1. 37-3 The Respiratory System
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Interesting Facts
The surface area of the lungs is about the same size as a tennis court
You lose about ½ L of water a day through breathing
Tuberculosis (TB) is caused by bacteria that destroy the air sacs in the lungs
2 million people die of TB each year
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Lizards can’t breathe when they are running their breathing depends on the muscles between their ribs which MUST be used during running
The vapour that comes out of your mouth when you cough travels at about 160 km/h
Some animals (some frogs) can breathe through their skin
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One acre of trees produces enough oxygen to keep 18 people alive for one year
Cigarettes and cigarette smoke contain over 4000 chemicals, including 43 known to cause cancer
Every cigarette shortens your life by ~14 minutes
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What Is Respiration?
What Is Respiration?
In biology, respiration means two different things.
Cellular respiration is the release of energy from the breakdown of food in the presence of oxygen.
At the organism level, respiration is the process of gas exchange—the release of carbon dioxide and the uptake of oxygen between the lungs and the environment.
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Importance of Gas Exchange
Composition of Atmosphere
 78% Nitrogen
 21% Oxygen
 0.03% Carbon Dioxide
Cells obtain energy by breaking down sugars. O2 is the required.
Humans need oxygen to survive (250 mL/min)
Humans may live several days without water, weeks without food, only minutes without oxygen.
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7. The Human Respiratory System
What is the function of the respiratory system?
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8. The Human Respiratory System
The basic function of the human respiratory system is the exchange of oxygen and carbon dioxide between the blood, the air, and tissues.
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9. The Human Respiratory System
The respiratory system consists of the:
nose
pharynx
larynx
trachea
bronchi
lungs
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10. The Human Respiratory System
Air entering the respiratory system must be warmed, moistened, and filtered.
Mucus moistens air and traps particles of dust or smoke.
Cilia sweep particles and mucus to the throat.
Mucus and particles are either swallowed or spit out.
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11. The Human Respiratory System
Pharynx
Nose
Larynx
Trachea
Mouth
Lungs
Epiglottis
Bronchus
Bronchioles
The respiratory system is responsible for the exchange of oxygen and carbon dioxide. Air moves through the nose, pharynx, larynx, trachea, and lungs. After reaching the lungs, the trachea branches into smaller and smaller tubes called bronchioles, which end in alveoli, or air sacs.
Diaphragm
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12. The Human Respiratory System
Pharynx
Nose
Air enters the nose or mouth and moves to the pharynx, or throat.
The pharynx serves as a passageway for both air and food.
The respiratory system is responsible for the exchange of oxygen and carbon dioxide.
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13. The Human Respiratory System
Air moves from the pharynx into the trachea, or windpipe.
The epiglottis covers the entrance to the trachea when you swallow.
Trachea
Epiglottis
The respiratory system is responsible for the exchange of oxygen and carbon dioxide.
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14. The Human Respiratory System
Larynx
At the top of the trachea is the larynx, which contains two elastic folds of tissue called vocal cords.
The respiratory system is responsible for the exchange of oxygen and carbon dioxide. Air moves through the nose, pharynx, larynx, trachea, and lungs.
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15. The Human Respiratory System
Air then passes through the trachea into two large passageways in the chest cavity called bronchi.
Each bronchus leads into one of the lungs.
Lungs
Bronchus
The respiratory system is responsible for the exchange of oxygen and carbon dioxide. Air moves through the nose, pharynx, larynx, trachea, and lungs. After reaching the lungs, the trachea branches into smaller and smaller tubes called bronchioles, which end in alveoli, or air sacs.
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16. The Human Respiratory System
In each lung, the bronchus subdivides into smaller bronchi, and then into bronchioles.
Bronchioles
The respiratory system is responsible for the exchange of oxygen and carbon dioxide. After reaching the lungs, the trachea branches into smaller and smaller tubes called bronchioles, which end in alveoli, or air sacs.
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17. The Human Respiratory System
Bronchioles subdivide into millions of tiny air sacs called alveoli.
Alveoli
Bronchiole
The respiratory system is responsible for the exchange of oxygen and carbon dioxide. After reaching the lungs, the trachea branches into smaller and smaller tubes called bronchioles, which end in alveoli, or air sacs.
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18. The Human Respiratory System
Alveoli are grouped in clusters.
A network of capillaries surrounds each alveolus.
Pulmonary artery
Pulmonary vein
The respiratory system is responsible for the exchange of oxygen and carbon dioxide.
Capillaries
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Gas Exchange
Gas Exchange
Gas exchange takes place in the alveoli.
Oxygen diffuses into the blood. O2
Gas exchange occurs by diffusion across the membrane of an alveolus and a capillary.
