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The Atmosphere

This is an image of a mobile phone with a message that reads Most of the gases in the Earth’s atmosphere are in the first 16 kilometres above the Earth’s surface. That’s 29 CN Towers high! #funfact.
 

AtmosphericComposition

Long Description

 

This is an image of a thought bubble drawn in black on a white background.   What Do You Think?

  • What surprised you about the composition of the atmosphere?
  • What gases in the atmosphere do you think are needed for us to breathe?
  • Do you think that any of the gases in the atmosphere might be harmful to us? Why do you think this?
Action.

ACTION

Gases of the Atmosphere

See long description for full description of this image.
The gases of the atmosphere, shown as molecules. 
Long Description
 

In this visual representation, the gases of the atmosphere are shown as molecules(definition:Individual atoms bonded together which can be one or more elements.). We are now going to describe each gas of the atmosphere using its chemical formula (recall this from the activity, Stomach Chemistry).

Two purple circles are attached with three black lines, with the letter N inside each circle.
Nitrogen Molecule

Take nitrogen, for example. The chemical formula for nitrogen is N2. This means that two nitrogen atoms are bonded together, as shown in the image above. 

In chemical formulae, the number of atoms of each element is represented by a subscript(definition:text written smaller and below the line)  number.  

A second example is methane, a gas found in small amounts in the atmosphere. Methane has a chemical formula of CH4. This means that the molecule is comprised of one carbon (C) atom and four hydrogen (H) atoms.

This is the question/answer icon. Questions

 
  1. What is the chemical formula of an oxygen molecule?  
    Two blue circles are attached with two black lines. Each circle contains the letter O.
    Answer

    O2 

    There are two oxygen atoms in a molecule of oxygen.

 
  1. What is the chemical formula of water?  
    A red circle is attached by one line to a blue circle attached in turn by one line to a red circle. The blue circle contains the letter O and the red circles contain the letter H.
    Answer

    H2

    There are two hydrogen atoms and one oxygen atom in a molecule of water.

 
  1. What is the chemical formula of carbon dioxide?  
    A blue circle is attached by two lines to a yellow circle attached in turn by two lines to a blue circle. The yellow circle contains the letter C and the blue circles contain the letter O.
    Answer

    CO

    A molecule of carbon dioxide contains one carbon and two oxygen atoms.

 

The Air You Breathe

This is an image of a phone with two text messages. The first message asks, Any #funfact 4, this topic? The responding message is, You breathe in and out about 11,000 L of air every day. That’s about the volume of a cement mixer truck! #funfact.
 

You have already learned that we have a digestive system made up of different organs. The purpose of that system is to break down food so that it can be stored as energy for our bodies.

Now let's look at our respiratory and circulatory systems, which function as a different set of organ systems working together to deliver oxygen to our cells.

Watch this video for an introduction to the ways in which they do that.

 

What Does This Word Mean?

Science can have a lot of terminology and sometimes this course will have words that are unfamiliar to you. Use these strategies to figure out the meaning of new words.

  1. See if there are parts of the word you already know that might give you an idea about what the new one means. For example, think about a word like bronchus that you already know, look at the word bronchiole in the course and think about whether a bronchiole is like a bronchus.
  2. See if you can figure out what the word might mean by reading the sentence carefully and thinking about what makes most sense. For example, you might not be sure what a ventricle is, but when you read the sentence, "Your heart muscle contracts and the blood flows into the left ventricle," it would seem to make sense that the ventricle is a part of the heart.
  3. See if the definition of the word is actually given in the sentence. For example, you might be unsure about the actual meaning of the word capillaries, but when you look at a sentence which includes the words very small, specialized blood vessels called capillaries, you can figure out the meaning from the sentence itself.
  4. See if the word is contained in a diagram label (this is an especially important strategy in science).
  5. Look up a definition of the word.
 

Oxygen and Carbon Dioxide

Oxygen in the air you breathe plays an essential role in the function of your body. Let's follow an oxygen molecule as it travels through the respiratory and circulatory systems. Click on the titles below to open.

This is a diagram of the respiratory system showing organs on a cross-sectional diagram of a human. These include the nose, ethmoid sinuses, tongue, pharynx, trachea, lung, bronchus and bronchioles. There is a magnified section of the bronchioles that shows alveoli, which look like a cluster of spheres.

