Parts of the Respiratory System and their Function
Introduction to parts of the respiratory system and their function
Respiratory system consists of the organs that help to breathe. Respiration also known as breathing
is the process which delivers oxygen from the external atmosphere to the body and removes the
carbon dioxide from body and expels out. The main parts of the respiratory system and their
functions are as follows
 The nostrils
 Trachea
 Bronchi
 Lungs
 Alveolus
 Diaphragm
Fig1:Parts of the respiratory system
Main Parts of the Respiratory System and their
Function
The nostrils: Nostrils are involved in air intake, i.e. they bring air into the nose, where air is warmed
and humidified. The tiny hairs called cilia filters out dust and other particles present in the air and
protects the nasal passage and other regions of the respiratory tract.

Trachea: The trachea is also known as windpipe. The trachea filters the air we inhale and branches
into the bronchi.
Bronchi: The bronchi are the two air tubes that branch off of from the trachea and carry atmospheric
air directly into the lungs.
Lungs: The main organ of the respiratory system is lungs. Lungs are the site in body where oxygen
is taken into and carbon dioxide is expelled out. The red blood cells present in the blood picks up the
oxygen in the lungs and carry and distribute the oxygen to all body cells that need it. The red blood
cells donate the oxygen to the cells and picks up the carbon dioxide produced by the cells.
Alveolus: Alveolus is the tiny sac like structure present in the lungs which the gaseous exchange
takes place.
Diaphragm: Breathing begins with a dome-shaped muscle located at the bottom of the lungs which
is known as diaphragm. When we breathe in the diaphragm contracts and flatten out and pull
downward. Due to this movement the space in the lungs increases and pulls air into the lungs. When
we breathe out, the diaphragm expands and reduces the amount of space for the lungs and forces
air out.
Diseases Associated with Respiratory System
Diseases associated with respiratory system are asthma, bronchiolitis, chronic obstructive
pulmonary disease (COPD), cystic fibrosis, pneumonia, etc.
Functions of Organs in Respiratory System
Major organs involved in the process of respiration are responsible for respective and cooperative work toallow gas
exchangetooccur at the cellular level.This article provides an introduction intothe anatomy of respiratory system
and functions of organs in respiratory system.
Respiratory System
Several organs of the respiratory system are responsible for the process of breathing. The nose, pharynx,
larynx, trachea, bronchi, and lungs work together to allow gas exchange to occur at the cellular level. Air
breathed in through the nose and mouth enters into the lungs at a continual pace to provide a new supply
of oxygen the body needs to work properly.

The primary function of the respiratory system is to allow the lungs to take in atmospheric oxygen through
inhalation and dispose of the waste products the body does not need through exhalation.
Inhalation is an active motion that causes the diaphragm to contract. During inhalation the diaphragm
moves downward as it contracts, increasing the size of the chest cavity. This creates a space of
emptiness, which causes air to enter in through the nose or mouth.
Exhalation is a passive process because muscle contraction does not occur. During exhalation, the
diaphragm moves back up as the stretched lung bounces back to its normal position. As the lung returns
to normal position, carbon dioxide, a waste product created by the body, moves out of the lungs through
the mouth and nose.
Functions of Organs in Respiratory System
Respiration begins when oxygen enters into the body through the nose and the mouth. The oxygen then
travels through the trachea and pharynx where the trachea divides into two bronchi. Here the bronchi are
divided into bronchial tubes, in the chest cavity, so air can be directly moved into the lungs.
Nose
The nose is the primary upper respiratory organ in which air enters into and exits from the body. Cilia and
mucus line the nasal cavity and traps bacteria and foreign particles that enter in through the nose. In
addition, air that passes through the nasal cavity is humidified and moistened.
The nasal septum divides the nose into two narrow nasal cavities: one area is responsible for smell and
the other area is responsible for respiration. Within the walls of the nasal cavity there are frontal, nasal,
ethmoid, maxillary, and sphenoid bones. Cartilage helps form the shape of the nose.
Pharynx
Besides the nose, air can enter into the lungs through the mouth. The pharynx is a tubular structure,
positioned behind the oral and nasal cavities, that allows air to pass from the mouth to the lungs. The
pharynx contains three parts: The nasopharynx, which connects the upper part of the throat with the
nasal cavity; the oropharynx, positioned between the top of the epiglottis and the soft palate; and the
laryngopharynx, located below the epiglottis.
Larynx
From the pharynx, air enters into the larynx, commonly called the voice box. The larynx is part of the
upper respiratory tract that has two main functions: a passageway for air to enter into the lungs, and a
source of vocalization. The larynx is made up of the hyoid bone and cartilage, which helps regulate the
flow of air. The epiglottis is a flap-like cartilage structure contained in the larynx that protects the trachea
against food aspiration.

