The Respiratory System
Lab 10 rev 4/11
• The primary function of the respiratory system is
to deliver oxygen (O2) to and remove carbon
dioxide (CO2) from the blood.
• The respiratory system also plays a role in
maintaining the blood pH (acid-base balance).
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The Respiratory System
Lab 10
Anatomy of the Respiratory System:
• Upper Respiratory Tract (see picture on page 130)
– nose, nasal cavities, sinuses and pharynx
(throat)
– The nose, nasal cavities and sinuses provide a
large area of highly vascularized tissues which
warm, filter and add moisture to air.
• As air comes into contact with the warm, moist
tissue of the nasal passages, it is warmed and
moistened. The sinuses also add moisture to the air.
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The Respiratory System
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– The pharynx (throat) connects the nasal cavity
and mouth to the larynx (voice box).
– union of the nasal passages and the pharynx and
the make it possible to breathe through your
mouth.
• Other structures which enter or are located in the
pharynx are:
– 2 tear ducts which carry fluid away from the
eyes (this is why excess tears also make your
nose runny)
– the esophagus— the passage for food
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The Respiratory System
Lab 10
– The 2 Eustachian tubes that drain the middle
ear and equalize air pressure between the
middle ear and outside air.
– Food
• Below the throat, the air passage crosses in front of
the esophagus. This makes it possible for food or
liquids to be accidentally sucked into the air
passages and can cause us to cough or choke. These
actions attempt to clear the food or liquid.
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The Respiratory System
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– Epiglottis-a flap of cartilage located in the back
of the throat.
• During swallowing, the epiglottis forms a tight seal
over the trachea so food can’t go down it.
– The Uvula-a flap of tissue in the back of the
mouth that hangs from the roof of your mouth.
• This closes the upper air passages so food does not
come out your nose. (This is also the part of the
body that causes snoring when air passes over it.)
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The Respiratory System
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• The lower respiratory tract includes
– the larynx, trachea, 2 bronchi, 2 lungs
(including the bronchioles and alveoli)
– the larynx or voice box is below the epiglottis
and pharynx and is protected by the thyroid
cartilage (nicknamed the Adam’s apple).
– Functions of the larynx
• maintains an open airway
• route food and air into their appropriate tubes
• assist in the production of sound
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The Respiratory System
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– The vocal cords consist of 2 folds of
connective tissue that extend across the airway.
The opening of this airway is called the glottis.
• Vocal cords are supported by ligaments.
Sound is produced as we expel air past them
causing the cords to vibrate.
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The Respiratory System
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– The trachea (or windpipe) is a tube below the
larynx. It is about 4 1/2 inches long, is
composed of C-shaped rings of cartilage (to
ensure that it stays open), and carries air to the
bronchi (see picture page 132).
– The trachea branches into airways which are
called the right and left bronchi. These
further subdivide into smaller and smaller
bronchi.
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The Respiratory System
Lab 10
– The walls of the bronchi contain fibrous
connective tissue and smooth muscle reinforced
with cartilage. As the branches get smaller, the
amount of cartilage declines. When they have
no cartilage, their name changes into
bronchioles.
– Surrounding the bronchi are the lungs. These
fill the thoracic cavity and extend from the
clavicles to the diaphragm (a thin sheet of
muscle).
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The Respiratory System
Lab 10
• Bronchioles lead to alveoli which are the air
sacs of the lungs. Alveoli are composed of a
single layer of flat, simple squamous cells
and this is where gas exchange takes place.
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The Respiratory System
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• Breathing
– Involves repetitive cycles of getting air into and
out of the lungs.
– This requires muscular effort.
– Since the lungs themselves do not have any
skeletal muscle tissue, expansion and
contraction occurs because the surrounding
bones and muscles expand the size of the chest
cavity.
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The Respiratory System
Lab 10
• Inspiration:
– As the diaphragm contracts and flattens, the
external intercostal muscles contract and lift
the ribcage. This causes a pressure drop in the
thoracic cavity.
– The scalene and sternocleidomastoid
(SCM) muscles also contract to help expand
the thoracic cavity space.
– As the volume (space) in the thoracic cavity
increases, air rushes in to fill this space.
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• Other things that help inspiration:
– The lungs and chest cavity are surrounded by a
membrane called “pleura”. There is fluid
between the layers of the pleura so the lungs
can stretch and contract with minimum friction.
• There is also a partial vacuum between the 2
pleural layers. This causes the lungs to stick to
the chest wall as it expands.
• Alveolar surfactant, a chemical within the
lungs, decreases the surface tension so the lung
tissue doesn’t stick to itself.
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The Respiratory System
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• Expiration:
– The diaphragm relaxes and intra-abdominal
pressure pushes the diaphragm up. The
internal intercostal muscles and gravity help
to drop the ribcage and thoracic cavity back to
its smaller size. This increases pressure within
the lungs and forces the air out of them.
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The Respiratory System
Lab 10
• Respiratory Volumes
• Tidal volume is the amount of air an individual
normally inhales and exhales.
• Our body's normal breathing strategy is to
ventilate the air sacs and also keep a minimal
residual volume in the lungs. This allows us to
keep some air for the blood passing through the
lungs between breaths. This air is referred to as
dead space volume.
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The Respiratory System
Lab 10
• The amount of air that can be forcibly inhaled
after a normal inspiration (tidal volume) is called
inspiratory reserve volume.
• The amount of air that can be forcibly exhaled
after a normal expiration (tidal volume) is called
expiratory reserve volume.
• The vital capacity is the maximal volume that you
can forcibly exhale after a maximal inhalation.
• After you forcibly exhale, there is always some air
left in the lungs. This is called the residual
volume.
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The Respiratory System
Lab 10
• These lung capacities are measured with a
spirometer, which you will be using in one of the
activities.
• Gases are transported from the lungs to the body
primarily by hemoglobin. They can also be
dissolved in the plasma. In plasma, carbon
dioxide dissolves and becomes carbonic acid or
bicarbonate. These are the chemicals that enable
the experiment on page 136 to work.
•
For more detailed explanation look in your textbook.
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The Respiratory System Lab 10
REMINDER, page 1:
1. Learn anatomy of the respiratory system on the
models (no pigs or slides).
2. On page 129, perform the activity of studying the
Upper Respiratory System.
3. Do both activities on page 131; study and know
the location of the nasal conchae, epiglottis,
thyroid cartilage, cricoid cartilage, pharynx, vocal
cords and trachea.
4. Learn everything listed in figure 14.4 (page 132)
except the esophagus.
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The Respiratory System Lab 10
REMINDER, page 2:
5. Perform activities on pages 131-137 with the
following exception on page 138—
DO NOT DO Deglutition Apnea
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REMINDER, page 3:
6. When using the wet spirometer,
– use the cardboard mouthpiece.
– Push the arrow on the top all the way to the
right
– There is a white tub which floars on the water
and you will push this up as you blow into the
spirometer
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