Wednesday, January 13, 2010

Breath of Life; Understanding our Respiratory System

This article is part of the Anatomy and Physiology section of

When we draw in a breath, we share that air with all other human beings and all other life on our planet. Through respiration, our oneness with trees becomes a manifest fact, and our communion with the oceans has immediate impact. The reality of the planetary whole reveals itself, with implication for all human life, through the circulation of the gases and energy of the atmosphere. This vision underlies holistic healing as much as it does ecology. The anatomy and physiology of the respiratory system is a complex and beautiful embodiment of integration and wholeness.

-David Hoffman, Herbalist

The respiratory system is divided into the upper and lower respiratory tracts.

The upper respiratory system consists of the organs located above the thorax.

This includes:




Part of the trachea

The lower respiratory system consists of:

Bronchial tree


The respiratory system plays a crucial role in delivering oxygen to the cells of our body. The cells of the body require a continuous supply of oxygen; without this oxygen, we would die within minutes.

In this article we will explore the different organs of the respiratory system to better understand the physiological function of breathing. At the end of this article we will explore different pathologies or problems within the respiratory system by reading articles written by herbalists.


Bones and cartilage support the protruding portion of the nose, which is made up of connective tissue and skin. The nostrils, which form two external passages, are lined with hairs that help to filter out large particles in the air. The nostrils open up into the nasal cavity. The nasal cavity is separated from the mouth by the hard and soft palettes. It is lined with ciliated columnar epithelium and cells within these structures produce mucous that line the upper respiratory system. This mucous is an important defense mechanism of our immune system as it traps airborne particles, including pathogens. The cilia move the mucous with the entrapped particles to the throat where it is swallowed. Gastric juices from the stomach then kill most micro-organisms.

The mucous in the nasal cavity also moistens air as it moves through the nasal passageways. The mucous membranes are blood rich and serve to warm the inhaled air. In this way, air traveling through the nasal passageways are filtered, warmed, and moistened before heading to the lungs, which is why it is better to breathe in through your nose and out through your mouth.

Several bones that surround the nasal cavity contain air-filled hollow areas called paranasal sinuses. Sinuses in this area serve to lighten the weight of the skull and increase voice resonance. They are also lined with the same ciliated mucous membranes found within the nasal cavity.


More commonly called the throat, the pharynx is a short tube that extends from behind the nasal cavity to open to the larynx and esophagus. It is a muscular wall that is lined with mucosal tissue. The tonsils are located within the pharynx and we will be discussing those in greater detail when we look at the immune system.


The larynx consists of cartilaginous tissues. It connects the pharynx to the trachea and the esophagus. The larynx houses the vocal chords whose vibrations produce the sounds of speech.

When swallowing, muscles lift the larynx, which causes the epiglottis to fold over and cover the opening to the trachea, which leads to the lungs. If food, water, or other particles somehow breach the trachea, a strong coughing reflex is produced that will expel the materials.


The trachea, commonly known as the windpipe, is a tube that connects the larynx to the bronchial tree and allows for inhaled air to proceed to the lungs and exhaled air to leave the body. Cartilaginous rings support the trachea and hold it open despite the changing air pressure within this tube.

The trachea is lined with the same ciliated mucous membranes that we find in the rest of the respiratory system. It also traps airborne particles and then transports the mucous upwards towards the pharynx where it is swallowed and proceeds to go down the esophagus.

The trachea splits into two sections at about the mid-chest to form the left and right primary bronchi.

Bronchial Tree

The term bronchial tree refers to a series of structures within the lungs that actually resembles a tree! I find this incredibly fascinating. Trees transform CO2 into oxygen. Humans transform oxygen to CO2, and the human organ for performing this process looks like a tree!

The left and right primary bronchi further branch to form smaller secondary bronchi. There is a secondary bronchi in each lobe of the lung. These secondary bronchi continue to branch into smaller and smaller tubules.

All of these airways continue to be lined with ciliated mucous membranes that also trap and then remove airborne particles.

