Lecture Notes: Anatomy and Physiology of the Kidney

Introduction

• The lecture discusses the complexity of kidney physiology compared to the respiratory system.
• Human kidney physiology is unique compared to other species due to evolutionary modifications.

Kidney Anatomy

• Six main urinary organs: 2 kidneys, 2 ureters, bladder, and urethra.
• Kidneys are located retroperitoneally and surrounded by fat.
• Fat supports kidney placement; significant weight loss can cause kidney displacement.

Blood Flow and Kidney Function

• Blood flow to kidneys decreases significantly during exercise.
• Kidneys filter nitrogen waste; essential for removing ammonia and uric acid.
• Overarching purpose: Maintain water balance and waste removal.

Nephron Structure and Function

• Nephron: functional unit of the kidney responsible for filtration and reabsorption.
• Components include the glomerulus, proximal convoluted tubule, loop of Henle, distal convoluted tubule, and collecting duct.
• Filtration occurs at the glomerulus, reabsorption and secretion in the proximal tubule.
• Loop of Henle: crucial in creating concentration gradients for water reabsorption.

Blood Vessel Anatomy

• Key vessels: renal artery, renal vein, afferent and efferent arterioles.
• Three capillary beds: glomerulus, peritubular capillaries, and vasa recta.
• No portal circulation in the kidneys; blood flows from glomerulus through arterioles and capillaries.

Physiological Processes

• Kidney filtration suppressed in sympathetic mode.
• Creatinine in blood and urine helps assess kidney function.
• Kidneys have a role in balancing body's electrolytes, including potassium secretion.

Kidney Diseases and Conditions

• Polycycstic kidney disease and kidney stones discussed.
• Kidney stones form in renal pelvis and can cause significant pain.
• Gout is caused by uric acid crystals, often affecting joints like toes.

Microscopic Kidney Anatomy

• Kidney cortex and medulla have distinct structures and functions.
• Nephrons in cortex and medulla differ in their loop of Henle lengths.

Water and Waste Management

• Kidneys adjust urine concentration to conserve water.
• Marine mammals and desert animals have adaptations for water management.

Summary

• Understanding kidney anatomy and physiology is essential for comprehending its role in waste removal and fluid balance.
• Complexities in physiological processes underscore the importance of thorough study and clinical awareness.