2Excretion and Waste Management What would happen if you never threw out your garbage or leftover food?Be as detailed and exact as possibleSpecific to your house and familyWhy do we sweat?Why do we urinate?
3Waste RemovalOne of the 7 life processes = removal of waste products produced by the cells of our bodiesWhat are the waste products in the human body?Brainstorm on a piece of paperCompile your ideas into the following table on chart paper:Waste ProductOriginOrgan of Excretion
4Waste Products Waste Product Origin Organ of Excretion Ammonia Breakdown of amino acids in the liverKidneyUreaConversion of ammonia in the liverCO2Cellular respirationLungsWaterKidneysMineral SaltsFood and waterLactic AcidAnaerobic cellular respirationLiver
6Excretory SystemWhy is feces not included in the list of metabolic wastes?Feces is not a product of cellular metabolism. It is a “leftover” after the body absorbs what nutrients it needs from the intestinesBrainstorm: the relationships between the excretory system and the respiratory system, and the digestive system.How might the excretory system be involved in homeostasis?
7Waste Products: Cellular Respiration We obtain energy by converting complex organic compounds into simpler compounds.BUT some of these simpler compounds can be harmfulCarbon DioxideHumans produce an average of 1kg per day!If levels become too high = our blood becomes acidicLeads to breakdown of enzymes, etc…Most is converted to bicarbonate ions (less harmful): HCO3-Lactic AcidConverted to pyruvate (aerobic respiration)OR removed through conversion to glucoseWater
10Waste Products: Metabolism The large intestine removes toxic waste from the digestive system.The liver transforms these ingested toxins into soluble compounds that can be eliminated by the kidneysAlcohol, heavy metals (Fe, Al, Hg)The liver also transforms the hazardous products of protein breakdown to be eliminated by the kidneys
11Waste Products: Metabolism Why are proteins so harmful?Fact: The average Canadian consumes more protein than is required to maintain tissues and promote cell growth.Excess protein is often converted into carbohydratesBUT proteins, unlike carbohydrates, contain nitrogen.When amino acids (the protein building blocks) are broken down we get the by-product: ammonia
12Ammonia Deamination = the breakdown of amino acids occurs in the liver.byproduct = ammonia (NH3)BUT ammonia is extremely toxic - a buildup of as little as mg is lethal!In the liver, two molecules of ammonia combine with another waste product, CO2, to form urea
16Urea Urea is 100 000 times less toxic than ammonia. The blood can dissolve 33 mg of urea per 100 mL of blood.
17Excretion: Simple Organisms For ALL organisms, getting wastes out of the cell is just as important as bringing in nutrientsOtherwise toxins would build up and the cell would soon dieIn unicellular organisms and in primitive multicellular organisms (e.g. a sponge) every cell is in direct contact with the external environmentTherefore, wastes are released directly from the cell and water currents carry the waste away
18Excretion: Simple Organisms BUT, unicellular organisms must regulate their internal fluidsMore dissolved solutes then their freshwater surroundingsTherefore, these cells should draw in water, expand, and eventually burstFluid Regulation: a contractile vacuole expels excess water, preventing this swelling
20Excretion: Complex Organisms Complex multicellular organisms are faced with the same problem but on a much bigger scale.Not every cell is in direct contact with the external environmentTherefore, wastes must be collected and temporarily storedA secondary problem: our cells are so specialized that not every cell is designed to remove wastesWastes must be transported to cells that are capable of excretion
21The earthworm uses a series of tubules to remove wastes from the blood and body cavity. Cells lined with cilia surround a funnel-like structure (the nephrostome) and draw fluids from the body cavity into tiny tubules. The wastes are stored as urine and are released through small pores (nephridiopores) along the body wall.
22Malpighian tubules that run throughout the body cavity of an insect absorb wastes by diffusion. Wastes are released into the gut and eliminated with solid wastes from the anus.
24Human Excretory System Major structures:KidneysLiverLarge IntestineLungsSkin
25Excretory System Structures Class ActivityStructure (how is it built, where is it in the body)Include a simple diagramRole (in terms of waste removal)One way in which it is related to one of the other structures in the excretory systemOne way in which it is related to digestive, respiratory, and circulatory systemHow it helps to maintain homeostasis (include one feedback loop/process)