RESPIRATORY SYSTEM
Main Function = gas exchange from O2  CO2
Other functions: speech (sounds) regulation of pH of blood.
1. NOSE: This is made of cartilage. Nose jobs involve taking a mallet, breaking the
nasal bone and shaving the cartilages.
a. NASAL CAVITY: This is where the nostrils are. They have hairs which
filter large particles in the respiratory tract. (insects, etc).
The functions of the nasal cavity is for the air you breathe:
1. Warm (cold air can freeze lungs); warmed by superficial veins
2. Clean (dirty air can clog lungs); mucous is sticky, and cilia will move
that dirt down the back of the throat, then it’s swallowed.
3. Humidify (dry lungs can crack). The fluid secreted by glands makes
the moisture, even on windy days the air goes to 100% humidity by the
time it gets to the lungs.
When you have a cold and get extra fluid (edema)  stuffed up or runny nose,
and the pressure can cause sinus headaches.
2. PHARYNX is where the nasal passages join with the oral passages. The
AUDITORY TUBE from the ears is located here.
A. SOFT PALATE: move your tongue along the roof of your mouth, and
going from the front to the back you’ll feel the hard part turning into a
soft part on the roof of your mouth.
B. UVULA: located at the end of the soft palate (seen in cartoons).
The function of the soft palate and uvula is to move upward when swallowing, to
prevent food from going into nasal cavities. When you vomit, they don’t close, and food
and stomach acids go into nasal cavity and cause problems. Can also see tonsils (lymph
nodes) and vocal cords.
3. LARYNX (model)
This is a very complex structure (show overhead). Made up of cartilages
It has two functions:
1. Produce sounds (vocal cords are located in the larynx)
2. Prevent food from entering lungs
A. EPIGLOTTIS closes when you swallow so nothing will go into the trachea and
lungs. When you get hiccoughs, it’s from a sudden movement of air into the lungs, so the
epiglottis closes to prevent more air from going in. It’s unknown why you get hiccoughs.
All the treatments you can try involve interrupting the normal breathing patterns.
B. GLOTTIS is the opening.
C. VOCAL CORDS
Vocal cords are attached to cartilage. If these cartilages move, the vocal cords open.
The type and pitch of sounds you make depend on how far apart the vocal cords are.
Way open = no sound (like when breathing)
Mostly closed = sounds
Men: their thyroid cartilage is larger, so their vocal cords are longer = deeper voice.
LARYNGITIS: inflamed vocal cords (↓ sound production).
Singers can get scar tissue nodules, requires surgery.
The number one sign that a person is lying is voice irregularities.
4. TRACHEA This is a tube that carries air from the larynx to the lungs. (See model)
It’s fairly rigid from about 16 rings of cartilage.
The purpose of the cartilage rings is to keep the trachea open like a hollow tube.
Otherwise, when you inhale, the trachea would collapse like when you suck hard on a
straw. That’s why your vacuum cleaner has rings on the hose.
The trachea is lined with epithelium interspaced with goblet cells, which are the cells that
produce mucous to trap dirt. The epithelial cells also have little hairs on them called cilia
which sweep dirt to larynx  swallowed. In this way, the respiratory passage is filtered.
Therefore, the cilia have several functions: they move the mucus, remove debris and
harmful organisms, and circulate the air.
The trachea branches out into smaller tubes called BRONCHI.
Bronchi branch out into smaller tubes called BRONCHIOLES.
Bronchioles branch out into smaller tubes that empty into a sack = ALVEOLI (overhead
picture). This sac is like a balloon surrounded by a capillaries. The alveoli are where the
gas exchange occurs: oxygen goes from the air in the lungs into the red blood cells
passing by there, and carbon dioxide diffuses out of the cells and into the air in the lungs
where it is exhaled. Therefore, inspired air (breathe in) contains oxygen, and expired air
(breathe out) contains more carbon dioxide than oxygen.
By the time these air tubes are this small, they don’t have any more cilia, so any particle
that gets down that far has to be eaten by macrophages or just stay there. Therefore,
within the alveoli are macrophages to eat the foreign object.
A cough can be expelled at 60 mph.
DIAPHRAGM is a muscle on the floor of the chest cavity. It is involved in breathing.
MYTH: Cover your head or catch a cold: Although 90% of the heat lost from the body is
lost from the head, covering your head will not prevent this heat loss. The heat is lost
from the warm air that you exhale.