Bronchi
The bronchi allow the passage of air to the lungs. The trachea is made of c-shaped ringed cartilage that
divides into the right and left bronchus. The right main bronchus is shorter and wider than the left main
bronchus. The right bronchus is subdivided into three lobar bronchi, while the left one is divided into two
lobar bronchi.
Lungs
The lungs are spongy, air-filled organs located on both sides of the chest cavity. The left lung is divided
into a superior and inferior lobe, and the right lung is subdivided into a superior, middle, and inferior lobe.
Pleura, a thin layer of tissue, line the lungs to allow the lungs to expand and contract with ease.
Respiration is the primary function of the lungs, which includes the transfer of oxygen found in the
atmosphere into the blood stream and the release of carbon dioxide into the air.
Alveoli
The average adult has about 600 million alveoli, which are tiny grape-like sacs at the end of the
respiratory tree. The exchange of oxygen and carbon dioxide gases occurs at the alveolar level. Although
effort is required to inflate the alveoli (similar to blowing up a balloon), minimal effort is needed to deflate
the alveoli (similar to the deflating of a balloon).
Diaphragm
The diaphragm is a muscular structure located between the thoracic and abdominal cavity. Contraction of
the diaphragm causes the chest or thorax cavity to expand, which occurs during inhalation. During
exhalation, the release of the diaphragm causes the chest or thorax cavity to contract.
What organs up the respiratory system? what tissues
make up those organs? what cells make up those
tissues?
The nose, larynx, trachea, bronchi, lungs, pharynx, epiglottis, alveloi, as well as diaphragm from
the breathing. Various types of tissues compose these types of organs, for example
cartilaginous tissue. Cells that comprise nearly all loose connective tissues are known as
fibroblasts.
The respiratory system is made of the conducting airways (bronchi, bronchioles, etc.) and the
alveoli (air sacs). Alveloi are lined with two major cell types: type I pneumocytes, which are
broad and flat and mediate gas exchange, and type II pneumocytes, which 1) make surfactant
to keep the alveoli from collapsing and 2) serve as stem cells to regenerate type I pneumocytes
after injury.

The Respiratory System
The respiratory system is made up of organs and tissues that help you breathe. The main parts of this
system are the airways, the lungs and linked blood vessels, and the muscles that enable breathing.
The Respiratory System
Figure A shows the location of the respiratory structures in the body. Figure B is an enlarged
view of the airways, alveoli (air sacs), and capillaries (tiny blood vessels). Figure C is a closeup
view of gas exchange between the capillaries and alveoli. CO2is carbon dioxide, and O2is
oxygen.
Airways
The airways are pipes that carry oxygen-rich air to your lungs. They also carry carbon dioxide, a waste
gas, out of your lungs. The airways include your:
 Nose and linked air passages (called nasal cavities)
 Mouth
 Larynx (LAR-ingks), or voice box
 Trachea (TRA-ke-ah), or windpipe
 Tubes called bronchial tubes or bronchi, and their branches

Air first enters your body through your nose or mouth, which wets and warms the air. (Cold, dry air
can irritate your lungs.) The air then travels through your voice box and down your windpipe. The
windpipe splits into two bronchial tubes that enter your lungs.
A thin flap of tissue called the epiglottis (ep-ih-GLOT-is) covers your windpipe when you swallow. This
prevents food and drink from entering the air passages that lead to your lungs.
Except for the mouth and some parts of the nose, all of the airways have special hairs called cilia (SIL-
e-ah) that are coated with sticky mucus. The cilia trap germs and other foreign particles that enter
your airways when you breathe in air.
These fine hairs then sweep the particles up to the nose or mouth. From there, they're swallowed,
coughed, or sneezed out of the body. Nose hairs and mouth saliva also trap particles and germs.
Lungs and Blood Vessels
Your lungs and linked blood vessels deliver oxygen to your body and remove carbon dioxide from your
body. Your lungs lie on either side of your breastbone and fill the inside of your chest cavity. Your left
lung is slightly smaller than your right lung to allow room for your heart.
Within the lungs, your bronchi branch into thousands of smaller, thinner tubes called bronchioles.
These tubes end in bunches of tiny round air sacs called alveoli (al-VEE-uhl-eye).
Each of these air sacs is covered in a mesh of tiny blood vessels called capillaries. The capillaries
connect to a network of arteries and veins that move blood through your body.
The pulmonary (PULL-mun-ary) artery and its branches deliver blood rich in carbon dioxide (and
lacking in oxygen) to the capillaries that surround the air sacs. Inside the air sacs, carbon dioxide
moves from the blood into the air. At the same time, oxygen moves from the air into the blood in the
capillaries.
The oxygen-rich blood then travels to the heart through the pulmonary vein and its branches. The
heart pumps the oxygen-rich blood out to the body. (For more information about blood flow, go to the
Health Topics How the Heart Worksarticle.)
The lungs are divided into five main sections called lobes. Some people need to have a diseased lung
lobe removed. However, they can still breathe well using the rest of their lung lobes.
Muscles Used for Breathing
Muscles near the lungs help expand and contract (tighten) the lungs to allow breathing. These muscles
include the:
 Diaphragm (DI-ah-fram)
 Intercostal muscles
 Abdominal muscles
 Muscles in the neck and collarbone area

