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Chapter 38: Excretory System. Functions of the Excretory System. a. Collect water and filter body fluids b. Remove and concentrate waste products from body fluids and return other substances to body fluids as necessary for homeostasis c. Eliminate excretory products from the body
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Functions of the Excretory System a. Collect water and filter body fluids b. Remove and concentrate waste products from body fluids and return other substances to body fluids as necessary for homeostasis c. Eliminate excretory products from the body - Include the kidneys (removes the most metabolic waste via urine),liver, lungs, and skin *** Responsible for regulating water balance in various body fluids - Osmoregulation is the active regulation of the osmotic pressure of an organism's fluids to maintain the homeostasis of the organism's water content; that is it keeps the organism's fluids from becoming too dilute or too concentrated (balance b/w sodium & water)
ANIMAL EXCRETORY STRUCTURES • PROTOZOA: CELL MEMBRANE (DIFFUSION) CONTRACTILE VACUOLE (EXCESS WATER) • FLATWORM(PLANARIA): FLAME CELLS • EARTHWORM: NEPHRIDIA, SKIN • GRASSHOPPER: MALPHIGIAN TUBULES, TRACHEAE • CRAYFISH: KIDNEYS, GILLS • HUMAN: LUNGS, SKIN, LIVER, KIDNEYS • SNAKE: KIDNEYS
Made-up of the kidneys, ureters, bladder, and urethra. • Nephron, an evolutionary modification of the nephridium the kidney's functional unit • Waste is filtered from the blood and collected as urine in each kidney • Urine leaves the kidneys by ureters, and collects in the bladder can distend to store urine that eventually leaves through the urethra
Renal artery brings blood into kidneys • Renal vein takes blood back to heart
Nephron- Urine Production Urine Production 1. Filtration in the glomerulus and nephron capsule 2. Reabsorption in the proximal tubule 3. Tubular secretion in the Loop of Henle Components of The Nephron a. Glomerulus: mechanically filters blood b. Bowman's Capsule: mechanically filters blood c. Proximal Convoluted Tubule: reabsorbs 75% of the water, salts, glucose, and amino acids d. Loop of Henle: countercurrent exchange, which maintains the concentration gradient e. Distal Convoluted Tubule: tubular secretion of H ions, potassium, and certain drugs
Capillaries Bowman’s capsule Cortex Glomerulus Renal artery Medulla Renal vein Collecting duct Ureter Vein To the bladder Artery To the ureter Loop of Henle Structure of the Kidneys Section 38-3 Kidney Nephron
The Nephron Section 38-3 Reabsorption As the filtrate flows through the renal tubule, most of the water and nutrients are reabsorbed into the blood. The concentrated fluid that remains is called urine. Filtration Most filtration occurs in the glomerulus. Blood pressure forces water, salt, glucose, amino acids, and urea into Bowman’s capsule. Proteins and blood cells are too large to cross the membrane; they remain in the blood. The fluid that enters the renal tubules is called the filtrate.
KANGAROO RAT – LIVE IN HYPERTONIC ENVIRONMENT ADAPTATIONS • VERY EFFICIENT KIDNEYS, WHICH ALLOW IT TO LIVE WITHOUT DRINKING! • HAVE A LONGER LOOP OF HENLE IN THEIR NEPHRONS, CAUSING THEM TO PRODUCE URINE THAT IS 5 TIMES MORE CONCENTRATED THAN HUMANS • DON’T SWEAT, AND LOSE WATER ONLY THROUGH EVAPORATION DURING GAS EXCHANGE • RETAIN 90% OF THEIR WATER, AND 10% COMES FROM THEIR DIET