CHAPTER 12: THE RENAL (URINARY) SYSTEM
The urinary system contributes to homeostasis by altering blood composition, pH, volume, pressure; maintaining blood osmolality; excreting wastes and foreign substances; and producing hormones.
The urinary or renal system consists of 2 kidneys, 2 ureters, 1 urinary bladder and 1 urethra.
The kidneys do the major work of this system. The other parts are mainly passageways and storage areas.
External Anatomy of the Kidneys
The kidneys sit retroperitoneal in location on the dorsal wall of the abdomen, held in place by the renal fascia. They are smooth externally and are dark, yellowish red to brown colour. The right kidney is heart-shaped and sits below T16-L1, while the left kidney is bean shaped and sits below T18-L3. Each kidney has a dorsal and ventral surface, a convex lateral and a concave medial border & cranial and caudal pole.
3 layers of tissue:
Deepest layer is the Renal Capsule continuous with the outer layer of the ureter. This layer serves as a barrier against trauma and helps to maintain the shape of the kidney. Middle layer is the Adipose Capsule and is a mass of fatty tissue surrounding the renal capsule. This layer also protects the kidney from trauma and holds it firmly in place within the abdominal cavity. Superficial layer is the Renal Fascia that anchors the kidney to surrounding structures and to the abdominal wall.
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