The respiratory system works to deliver oxygen to the body and remove carbon dioxide. It includes the mouth, nose, pharynx, larynx, lungs, trachea, bronchi, and diaphragm. Air enters through the nose or mouth and travels down the trachea to the lungs, where oxygen passes into blood vessels and carbon dioxide is removed. The lungs, trachea, and bronchi form a branching tree structure ending in tiny air sacs called alveoli that facilitate gas exchange with blood in the pulmonary circulation. The diaphragm and intercostal muscles help drive breathing by expanding the lungs and lowering their pressure.

1. Introduction to the
Respiratory System
Yoga Life Asanas and Meditation

2. Introduction to
the
Respiratory
System
When the respiratory system is mentioned,
people generally think of breathing, but
breathing is only one of the activities of the
respiratory system. The body cells need a
continuous supply of oxygen for the
metabolic processes that are necessary to
maintain life. The respiratory system works
with the circulatory system to provide this
oxygen and to remove the waste products
of metabolism. It also helps to regulate pH
of the blood.

3. Introduction to the
Respiratory System
Respiration is the sequence of events that results in the exchange of oxygen and
carbon dioxide between the atmosphere and the body cells. Every 3 to 5
seconds, nerve impulses stimulate the breathing process, or ventilation, which
moves air through a series of passages into and out of the lungs. After this, there
is an exchange of gases between the lungs and the blood. This is called external
respiration. The blood transports the gases to and from the tissue cells. The
exchange of gases between the blood and tissue cells is internal respiration.
Finally, the cells utilize the oxygen for their specific activities: this is called cellular
metabolism, or cellular respiration. Together, these activities constitute
respiration.

4. Mechanics of Ventilation
Ventilation, or breathing, is the
movement of air through the
conducting passages between the
atmosphere and the lungs. The air
moves through the passages because
of pressure gradients that are
produced by contraction of the
diaphragm and thoracic muscles

5. Mechanics of
Ventilation
Pulmonary ventilation
Pulmonary ventilation is commonly referred to as
breathing. It is the process of air flowing into the lungs
during inspiration (inhalation) and out of the lungs during
expiration (exhalation). Air flows because of pressure
differences between the atmosphere and the gases inside
the lungs. Air, like other gases, flows from a region with
higher pressure to a region with lower pressure. Muscular
breathing movements and recoil of elastic tissues create
the changes in pressure that result in ventilation.
Pulmonary ventilation involves three different pressures:
• Atmospheric pressure
• Intrapulmonary pressure
• Intrapleural pressure

6. Mechanics of
Ventilation
Pulmonary ventilation
Atmospheric pressure is the pressure of the air outside the body. Intrapulmonary pressure is the
pressure inside the alveoli of the lungs. Intrapleural pressure is the pressure within the pleural
cavity. These three pressures are responsible for pulmonary ventilation.
Inspiration
Inspiration (inhalation) is the process of taking air into the lungs. It is the active phase of ventilation
because it is the result of muscle contraction. During inspiration, the diaphragm contracts and the
thoracic cavity increases in volume. This decreases the intrapulmonary pressure so that air flows
into the lungs. Inspiration draws air into the lungs.
Expiration
Expiration (exhalation) is the process of letting air out of the lungs during the breathing cycle.
During expiration, the relaxation of the diaphragm and elastic recoil of tissue decreases the thoracic
volume and increases the intrapulmonary pressure. Expiration pushes air out of the lungs.

7. Respiratory Volumes
and Capacities
Under normal conditions, the average adult takes 12 to 15
breaths a minute. A breath is one complete respiratory
cycle that consists of one inspiration and one expiration.
An instrument called a spirometer is used to measure the
volume of air that moves into and out of the lungs, and the
process of taking the measurements is called spirometry.
Respiratory (pulmonary) volumes are an important aspect
of pulmonary function testing because they can provide
information about the physical condition of the lungs.
Respiratory capacity (pulmonary capacity) is the sum of
two or more volumes.
Factors such as age, sex, body build, and physical
conditioning have an influence on lung volumes and
capacities. Lungs usually reach their maximum in capacity
in early adulthood and decline with age after that.

