The HUMAN RESPIRATORY SYSTEM
Take
a nice deep breath. Inhale through the nose, exhale through your mouth.
Aaaaahh...........
Inhale, exhale. Inhale, exhale. Inhale, exhale.
Hey --- wake up ! Time to learn about the system of organs
that's responsible for taking in oxygen and getting rid of carbon dioxide ...
the respiratory system.
First, allow me to list the structures and organs that together
make up the respiratory system. Your job is to write them down in the
order that air passes through them as it is inhaled. OK?
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alveoli, bronchiole, bronchus, larynx, lung, pharynx, nasal cavity, nostril, trachea |
cLick HeRe to see THe RiGHT ordER
Now let's take a look at what those respiratory structures look like.
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Can
you identify those same organs that we listed just a minute ago? |
Notes:
Click <here> to see answers
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Here is a summary of the functions of each Respiratory Structure
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STRUCTURE |
FUNCTION |
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nose / nasal cavity |
warms, moistens, & filters air as it is inhaled |
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pharynx (throat) |
passageway for air, leads to trachea |
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larynx |
the voice box, where vocal chords are located |
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trachea (windpipe) |
tube
from pharynx to bronchi |
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bronchi |
two branches at the end of the trachea, each lead to a lung |
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bronchioles |
a network of smaller branches leading from the bronchi into the lung tissue & ultimately to air sacs |
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alveoli |
the functional respiratory units in the lung where gases (oxygen & carbon dioxide) are exchanged (enter & exit the blood stream) |
Let's take a closer look at the air sacs (alveoli) in the lungs.
As the bronchioles branch out into smaller & smaller & smaller & smaller & smaller tubes, they eventually lead to microscopic clusters of alveoli, which are referred to as air sacs. You can think of the air sacs as a bunch of grapes, with each individual grape representing a single alveolus. Like this:
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A close-up of the air sacs, which are located at the ends of the bronchioles. Each "air sac" is comprised of a cluster of alveoli. The red structures represent blood vessels leading to & from the air sacs. |
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An even closer look at an alveolus. Notice that the wall of an alveolus is only one cell thick. This allows gases to diffuse into & out of the alveoli. Also notice that the alveoli are surrounded by capillaries so that oxygen and carbon dioxide can be exchanged between the lungs & the blood. Oxygen in the alveolus can diffuse into the bloodstream (& be transported throughout the body) and carbon dioxide in the bloodstream can enter the alveoli (& then be exhaled). |
And now a few words about breathing ...........
There are no muscles in your lungs. They do not actively pump air in & out, in & out. The muscle responsible for breathing actually lies below the lungs. It is like a rubber sheet that separates your chest cavity & your abdominal cavity. It's name is diaphragm.
When you inhale, the diaphragm contracts & moves downward, which creates more space in your chest cavity & draws air into the lungs. When you exhale, the diaphragm relaxes & moves upward, forcing air out of the lungs.
A common demonstration of the mechanics behind breathing involves a bell jar, some glass tubing, and a couple of balloons. Like so:
If you look closely at the right side of the diagram, which represent exhaling, you can see how the Heimlich maneuver works. The Heimlich maneuver is the "bear hug" that helps to dislodge food from the windpipe of a choking victim. By pushing upwards below the victims ribs, the diaphragm is forced up & air is forced out of the trachea, hopefully with enough "UmmppHH" to remove the blockage. See, biology can save you life.
One more tidbit: hiccups are muscle spasms in the diaphragm.
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Malfunctions & Diseases of the Respiratory System |
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asthma |
severe allergic reaction characterized by the constriction of bronchioles |
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bronchitis |
inflammation of the lining of the bronchioles |
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emphysema |
condition in which the alveoli deteriorate, causing the lungs to lose their elasticity |
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pneumonia |
condition in which the alveoli become filled with fluid, preventing the exchange of gases |
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lung cancer |
irregular & uncontrolled growth of tumors in the lung tissue |
Keep your lungs happy & healthy --- keep them SMOKE
FREE. 
It's !
Jot down
your answers to the following questions. Try to answer them without peeking
back.
And NO
LOOKING AT THE ANSWERS until you're all done.
1. Which choice lists
the structures adapted for permitting air flow from the external environment to
the human lungs in the correct order?
a) nasal cavity, bronchi,
bronchioles, pharynx, trachea
b) nasal cavity, trachea,
pharynx, bronchi, bronchioles
c) nasal cavity, pharynx,
trachea, bronchi, bronchioles
d) nasal cavity,
bronchioles, trachea, pharynx, bronchi
2. A structural
difference between the trachea and esophagus that prevents the trachea from
collapsing is the presence of:
a) smooth muscle
b) skeletal muscle
c) respiratory cilia
d) rings of cartilage
3. In order for gas
exchange to take place, alveoli must be closely associated with:
a) capillaries
b) villi
c) veins
d) arteries
4. Deposits from
cigarette smoke interfere with the normal functioning of cilia in the:
a) trachea
b) esophagus
c) bronchioles
d) pharynx
5. The exchange of air
between the human body and the environment is the result of coordinated contractions
of the muscles of the rib cage and the:
a) lung
b) diaphragm
c) heart
d) pleura
6. The site of gas
exchange in humans is the:
a) nasal cavity
b) trachea
c) pleura
d) alveoli
7. A disease involving
the breakdown of the air sacs in the lungs is:
a) asthma
b) emphysema
c) pneumonia
d) bronchitis
Base your answers to questions 8 through 11 on the diagram below:
8. The process responsible for gas exchange between areas
"B" & "D" is:
a) breathing
b) diffusion
c) osmosis
d) peristalsis
9. The type of blood
vessel shown in the diagram is:
a) an artery
b) a capillary
c) a vein
d) none of the above
10. At which location
would blood with a low oxygen content and a high carbon dioxide content be
found?
a)
A b) B c)
C d) D
11. This diagram is
based on structures found in which respiratory organ?
a) the bronchi
b) the lungs
c) the pharynx
d) the nasal cavity
Base your answers
on questions 12 through 20 on the diagram over there =>
12. Which structure warms
& filters air as it is inhaled?
13. Bronchitis effects
which two structures?
14. Which structure is
referred to as the "voice box"?
15. What are two names
for structure #9?
16. What is the
number and name of the muscle responsible for breathing?
17. What is the importance
of the epiglottis?
18. Where does the actual
exchange of oxygen and carbon dioxide take place?
19. What is the name of
the membrane surrounding structure #5?
20. In what direction
does structure #6 move during inhalation?
Check your answers by
clicking ----------------------> HERE.
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