As these branches become tubules they are called bronchioles. Structures the size of bronchioles are not lined with the same mucosal tissue as the rest of the respiratory system. As a result, foreign particles that reach these sections are harder to remove. If the mucosal tissue that contains the ciliated mucous membranes becomes damaged, say from cigarette smoke, more particles can reach these vulnerable areas and create more bronchial infections.

Bronchioles continue to branch until finally leading to microscopic alveolar ducts that then terminate in alveoli. Back to our image of a tree, the primary bronchi is similar to the trunk of a tree, the secondary bronchi are the main branches, which then become smaller branches and, finally, leaves.

There are 300 million alveoli in each lung. They resemble a grape cluster on a vine and have a surface area of 75 square meters. A capillary network surrounds each alveolus.

The alveoli perform the magical task of infusing blood with oxygen, while removing excess CO2 from the body. This chemical process takes place between the alveoli membranes and the rich capillary network that surround them.


The lungs are two large organs that fill much of the rib cage. The right lung is slightly larger than the left and is made up of three lobes. The smaller left lung is made up of two lobes. A secondary bronchus, blood and lymphatic vessels, and nerves support each lobe of the lungs. The heart and the mediasteinum separate the two lungs from each other.

The lungs are primarily made up of connective tissue, which gives them their soft and spongy texture. They also consist of blood, lymphatic tissue, air passageways, and alveoli.

Surrounding each lung is the serous membrane. It serves to protect and enclose each lung. The visceral pleura is the next layer of tissue around the lungs. The parietal pleura encases the inner wall of the rib cage. The space between the parietal pleura and the visceral pleura is referred to as the pleural cavity.


Here’s an overview of the breathing process.

Air is inhaled through the nose and or mouth and travels down a series of tubes including the pharynx and trachea until it reaches the bronchi and finally down to the microscopic aveloi. At the membrane surface of each alveolus, a gas exchange between oxygen and CO2 takes place. The oxygen enters in the blood stream and binds to red blood cells while the CO2 is expelled back out of the respiratory system and exhaled into the atmosphere.

Inspiration – The act of inhalation

We breathe about 5,000 times a day or about 15 to 20 times each minute. With each inhalation the muscles of respiration contract. When the diaphragm, a flat skeletal muscle tissue at the base of the rib cage, contracts it flattens and creates more space in the thoracic cavity for the lungs to expand. Concurrently, the external intercostals elevate the ribs and sternum, creating even more space for lung expansion.

This expansion of the lungs increases the volume of internal air passageways, which then means that the air pressure inside the lungs decreases below the air pressure of the air outside the body. This change in air pressure causes the atmospheric air to rush into the lungs, because gas likes to move from regions of high pressure to low pressure.

Expiration – The act of exhaling

With each exhalation the diaphragm and external intercostal muscles relax. This causes the elastic fibers in lung tissue to recoil to their original volume. Air pressure is now reversed and so the air rushes out. During times of rapid breathing such as exercising, exhaling is further facilitated by the intercostals muscles and the abdominal muscles contracting.

“Chronic lung conditions compromise quality of life for millions of people around the world”

Dr. Michael Alberts

Support the health of your respiratory system

There are many things we can do to help encourage the health of our respiratory system and prevent any problems later on down the road. I’ve listed some important elements below and you may also find this comprehensive article informative as well.

Food and herbs

Many studies show that what we eat has a direct correlation with our respiration health. Diets high in fish (omega 3s) and anti-oxidants from fruits and vegetables seem to have the most positive benefits. 1, 2

Vitamin D

Recent studies have shown that vitamin D has a huge impact on the health of our respiratory system. 1 In one study the difference in people with normal levels of Vitamin D and low levels of Vitamin D was essentially the same difference as in people who do not smoke and those who do in terms of mortality rates.

Breathing Exercises

All around the world ancient traditions have supported the breath. Although the Anatomy and Physiology series on has been entirely focused on a Western view of the body systems, I would like to briefly go into how the Chinese view the Lungs. According to acupuncturist Suzanne E. Sky,

“Chinese medicine states the Lungs receive Pure Qi from the heavens. The air we breathe is an essential ingredient that sparks the formation of Qi, the life force that flows through our body. Qi flows throughout specific pathways in our bodies to nourish and vitalize all our organs, tissues, and systems and to energize biochemical and electrical activity in our body. Thus, the Lungs are the root of the body’s Qi and are said to dominate the Qi. The Lungs rule physical strength and stamina and are also called the Master of Breaths.”