8. Conducting Passages
The respiratory conducting passages are
divided into the upper respiratory tract and
the lower respiratory tract. The upper
respiratory tract includes the nose,
pharynx, and larynx. The lower respiratory
tract consists of the trachea, bronchial tree,
and lungs. These tracts open to the outside
and are lined with mucous membranes. In
some regions, the membrane has hairs that
help filter the air. Other regions may have
cilia to propel mucus.

9. Nose, Nasal Cavities, & Paranasal
Sinuses
Nose & Nasal Cavities
The framework of the nose consists of bone and cartilage.
Two small nasal bones and extensions of the maxillae
form the bridge of the nose, which is the bony portion. The
remainder of the framework is cartilage and is the flexible
portion. Connective tissue and skin cover the framework.
Air enters the nasal cavity from the outside through two
openings: the nostrils or external nares. The openings
from the nasal cavity into the pharynx are the internal
nares. Nose hairs at the entrance to the nose trap large
inhaled particles.

10. Nose, Nasal Cavities, & Paranasal
Sinuses
Paranasal Sinuses
Paranasal sinuses are air-filled cavities in the frontal,
maxillae, ethmoid, and sphenoid bones. These sinuses,
which have the same names as the bones in which they
are located, surround the nasal cavity and open into it.
They function to reduce the weight of the skull, to produce
mucus, and to influence voice quality by acting as
resonating chambers.

11. The pharynx, commonly called the throat, is a
passageway that extends from the base of the skull to
the level of the sixth cervical vertebra. It serves both
the respiratory and digestive systems by receiving air
from the nasal cavity and air, food, and water from the
oral cavity. Inferiorly, it opens into the larynx and
esophagus. The pharynx is divided into three regions
according to location: the nasopharynx, the
oropharynx, and the laryngopharynx (hypopharynx).
The upper part of the pharynx (throat) lets only air pass
through. Lower parts permit air, foods, and fluids to
pass.
Pharynx

12. Larynx & Trachea
Larynx
The larynx, commonly called the voice box or glottis, is the passageway for air
between the pharynx above and the trachea below. It extends from
the fourth to the sixth vertebral levels. The larynx plays an essential role
in human speech. During sound production, the vocal cords close together
and vibrate as air expelled from the lungs passes between them. The false
vocal cords have no role in sound production but help close off the larynx when
food is swallowed.
The thyroid cartilage is the Adam's apple. The epiglottis acts like a trap
door to keep food and other particles from entering the larynx

13. Larynx & Trachea
Larynx
• The larynx, commonly called the voice box or
glottis, is the passageway for air between the pharynx
above and the trachea below. It extends
from the fourth to the sixth vertebral levels. The larynx
plays an essential role in human speech. During
sound production, the vocal cords close together
and vibrate as air expelled from the lungs passes
between them. The false vocal cords have no role in
sound production but help close off the larynx when
food is swallowed.
• The thyroid cartilage is the Adam's apple. The
epiglottis acts like a trap door to keep food and other
particles from entering the larynx

14. Trachea
Trachea
• The trachea, commonly called the
windpipe, is the main airway to the lungs. It
divides into the right and left bronchi at the
level of the fifth thoracic vertebra,
channeling air to the right or left lung.
• The hyaline cartilage in the tracheal wall
provides support and keeps the trachea
from collapsing.
• The mucous membrane that lines the
trachea is like that in the nasal cavity and
nasopharynx. Goblet cells produce mucus
that traps airborne particles and
microorganisms, and the cilia propel the
mucus upward, where it is either swallowed
or expelled.

15. Bronchi,
Bronchial
Tree, &
Lungs
Bronchi and Bronchial Tree
• The trachea divides
into the right and
left primary bronchi.
The bronchi branch
into smaller and
smaller
passageways until
they terminate in
tiny air sacs called
alveoli.
• The cartilage and mucous membrane of the primary
bronchi are like that in the trachea. As the branching
continues through the bronchial tree.
• The alveolar ducts and alveoli consist primarily of simple
squamous epithelium, which permits rapid diffusion of
oxygen and carbon dioxide. Exchange of gases between
the air in the lungs and the blood in the capillaries occurs
across the walls of the alveolar ducts and alveoli.

