Presentation on theme: "Excretory System Yixuan He. Function Collect water and filter body fluids. Maintain homeostasis Remove and concentrate waste products from body fluids."— Presentation transcript:
Excretory System Yixuan He
Function Collect water and filter body fluids. Maintain homeostasis Remove and concentrate waste products from body fluids and return other substances to body fluids as necessary Eliminate excretory products from the body.
Kidney Eliminate wastes from the bloodstream by production of urine. Function: Maintain volume of extracellular fluid Maintain ionic balance in extracellular fluid Maintain pH and osmotic concentration of the extracellular fluid. Excrete toxic metabolic by-products
Ureters Muscular ducts that propel urine from the kidneys to the urinary bladder. Urine enters the bladder through the ureters
Bladder collects urine excreted by the kidneys prior to disposal by urination. It is a hollow,muscular, and elastic organ Sits on the pelvic floor.
Urethra A tube which connects the urinary bladder to the outside of the body Urine leaves the bladder through the urethra.
Nitrogenous Waste: Ammonia Very soluble Can only be tolerated at very low concentrations Common in aquatic species. Animals that excrete ammonia need access to lots of water Ammonia molecules easily pass through membranes and are readily lost by diffusion to the surrounding water.
Nitrogenous Waste: Urea Produced in the vertebrate liver by a metabolic cycle that combines ammonia with carbon dioxide. Low toxicity. Permits animals to transport and store urea safety at high concentrations Mammals, adult amphibians, sharks, and some marine bony fishes and turtles Do not have constant access to sufficient water to excrete ammonia Urea-excreting animals requires much less water, because much less water is lost when a given quantity of nitrogen is excreted
Nitrogenous Waste: Uric Acid Nontoxic Largely insoluble in waste Can be excreted as a semi-solid paste with very little loss Insects, land snails, and many reptiles, including birds Little access to water However, it is energetically expensive
Proximal tubule The portion of a nephron immediately downstream from Bowman’s capsule Conveys and helps refine filtrate Loop of Henle The long hairpin turn, with a descending and ascending limb, of the renal tubule in the vertebrate kidney. Functions in water and salt reabsorption Distal tubule Helps refine filtrate and empties it into the collecting duct Collecting duct Where filtrate from renal tubules is collected The filtrate, once in the collecting duct, is called urine. Cortical nephrons Nephrons located almost entirely in the renal cortex. These have a reduced loop of Henle Juxtamedullary nephrons Nephrons with well-delevoped loops of Henle that extend deeply into the renal medulla
Filtration The extraction of water and small solutes, including metabolic wastes, from the body fluid into the excretory system. Occurs as blood pressure forces fluid from the blood in the glomerulus of the nephron into the lumen of the Bowman’s capsule.
Reabsorption The uptake of solutes from a filtrate of blood, coelomic fluid, or hemolymph in the excretory organs of animals The proximal tubules reabsorb about 90% of the important buffer bicarbonate to maintain the pH. They also reabsorb most of the NaCl and water from the initial filtrate volume. Reabsorption of water continues into the descending limb of the loop of Henle. The Distal tubule is similar to the proximal tubules in that it reabsorbs buffer bicarbonate and NaCl
Secretion The discharge of wastes from the body fluid into the filtrate. Active transport The Proximal tubules and the Distal tubules maintains pH by controlling the secretion of H + and K + The Proximal tubule secretes ammonia
Excretion The disposal of nitrogen-containing waste products of metabolism The collecting duct of a nephron, carrying the filtrate through the medulla to the renal pelvis, becomes permeable to urea in the inner medulla. Along with the salt, the urea contributes to high osmolarity of the interstitial fluid in the medulla, and this high osmolarity enables the kidney to excrete urine, which is hyperosmotic to the general body fluids.
Kidney Stone A solid piece of material that forms in a kidney when substances that are normally found in the urine become highly concentrated. Symptoms pain while urinating blood in the urine a sharp pain in the back or lower abdomen. Kidney stones affect approximately 1 in 11 people in the United States. Treatment Shock wave lithotripsy Ureteroscopy Percutaneous nephrolithotomy
Nephritis inflammation of the nephrons in the kidneys. Symptoms Swelling of the tissues Reduction in urine volume Dark urine (contains blood which may not be visible) Increase in blood pressure Headaches Drowsiness Visual disturbances Nausea Treatment: Restriction of salt Antibiotics renal dialysis affects 1 in 4,428 Americans
Sources BBC shtml shtml excretorysystemdiseases Prevalence of Kidney Stones in the U.S. NKUDIC px#symptoms px#symptoms t.html t.html AP Biology Textbook Campbell, Neil A., Jane B. Reece, Lisa A. Urry, Michael L. Cain, Steven A. Wasserman, Peter V. Minorsky, and Robert B. Jackson. AP Edition: Biology. New York: Benjamin/Cummings, 2008.