Slide 1 of 37 Copyright Pearson Prentice Hall 37-3 The Respiratory System.

Copyright Pearson Prentice Hall

Slide 1 of 37

37-3 The Respiratory System



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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

Interesting FactsInteresting Facts



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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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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.

Importance of Gas Exchange



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The Human Respiratory System


What is the function of the respiratory system?



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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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The respiratory system consists of the:

• nose

• pharynx

• larynx

• trachea

• bronchi

• lungs



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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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Epiglottis

Trachea

Nose Pharynx

Larynx

Lungs

Bronchus

Mouth

Diaphragm

Bronchioles



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Air enters the nose or mouth and moves to the pharynx, or throat.

The pharynx serves as a passageway for both air and food.

Nose Pharynx



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Air moves from the pharynx into the trachea, or windpipe.

The epiglottis covers the entrance to the trachea when you swallow.

Epiglottis Trachea



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At the top of the trachea is the larynx, which contains two elastic folds of tissue called vocal cords.

Larynx



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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



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In each lung, the bronchus subdivides into smaller bronchi, and then into bronchioles.

Bronchioles



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Bronchioles subdivide into millions of tiny air sacs called alveoli.

Alveoli

Bronchiole



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Alveoli are grouped in clusters.

A network of capillaries surrounds each alveolus.

Pulmonary vein

Capillaries

Pulmonary artery



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Gas Exchange

Gas Exchange

Gas exchange takes place in the alveoli.

Oxygen diffuses into the blood.

Capillary

O2



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Gas Exchange

Carbon dioxide in the blood diffuses into the alveolus.

Capillary

O2

CO2

Gas Exchange Animation

http://highered.mcgraw-hill.com/sites/0072495855/student_view0/chapter25/animation__gas_exchange_during_respiration.html



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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.



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Breathing

During inhalation, the diaphragm contracts and the rib cage rises up.

This expands the volume 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.

Exhalation

Rib cage lowers

Air Exhaled



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How Breathing Is Controlled

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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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

Measurement of Lung Function



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Tobacco and the Respiratory System


Tobacco smoke contains three dangerous substances that affect the body:

• nicotine

• carbon monoxide

• tar



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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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Diseases Caused by Smoking

How does smoking affect the respiratory system?



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Smoking reduces life expectancy.

Smoking can cause such respiratory diseases as chronic bronchitis, emphysema, and lung cancer.



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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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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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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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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

a. bronchi.

b. alveoli.

c. epiglottis.

d. bronchioles.


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37-3

The function of the cilia lining the respiratory surfaces is to

a. improve the amount of oxygen and carbon dioxide exchanged in the lungs.

b. cover the opening of the trachea when you swallow.

c. move air in and out of the lungs.

d. sweep trapped particles and mucus away from the lungs.


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37-3

Oxygen diffuses from the alveolus into the blood because

a. blood entering the capillaries of the lungs is oxygen-poor.

b. blood entering the capillaries of the lungs is oxygen-rich.

c. air entering the lungs has more carbon dioxide than oxygen.

d. 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

a. tar.

b. carbon monoxide.

c. nicotine.

d. 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

a. chronic bronchitis.

b. lung cancer.

c. emphysema.

d. pneumonia.

END OF SECTION

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Slide 1 of 37 Copyright Pearson Prentice Hall 37-3 The Respiratory System.

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