16. Bronchi,
Bronchial
Tree, &
Lungs
Lungs
• The two lungs, which contain all the components of the bronchial tree
beyond the primary bronchi, occupy most of the space in the thoracic
cavity. The lungs are soft and spongy because they are mostly air
spaces surrounded by the alveolar cells and elastic connective
tissue.
• The only point of attachment for each lung is at the hilum, or root, on
the medial side. This is where the bronchi, blood vessels, lymphatics,
and nerves enter the lungs.
• The right lung is shorter, broader, and has a greater volume than the
left lung. It is divided into three lobes and each lobe is supplied by
one of the secondary bronchi. The left lung is longer and narrower
than the right lung.
• Each lung is enclosed by a double-layered serous membrane, called
the pleura.
• It contains a thin film of serous fluid that is produced by the pleura.
The fluid acts as a lubricant to reduce friction as the two layers slide
against each other, and it helps to hold the two layers together as the
lungs inflate and deflate.

17. Diaphragm
• Diaphragm, dome-shaped, muscular and membranous
structure that separates the thoracic (chest) and
abdominal cavities in mammals; it is the principal
muscle of respiration.
• Contraction of the diaphragm increases the internal
height of the thoracic cavity, thus lowering its internal
pressure and causing inspiration of air. Relaxation of
the diaphragm and the natural elasticity of lung tissue
and the thoracic cage produce expiration. The
diaphragm is also important in expulsive actions—e.g.,
coughing, sneezing, vomiting, crying, and expelling
feces, urine,
• The diaphragm is a thin skeletal muscle that sits at the
base of the chest and separates the abdomen from the
chest. It contracts and flattens when you inhale. This
creates a vacuum effect that pulls air into the lungs.
When you exhale, the diaphragm relaxes, and the air is
pushed out of lungs.

19. •Diaphragmatic breathing gently massages the
digestive organs. This is thought to contribute to
proper blood perfusion in these organs and
maintain the intestine’s peristaltic movement. This
massaging does not take place during chest
breathing. Diaphragmatic breathing is also an
excellent tool in controlling stress.
•Chest breathing fills the middle and upper portion
of the lungs, which constitute only the upper two-
thirds of the lungs. When the body is upright, most
of the blood is collected at the lowest one-third of
the lungs, so air is not mixed as thoroughly with
blood if we breathe through the chest.
Consequently, gas exchange is insufficient,
making the heart and lungs work more to achieve
the proper oxygenation amount.
•On the other hand, in diaphragmatic breathing,
the air is pulled all the way down into the blood-
rich lower lobes. This increases the efficiency of
the entire cardiorespiratory functioning.
Diaphragmatic breathing VS.
Chest breathing

20. .
Whichever way one breathes, there is no difference in the amount
of oxygen consumed by the body. Still, there is a vast difference in
the amount of work required by the lungs and heart to accomplish
the same amount of oxygenation. The cardio-respiratory system’s
workload may be reduced by as much as fifty percent by changing
from chest to diaphragmatic breathing (Freedom from stress, Dr.
Phil Nuernberger Ph.D.).
This can be seen by the number of breaths one takes in one
minute. While those who breathe through the chest will average
about sixteen to twenty breaths per minute, those who breathe
through the diaphragm will average only six to eight breaths per
minute. In 24 hours, chest breathers will take 22,000 to 25,000
breaths, while diaphragmatic breathers will take only 10,000 to
12,000. This is a significant difference.

21. .
Many of us confuse the term regular breathing and natural
breathing. Most of us believe that our breathing pattern is natural
for us when the truth is that it is shaped primarily by habit. Natural
breathing can best be seen in a healthy infant. If you observe one
closely, you will see little or no movement of the chest when it
breathes only the stomach goes up and down (which indicates
diaphragmatic breathing). But when the infant is under stress
(through hunger or discomfort) and begins to cry, you will see the
chest moving up and down in rhythm with the diaphragm.
As we grow up, we develop poor and unhealthy breathing patterns
that replace natural breathing. Eventually, we do not utilize the
diaphragm in our typical day to day resting breathing pattern. In
fact, in many cases, the diaphragm gets ‘frozen’, showing little to
absolutely no movement at all.
There are several reasons why we develop poor breathing
patterns.

22. .
The psychological traumas we undergo as we grow
up also contribute to the development of thoracic
breathing. You can observe that fear tightens the
stomach muscles, preventing diaphragmatic
breathing. For example, suppose you watch children
being scolded by their parents. In that case, they
tighten their stomach muscles, forcing them to
breathe through the chest. We all experience these
small traumas as we grow up - and they have their
effect on our breathing pattern.
Poor posture also prevents diaphragmatic breathing,
and one makes one rely entirely on thoracic
breathing.
For these and many more reasons, we develop a
habitual breathing pattern, which results in increased
stress, anxiety, depression, and inefficient use of the
cardiopulmonary system.

