RESPIRATORY SYSTEM
Main Function = gas exchange from O2  CO2
Other functions: speech (sounds) regulation of pH of blood.
1. NOSE: This is there because of a number of hyaline cartilages. It’s fairly
complex. A cartilage nasal septum divides the right and left sides of the nose.
Nose jobs involve taking a mallet, breaking the nasal bone and shaving the
cartilages.
2. NASAL CAVITY: The outer skin folds into the anterior nostrils (stratified
squamous epithelium); has hairs which filter large particles (insects and dust).
The nasal cavity is lined by:
a. NASAL MUCOSA (pseudostratisfied ciliated epithelium).
b. LAMINA PROPRIA (loose fibrous connective tissue) which has a lot of
mucous and serous glands. You produce one liter of fluid a day. There
are lots of veins in this tissue.
The functions of the nasal cavity is for the air you breathe:
1. Help warm the air (cold air can freeze lungs); warmed by superficial veins
2. Enhance the sense of smell
3. 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.
4. Moisten the air (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.
5. Increase the turbulence in the flow of air through the nasal cavity. The increase in
turbulence allows more time for the air to be warmed and moistened.
NASAL CONCHAE
To make the nasal cavity function more efficiently, there are superior, middle, and inferior
nasal conchae, which are covered with a mucous membrane. They function to help warm and
moisten the air, and increase the turbulence in the flow of air through the nasal cavity. They
also have sensory receptors to enhance the sense of smell. When you have a cold and get
extra fluid (edema)  runny nose.
Nasal Conchae
 The nasal conchae contain blood vessels that can dilate, causing the tissue to swell,
closing off one side of your nasal airway at a time. This allows the closed side to
increase its moisture.
 Then it will open again and the other side may close. These cycles occur every eight
hours throughout the day.
What causes snoring?
 When we are asleep the area at the back of the throat sometimes narrows.
 The same amount of air passing through this smaller opening can cause turbulence in
the airflow and some vibration of the tissues in the nose and mouth.
 People who snore have different reasons for the narrowing. The narrowing can be in
the nose, mouth, or throat.
 Obstruction of the nasal passages can be caused by a deviation of the nasal septum,
allergies, sinus infections, swelling of the conchae, or large adenoids (tonsils in the
back of the throat).
 Those who have nasal obstructions cannot breathe through their noses well, so they
breathe through their mouths.
 Many mouth breathers snore because the flow of air through the mouth causes greater
vibration of tissues.
 When we lie on our backs, gravity pulls the palate, tonsils, and tongue backwards.
This often narrows the airway enough to cause turbulence in airflow, tissue vibration,
and snoring. Frequently, if the snorer is gently reminded to roll onto his or her side,
the tissues are no longer pulled backwards and the snoring lessens.
 Some medications as well as alcohol can lead to enhanced relaxation of muscles
during sleep. This will increase snoring.
Deviated Septum
 Nasal septa which are deviated to one side of the nasal passage can cause sinus
problems and decreased ability to smell and taste.
 A surgery can be performed to correct it:
 http://www.youtube.com/watch?v=SP01dYof8RU
Apnea
 An apnea is a period of time during which breathing stops for 10+ seconds or the
breath is less than 25% of normal. Apnea is also a term for blood oxygen levels less
than 4% of normal.
 These episodes often occur during sleep.
 The two types of sleep apnea are Central Sleep Apnea and Obstructive Sleep Apnea.
Central Sleep Apnea (CSA)
 Occurs when the brain does not send the signal to breathe to the muscles of breathing.
 This usually occurs in infants or in adults with heart disease, cerebrovascular disease,
or congenital diseases, but it also can be caused by some medications and high
altitudes.
Obstructive Sleep Apnea (OSA)
 People with OSA have an airway that is more narrow than normal, usually at the base
of the tongue and palate. It is common among adults but rare among children.
