Urinary System Overview and Functions

Urinary System Overview

• The urinary system transports waste from the kidneys to the bladder.
• In females, the kidneys are positioned near the ovaries.
• Kidneys are located in the upper part of the posterior abdominal wall, on either side of the vertebral column.
• The right kidney is positioned at the level of T12 to L3, while the left kidney is located at the level of T11 to L2.

Kidney Functions

• Blood filtration, removing waste products.
• Maintaining electrolyte balance.
• Maintaining acid-base balance.
• Regulating blood volume and pressure.
• Activating vitamin D.
• Producing erythropoietin (for red blood cell creation) and other hormones.

Kidney Structure & Location

• Located in the posterior abdominal wall, on either side of the vertebral column.
• The left kidney is typically situated higher than the right kidney.
• The right kidney is situated at the level of T12 to L3, while the left kidney is located at the level of T11 to L2.

Urinay System Structures

• Kidneys: Filter blood, forming urine.
• Ureters: Tubes that transport urine from the kidneys to the bladder.
• Urinary bladder: Stores urine until it is expelled.
• Urethra: Tube through which urine exits the body.

Stages of Urine Formation

• Filtration: Plasma fluid from the glomerulus moves into the glomerular capsule.
• Reabsorption: Beneficial substances (water, glucose, electrolytes) are transported back into the bloodstream.
• Excretion: Metabolic waste products are transferred from capillaries into the tubules and become part of the urine.

Ureters

• Channels approximately 25-30 cm long.
• Transport urine from the kidneys to the bladder.
• Pass through the linea terminalis to enter the pelvis minor.
• Travel along the lateral wall of the pelvis to reach the bladder.

Bladder

• Reservoir for urine.
• Located posterior to the symphysis pubis.
• Located anterior to the uterus in females and anterior to the rectum in males.
• Normal capacity is about 220 mL, but can hold up to 500 mL.
• Empty bladder lies within the pelvis minor, and when full can extend to the level of the umbilicus.

Urethra

• Tube through which urine exits the body.
• Male urethra is longer (20 cm), while the female urethra is shorter (3-5 cm).
• Contains internal and external sphincters which control urine release.
• The urethra is shorter in females than in males and is subject to more infections.

Kidney Structure

• Cortex: Outer layer containing the glomeruli and tubules.
• Medulla: Inner layer containing the loop of Henle.
• Renal pelvis: Collecting area for urine.
• Calyces: Cup-shaped structures in the renal pelvis to initially collect urine.