Urinary System

15.1a. Location and structure

• The kidneys are located along the dorsal wall in a retroperitoneal position from vertebra T₁₂ to L₃

• Each roughly the size of a large bar of soap, the kidneys sit inferior to the adrenal glands and are protected by a renal fascia, perirenal fat capsule, and fibrous capsule (superficial to deep)

• When the kidney is viewed in a longitudinal section, the outermost portion is the renal cortex; inside that are the renal pyramids (also called medullary pyramids) separated by renal columns; draining the kidney are the calyces and the renal pelvis

• Blood is supplied to the kidney by the following vessels: renal artery, segmental arteries, interlobar arteries, arcuate arteries, cortical radiate arteries

• Blood is drained from the kidney by the following vessels: cortical radiate veins, arcuate veins, interlobar veins, renal vein

15.1b. Nephrons

• A nephron is the structural and functional unit of the kidney; each acts as a blood filter

  • Cortical nephrons are located in the cortex; juxtamedullary nephrons are located near the junction between the cortex and medulla of the kidney

  • Nephrons have two parts: renal corpuscle (the glomerulus) and glomerular capsule (Bowman’s capsule) and the renal tubule

    • Each renal tubule includes the proximal convoluted tubule (PCT), nephron loop (loop of Henle), distal convoluted tubule (DCT), collecting duct

  • Each nephron is associated with two capillary beds

    • The glomerulus is a special capillary bed fed by the afferent arterio

15.1a. Location and structure

• The kidneys are located along the dorsal wall in a retroperitoneal position from vertebra T₁₂ to L₃

• Each roughly the size of a large bar of soap, the kidneys sit inferior to the adrenal glands and are protected by a renal fascia, perirenal fat capsule, and fibrous capsule (superficial to deep)

• When the kidney is viewed in a longitudinal section, the outermost portion is the renal cortex; inside that are the renal pyramids (also called medullary pyramids) separated by renal columns; draining the kidney are the calyces and the renal pelvis

• Blood is supplied to the kidney by the following vessels: renal artery, segmental arteries, interlobar arteries, arcuate arteries, cortical radiate arteries

• Blood is drained from the kidney by the following vessels: cortical radiate veins, arcuate veins, interlobar veins, renal vein

15.1b. Nephrons

• A nephron is the structural and functional unit of the kidney; each acts as a blood filter

  • Cortical nephrons are located in the cortex; juxtamedullary nephrons are located near the junction between the cortex and medulla of the kidney

  • Nephrons have two parts: renal corpuscle (the glomerulus) and glomerular capsule (Bowman’s capsule) and the renal tubule

    • Each renal tubule includes the proximal convoluted tubule (PCT), nephron loop (loop of Henle), distal convoluted tubule (DCT), collecting duct

  • Each nephron is associated with two capillary beds

    • The glomerulus is a special capillary bed fed by the afferent arterio