Excretory System Biology PDF

The Excretory (urinary) System The excretory system removes waste and excess fluids from the body through the kidneys, ureters, bladder, and urethra. The Structures Involved: -​ kidneys -​ ureter -​ bladder -​ urethra Purpose: -​ Remove waste (urea) and unneeded substances from the...

The Excretory (urinary) System The excretory system removes waste and excess fluids from the body through the kidneys, ureters, bladder, and urethra. The Structures Involved: -​ kidneys -​ ureter -​ bladder -​ urethra Purpose: -​ Remove waste (urea) and unneeded substances from the body -​ Protein breakdown creates ammonia in the liver (toxic), which is converted to less toxic urea -​ Blood carries urea to kidneys for elimination The Kidney & Urine Formation: 4 Phases: -​ Filtration -​ Reabsorption -​ Secretion -​ Excretion Filtration: -​ Renal arteries bring blood to kidneys -​ Blood goes to nephron, fluids enter Bowman’s Capsule, blood cells can't pass through Reabsorption: -​ Happens in the Loop of Henle -​ 119 ml returned to blood, 1 ml becomes urine (95% water, 5% waste) Secretion:​ ​ -​ Excess substances transferred into nephron for elimination Excretion:​ ​ -​ Urine is carried by ureters to the bladder for storage -​ When it is time, urinary sphincter opens, urine exits through urethra Kidney-Related Diseases:​ -​ Kidney Stones: Hard material of minerals and salts formed in kidneys or urinary tract -​ Gout: Arthritis caused by uric acid crystals in joints, very painful Urinary Tract Infection (UTI): Bacteria in urinary tract causing infection: -​ Urethritis: Urethra infection -​ Cystitis: Bladder infection -​ Pyelonephritis: Kidney infection 2 Types of Kidney Dialysis (solutions) Hemodialysis (HD): -​ Blood is filtered outside the body and returned -​ Takes 3-4 hours, 3 times a week -​ Vein surgically enlarged for easy catheter access Peritoneal Dialysis (PD): -​ Solution added to peritoneal cavity via abdominal catheter -​ Osmosis/diffusion removes waste from blood -​ Takes 30 minutes, 4 times a day -​ Can be done at home, more convenient