Oxygen enters your body through your nose and mouth and then travels down your trachea. Note that this is not the same as the esophagus (in the digestive system) which carries food to your stomach. Your trachea is lined with cells that produce mucus to trap any particles that could damage your body. It branches off into the bronchus, which further branches into bronchioles that get smaller and smaller until they reach the alveoli, which are tiny sacs at the end of the branches. Think of it as a tree trunk whose branches eventually become small twigs, with the alveoli at the tip of the smallest twig

This is an image of a pink circle outlined in blue on the left and red on the right. There are many smaller circles in the outlined area representing blood cells. There is an arrow showing O2 exiting the pink circle and CO2 entering it.
A close-up of an alveolus (one aleveoli).
by Wikimedia

Very small, specialized blood vessels called capillaries surround your alveoli and pick up oxygen for transportation throughout your body.

The walls of the alveolus are so thin that gas can be exchanged through them. This process is called diffusion.(definition:movement of O2 from an area where there are many molecules (in the alveolus) to an area of fewer molecules in the capillary)  

Oxygen (O2) is carried by red blood cells(definition:red, disc-like cells in your blood) throughout the body and makes blood appear more red.  

We will discuss carbon dioxide (CO2) entering the alveoli later.

This is a diagram of the anatomy of the heart. It shows blue and red tubular blood vessels and a cross-section of the heart with four chambers. The diagram labels include aorta, blood to lung, blood from lung, left atrium, valves, left ventricle, septum, blood to body, blood from body, right ventricle and right atrium.
by Nucleus Medical Media

The blood carrying the oxygen travels from your lungs to your heart. It then enters your heart through the left atrium.

Your heart muscle contracts and the blood flows into the left ventricle.  

Then your heart muscle contracts again, causing the blood to exit your heart and travel to the rest of your body. 

A blood vessel which carries blood away from your heart is called an artery. Veins are blood vessels which carry blood toward your heart. 

This is an image of an enlarged artery containing red circular blood cells. This artery is connected to the heart. There are many other blue and red blood vessels displayed over a transparent outline of the human body.

Oxygen is carried by red blood cells and transported throughout your body.

The cells in your body use oxygen to perform a chemical reaction called cellular respiration, which allows them to live and perform their functions.  

These cells make up your body's tissues and are located throughout your body, including in the digestive system. 

The food that you eat and the oxygen that you breathe react to form energy and carbon dioxide. 

Cellular Respiration Chemical Reaction

glucose (sugar from the food we eat) + oxygen → carbon dioxide + water + energy

All of the cells in your entire body - the lungs, the heart, the stomach or the intestine - need both oxygen and food to survive!

This is an image of blood vessels. There are red tubes on the left branching to blue tubes on the right. The background is brown. From left to right, the labels read artery, capillaries, tissue cells and vein.

Your arteries get smaller and branch out until they become capillaries, where the oxygen carried by your red blood cells diffuses into the surrounding tissue cells.  

At the same time, carbon dioxide (from cellular respiration) diffuses from the cells into your blood.  

The capillaries then expand and turn into veins, where the carbon dioxide is carried through your blood to your heart.

This is a diagram of the anatomy of the heart. It shows blue and red tubular blood vessels and a cross-section of the heart and its four chambers. Labels include aorta, blood to lung, blood from lung, left atrium, valves, left ventricle, septum, blood to body, blood from body, right ventricle and right atrium.
by Nucleus Medical Media

The blood carrying the carbon dioxide enters the right atrium of the heart. Your heart contracts to push this blood into the right ventricle. 

From here, the heart contracts again and the blood carrying carbon dioxide gets pumped back to your lungs.

This is an image of a pink circle. It is outlined in blue on the left and red on the right. There are many smaller circles in the outlined area. There is an arrow showing O2 exiting the pink circle and CO2 entering it.
by Wikimedia

Once in your lungs, the carbon dioxide that has been carried by your blood diffuses into the alveoli. This happens at the same time as oxygen is entering your bloodstream.

This is a diagram of the respiratory system using a cross-sectional diagram of a human. The diagram includes the nose, ethmoid sinuses, tongue, pharynx, trachea, lung, bronchus and bronchioles. There is a magnified section of the bronchioles that shows alveoli, which look like a cluster of spheres.

The carbon dioxide diffused into your lungs from your blood then travels back up through your bronchioles, bronchi and trachea to your mouth or nose, then back out into the atmosphere.

Consolidation

CONSOLIDATION

The Law of Conservation of Mass

When a chemical reaction occurs, matter can change, but it cannot be created or destroyed.

This means that when there is a chemical reaction, like the cellular respiration reaction that happens in your body, the number of atoms of the elements present at the beginning of the reaction (reactants) is the same as the number of atoms of the elements present at the end of the reaction (products).

