The Respiratory System...
Give it R-E-S-P-E-C-T!

The respiratory system is intimately and inseparably married to the cardiovascular system.  So complex, yet so simple.  Breathe in, breathe out, and go about your day.  What happens in between those breaths
is life.

The Italian journalist and novelist, Giovanni Papini wrote that "breathing is the greatest pleasure in life".  Not to be outdone, Oprah said, "Breathe. Let go. And remind yourself that this very moment is the only one you know you have for sure.” 

These two people certainly know the importance of "taking a breather".  I doubt that anyone would dispute that breathing matters and our respiratory system makes it happen.

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What the Respiratory System Does...
It Does Very Well.

In the big picture, the respiratory system does three things.  It takes in oxygen, collects it in the pulmonary veins, carries it to the heart where it gets transported to our cells.

How much air are we talking about?  If we think of the lungs as a couple of hollow balloons (which they're not), they would inflate at about six quarts of air a minute.  That would be about 10 million balloons in an average lifetime.
Second, it receives oxygen depleted blood from the heart via the pulmonary arteries and expels carbon dioxide waste from cellular metabolism.

Third, the respiratory system regulates the acid-base balance of the body, known as the pH balance.  On a scale of 0 (strongly acidic)to 14 (strongly basic or alkaline), the brain and lungs works together to maintain the blood at a slightly acidic 7.40. It’s a tightly controlled balance since even a slight deviation from normal can severely affect many organs. 

Since carbon dioxide is a slightly acidic waste product and as with all waste products, it gets excreted to the blood.  Briefly, the brain senses when the carbon dioxide rises in the blood and kicks in to regulate it by instructing the lungs to breathe deeper and faster.  Talk about great teamwork!

The Respiratory System:
Some Assembly Required.

Like the air-conditioning duct work in our homes, our body has a similar conduction network.  The intake is the mouth and throat where air is directed to the larynx, where it gets moisturized; like our home humidifier.

The nose is an interconnected part of the intake where air is also shuttled to the larynx while performing a moisturizing function, but also warming and filtering the incoming air.  Ever see out how much dust and dirt is removed from our homes by the air conditioning filter?  When's the last time you replaced yours?

By the way, that larynx is also known as the voice box.

Going deeper into the respiratory system, we pass the voice box and hit the trachea, made of stacked rings of cartilage. The trachea splits into two branches called bronchi or bronchial tubes that carry air straight to the right and left lungs.

Entering the lungs, we will encounter three lobes: the upper, middle and lower.  But wait a second, we're missing a middle lobe in the left lung.  What's going on?  If we could open up our chest and take a look, we would see that our heart isn't right in the middle where most people think it is. 

The heart is more on the left side and since a heart and left lung can't occupy the same space, the creator saw fit to make the left lung with only two lobes to make room for the heart.  Pretty good planning!

While we are looking at our open chest, we would also notice that the lobes are separated by fissures, like tiny San Andreas fault lines.

Going still deeper into the respiratory system, we see that the pulmonary veins and arteries divide and divide and divide and keep dividing into a fine mesh of capillaries, 5-10 um (micron) in diameter; for comparison, a human hair averages 100 um in diameter.

Courtesy Patrick J. Lynch, medical illustrator; C Carl Jaffe, MD, Cardiologist

Photo:  Bronchial Anatomy showing detail of alveoli and lung circulation.

This network of capillaries spread out to about 480 million alveoli.  Alveoli are the final branching of the respiratory tree and are the primary gas exchange units of the lung. 

Flattened out, they would cover between 70 and 90 square meters.  Each individual alveolus is wrapped in a net of capillaries.
Interesting thing about the respiratory system is that it's the small things that matter.  The nose, throat and larynx will take care of the big dust, dirt, pollen and other sizeable pollutants and the millions of cilia (small hairs) in the lungs will sweep out the smaller particles that make it past the larynx. 

The really tiny particles that get down into the lungs can cause an inflammatory reaction that destroys part of the lung.  Nanotechnology may prove to be a severe threat to our respiratory system due to the extremely small size of waste particles.

What Can Go Wrong In Our
Respiratory System?

Malfunctions occur and stuff happens but when it happens to our lungs or any part of our respiratory system, it's more than just an irritant.  The results can range from discomfort to death.

Here's another quote I like; "If you woke up breathing, congratulations!  You have another chance." ~Andrea Boydston. 

Thanks, I'll take a second chance anytime I can get one.  Let's go over some of the things that can make our breathing a painful experience instead of the refreshing experience it's supposed to be.

