This presentation helpful to all students of Life Sciences.

1. Respiratory organ in man
Prepared by
Dr. Jayvardhan V Balkhande
Assistant Professor
Department of
Digambarrao Bindu ACS College, Bhokar Dist.
Nanded.(Maharashtra)
Email: cageculture2014@gmail.com
S. R. T. M. University, Nanded.
B.Sc. Second Year (Zoology) Sem III

2. Respiratory organ in man
Respiration is simply defined as the exchange of oxygen and carbon
dioxide into the body.
The released energy is utilized to perform various life activities.
The metabolic waste like CO2 is removed from the body through
lungs.The compounds oxidized in respiration are called respiratory
substrates.

3. • Respiration is categorized into two types on the basis of site of
gaseous exchange:
• i. - exchange of gases between lungs
and blood. It is the process of absorption of oxygen and
removal of carbon dioxide from the body through lungs.
• ii. exchange of gases between blood
and cells. It is the process of utilization of oxygen to
produce energy and carbon dioxide by oxidation of food
material inside the cell.

4. • Respiration is of two types on the basis of availability of oxygen:
• i. Aerobic respiration: The process which consists external and
internal respiration occurs in higher animals including human
beings are called aerobic respiration.
• ii. Anaerobic respiration:

5. Respiratory organs
Organs involved in respiratory system are:
• 1.Nose and nasal cavity
• 2.Pharynx
• 3.Larynx
• 4.Trachea
• 5.Bronchi
• 6.Lungs
• 7.Alveoli

6. 1. Nose and nasal cavity
Nose is a part of respiratory tract lying above mouth. It is made by
hyaline cartilage.It is divided into right and left nasal cavity by
nasal septum.
Its anterior portion is cartilaginous and posterior portion bony.
The nasal cavities open outside through nostrils or external
nares.
The nasal cavities open posteriorly into the nasopharynx
through internal nares. The opening of paranasal sinuses and
nasolacrimal ducts lie in the nasal cavities.
Internally, nasal cavity is lined with mucous membrane and
ciliated columnar epithelium. It contains nasal hairs.
Function
ü It prevents the entry of dust particles into the lungs by trapping
those dusts on mucus or by nasal hair.
ü The ciliated epithelium prevents infection by sweeping out
microorganisms.
ü It warms the cold air and moistens the dry air.
It detects smell. The superior one third of nasal mucosa is the
olfactory area which contains olfactory cells. These cells are
involved in perception of smell

7. 2.Pharynx
• It is both digestive and respiratory organ. It is a tube of 12-
14 cm that extends the base of skull to the level of 5th
cervical vertebra. It lies behind mouth, nose and larynx. It
is connected to nasal cavity through the internal opening
of nares and to the mouth.
• It is divided into three parts:
• a. Nasopharynx
• b. Oropharynx
• c. Laryngopharynx
• a.Nasopharynx
• It is the nasal part of pharynx,lies behind the nose and
superior to the soft palate. It lined with ciliated epithelium
that help in cleaning inspired air. On the lateral wall, there
are two opening of auditory tubes and on posterior wall,
there is a pharyngeal tonsils, consisting of lymphoid
tissues.

8. 2.Pharynx
• b.Oropharynx
• Oral part of pharynx Lies at the posterior part of mouth,
extends from soft palate to epiglottis. It is separated from
mouth by a pair of membranous narrow passage called
fauces.
• c.Laryngopharynx
• It is the lower most portion of pharynx and has a slit like
aperture called glottis. This can be closed by leaf like
bilobed cartilage, epiglottis, during swallowing of the food.
• Function
• Pharynx helps in passage of air from nose to trachea.
• The air is further warmed and moistened as it passes
through pharynx.
• There are olfactory nerve endings of the sense of smell.
• Protection: The lymphatic tissue of the pharyngeal and
laryngeal tonsils produces antibodies in response to
antigen.
• Hearing: The auditory tube, extending from the
nasopharynx to each middle ear, allows air to enter the
middle ear.