Chemical Equations

Chemical reactions can be expressed as chemical equations, using words or chemical symbols. 

A word equation uses words instead of chemical formulae. For example, the formation of water as a word equation would be:

hydrogen + oxygen  → water

Below you will see the chemical equation for the formation of water using chemical formulae.

This is an image of a labelled diagram explaining the terminology of a chemical formula. It shows the chemical reaction 2H2 + O2 arrow 2H2O. The 2 in front of H2 is a coefficient. The arrow between the chemicals represents the word produces. 2H2 + O2 are reactants. 2H2O are products.

The chemical equation above indicates that the reactants are H2 and O2 and the product is H2O. You will notice that there are large numbers (coefficients) in front of some of the chemical formulae. This indicates the number of each reactant or product that is present. 

For example, there are two H2 molecules in this equation.

This is the example icon. Cellular Respiration Example

Cellular respiration occurs when oxygen and food (glucose) react to form carbon dioxide and water.

Word equation: glucose + oxygen → carbon dioxide + water + energy.

Chemical equation: C6H12O6 + 6 O2 → 6 CO2  + 6 H2O + energy.

Reactants: glucose (C6H12O6) and oxygen (O2).

Products: carbon dioxide (CO2), water (H2O) and energy.

 

Carbon Monoxide Poisoning  

This is an image of a black skull and crossbones containing the words carbon monoxide CO. There is a green cloud of gas in the background.

We have discovered that carbon dioxide (CO2) is created by our bodies during cellular respiration. 

Carbon dioxide is also produced by the combustion (burning) of fossil fuels(definition:fuels such as natural gas, coal, gasoline, oil that are formed by geologic processes. often used to heat our homes. When not enough oxygen is present, carbon monoxide (CO) can be produced by fossil fuel combustion. 

This can occur if your furnace or fireplace is malfunctioning, or if too little fresh air is reaching your gas-burning appliance. It can also happen if you use a gas-burning appliance meant for outdoor use only (such as a barbeque or camping stove) indoors where there is not enough fresh air. Exhaust from a car left running in a garage or an enclosed space will also produce carbon monoxide because there is not enough oxygen present.

Carbon monoxide is extremely dangerous. If you do breathe it in, carbon monoxide attaches to your red blood cells instead of oxygen and is then transported through your body. 

As a result, the cells in your body will not receive the oxygen they need to perform cellular respiration, which has the same effect as suffocation. Carbon monoxide poisoning can quickly result in death.

Complete the interactive activity below to investigate how low oxygen availability can produce carbon monoxide.

CarbonMonoxideFormation

Long Description

 

Carbon Monoxide Detector

In Ontario, there is a law requiring all residences with gas-burning appliances, fireplaces and attached garages to have carbon monoxide detectors near sleeping areas. 

Carbon monoxide has no smell, colour or taste, making it invisible and impossible to detect by humans. Carbon monoxide detectors are electrical devices which sound an alarm when carbon monoxide is detected.

If you want to view any links in this pdf, right click and select Open Link in New Tab to avoid leaving this page. (View the original article.)

 

This is the dropbox icon. Carbon Monoxide Safety

Your task now is to assess your own home for carbon monoxide safety. You are encouraged to perform this assessment with others who live there too.

Complete the following:

  1. Investigate your home. Take note if you have any of the following: a fireplace (gas or wood), a gas stove, gas boiler or gas furnace.
  2. Are there carbon monoxide detectors in your home? If so, how many do you have? Where are they located? If you do not have any in your house, persuade your parent, caregiver or landlord to purchase at least one from a local hardware store. They really do save lives!
  3. Give your home a letter grade on carbon monoxide safety (A, B, C, D, E or F).
  4. Write a short paragraph explaining your assigned grade. Include your observations and conclusions, as well as any action that needs to be taken to improve the carbon monoxide safety of your home, if necessary. 

This is the example icon. Example of Paragraph

When I looked around my house, I found that ______________ (list observations here).

Based on these observations, I would say that _______________ (give conclusions, positive and/or negative).

Based on my investigation, I would give my home a grade of ___ because _____________ (provide main reasons based on conclusions).

An area that needs carbon monoxide safety improvement in my home is ______________ (if your home requires more carbon monoxide detectors, explain this here).

 

This is an image of a green check mark in a black box.Self Check  

  Self Check - Carbon Monoxide Detectors
I have identified whether there are carbon monoxide detectors and gas burning appliances in my home.
I have given my home a grade on carbon monoxide safety.
I have drawn conclusions about the benefits of science and of knowing science by explaining my carbon monoxide safety grade.
 
test text.