Anatomy of Urinary System Lecture 11

Functions of the Urinary System

• The urinary system is the major excretory system of the body, consisting of two kidneys, ureters, urinary bladder, and urethra.
• The kidneys filter a large volume of blood, collecting waste products and forming urine, which consists of excess water, ions, metabolic wastes, and toxic substances.
• As long as about one-third of one kidney remains functional, survival is possible.
• The kidneys' functions include excretion, regulation of blood volume and pressure, regulation of blood solute concentrations, regulation of extracellular fluid pH, regulation of red blood cell synthesis, and regulation of vitamin D synthesis.

Anatomy of the Kidneys

• The kidneys are bean-shaped organs, located behind the peritoneum on each side of the vertebral column, and surrounded by a layer of connective tissue called the renal capsule and a thick layer of adipose tissue.
• Each kidney has a medial side with a hilum, where the renal artery and nerves enter, and the renal vein, ureter, and lymphatic vessels exit.
• The hilum opens into a cavity called the renal sinus, which contains blood vessels, part of the system for collecting urine.

Internal Anatomy of the Kidneys

• The kidneys are organized into two major regions: the outer cortex and the inner medulla that surrounds the renal sinus.
• The cortex is the location for the blood-filtering structures of the kidney.
• The medulla is composed of many cone-shaped renal pyramids, whose bases project into the cortex.
• The renal pyramids transport fluid throughout the kidney and modify it into urine, which is then collected by ducts in the renal pyramids.
• The tips of the pyramids, the renal papillae, point toward the renal sinus, where urine is collected for movement to the urinary bladder.
• Urine from several calyces is emptied into a single, enlarged, funnel-shaped chamber called the renal pelvis, which narrows into the small-diameter tube called the ureter for transport to the urinary bladder.