Breathing exercises can be employed to support our health, reduce anxiety, promote meditation and mindfulness, and increase overall vitality.

Pranayama of Yoga, A fabulous overview of the importance of breath in the yogic tradition

Breathing Exercises, by Dennis Lewis (an expert on breathing)

Breathing article by herbalist Chanchal Cabrera

Another short but important article on Breathing by herbalist Todd Caldecott

Breathing Clean Air

The air we breathe directly influences the health of our respiratory system. Environmental pollution such as car exhaust and other toxins can weaken our lungs over time. Harsh household cleaners can do the same. Dust and smoke from a wood fire can taint even the most pristine country locations. And not only does smoking directly inhibit our lungs’ ability to work well, but second hand smoke (breathing smoke from someone else’s cigarette) and third hand smoke (breathing fumes on someone’s clothes, car, house) can also impact the health of the lungs. 1

Reducing stress, including excessive grief

Stress has a direct effect on our overall health and the respiratory system is no exception. Here is an article outlining Stress and Respiratory Health.

In Chinese medicine the lungs are where we hold our grief. If that sounds strange to you, think of how you feel when you are really sad and you may be reminded of that crushing or overwhelming feeling right in your lungs. Getting the support we need during times of grieving can go a long ways in supporting lung health.

Avoiding excessive mucous in the body

Mucosal membranes line the respiratory system and the digestive tract. These membranes and the mucous they produce are an integral part of our vitally functioning body. However, excess mucous in the body can create problems. Eating large amounts of cold foods (raw fruits, veggies, dairy), especially in the cold months can create this. For many people cold dairy food such as yogurt, milk, and cheese can create an overabundance of mucous. Fresh-from-the-farm milk, drank warm with warming herbs such as cinnamon, may reduce this effect.

Lung tonics

There are many herbs that affect the respiratory system. Some are even tonifying or strengthening to the respiratory system. A classic Chinese combination includes Astragalus root and Codonopsis root. In Western Herbalism, Red Clover (Trifolium pratense) and Mullein (Verbascum thapsus) are often used to strengthen respiratory health. In this pdf, 7song has listed a comprehensive materia medica for the respiratory system.

Common complaints within the respiratory system


A pdf from David Winston outlining the eclectic protocols for asthma

David Hoffman gives an overview of asthma here

An overview of childhood asthma by Janet Zand


David Hoffman has two articles delineating the difference between acute and chronic bronchitis.

Jill Stansbury discusses Bronchitis Recipes and Formulae


jim mcdonald has written the ultimate view on surviving sinusitis here

An article by David Hoffman looking at sinusitis

Upper Respiratory Infections and Coughs

The Herbal Remedies for Cold and the Flu Ebook extensively covers coughs

Aviva Romm gives a comprehensive overview of Upper Respiratory Infections in Children (pdf)

An article on herbal expectorants by Shane Foley

Henriette looks at Herbs for Coughs and then at Lung Grunges and what you can do to strengthen your lungs.

Botanical Approaches to Winter Respiratory Complaints

by Jill Stansbury, N.D.

Tonics for the Upper Respiratory System by David Hoffman


An article by David Hoffman


An article by David Hoffman


Henriette gives an overview of considerations

Guido Mase’ looks at asthma and allergies

David Hoffman explores Hay Fever


An article by David Hoffman

Stop smoking cigarettes

A formula by David Winston

Neti Pot

Neti pots can be an important aid in maintaining respiratory health. Here is a pdf from Todd Caldecott explaining how to use a neti pot and other ayurvedic means to support the respiratory system.

Works Consulted

The anatomy of physiology of this article was extracted mainly from The Principles of Anatomy &f Physiology, Tortora, Grabowski. I also used Anatomy and Physiology by Stanley E. Gunstream 4th ed.

The second half of this article giving us an herbal perspective on the nervous system would not have been possible without jim mcdonald’s Article Index. Thanks a thousand times to jim for putting this together.