Urinary System Overview Quiz

Urinary System Overview

• The urinary system is comprised of the kidneys, ureters, urinary bladder, and urethra.
• The kidneys are located on either side of the vertebral column, extending from the 12th thoracic to 3rd lumbar vertebrae.
• The right kidney is slightly lower than the left.
• Each kidney is approximately 12 cm long, 6 cm wide, and 3 cm thick.

Kidney Structure

• The kidney tissue is differentiated into cortex and medulla.
• Kidneys have two surfaces, two borders, and two ends.
• The lateral border is convex, the medial border is convex at both ends and concave in its middle.
• The middle of the medial border is the hilum.
• The hilum provides passage for renal vessels, nerves, and the pelvis of the kidney.
• The pelvis is a dilated sac, extending beyond the hilum, and connecting to the ureter.

Kidney Relations (Anterior Surface)

• Right Kidney:
  • Right suprarenal gland
  • Duodenum
  • Liver
  • Colon
  • Small intestine
• Left Kidney:
  • Left suprarenal gland
  • Stomach
  • Spleen
  • Pancreas
  • Colon
  • Small Intestine

Kidney Relations (Posterior Surface)

• Diaphragm
• Muscles of posterior abdominal wall (psoas major, quadratus lumborum, transversus abdominis)

Kidney Coverings

• Fibrous capsule
• Perirenal fat
• Renal fascia
• Pararenal fat

Ureters

• Two muscular tubes, one on each side of the body.
• Convey urine from kidneys to the urinary bladder.
• Approximately 25-30 cm in length.
• Half of the ureter course is in abdomen, while the other half is in the pelvis.
• A continuation of the hilum of the kidney.
• Opens into the postero-superior angle of the urinary bladder.
• Three sites of constriction:
  • Pelvi-ureteric junction
  • Crossing common iliac artery
  • Ureter-vesical junction

Urinary Bladder

• A hollow viscus with a strong muscular wall.
• Serves as a reservoir for urine.
• Located in the pelvic cavity, behind the pubic bones.
• Shaped like a three-sided pyramid, placed on one of its angles.
• Capacity is approximately 220 cc, but can accommodate up to 500 cc without discomfort.
• Apex is behind the upper part of the symphysis pubis and continuous with the median umbilical ligament. The base is directed posteriorly.

Urinary Bladder (continued)

• Has three surfaces (one superior and two inferolateral).
• Each surface and base are triangular in shape.
• Related to:
  • Seminal vesicles and ampulla of vas deferens (in males)
  • Cervix of uterus and anterior wall of vagina (in females)
• Ureter enters superolateral angle of base.
• Inferior angle (neck) gives rise to urethra.
• In males, the neck rests on prostate and continues with the prostatic part of the urethra. - In females, it is continuous with the urethra.

Male Urethra

• 20 cm long, divided into three parts
• Prostatic part: 3 cm long, widest portion, begins at bladder neck, surrounded by prostate. Ejaculatory duct opens into it.
• Membranous part: 1 cm long, narrowest/shortest, surrounded by sphincter urethra.
• Spongy part: 16 cm long, longest, traverses penis, and ends at the external urethral orifice.

Female Urethra

• Very short (4 cm).
• Begins at neck of bladder.
• Its upper part is surrounded by the sphincter urethra.
• Shorter, wider, and more dilatable than the male urethra.