The Respiratory System

1. Unit VI
The Respiratory System
SUBMITTED TO
MRS. JISHA S.
PRINCIPAL,
ST. CATHERINE’S HOSPITAL
& SCHOOL OF NURSING
SUBMITTED BY
MR. EARNEST LAMUEL
NURSING TUTOR,
ST. CATHERINE’S HOSPITAL
& SCHOOL OF NURSING

3. STRUCTURE AND
FUNCTIONS OF
RESPIRATORY ORGANS

4. Introduction
The respiratory system (also respiratory apparatus, ventilatory
system) is a biological system consisting of specific organs and
structures used for gas exchange in animals and plants. The
anatomy and physiology that make this happen varies greatly,
depending on the size of the organism, the environment in which it
lives and its evolutionary history. In land animals the respiratory
surface is internalized as linings of the lungs. Gas exchange in the
lungs occurs in millions of small air sacs called alveoli in mammals
and reptiles, but atria in birds. These microscopic air sacs have a
very rich blood supply, thus bringing the air into close contact with
the blood.

5. Introduction
These air sacs communicate with the external environment via a
system of airways, or hollow tubes, of which the largest is
the trachea, which branches in the middle of the chest into the two
main bronchi. These enter the lungs where they branch into
progressively narrower secondary and tertiary bronchi that branch
into numerous smaller tubes, the bronchioles. In birds the
bronchioles are termed parabronchi. It is the bronchioles, or
parabronchi that generally open into the microscopic alveoli in
mammals and atria in birds. Air has to be pumped from the
environment into the alveoli or atria by the process
of breathing which involves the muscles of respiration.

6. Exchange of Gases
External Respiration – the external respiration takes place in the
lungs. The oxygen is absorbed from air into the blood and carbon
dioxide is excreted from the blood into the air.
Internal Respiration – the internal respiration or tissue respiration :
oxygen is transferred from blood to the tissues, which give up
carbon dioxide.

7. Air Passages
 Nose
 Pharynx
 Larynx
 Trachea
 Bronchi
 Bronchioles

8. Nose
 The human nose is the most protruding part of the face. It bears the nostrils and
is the first organ of the respiratory system. It is also the principal organ in
the olfactory system. The shape of the nose is determined by the nasal bones
and the nasal cartilages, including the nasal septum which separates the nostrils
and divides the nasal cavity into two. On average the nose of a male is larger
than that of a female.
 The main function of the nose is respiration, and the nasal mucosa lining the
nasal cavity and the paranasal sinuses carries out the necessary conditioning of
inhaled air by warming and moistening it. Nasal conchae, shell-like bones in the
walls of the cavities, play a major part in this process. Filtering of the air by nasal
hair in the nostrils prevents large particles from entering the lungs. Sneezing is
a reflex to expel unwanted particles from the nose that irritate the mucosal
lining. Sneezing can transmit infections, because aerosols are created in which
the droplets can harbour pathogens.

10. Pharynx
 The pharynx (plural: pharynges) is the part of the throat behind the mouth
and nasal cavity, and above the esophagus and larynx – the tubes going down to
the stomach and the lungs. It is found in vertebrates and invertebrates, though
its structure varies across species.
 In humans, the pharynx is part of the digestive system and the conducting
zone of the respiratory system. (The conducting zone—which also includes the
nostrils of the nose, the larynx, trachea, bronchi, and bronchioles—filters, warms
and moistens air and conducts it into the lungs). The human pharynx is
conventionally divided into three sections: the nasopharynx, oropharynx, and
laryngopharynx. It is also important in vocalization.
 In humans, two sets of pharyngeal muscles form the pharynx and determine the
shape of its lumen. They are arranged as an inner layer of
longitudinal muscles and an outer circular layer.

12. Larynx
 The larynx commonly called the voice box, is an organ in the top of
the neck involved in breathing, producing sound, and protecting
the trachea against food aspiration. The larynx houses the vocal folds, and
manipulates pitch and volume, which is essential for phonation. It is situated
just below where the tract of the pharynx splits into the trachea and
the esophagus. The word larynx (plural larynges) comes from a similar Ancient
Greek word (λάρυγξ lárynx).
 The triangle-shaped larynx consists largely of cartilages that are attached to
one another and to surroundings structures by muscles or by fibrous and
elastic tissue components. It is lined by a ciliated mucous membrane. The
cavity of the larynx extends from its triangle-shaped inlet the epiglottis to the
circular outlet at the lower border of the cricoid cartilage, where it is
continuous with the lumen of the trachea.

