Lecture Notes: Urinary System

Overview

• Restart of the urinary system: includes ureter, urinary bladder, and urethra
• Urinary system organs positioned retroperitoneal

Anatomy of the Kidneys

• Located posterior to the abdomen
• Right kidney: lower than the left due to the liver's position
• Each kidney has an adrenal gland on top
• Outer surface is convex, medial side has an indentation called the hilum
• Blood vessels, lymphatics, ureter, and nerves enter/exit at the hilum
• Three protective layers: renal fascia, perirenal fat capsule, and fibrous capsule
• Fibrous capsule prevents infections from spreading

Kidney Structure

• Functional unit: nephron (about 1 million per kidney)
• Internal structure: cortex (outer region), medulla (inner region)
• Medulla contains renal pyramids separated by renal columns
• Pyramids drain urine into minor calyces, which drain into major calyces and then into the renal pelvis

Nephron Structure

• Consists of renal corpuscle and renal tubule
• Renal corpuscle includes glomerulus and glomerular (Bowman's) capsule
• Filtration membrane: capillary endothelium, basement membrane, and foot processes of podocytes
• Proximal convoluted tubule, nephron loop (Loop of Henle), and distal convoluted tubule make up the renal tubule

Kidney Functions

• Regulates blood volume and pressure
• Maintains osmolarity of blood
• Acid-base balance: excretes hydrogen ions and reabsorbs bicarbonate
• Removes metabolic waste and excess substances
• Produces hormones: erythropoietin (stimulates RBC production) and renin (regulates blood pressure)
• Activates Vitamin D
• Plays a role in glucose metabolism during fasting

Important Distinctions

• Understand the protective layers and structures surrounding the kidney
• Recognize the parts of the nephron and their roles
• Comprehend the functional significance of each kidney component and their role in homeostasis