Many of these issues arise over time as a result of bad lifestyle choices.  No surprise that smoking is at the top of the list.  Remember all those little capillaries and alveoli?   In our respiratory system, that's where the rubber meets the road, or should I say where the actual exchange of gasses take place. 

Wonder what all those cigarettes, cigars and second-hand smoke do to that machinery?

Healthy pink lung tissue

They say a picture is worth a thousand words so below is an autopsy photo of a lung section from a heavy smoker.  Not very pretty; even worse to die from.  On the right is a photo of healthy lung tissue; which would you rather have?

The Big "LC"; Lung Cancer

Lung cancer, like all cancers, is a disease of uncontrolled cell growth.  It's called lung cancer because it occurs in lung tissue.  A cancer is generally defined by where it originates in the body. 

lung cancer shown as white area

As with most cancers, this uncontrolled cell growth may lead to metastasis.

Photo:  Lung cancer shown in white area, black areas show patient was a smoker.

This is where the killer army of mutated cancer cells leaves its home base, lungs in this case, and invades new territory; it could be very far from the lungs depending on where it rides the blood stream.

Very interesting; a pathologist might look at cells from a cancerous liver and say, "I see lung cancer".  That would be because the cancer started in the lungs and retained its identity.

Lung cancer is the most common cause of cancer-related death in men and the second most common in women.  It is estimated that lung cancer takes 1.3 million people each year worldwide. Early symptoms aren't all that bad; shortness of breath, coughing and weight loss; but it goes downhill fast from there. 

Smoking and cancer highly correlated

Smoking and long-term <em>exposure</em> to tobacco smoke is by far the most common cause of lung cancer and other respiratory system failures.  The chart above shows that smoking and the incidence of lung cancer are in lockstep with a 20-year delay between smoking and being diagnosed with lung cancer. 

About 20% of lung cancers are seen in nonsmokers although the statistics do lump second hand smoke into that percentage.  People who have to breathe second hand smoke are still smokers, just not voluntary ones. 

Remember when smoking was allowed on commercial airplanes?  What were we thinking!  Also in that 20% are genetic factors, radon gas, asbestos, and air pollution.

microscopic view of small cell carcinoma

Photo:  Core needle biopsy showing small cell carcinoma.

Small cell and non-small-cell are the two main types of lung cancer and it's only important because the two are treated differently.   Non-small cell lung cancer is sometimes treated with surgery, while small cell usually responds better to chemo and radiation.

Lung cancer is first seen in a chest x-ray and/or a CT scan (computed tomography) then confirmed with a biopsy. Treatment and prognosis depends on the type of cancer, the stage or how far it has spread, and the patient's ability to withstand the treatment.  With treatment, the five-year survival rate is 14%.  Not great odds I would say; that doesn't even come close to matching my credit card interest rates. DON'T SMOKE!

Chronic Obstructive Pulmonary Disease (COPD)

COPD is the 4th leading cause of death in the U.S. and 9 of 10 such deaths are due to smoking.  An estimated 24 million Americans now suffer from COPD.

Another 12 million may have COPD but remain undiagnosed despite recognizable symptoms.

Comparison of healthy alveoli vs COPD afflicted alveoli

COPD usually hits people over 45, especially those who smoke or have smoked.  Other risk factors include an inherited COPD and environmental exposures.

Symptoms are the characteristic "smoker's cough", shortness of breath, wheezing, not being able to take a deep breath, and excess sputum production.


Emphysema is a type of COPD involving damage to the air sacs (alveoli) in the lungs. As a result, your body does not get the oxygen it needs.

pathology of center lobe emphysema characteristic of smoking

It becomes hard to catch your breath and you may have a chronic cough and have trouble breathing during exercise.

Emphysema causes the walls between the alveoli to lose their ability to stretch and relax and they become weakened and break.

Photo:  Emphysema; pathology of smokers lung showing heavy carbon deposits
Elasticity of lung tissue is lost, causing air to be trapped in the air sacs and impairing the exchange of oxygen and carbon dioxide.  In addition, support of the airways is lost, allowing for airflow obstruction.  DON'T SMOKE!

It is estimated that 100,000 Americans living today were born with a hereditary trait causing a deficiency of a protein known as alpha 1-antitrypsin (AAT) whose duty is to protect the lung.


Chronic bronchitis is another respiratory system disease linked to cigarette smoke and is considered to be a subcategory of COPD.

In bronchitis, the membranes lining the larger air passages (Bronchi) become inflamed and an excessive amount of mucus is produced. The person with bronchitis develops a bad cough to get rid of the mucus.

Airflow into and out of the lungs is partly blocked because of the swelling and extra mucus in the bronchi.