23. Review: Introduction to the Respiratory System
Here is what we have learned from Introduction to the Respiratory System:
• The entire process of respiration includes ventilation, external respiration, transport of gases, internal
respiration, and cellular respiration.
• The three pressures responsible for pulmonary ventilation are atmospheric pressure, intraalveolar
pressure, and intrapleural pressure.
• A spirometer is used to measure respiratory volumes and capacities. These measurements provide
useful information about the condition of the lungs..
• The pharynx, commonly called the throat, is a passageway that extends from the base of the skull to
the level of the sixth cervical vertebra.
• The larynx, commonly called the voice box, is the passageway for air between the pharynx above and
the trachea below.
• The trachea, commonly called the windpipe, is the main airway to the lungs.
• The trachea divides into the right and left primary bronchi, which branch into smaller and smaller
passageways until they terminate in tiny air sacs called alveoli.
• The two lungs contain all the components of the bronchial tree beyond the primary bronchi.
• The right lung is shorter, broader, and is divided into three lobes.
• The left lung is longer, narrower, and is divided into two lobes.

24. The respiratory system is made up of the organs which help us
breathe. Respiration is about breathing. The goal of breathing is to
deliver oxygen to the body and to remove carbon dioxide.
How Does the Respiratory System Work?
The respiratory system includes the mouth, nasal passage, pharynx,
larynx, lungs, trachea, bronchi, bronchioles, alveoli, epiglottis, and
diaphragm.
Mouth: Air enters the body through either the open mouth or the nose.
It travels down the trachea to the lungs, where the oxygen in it passes
into the bloodstream.
Nasal passage: Air enters the body through either the open mouth or
the nose—tiny hairs in the nose trap unwanted particles.
Simultaneously, a sticky liquid called mucus catches many of the germs
before they can go too far into the respiratory system. The mucus also
warms and moistens the air.

25. Pharynx: It is divided into the nasopharynx, oropharynx, and
laryngeal pharynx. The nasopharynx serves only the respiratory
system. The laryngeal and oro-pharynx both act as a passage
for respiratory and digestive functions and as a resonating
chamber for speech sounds.
Larynx: The upper part of the windpipe which contains the
vocal cords. It also produces sound vibrations.
Epiglottis: It is a flap in the throat that blocks the windpipe
when food or liquid is swallowed.
Trachea: The trachea is sometimes called the windpipe. About
half of its 13 cm length is inside the chest, and the other half is
in the neck. The lower end of the trachea divides into two
bronchi (tubes) that carry air into the lungs. The trachea filters
the air we breathe and branches into the bronchi.

26. Lungs: It is a balloon-like structure in the chest that brings
oxygen into the body and expels carbon dioxide from the body.
There are two lungs in the human body, and they are
The main organs of the respiratory system. In the lungs, oxygen
is taken into the body, and carbon dioxide is breathed out. The
red blood cells are responsible for picking up the oxygen in the
lungs and carrying it to the body cells that need it. The red blood
cells drop off oxygen to the body cells and then pick up carbon
dioxide, a waste gas product produced by our cells. The red
blood cells transport the carbon dioxide back to the lungs, and
we breathe it out when we exhale.
Bronchi: This is the lower end of the trachea, divided into two
bronchi (tubes) that carry air into the lungs. One bronchus goes
to the left lung, the other to the right lung.
Bronchioles: Each bronchus divides into smaller tubes called
bronchioles.

27. Alveoli: Bronchioles eventually lead to tiny, stretchy sacs called
alveoli. These sacs blow up like small balloons when you
breathe in. Oxygen from the air passes through the alveoli walls
into capillaries, while carbon dioxide is passed out.
Diaphragm: Breathing starts with a dome-shaped muscle at the
bottom of the lungs called the diaphragm. It is the primary
muscle used in breathing. When we breathe in, the diaphragm
contracts, flattens out, and pulls downward. This movement
enlarges the space that the lungs are in. This larger space pulls
air into the lungs. When we breathe out, the diaphragm
expands, reducing the lungs’ amount of space and forcing air
out.