Transcript Respiratory System

Respiratory System
Anatomy and Physiology
Parts of the Respiratory System
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Nasal Cavity
Pharynx – common passage of food and air
Larynx – 8 rings or cartilage and the mucous
membrane has 2 pairs of folds – vocal cords –
vibrate for speech
Epiglottis – flap of cartilage that closes off the
larynx when swallowing so that food goes down the
esophagus and not to the lungs (if anything but air
enters the larynx – it causes us to cough)
Thyroid cartilage – big piece of shield-shaped
cartilage in front of the larynx (Adam’s apple) –
only males have
Trachea – windpipe (4”) – lined with ciliated
mucosae – reinforced with cartilage rings to keep it
open
Parts Continued
Bronchi – trachea divides into 2 to go to
each lung
 Bronchioles or bronchiole tree – smaller
and smaller branches
 Alveoli – air sacs lined with epithelium
 Lungs – most of the lungs are made of the
alveoli (millions) with connective tissue
 Left lung – 2 lobes/ Right lung – 3 lobes
 Covered by serous membrane (pleura) –
keep the lungs from rubbing against the
thoracic cavity and adhere lungs to the
chest wall for inflation during breathing
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Alveoli
Happens from the alveoli to the capillaries
by simple diffusion (oxygen enters the
capillaries and carbon dioxide leaves them
and enters the alveoli)
 Macrophages move in and out and destroy
bacteria that get in
 Embedded in the epithelial cells are cells
that make lung surfactant – lipid coating
that keeps alveoli from collapsing
 Surface area for gas exchange of each
lung is about the size of 1 tennis court
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Alveoli
Breathing
Diaphragm contracts (pulls down)
 The volume in the lungs increases so the
pressure decreases
 Atmospheric pressure is higher than the
pressure in the lungs so it automatically
flows in
 Intercostal muscles also expand the ribs
aiding in lung expansion and the decrease
in pressure (lungs adhere to the thoracic
wall by the pleural membrane)
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Breathing Continued
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Tidal Volume – volume of air inhaled and
exhaled (500 mls/1pt.)
Inspiratory Reserve Volume – amount that
can forcibly be taken in over tidal volume (20003000 mls)
Vital capacity – Maximum air the lungs can hold
(4500 mls)
Expiratory Reserve Volume – amount that can
be forcibly exhaled after tidal expiration (about
1000 mls)
Residual Volume – amount of air left in the
lungs even after forced expiration (about 1000
mls) – allow gas exchange between breaths and
keeps alveoli inflated
Sneezing and coughing clear the air passages of
debris and excess mucous
Gas Exchange
 Oxygen
diffuses from inside the
alveoli (20%) to the capillaries of the
lungs (~0%)
 Most of it is picked up by hemoglobin
 After the blood is pumped to the
body and reaches the capillaries of
the body’s tissues – the oxygen is
dumped off by hemoglobin and
diffuses out of the RBC into the
interstitial fluid surrounding the cells
– it then diffuses into the cells
How does more Oxygen Get to
the Cells that Need it the Most?
i.e. cells doing the most work
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Blood is diverted to the most active
areas (precap. sphincters shut off blood
to certain areas not in use)
Hemoglobin drops off Oxygen quicker in
areas of low oxygen and high CO2
(higher acidity)
The higher the concentration difference
of oxygen between blood and cells, the
faster the rate of diffusion
Control of Respiration
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Controlled by the autonomic nervous system
Normally breath 12-15 times/minute
Do have some conscious control over breathing
but autonomic centers will ignore information if
ph of blood is low (can’t hold your breath until
you die)
Mostly controlled by level of carbon dioxide in the
blood (pH) – act on the medulla oblongata in the
brain
Oxygen concentration is also measured in the
aorta and carotid arteries which send signals to
the medulla – only when oxygen is dangerously
low
Hyperventilating – breathing real fast – lose too
much carbon dioxide too fast, blood becomes a
little basic and breathing may stop – breath into
a bag to increase carbon dioxide levels
Lung Disease
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COPD – usually caused by smoking – hard to
breath, coughing, lung infections, don’t properly
get rid of carbon dioxide
– Emphysema - lungs become less elastic and airways
collapse during expiration so air can’t get out – take
huge amounts of energy to exhale
– Chronic Bronchitis – mucous membranes become
inflamed and excess mucus clogs air passages
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Lung cancer – 1/3 of all cancer deaths – over
90% of people with lung cancer smoked – about
15 carcinogens in cigarette smoke – metastasizes
quickly with a 7% survival rate