9. 3.Larynx
• It is also called sound box or voice box. It is situated in the anterior
neck i.e. in front of esophagus.
• It is small, thin walled, tubular part present in the neck at the apex of
trachea.
• It connects the lower part of pharynx and trachea. Pharynx opens in
larynx through glottis which is guarded by a leaf like unpaired
cartilage which is called epiglottis. It prevents the entrance of food
into trachea. It is composed of several irregular shaped cartilages-
they are: 1 thyroid cartilage, 1 cricoid cartilage and 2 arytenoids
cartilage. They prevent the larynx from collapsing. There are two
vocal folds (true vocal cords) situated in the cavity of larynx between
thyroid and arytenoid cartilage. Also a pair of vestibular folds is
protective in function.
• Function
• It plays important role in sound production.
• It links pharynx with trachea, thus it allows passage of air.
• Speech is produced when sound produced by vocal cords are
manipulated by tongue, cheeks and lips.
• During swallowing the larynx moves upward, blocking the opening
into it from the pharynx. In addition the epiglottis also closes over
the larynx. This ensures the food passes into oesophagus and not
into trachea.

10. 4.Trachea (Wind pipe)
• It is hollow tube of about 11-12 cm in length and 2.5 cm in
diameter.
• It extends from the base of larynx to thoracic cavity. It runs in the
neck in front of oesophagus.
• It is supported by 16-20 C-shaped cartilaginous tracheal rings.
These rings prevent the trachea from collapsing due to continuous
relaxation and expansion.
• Internally, the wall of trachea is lined by pseudostratified ciliated
epithelium with mucus secreting goblet cells.
• The secretion of mucus cells keep the wall of tube moist and trap
dust particles.
• The mucus lubricates the passage and cilia help to filter out dust.
• The constant beating of cilia carry mucous and debris upward into
pharynx where upon it is swallowed or coughed up.
• Help in cough reflex. It supports head and neck.

11. 5.Bronchi
• As the trachea reaches into the thoracic cavity, it divides into
two branches called bronchi- right and left bronchi.
• Each bronchus has the structure similar to trachea. The right
bronchus is wider and shorter than left bronchus.
• It is about 2.5 cm long and left bronchus is about 5 cm in
length.
• Each bronchus when enter into corresponding lungs, it divides
into smaller secondary bronchi and then into tertiary bronchi.
• These bronchi progressively subdivide into smaller and smaller
tube called bronchioles and then into terminal bronchioles.
• Bronchioles continue to branch, and open into respiratory
bronchioles which in turn branch into alveolar duct that lead
into alveoli (microscopic air sac).
• Function
• Bronchi connect the trachea to the lungs, allowing air from
external respiratory openings into the lungs.

12. 6.Alveoli
• Bronchioles continue to branch, and open into
respiratory bronchioles which in turn branch into
alveolar duct that lead into microscopic air sac called
alveoli.
• Gaseous exchange takes place in alveoli. The alveoli
are richly supplied with blood capillaries.
• The wall of alveoli is lined with type I pneumocytes
which help in gaseous exchange and type II
pneumocytes produce surfactant.
• The surfactant reduces the surface tension so that the
lungs do not collapse.
• Function
• Alveoli help in purification of blood and allow
exchange of oxygen and carbon dioxide in the lungs.

13. 7. Lungs
• Lungs are a pair of conical organ situated one on either side of thoracic
cavity.
• They are hollow, soft, spongy, elastic, light and pink colored. There are
one pair of lungs- they are right lung and left lung.
• Lungs are externally surrounded by two layers called pleural membrane.
• The outer membrane is called parietal pleural membrane and the inner
layer is called visceral pleural membrane.
• These membranes protect lungs and stop leaking of air into thoracic
cavity. The space between two layers is called pleural cavity which is
filled with pleural fluid.
• The pleural fluid performs following function:
• i. Allows smooth/ free frictionless movement of lungs.
• ii. Protects the lungs from mechanical shocks.
• iii. Keeps the pleura together and lungs expanded.

14. • Lobes of lungs
• Lungs are divided into distinct lobes.
Right lung has three lobes- right
superior, middle and inferior lobe.
These lobes are demarcated by
transverse and oblique fissures.
• Left lung has two lobe- superior and
inferior lobe. The left lung is smaller
than right lung and has a cardiac
notch to accommodate heart.