream
  • Loop of Henle: concentrates or dilutes the urine
  • Distal convoluted tubule: further regulates electrolyte balance
  • Collecting duct: collects and transports urine to the renal pelvis

Blood Supply and Nerve Supply

• Renal artery: supplies oxygenated blood to the kidney
• Renal vein: returns deoxygenated blood to the heart
• Nerve supply: sympathetic and parasympathetic nerves regulate kidney function and respond to changes in blood pressure