Presentation on theme: "Explain How do insects, reptiles, and birds eliminate ammonia and how do mammals eliminate ammonia Apply Concepts How do kidneys help maintain homeostasis."— Presentation transcript:
1Explain How do insects, reptiles, and birds eliminate ammonia and how do mammals eliminate ammonia Apply Concepts How do kidneys help maintain homeostasis while processing nitrogenous wastesReview In what form do (a) annelids and mollusks, (b) insects and arachnids, (c) mammals and land amphibians, and (d) reptiles and birds excrete nitrogenous wastesRelate Cause and Effect Explain how differing water balance needs relate to an animals conversion of ammonia to wither urea or uric acid
3The Ammonia ProblemBreakdown of proteins by cells releases a nitrogen- containing waste: ammoniaAmmonia is poisonousModerate concentrations of ammonia can kill most cells.
4ExcretionElimination of metabolic wastes, such as ammoniaSmall animals in wet environments get rid of ammonia by allowing it to diffuse out of their body fluids across their skinMost larger animals have excretory systems that process ammonia and eliminate it from the body.
5Animals that cannot dispose of ammonia continuously have evolved ways to store nitrogenous wastes until they can be eliminated.
6Storing Nitrogenous Wastes Ammonia itself cannot be stored in body fluids because it is too toxicInsects, reptiles, and birds convert ammonia into a sticky white compound called uric acidMuch less toxic than ammonia and is less soluble in water.
7Mammals and some amphibians convert ammonia to urea Urea is less toxic than ammoniaIs highly soluble in water.
8Maintaining Water Balance Excretory systems are extremely important in maintaining the proper balance of water in blood and body tissuesMay also excrete excess water or have to conserve water.
9Kidneys Separate wastes and excess water from blood to form urine Pump ions from salt to create osmotic gradientsWater then “follows” those ions passively by osmosisUsually cannot excrete excess salt.
10Freshwater AnimalsFreshwater invertebrates lose ammonia to their environment by simple diffusion across their skin.
11Freshwater fishes and amphibians eliminate ammonia by diffusion across the same gill membranes they use for respiration.
12Bodies of freshwater animals, such as fishes, contain a higher concentration of salt than the water they live in.
13Water moves into their bodies by osmosis Salt diffuses out.
14Freshwater fish excrete lots of watery urine Don't drink waterActively pump salt in across their gills.
15Saltwater AnimalsTypically release ammonia by diffusion across their body surfaces or gill membranes.
16Many marine invertebrates have body fluids with water concentrations similar to that of the seawater around them.
17Many saltwater animals, such as fishes, contain a lower concentration of salt than the water they live in.
18Lose water through osmosis, and salt diffuses in.
19Saltwater fish conserve water by producing very little concentrated urine Drink waterActively pump salt out across their gills.
20Excretion in Terrestrial Animals Land animals can lose large amounts of water from respiratory membranes that must be kept moistMust eliminate nitrogenous wastes in ways that require disposing of water.
21Terrestrial Invertebrates Produce urine in nephridiaNephridiaTubelike excretory structures that filter body fluid.
22Terrestrial Invertebrates Body fluid enters the nephridia through nephrostomes and becomes more concentrated as it moves along the tubesUrine leaves the body through excretory pores.
23Terrestrial Invertebrates Insects and arachnids convert ammonia into uric acidMalpighian tubulesAbsorb uric acid from body fluidsConcentrate the wastes and add them to digestive wastes.
24Water is absorbed from wastes Crystals form a thick paste which leaves the body through the anusPaste contains little waterMinimizes water loss.
25Terrestrial Vertebrates Mammals and land amphibians convert ammonia into ureaExcreted in urine by the kidneys.
26Reptiles and birds convert ammonia into uric acid Passed through ducts into a cavity that also receives digestive wastes from the gutWalls of cavity absorb waterUric acid separates as thick, milky-white paste recognized as “bird droppings.”
27Most vertebrate kidneys cannot excrete concentrated salt Most vertebrates cannot survive by drinking seawaterAll that extra salt would overwhelm the kidneys, and the animal would die of dehydration.