Bronchitis is commonly treated with inhalers similar to asthma (see below). Most use the drugs Ventolin, Salbutomal or Novo-Salmol for a respiratory emergency.

Allergy sufferers horizontal banner

Sleep Apnea

Sleep Apnea is one of the fastest growing airway problems.  It is usually mentioned in context of a respiratory system problem because it does interfere with breathing numerous times during the course of the night. 

"Interfering" is a bad choice of words.  What it does is stop breathing entirely for ten seconds or more per occurrence and wakes you up if your lucky. 

This condition is covered in greater detail in the website section on sleep disorders but simply put, sleep apnea is a blockage of the airway through the throat due to a collapse of soft tissue in the tonsil area.

Fat is a major culprit and as our population continues to trend toward obesity, we will see more and more cases of sleep apnea in the future.


Asthma is a chronic respiratory system ailment that inflames and narrows the airways causing recurring periods of wheezing, chest tightness, shortness of breath, and coughing. The coughing often occurs at night or early in the morning.

Asthma effects on lung airways

Asthma affects people of all ages, but it most often starts in childhood. In the United States, more than 22 million people are known to have asthma. Nearly 6 million of these people are children.

People who have asthma exhibit an inflammation of the airways making them swollen and very sensitive. They tend to react strongly to certain substances that are breathed in.

When the airways react, the muscles around them tighten, much like a vise. This causes the airways to narrow, and less air flows to the lungs.

Typical asthma inhaler using the drug Serevent, a long acting bronchodilator

The swelling also can worsen, making the airways even narrower.

Photo:  Typical asthma inhaler.  Don't be surprised to see more and more kids carrying these around.

Cells in the airways may make more mucus than normal that can further narrow the airways.

This chain reaction can result in asthma symptoms which will likely recur each time the airways are irritated.

For an incredibly detailed and complete coverage of all aspects of asthma, visit Shane in the UK has done a marvelous job of compiling a wealth of useful information about this debilitating disease of the respiratory system.


Tuberculosis, mostly just referred to as "TB" (from tubercle bacillus) is a common and often deadly infectious disease caused by bacteria, mainly Mycobacterium tuberculosis.  TB usually attacks the lungs in the respiratory system but can also affect many other systems as well as bones, joints, and even the skin.
We don't hear much about TD today unless an infected person gets on an airplane and breathes on a couple of hundred people.

The classic symptoms are a chronic cough with blood-tinged sputum, fever, night sweats, and weight loss.  Infection of other organs causes a wide range of symptoms.

The diagnosis usually depends on a chest x-ray, a TB skin test, blood tests, as well as microscopic examination and microbiological culture of bodily fluids. TB treatment is difficult and requires long courses of multiple antibiotics. Contacts are also screened and treated if necessary.

Antibiotic resistance is a growing problem and multi-drug-resistant TB is a real fear. Prevention relies on screening programs and vaccination, usually with Bacillus Calmette-Guérin vaccine.

Click here for a discussion of antibiotic resistance and the rise of the superbugs.

Respiratory Syncytial Virus Infection;
aka RSV

RSV is one of the most common respiratory system infections you've never heard of, that is, unless you have a child who is dealing with it.

According to the CDC, "RSV is a respiratory virus that infects the lungs and breathing passages."  If one is healthy, the infection will run its course in one or two weeks.  Unfortunately, in infants, young children and the elderly, RSV can be a very severe ordeal.

CDC also claims that "RSV is the most common cause of bronchiolitis and pneumonia in children under one year of age in the United States. In addition, RSV is more often being recognized as an important cause of respiratory illness in older adults."

What we need to know about RSV is that it is contagious via coughs and sneezes, there is no vaccine to prevent it, catching it does not bestow immunity, almost everyone contracts RSV by age 2 but most often it is mistaken for a cold and day-care centers are the great distribution center for RSV.

Prevention mostly takes the form of avoidance.   Don't share utensils or cups with anyone with cold symptoms, wash your hands frequently, don't let anyone with cold symptoms breathe in your face much less sneeze on you and don't be doing kissy-face with anyone with cold symptoms, especially babies, young kids or grandma.

Care and Feeding of
Your Respiratory System

There's a really simple test to see if your respiratory system is healthy.  If you can run up two flights of stairs or walk six blocks without having to stop and rest and without experiencing shortness of breath, chances are, your lungs are in decent shape.

You did it?  Great, now let’s see how we can keep our respiratory system in tip-top shape. 

It might be helpful to take it in steps, so...

Step 1 is to control your environment to the extent that you can. 

We can't do much about the work environment but home is definitely under our control.  Most of it is just common sense.  Keep the house clean and dust free.  If you have carpets, vacuum frequently. 