 OSA is associated with higher risks of heart attacks and strokes because of higher
prevalence of hypertension in individuals with obstructive sleep apnea.
Polyps
 Nasal polyps are overgowths of the mucosal tissue in the nasal cavities.
 Usually caused from chronic allergies
 Can cause difficulty breathing through nose, loss of smell, headaches.
 Treated with steroid sprays or surgery.
The nasal cavity is connected to PARANASAL SINUSES (ETHMOID,
SPHENOID, FRONTAL, AND MAXILLARY SINUSES). They are also lined
with the same kind of mucosa. When you have a cold, you get stuffed up, and the
pressure can cause sinus headaches.
There is another connection to the nasal cavity: LACRIMAL DUCT. There’s a
hole in the lacrimal bone. Excess tears drip down there. When you cry, you get a
runny nose. If the duct overflows, you see tears on face.
3. PHARYNX (three parts)
a. NASOPHARYNX: a continuation of the nasal cavity. The EUSTACIAN
TUBE is located here. It’s covered by the same type mucosa.
b. OROPHARYNX is the back of the mouth; visible when you open your
mouth and look all the way back.
Separating the oropharanyx and the nasopharynx:
1. 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.
2. 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.
c. LARYNGOPHARYNX: Stick out your tongue and say Ah! You’re
looking here. Can also see the vocal cords.
4. LARYNX
This is a very complex structure.
It has two functions:
1. Produce sounds (vocal cords)
2. Prevent food from entering lungs
Made up of nine separate cartilages:
EPIGLOTTIS
THYROID CARTILAGE
CRICOID CARTILAGE
(2) ARYTENOID CARTILAGES
(4) Smaller cartilages we’re not going to name
GLOTTIS is the opening. It stays all the way open when you are breathing hard.
EPIGLOTTIS flaps over the glottis when you swallow so nothing will go into the
trachea. 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’ unknown why you get
hiccoughs. All the treatments you can try involve interrupting the normal breathing
patterns.
VOCAL CORDS (vocal folds)
Vocal cords are attached to the ARYTENOID CARTILAGES. If these cartilages move,
the vocal cords open. When they go back to normal, the glottis will close. The ability to
vary the pitch of the voice results from varying the tension in the vocal folds.
For air to move through, muscles have to contract. If muscles here are paralyzed, the
airway closes. In surgery, have to intubate. In an emergency, have to do a tracheotomy
above the jugular notch.
The type 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). Usually caused from overuse or a viral infection.
 Extreme overuse (professional singers) can get scar tissue nodules, requires
surgery.
FUN FACTS
What is the Adam's apple and what does it do?
 When boys go through puberty, hormones cause the larynx to grow rapidly,
deepening their voices and causing the bulge to form.
 Enlargement of the Adam's apple is considered, like pubic hair growth, one of the
secondary sexual characteristics.
 Girls' voices also deepen with puberty, but since their larynxes don't tend to grow
as much, they don't usually develop an "Eve's apple."
 The protrusion is the thyroid cartilage.
 Some folks undergo cosmetic surgery to make it less prominent.
Origin of the term:
 It is usually said that Adam's apple takes its name from the biblical story about
Adam, Eve. The serpent and the apple. A piece of the forbidden fruit stuck in
Adam's throat and created the anatomic Adam's apple.
 However, it may be wrong. Adam's apple in Latin is "pomum Adami." This may
have been a mistranslation of the Hebrew "tappuach ha adam" which also means
male bump. Between Latin and English there's many a slip.
Why does your voice sound funny after you inhale helium from a balloon?
 A healthy 13-year-old boy suffered a cerebral gas embolism after inhaling helium
from a pressurized tank at a party.
 Repeated inhalation of helium can hinder your ability to breathe.
 Helium is lighter than air, so it causes the tissues to vibrate faster, resulting in a
higher-pitched, cartoon-character sound.
5. TRACHEA
This is a tube that carries air from the larynx to the lungs.