Capillary
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Gas Exchange
Carbon dioxide in the blood diffuses into the alveolus. O2
CO2
Gas Exchange Animation
Gas exchange occurs by diffusion across the membrane of an alveolus and a capillary. 
Capillary
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Breathing
Breathing
Breathing is the movement of air into and out of the lungs.
The force that drives air into the lungs comes from air pressure.
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Breathing
Lungs are sealed in pleural membranes inside the chest cavity.
At the bottom of the cavity is a large, flat muscle known as the diaphragm.
During inhalation the rib cage rises and the diaphragm contracts, increasing the size of the chest cavity.
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Breathing
During inhalation, the diaphragm contracts and the rib cage rises up.
This expands the volume of the chest cavity.
During inhalation the rib cage rises and the diaphragm contracts, increasing the size of the chest cavity.
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Breathing
The chest cavity is sealed, so this creates a partial vacuum inside the cavity.
Atmospheric pressure fills the lungs as air rushes into the breathing passages.
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Breathing
Often exhaling is a passive event.
When the rib cage lowers and the diaphragm relaxes, pressure in the chest cavity is greater than atmospheric pressure.
Air is pushed out of the lungs.
Air Exhaled
Rib cage lowers
During inhalation the rib cage rises and the diaphragm contracts, increasing the size of the chest cavity.
Exhalation
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26. How Breathing Is Controlled
Breathing is controlled by the medulla oblongata.
The medulla oblongata monitors carbon dioxide in the blood.
As carbon dioxide increases, nerve impulses make the diaphragm contract, bringing air into the lungs.
The higher the carbon dioxide level, the stronger the impulses.
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Measurement of Lung Function
Tidal volume: volume of air inhaled and exhaled in a single breath
Residual Volume: the air that remains in the airways and does not participate in gas exchange
Vital capacity: the maximal volume that can be exhaled after maximal inhalation
Inspiratory reserve volume: the amount of air that can be inhaled beyond the tidal volume
Expiratory reserve volume: the amount of air that can be forcibly exhaled beyond the tidal volume
Residual volume: the amount of air remaining in the lungs, even after a forceful maximal expiration
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29. Tobacco and the Respiratory System
Tobacco smoke contains three dangerous substances that affect the body:
nicotine
carbon monoxide
tar
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30. Tobacco and the Respiratory System
Effects on Respiratory System
Nicotine is a stimulant that increases heart rate and blood pressure.
Carbon monoxide is a poisonous gas that blocks the transport of oxygen by hemoglobin in the blood.
Nicotine and carbon monoxide paralyze the cilia.
Tar contains compounds that are known to cause cancer.
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31. Tobacco and the Respiratory System
Diseases Caused by Smoking
How does smoking affect the respiratory system?
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32. Tobacco and the Respiratory System
Smoking reduces life expectancy.
Smoking can cause such respiratory diseases as chronic bronchitis, emphysema, and lung cancer.
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33. Tobacco and the Respiratory System
In chronic bronchitis, the bronchi become swollen and clogged with mucus.
Emphysema is the loss of elasticity in lung tissues.
People with emphysema cannot get enough oxygen to the body tissues or rid the body of excess carbon dioxide.
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34. Tobacco and the Respiratory System
Smoking is a preventable cause of lung cancer.
Lung cancer is deadly because its cells can spread to other locations.
Smoking is also a major cause of heart disease.
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35. Tobacco and the Respiratory System
Smoking and the Nonsmoker
Passive smoking is damaging to young children because their lungs are still developing.
Studies show that children of smokers are twice as likely as children of nonsmokers to develop respiratory problems.
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36. Tobacco and the Respiratory System
Dealing With Tobacco 
The best way to avoid tobacco-related illness is not to smoke.
If a smoker quits, his or her health can be improved, and some of the damage can be reversed.
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37-3
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37-3
Air passes through the trachea into two large passageways in the chest cavity known as the
bronchi.
alveoli.
epiglottis.
bronchioles.
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37-3
The function of the cilia lining the respiratory surfaces is to
improve the amount of oxygen and carbon dioxide exchanged in the lungs.
cover the opening of the trachea when you swallow.
move air in and out of the lungs.
sweep trapped particles and mucus away from the lungs.
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37-3
Oxygen diffuses from the alveolus into the blood because
blood entering the capillaries of the lungs is oxygen-poor.
blood entering the capillaries of the lungs is oxygen-rich.
air entering the lungs has more carbon dioxide than oxygen.
air entering the lungs has less oxygen than is found in the blood.
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37-3
A stimulant drug found in tobacco that increases the heart rate and blood pressure is
tar.
carbon monoxide.
nicotine.
carbon dioxide.
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37-3
A respiratory disease that results in the loss of elasticity in the tissues of the lung is
chronic bronchitis.
lung cancer.
emphysema.
pneumonia.
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