Change the furnace filter regularly; a clogged filter does more harm than good. 

Room air filters are good if they are well maintained but there are competing technologies as well as superior and not-so-great brands within the same technology. 

Personally I prefer the HEPA (High Efficiency Particulate Air) technology for portable room air purifiers in that they can remove over 99% of particulates of .3 microns and larger.

We have been running the Enviracaire HEPA units from Honeywell in our home and have been pleased with their performance. In addition, we have just installed a whole house AccuClean system from American Standard.

Click on Air Quality and Health to see a description and comparison of the available home air filtration systems.

We also had three Oreck XL Professional Air Purifiers that we eventually unplugged and quit using.  They are noisy unless you run them on silent mode but don't seem to work very well in silent mode.  Also they have an ionizer switch that generates ozone to give the room a pleasant fresh smell.  Keep reading.

I am not in favor of any ozone generators (air ionizers) in the home.

Photo:  An inflammed lung air passage courtesy of ozone.

Lung air passage inflammed by ozone

Ozone is an ionized oxygen atom that can cause lung damage and other respiratory system complications when inhaled depending on concentration and length of exposure.

The following is a health statement from the EPA on ozone:

    "Relatively low amounts can cause chest pain, coughing, shortness of breath, and, throat irritation. Ozone may also worsen chronic respiratory diseases such as asthma and compromise the ability of the body to fight respiratory infections. People vary widely in their susceptibility to ozone. Healthy people, as well as those with respiratory difficulty, can experience breathing problems when exposed to ozone. Exercise during exposure to ozone causes a greater amount of ozone to be inhaled, and increases the risk of harmful respiratory effects. Recovery from the harmful effects can occur following short-term exposure to low levels of ozone, but health effects may become more damaging and recovery less certain at higher levels or from longer exposures (US EPA, 1996a, 1996b)."

Since this page is about respiratory system health, it is clear to me that ozone is part of the problem, not the solution; best to treat it as a harmful air contaminant and keep it out of your home.<br>

Photo right:  Ozone is a key component of smog.

Ozone is a key component of smog

Step 2 is to avoid inhaled toxins.

Carbon monoxide, radon gas, mold, fumes from dry cleaning, fumes from many household cleansers and the like can do real damage to deep lung tissue. 

Many states real estate statutes require a radon gas statement before a home with a basement can be sold. Avoiding these types of pollutants can have the effect of adding three years to your life.  

Since modern homes are now so tightly sealed, it is not unusual to find the indoor air much more polluted than the outdoor air.  As weather permits, it's a good idea to open the windows and air out the house from time-to-time.

One more thing.  Since its fall as I write this and the leaves are on the ground. If you are like me and mulch the leaves with your mower, wear one of those gauze masks while doing the mulching.  There's lots of
mold on those leaves that we shouldn't be breathing and that mower kicks up an unhealthy amount of micro particles from the soil that also shouldn't be getting in our lungs.

And do we have to say it again?  DON'T SMOKE!  If your must smoke do it outdoors, at least your only killing yourself and not your loved ones.  Second hand smoke kills too.  Our respiratory system will definitely rebel at this type of disrespect.

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Step 3 is to take supplements.     

A good respiratory system supplementation will include 400mg/day of magnesium.  This is an essential mineral that relaxes the bronchial tubes and can help with asthma.

If you have an excessive mucus problem, coughing up lots of mucus from the lungs as opposed to sinus mucus, take about 600 mg twice a day of N-acetylcysteine (NAC).  This works to loosen the mucus and boost glutathione production.

Glutathione is an antioxidant and protects cells, including lung tissue, from free radicals formed by the toxins mentioned previously.

While not exactly a supplement, drinking coffee can stabilize and contract the lining of the airways, thus making breathing easier.  It's not the coffee that does it but the caffeine.  Don't drink coffee? How about some nice dark chocolate?

Step 4 is to learn deep breathing.

For starters, practice taking deep, full breaths; five seconds in, seven seconds out.  If you were to enroll in yoga class, one of the first things they would teach you is how to breathe. 

What's the benefit?  One major benefit is that deep breathing helps move nitric oxide to the lungs.  Nitric oxide comes from the nasal passages and is a very effective lung and blood vessel dilator.  What this means to your respiratory system is that the lungs work better and can give 100% oxygen saturation.

Other benefits include better drainage of the lymphatic system which removes toxins from the body as well as helps with stress relief.  Ever heard the old advice to take a deep breath when you get mad or all tensed up.  There's good reason to do just that, in fact take ten deep breaths.

Breathe well and live long.

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