It’s fairly rigid from about 16 rings of cartilage.
The purpose of the cartilage rings is to keep the trachea open. 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.
Histology of the trachea
• MUCOSA (Inner layer)
– EPITHELIUM (pseudostratisfied ciliated epithelium) and goblet cells.
Function of goblet cells is to produce mucous to trap dirt. Cilia move dirt
to larynx  swallowed.
– LAMINA PROPRIA (loose fibrous connective tissue) with lots of elastic
fibers to make the trachea flexible.
• SUBMUCOSA (Deep to the mucosa) This is the serous portion to humidify the
air.
•
ADVENTITIA (Deep to the submucosa) This is dense connective tissue with
hyaline cartilage.
6. BRONCHI
The trachea branches into the RIGHT and LEFT BRONCHUS (the primary bronchi).
These branch into the secondary bronchi, which branch into the tertiary bronchi.
The layers become thinner, and the hyaline cartilage no longer has nice rings; just bits.
The tertiary bronchi are microscopic. The distal part of the tertiary bronchi are called
terminal bronchioles. These are the last parts of the respiratory tree that have smooth
muscle and bits of hyaline cartilage. Beyond them are the respiratory bronchioles.
If you inadvertently inhale something, which lung does it go into? Right lung.
Lung cancer occurs slightly more frequently in the right lung than in the left lung (about
53% vs. 47% of the time). The most logical explanation for this is that the right primary
bronchus is wider than the left one (and the right lung is larger than the left lung), so the
right lung receives slightly more carcinogenic cigarette smoke with each puff.
The left lung has a cardiac notch; this is where the heart sits.
The left lung has TWO lobes, but the right lung has THREE lobes.
The tertiary bronchi are microscopic. Beyond them are the bronchioles.
7. BRONCHIOLES (simple columnar epithelium, no cilia, no mucosa). The terminal
bronchioles still have a smooth muscle layer, which functions to direct the flow of air to
particular portions of the lungs. Right now, only a small percentage of your lungs are
needed, compared to if you are running.
Since there are no cilia, any particle that gets down that far has to be eaten by
macrophages or just stay there. 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.
Respiratory Bronchioles
 Distal to the terminal bronchioles, the branches of the respiratory tree are now
called respiratory bronchioles.
 These end in alveoli (air sacs)
8. ALVEOLI
 These are made of simple squamous epithelium.
 This sac is like a balloon surrounded by a capillary bed.
 Within the alveoli are macrophages and surfactant secreting cells.
The Respiratory Tree
As the conducting tubes of the respiratory tree become smaller, the following changes
occur
 Cartilage rings are replaced by irregular plates of cartilage
 Cartilage disappears in the bronchioles
 The lining epithelium thins
 Smooth muscle disappears
 Elastin remains in the walls
Partial Pressure of Oxygen (pO2)
 The air we breath is a mixture of gasses: primarily nitrogen, oxygen, & carbon
dioxide. So, the air you blow into a balloon creates pressure that causes the
balloon to expand.
 However, the total pressure generated by the air is due in part to nitrogen, in part
to oxygen, in part to carbon dioxide.
 That part of the total pressure generated by oxygen is the 'partial pressure' of
oxygen, while that generated by carbon dioxide is the 'partial pressure' of carbon
dioxide. A gas's partial pressure, therefore, is a measure of how much of that gas
is present (e.g., in the blood or alveoli).
 The pO2 of blood therefore refers to the amount of dissolved oxygen in the blood
plasma.
9. DIAPHRAGM
When the diaphragm muscle contracts, the size of the thoracic cavity INCREASES.
 Pressure and volume are inversely related, so air rushes into the lungs.
 When the lungs inflate, the thoracic cavity expands for two reasons:
 The diaphragm pulls down, increases volume
 The rib cage expands, increases volume.
 When the diaphragm contracts, the size of the thoracic cavity increases, the
pressure inside the thoracic cavity drops, and air flows into the lungs.