14. Trachea
 The trachea, colloquially called the windpipe, is a cartilaginous tube that
connects the pharynx and larynx to the lungs, allowing the passage of air, and so
is present in almost all air-breathing animals with lungs. The trachea extends
from the larynx and branches into the two primary bronchi. At the top of the
trachea the cricoid cartilage attaches it to the larynx. This is the only complete
tracheal ring, the others being incomplete rings of reinforcing cartilage.
The trachealis muscle joins the ends of the rings and these are joined vertically
by bands of fibrous connective tissue – the annular ligaments of trachea.
The epiglottis closes the opening to the larynx during swallowing.
 The trachea develops in the second month of development. It is lined with
an epithelium that has goblet cells which produce protective mucins.
An inflammatory condition, also involving the larynx and bronchi,
called croup can result in a barking cough.

16. Bronchi
A bronchus is a passage or airway in the respiratory system that
conducts air into the lungs. The first bronchi to branch from
the trachea are the right main bronchus and the left main
bronchus, also known as the primary bronchi. These are the widest
and enter the lungs at each hilum, where they branch into narrower
secondary bronchi or lobar bronchi, and these branch into
narrower tertiary bronchi or segmental bronchi.
Further divisions of the segmental bronchi are known as 4th order,
5th order, and 6th order segmental bronchi, or grouped together
as sub segmental bronchi. The bronchi when too narrow to be
supported by cartilage are known as bronchioles. No gas
exchange takes place in the bronchi.

18. Bronchioles
 The bronchioles or bronchioli are the smaller branches of the bronchial airways in
the respiratory tract. They include the terminal bronchioles, and finally the
respiratory bronchioles that mark the start of the respiratory zone delivering air to
the gas exchanging units of the alveoli. The bronchioles no longer contain the
cartilage, that is found in the bronchi, or glands in their submucosa.
 A pulmonary lobule is the portion of the lung ventilated by one bronchiole.
Bronchioles are approximately 1 mm or less in diameter and their walls consist
of ciliated cuboidal epithelium and a layer of smooth muscle. Bronchioles divide into
even smaller bronchioles, called terminal, which are 0.5 mm or less in diameter.
Terminal bronchioles in turn divide into smaller respiratory bronchioles which divide
into alveolar ducts. Terminal bronchioles mark the end of the conducting division of
air flow in the respiratory system while respiratory bronchioles are the beginning of
the respiratory division where gas exchange takes place.

20. PHYSIOLOGY OF
RESPIRATION

21. Definition
It is the process of exchange of gases in the lung where there is
uptake of oxygen in exchange for carbon dioxide. This is called
external respiration. The exchange of oxygen and carbon
dioxide at tissue level is called internal respiration.

22. Composition of Air
Oxygen – 21%
Carbon Dioxide - .03%
Nitrogen – 78%
Other gases – 1%

23. Respiratory Processes
Inspiration – It is accompanied by expansion of lungs for
uptake of air
Expiration – It is the expulsion of air from the lungs due to
retraction of lungs. These movements are accompanied by
corresponding movements of the thoracic cage.

24. CHARACTERISTICS
OF NORMAL
RESPIRATION

25. Characteristics
The normal respiration rate in adults at rest is 12 breaths/min.
Normal breathing is strictly characterized by three features: Nasal
(in and out), mainly diaphragmatic (i.e., abdominal), slow (in
frequency) and imperceptible (no feelings or sensation about one’s
own breathing at rest

26. Characteristics
The physiological and medical norm for respiratory minute ventilation
at rest is 6 litres per minute for a 70 kg man. These guidelines also
provide the following numbers for normal breathing at rest:
Normal TV (tidal volume or air volume breathed in during a single
breath): 500 ml
Normal RF (respiratory frequency or respiratory rate): 12 breaths per
minute
Inspiration: about 1.5-2 seconds
Normal exhalation is 1.5-2 seconds, followed by an automatic pause
(no breathing for 1-2 seconds).

27. THANK YOU