PROBLEMS WITH THE LUNGS
In allergic conditions, bronchioles will constrict, blocking air flow to the lungs =
ASTHMA. This can also be caused by irritants in the environment, especially by
pollution in the city.
SMOKING
Smoking destroys cilia, and smoke of any kind is toxic. Particles in the lungs can’t clear.
Cigarettes contain tar, which is the same kind of tar used to pave roads. When there is a
thin lining of tar on the alveoli, there is no oxygen exchange to the lungs there. Large
chunks of the lung become useless. Damage to the lungs shows up several ways.
If a person smokes for 10 years and then stops, the damage will repair. If they have been
smoking longer than 10 years, they may have some residual damage. It takes 7 years for
lungs to repair. Smoking right after exercise is worse because you are breathing more
deeply, so the particles go in deeper. Pollution in the air can also cause particles in the
lungs, and the ozone can damage the lungs. Living in southern California is like smoking
one pack a day.
A mother who smokes during pregnancy will give birth to a baby with a lower birth
weight. Smoking also is associated with heart disease, cancer of the lung, bladder,
and pancreas. It also causes emphysema, pneumonia, and bronchitis. Some people try
to quit smoking by smoking less, trying not to inhale, or switching to chewing tobacco,
but there is no safe way to use tobacco.
CHRONIC OBSTRUCTIVE PULMONARY DISEASE (COPD)
Number 5 killer in the USA.
It is a combination of two conditions:
1. CHRONIC BRONCHITIS: inflammation of the bronchi, produces mucous, the
openings become smaller = obstructed.
2. EMPHYSEMA: loss of elastic tissue on the bronchioles and alveoli, which
collapse now during exhalation. Alveoli lose their shape and their surface area.
When you see someone at the mall with an oxygen tank, they probably have
emphysema, and need pure oxygen.
LUNG CANCER
There are many types of lung cancers. About 150,000 die each year from them.
It is the #1 or #2 most deadly form of cancer. 85% of lung cancer is caused from
smoking.
The problem is that it starts as a hard nodule deep in the spongy tissue of the lung, where
it has no symptoms until it presses against a structure. By then, it has also
METASTASIZED (bits of it break off and travel to another location in the body, lodge
there, and start multiplying).
Surgery on the lung cancer of a smoker won’t work because the lungs are too weak, and
they can’t do without the lung tissue. There are no good screening procedures for lung
cancer.
SURFACTANT is a slippery agent that is made by the alveoli, which coats it and keeps
the walls of the alveoli from sticking together when they collapse during exhalation. If
you have two wet pieces of paper and stick them together, they are hard to pull apart
without ripping. Put soapy water between them, and you can pull them apart.
The reason this is important is because surfactant is not produced in a fetus until the ninth
month, so premature babies don’t have enough surfactant  RESPIRATORY
DISTRESS SYNDROME, which is the #1 cause of death in premature babies. You
know how hard it is to blow up a brand new balloon? Imagine a baby having to do that
with every single breath. You get tired. The treatment is to spray artificial surfactant into
the lungs, and put them on a respirator to push air in. The more distal regions are still
collapsed, so there are still problems.
PNEUMONIA is when there is fluid in the lungs, usually from a viral or bacteria
infection of the bronchi and alveoli. Blood plasma leaks out and fills the lungs, making it
difficult to breathe. Needs hospitalization with iv antibiotics.
TUBERCULOSIS is an infection of a really bad bacteria that get in the lungs and
make themselves a capsule to hide in, where antibiotics can’t reach. They set up shop
in the lungs and reproduce. Soon, the lungs fill up with these hard nodes and make it
difficult to breathe. It causes extreme coughing, and then lots of these bacteria break off
and get spewed into the air, where someone else can inhale them. It is extremely
contagious and very deadly. If a person gets TB, the State Health Department has to be
notified. They will show up at your house every morning for six months and stand there
and watch you take your pills. If you don’t accept this, they have the right to haul you
away to a lock-up facility and force the medicine in you for six months. There are only a
few diseases where the State Health Department will step in like this: anthrax, typhoid
fever, and bubonic plague are other diseases where you don’t get a choice; you are forced
into isolation. Diseases like TB and the plague have almost wiped out Europe! A TB test
will be positive if you have been exposed to the organism at any point in your life. Then
you’ll have to go in for an x-ray to see if it is an active case of TB or not. Once you
recover from TB you will always have a positive TB test, so tell the nurse that in
advance. You may have to provide documentation that you have been treated for it
already. Most employers require TB tests before hiring. I had to take one to work here.