The diaphragm is a dome-shaped muscle located below your lungs. It separates the chest cavity from
the abdominal cavity. The diaphragm is the main muscle used for breathing.
The intercostal muscles are located between your ribs. They also play a major role in helping you
breathe.
Beneath your diaphragm are abdominal muscles. They help you breathe out when you're breathing
fast (for example, during physical activity).
Muscles in your neck and collarbone area help you breathe in when other muscles involved in
breathing don't work well, or when lung disease impairs your breathing.
The cells of the human body require a constant stream of oxygen to stay alive. The respiratory
system provides oxygen to the body’s cells while removing carbon dioxide, a waste product that can
be lethal if allowed to accumulate. There are 3 major parts of the respiratory system: the airway, the
lungs, and the muscles of respiration. The airway, which includes the nose, mouth, pharynx, larynx,
trachea, bronchi, and bronchioles, carries air between the lungs and the body’s exterior. The lungs act
as the functional units of the respiratory system by passing oxygen into the body and carbon dioxide
out of the body. Finally, the muscles of respiration, including the diaphragm and intercostal muscles,
work together to act as a pump, pushing air into and out of the lungs during breathing.
The human respiratory system consists of a complex set of organs and tissues that capture oxygen
from the environment and transport the oxygen into the lungs. The organs and tissues that comprise
the human respiratory system include the nose and pharynx, the trachea, and the lungs.
Nose and pharynx
The respiratory system of humans begins with the nose, where air is conditioned by warming and
moistening. Bone partitions separate the nasal cavity into chambers, where air swirls about in
currents. Hairs and hairlike cilia trap dust particles and purify the air.
The nasal chambers open into a cavity at the rear of the mouth called the pharynx(throat). From the
pharynx, two tubes called Eustachian tubes open to the middle ear to equalize air pressure there. The
pharynx also contains tonsils and adenoids, which are pockets of lymphatic tissue used to trap and
filter microorganisms.
Trachea
After passing through the pharynx, air passes into the windpipe, or trachea. The trachea has a
framework of smooth muscle with about 16 to 20 open rings of cartilage shaped like a C. These rings
give rigidity to the trachea and ensure that it remains open.
The opening to the trachea is a slitlike structure called the glottis. A thin flap of tissue called
the epiglottis folds over the opening during swallowing and prevents food from entering the trachea.
At the upper end of the trachea, several folds of cartilage form thelarynx, or voicebox. In the larynx,
flaplike pairs of tissues called vocal cords vibrate when a person exhales and produce sounds.
At its lower end, the trachea branches into two large bronchi (singular, bronchus). These tubes also
have smooth muscle and cartilage rings. The bronchi branch into smaller bronchioles, forming a
bronchial “tree.” The bronchioles terminate in the air sacs known as alveoli.
Lungs
Human lungs are composed of approximately 300 million alveoli, which are cup-shaped sacs
surrounded by a capillary network. Red blood cells pass through the capillaries in single file, and
oxygen from each alveolus enters the red blood cells and binds to the hemoglobin. In addition, carbon

dioxide contained in the plasma and red blood cells leaves the capillaries and enters the alveoli when a
breath is taken. Most carbon dioxide reaches the alveoli as bicarbonate ions, and about 25 percent of
it is bound loosely to hemoglobin.
When a person inhales, the rib muscles and diaphragm contract, thereby increasing the volume of the
chest cavity. This increase leads to reduced air pressure in the chest cavity, and air rushes into the
alveoli, forcing them to expand and fill. The lungs passively obtain air from the environment by this
process. During exhalation, the rib muscles and diaphragm relax, the chest cavity area diminishes,
and the internal air pressure increases. The compressed air forces the alveoli to close, and air flows
out.
The nerve activity that controls breathing arises from impulses transported by nerve fibers passing
into the chest cavity and terminating at the rib muscles and diaphragm. These impulses are regulated
by the amount of carbon dioxide in the blood: A high carbon-dioxide concentration leads to an
increased number of nerve impulses and a higher breathing rate.

COMPILATION
IN
SCIENCE
JOCELLE P. DIVINO
VII-RIZAL

MRS. AMY C. MALAGUM
NOSTRIL NASAL CAVITY
PHARYNX LARYNX
TRACHEA LUNGS
ALVEOLI BRONCHIOLES
BRONCHI DIAPHRAGM

EPIGLOTTIS
PULMONARY ARTERY