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DESCRIPTIONExcreting wastes. 7.3. Introduction. Many products from metabolism harmful. Lungs eliminate CO2 Large intestine removes toxic waste digestive system Liver transforms toxins (alcohol & heavy metals) into soluble compounds that kidneys can deal with. - PowerPoint PPT Presentation
Excreting wastes7.3IntroductionMany products from metabolism harmful.Lungs eliminate CO2Large intestine removes toxic waste digestive systemLiver transforms toxins (alcohol & heavy metals) into soluble compounds that kidneys can deal with.Kidneys play crucial role in removing waste, balancing pH, and maintaining water balance. Protein metabolismAverage Canadian consumes more protein than needed. Excess protein carbohydratesNitrogen + 2H need to be removed from amino acidsDeamination: occurs in the liver. Ammonia is a water-soluble gas: extremely toxic.Build-up of 0.005 mg can kill a human. Two ammonia + CO2 urea: 100 000 x less toxic
Nucleic acid metabolismUric acid: formed by breakdown of nucleic acids. Kidneys help in excretionWater balanceMaintained by kidneysHumans lose approx. 2L of water a day: urine, perspiration, exhaled air. Drop in fluid intake by 1% = thirst. 5% = pain and collapse. 10% = death. Excretion: simpleUnicellular & simple multicellular (sponge)Every cell in contact with external environmentWastes released directly from cellFluid regulation? Ameoba & paramecium: hypertonic to freshwater: contractile vacuoles.
Excretion: complexNot every cell in contact with external environment. Wastes need to be collected and temporarily stored. Excretory system: cells work together to remove wastes from body or store waste until signalled to remove them. earthwormNephrostome: funnel-like structure: draws fluids from body cavity into tiny tubules. Collecting tubule: collects fluids from nephrostome. Bladder. Nephridiopore: small pores in which wastes are released.
GrasshopperMalpighian tububles: throughout body cavity: absorb wastes by diffusion. Wastes released into gut and eliminated as solid wastes from the anus.
..to more complex...
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