UNIT 4: EXCRETION AND WASTE MANAGEMENT. Excretion and Waste Management What would happen if you...
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Transcript of UNIT 4: EXCRETION AND WASTE MANAGEMENT. Excretion and Waste Management What would happen if you...
Excretion and Waste Management What would happen if you never threw
out your garbage or leftover food? Be as detailed and exact as possible Specific to your house and family
Why do we sweat?
Why do we urinate?
Waste Removal
One of the 7 life processes = removal of waste products produced by the cells of our bodies
What are the waste products in the human body? Brainstorm on a piece of paper Compile your ideas into the following table
on chart paper:Waste Product Origin Organ of Excretion
Waste Products
Waste Product Origin Organ of
Excretion
Ammonia Breakdown of amino acids in the liver Kidney
Urea Conversion of ammonia in the liver Kidney
CO2 Cellular respiration Lungs
Water Cellular respiration Kidneys
Mineral Salts Food and water Kidneys
Lactic Acid
Anaerobic cellular respiration Liver
Excretory System
Why 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 intestines
Brainstorm: the relationships between the excretory system and the respiratory system, and the digestive system.
How might the excretory system be involved in homeostasis?
Waste Products: Cellular Respiration
We obtain energy by converting complex organic compounds into simpler compounds. BUT some of these simpler compounds can be harmful
Carbon Dioxide Humans produce an average of 1kg per day! If levels become too high = our blood becomes acidic
Leads to breakdown of enzymes, etc… Most is converted to bicarbonate ions (less harmful):
HCO3-
Lactic Acid Converted to pyruvate (aerobic respiration) OR removed through conversion to glucose
Water
Waste 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 kidneys Alcohol, heavy metals (Fe, Al, Hg)
The liver also transforms the hazardous products of protein breakdown to be eliminated by the kidneys
Waste 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 carbohydrates
BUT proteins, unlike carbohydrates, contain nitrogen.
When amino acids (the protein building blocks) are broken down we get the by-product: ammonia
Ammonia
Deamination = the breakdown of amino acids occurs in the liver. byproduct = ammonia (NH3)
BUT ammonia is extremely toxic - a buildup of as little as 0.005 mg is lethal!
In the liver, two molecules of ammonia combine with another waste product, CO2, to form urea
3 Hydrogen atoms (H+) that can be donated to
increase acidity
This acidity makes it a useful agent for
household cleaners
Urea
Urea is 100 000 times less toxic than ammonia. The blood can dissolve 33 mg of urea per 100 mL of
blood.
Excretion: Simple Organisms For ALL organisms, getting wastes out of the
cell is just as important as bringing in nutrients Otherwise toxins would build up and the cell
would soon die In unicellular organisms and in primitive
multicellular organisms (e.g. a sponge) every cell is in direct contact with the external environment Therefore, wastes are released directly from the
cell and water currents carry the waste away
Excretion: Simple Organisms BUT, unicellular
organisms must regulate their internal fluids More dissolved solutes
then their freshwater surroundings
Therefore, these cells should draw in water, expand, and eventually burst
Fluid Regulation: a contractile vacuole expels excess water, preventing this swelling
Excretion: 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 environment Therefore, wastes must be collected and
temporarily stored A secondary problem: our cells are so
specialized that not every cell is designed to remove wastes Wastes must be transported to cells that are
capable of excretion
The 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.
Malpighian 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.
Excretory System StructuresClass Activity1. Structure (how is it built, where is it in the
body) Include a simple diagram
2. Role (in terms of waste removal)3. One way in which it is related to one of the
other structures in the excretory system4. One way in which it is related to digestive,
respiratory, and circulatory system5. How it helps to maintain homeostasis (include
one feedback loop/process)