2. 3 major functions: Excretion: removal of organic wastes from body fluids (KIDNEYS) Elimination: discharge of those wastes into the environment (URINARY BLADDER, URETHRA) Homeostatic regulation of volume and solute concentration of blood plasma The Urinary System
4. Kidneys Located on either side of vert. Column Left is slightly superior to right Each kidney is protected and stabilized by 3 layers of connective tissue Renal capsule (covers entire outer surface) Adipose capsule (adipose tissue that surrounds renal capsule) Renal fascia (anchors the kidney to surrounding structures)
5. Kidneys Cont’d Renal cortex: superficial part, in contact with the renal capsule Renal medulla: contains 16-18 renal pyramids Renal pyramids: base abuts the cortex, tip (renal papillae) projects into renal sinus Renal columns separate renal pyramids Hilus: point of entry and exit for blood vessels, nerves, and ureter
7. Urine Formation 3 Basic Processes Filtration: blood pressure forces water and solutes across the wall of the glomerular capillaries and into the capsular space Reabsorption: removal of water and solutes from the filtrate; occurs after filtrate has left renal corpuscle Secretion: transport of solutes from the peritubular fluid into tubular fluid; backup process for filtration
8. ADH= antidiuretic hormone 3 organic waste products: Urea, creatinine, and Uric acid These can only be eliminated from the body when dissolved in urine, so there is always some water loss