The diaphragm and the external intercostals are the muscle group that produces
inspiration.
Lining the thoracic cavity is PARIETAL PLEURA.
Lining the lungs is the VISCERAL PLEURA.
Both of these are made of 2 layers (simple squamous epi and loose fibrous ct), same as
the pericardium. Between these pleura is a tiny space: PLEURA CAVITY.
The pleura lubricate the lungs so when the lungs move, it is smooth. They also form an
airtight seal to allow the lungs to inflate.
PLEURISY is the rubbing together of inflamed pleural membranes that produces a
stabbing pain in the chest with every breath; it feels like a broken rib. Usually the
inflammation is caused from an infection.
When the lungs inflate, the thoracic cavity expands for two reasons:
1. The diaphragm pulls down, increases volume
2. The rib cage expands, increases volume.
When the diaphragm contracts, the size of the thoracic cavity increases, the pressure
inside the thoracic cavity drops, and air flows into the lungs.
FUN FACTS
Exactly what happens when you get the wind knocked out of you?
It’s all about your diaphragm. This dome-shaped muscle sits below your lungs, and it
helps your windbags inhale and exhale. When you get hit in the abdomen, this can cause
a pressure difference that makes your diaphragm spasm for a few seconds. You can't
catch your breath until the spasm stops.
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.
PNEUMOTHORAX
If there is a hole in the pleura (injury from broken rib, knife), it’s like opening the
stopper; air flows in through the hole, and the lungs don’t inflate = PNEUMOTHORAX
(air in thorax)  COLLAPSED LUNG.
LUNG DAMAGE
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.
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. Emphysema is characterized by a person with
a large, “barrel” chest. A person with emphysema is like this:
a. Inhale all the way, then exhale a little bit, and hold it. Now inhale and
exhale to that same point.
b. They cannot exhale all the way. They start using their abdominal muscles,
and get a large, barrel chest.
c. They have chronic acid-base balance problems, and the kidneys have to
work harder. They usually develop kidney problems.
If a person stops smoking after 10 years, damage will repair. Longer than 10 years 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. 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.
New hope for smokers who want to quit: Electronic cigarettes
These are actually water vapor sticks…it feels like smoking, but it is non-toxic water
vapor. Comes in various flavors and nicotine levels, including zero nicotine
greensmoke.com
PNEUMONIA
An infectious illness that results in the accumulation of fluid in the alveoli
RESPIRATORY DISORDERS
 Upper Respiratory Infection (URI)
 Lungs are not involved
 Usually caused by a cold virus or allergies
 Usually not associated with a fever (antibiotics don’t work)
 Lower Respiratory Infection (LRI)
 Lungs are involved
 Usually caused by bacteria
 Usually associated with a fever (antibiotics work)
INFLUENZA
This is the “flu” caused by a virus. This is what you are vaccinated against when you get
the flu vaccine.
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.
Surgery on 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.
In lung cancer, the cancer cells usually arise from the epithelium lining a large bronchus.
RESPIRATORY DISTRESS SYNDROME:
SURFACTANT is a detergent produced within the alveoli, which coats it. It functions
to help with lung inflation by keeping 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.
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 problems.
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 xray 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.
CYSTIC FIBROSIS
Cystic fibrosis is an inherited disease that causes thick, sticky mucus to build up in the
lungs and digestive tract. It is one of the most common type of chronic lung disease in
children and young adults, and may result in early death.
Millions of Americans carry the defective CF gene, but do not have any symptoms.
That's because a person with CF must inherit two defective CF genes -- one from each
parent. An estimated 1 in 29 Caucasian Americans have the CF gene. The disease is the
most common, deadly, inherited disorder affecting Caucasians in the United States. It's
more common among those of Northern or Central European descent.
Most children with CF are diagnosed by age 2. A small number, however, are not
diagnosed until age 18 or older. These patients usually have a milder form of the disease.