Respiratory system
Mr N.JEGAN
Associate Professor
K.M.COLLEGE OF PHARMACY.
MADURAI.

The structure and Functions
of Respiratory system

Respiratory system-Introduction
 The cells of the body need energy for their
chemical activity that maintains homeostasis
(Balance mechanism in our body).
 Most of this energy is derived from chemical
reactions which can only take place in the
presence of oxygen (O2).
 The main waste product of these reactions is
carbon dioxide (CO2).

Respiratory system
Blood provides the transport system for
these gases between the lungs and the
cells of the body.
The respiratory system allow inhale of
Oxygen(O2) and Eliminate carbon dioxide
(CO2).

Respiratory system
Breathing consist of two Phases
1.Inspiration:
The process of taking in air.
2. Expiration:
The process of expel out the air.

The organs of the respiratory
system
Nose
Pharynx (Throat)
Larynx (Voice box)
Trachea (Wind Pipe)
Two bronchi
Bronchioles and smaller air passages
 Alveoli
Two lungs

Nose
 Also called external Nares.
 Divided into two halves by the Nasal septum.

Nasal Cavity
 The nose is lined with very vascular ciliated columnar
epithelium.
 Olfactory mucosa – mucous membranes that
contain smell receptors.
 It contains cilia.

Functions of Nose
Provides airway
Filtering and cleaning air
Humidification of air
Resonating chamber for speech
Olfactory receptors-Sense of smell

Pharynx
 The pharynx is a tube 12 to 14 cm long that
extends from the base of the skull
 Common space used by both the respiratory
and digestive systems(Common pathway for
both air and food).
 Pharynx is divided into three parts:
Nasopharynx
Oropharynx
Laryngopharynx

Functions of Pharynx
Passageway for air
and food.
Warming and
humidifying.
Taste.
Hearing.
Speech.

Larynx (Voice Box)
 The larynx is composed of irregularly shaped
cartilages attached to each other by ligaments and
membranes.
 The main cartilages are:
1 thyroid cartilage
1 cricoid cartilage Elastic Cartilage
2 arytenoid cartilages
1 epiglottis Hyaline Cartilage

Larynx-Structure

Functions of Larynx
Production of sound
Speech
Protection of the lower respiratory
tract
Passageway for air
Humidifying, filtering and warming

Trachea(windpipe)
 It is the continuation of the larynx
 It enter the right and left bronchi, one bronchus
going to each lung.
• It is approximately 10 to 11 cm long

Trachea-Structure
 The trachea is composed of from 16 to 20
incomplete (C-shaped) rings of hyaline cartilages
lying one above the other.
 There are three layers of tissue- Fibrous ,elastic
tissue, smooth muscle, ciliated columnar
epithelium.

Trachea-Functions
1. Support and patency
The arrangement of cartilage and elastic tissue
prevents kinking and obstruction of the airway as the head
and neck move.
2. Mucociliary escalator
Particles upwards towards the larynx where it is
swallowed.
3. Cough reflex
4. Warming, humidifying and filtering of air

Cough reflex
Nerve endings in the larynx, trachea and bronchi are sensitive
to irritation that generates nerve
Impulses which are conducted by the vagus nerves
The respiratory centre in the brain stem
The reflex motor response is deep inspiration followed by
closure of the epiglottis
The abdominal and respiratory muscles then contract
Suddenly the air is released under pressure expelling mucus
and/or foreign material from the mouth.

Bronchi
 Formed by division of
the trachea.
 Types of Bronchus
1.Primary bronchi
2.Secondary bronchi
3.Tertiary bronchi

Bronchi
 It divide and enter into lungs as
1.Right bronchus
2.Left bronchus

Right bronchus
 This is wider, shorter and more vertical than the left
bronchus .
 It is approximately 2.5 cm long.
 After entering the right lung , it divides into three
branches, one to each lobe.
 Each bronchus subdivide into numerous smaller
branches.

Left bronchus
 This is about 5 cm long and is narrower than the right.
 After entering the lung it divides into two branches, one to
each lobe.

Bronchioles
 Bronchioles are tube air passages inside the lungs
that branch off like tree limbs from the bronchus.
 The bronchioles deliver air to tiny sacs called alveoli.

Bronchi and bronchioles-Structure
 The bronchi have cartilage and a mucous
membrane that are similar to trachea.
 Additionally, hyaline cartilage forms an incomplete
ring in the bronchi .

Bronchi and bronchioles-Function
 The bronchi function primarily as a
passageway for air to the alveoli, and back out
of the body.
 In bronchi and bronchioles , mucus layer
provides an important "barrier" to inhaled
pathogens that can help prevent infections .

Alveoli

Alveoli
 It looks like Grape.
 We have about 480 millions alveoli in our lungs.

Alveoli-Structure
It consists of following parts.
1.Alveolar duct- is a tube of smooth muscle and
connective tissue, which opens into a cluster of
alveoli.
2. Alveolus is one of the many small, grape-like
sacs that are attached to the alveolar ducts.
3. An alveolar sac is a cluster of many individual
alveoli that are responsible for gas exchange.
4. Alveolar pores – It connect alveoli

Cells of the Alveoli
The alveoli are made up of two different types of cells
that have different functions:
 Type I pneumocytes- Responsible for the exchange of
oxygen and carbon dioxide.
 Type II pneumocytes- Responsible for repairing
damage to the alveolar lining and also secrete
surfactant.

Alveoli-Functions
 The function of the alveoli is to get oxygen into the
blood for transport to the tissues, and to remove
carbon dioxide from the blood stream.(Exchange
of Gases like O2 and CO2).

Lungs

Lungs
Location- There are two lungs, one lying
on each side of the midline in the thoracic
cavity.

Lungs-Structure
It is cone-shaped organ and having
 Apex -Round in shape-Upper part
 Base -Semilunar shape-Lower part
 Costal surface – Right side border
 Medial surface- Medial layer

Lungs-Lobes
 The Right lung is
divided into three lobes:
Superior
Middle
Inferior
 The Left lung is divided
into two lobes:
Superior
Inferior

Layers of Lungs
Lungs are surrounded by the layer called
Pleura
It is made up of two layers:
1.The outer surface of each lung is tightly covered by
the visceral pleura.
2.Internal layer called parietal pleura.
The pleural cavity(sac between visceral and
parietal pleura) contains serous fluid.

Lungs-Functions
 Breathing- Moving of air(o2 and co2) in and out of
lungs.
 Changing the pH of blood by increasing or
decreasing the amount of CO2 in the body.
 Filtering out small gas bubbles in bloodstream.
 Control the blood pressure by convert angiotensin I
to angiotensin II.