8. respiratory system

THE RESPIRATORY SYSTEM
Dr. S P SRINIVAS NAYAK, PharmD, MSc.,PGDND.,(PhD)
Dept. of Pharmacy Practice
Assistant Professor, Parul institute of Pharmacy
and Research, PU

INTRODUCTION
• Your body’s cells continually use oxygen (O2) for
the metabolic reactions that generate ATP from
the breakdown of nutrient molecules, these
reactions release carbon dioxide (CO2) as a waste
product.
GLU + OXYGEN --- CO2 + H2 O + ATP
• The branch of medicine that deals with the
diagnosis and treatment of diseases of the ears,
nose, and throat (ENT) is called
otorhinolaryngology

THE STEPS INVOLVED IN RESPIRATION
• The process of supplying the body with O2 and
removing CO2 is known as respiration, which has three
basic steps.
1. Pulmonary ventilation: the exchange of air between
the atmosphere and the alveoli of the lungs.
2. External (pulmonary) respiration: It is the exchange of
gases between the alveoli of the lungs and the blood in
pulmonary capillaries across the respiratory membrane
3. Internal (tissue) respiration: In this step the blood
loses O2 and gains CO2. Within cells, the metabolic
reactions that consume O2 and give off CO2 during the
production of ATP are termed cellular respiration

THE STEPS INVOLVED IN
RESPIRATION
The process of supplying the body with O2 and
removing CO2 is known as respiration, which has
three basic steps.
1. Pulmonary ventilation: the exchange of air
between the atmosphere and the alveoli of
the lungs.
2. External (pulmonary) respiration: It is the
exchange of gases between the alveoli of the
lungs and the blood in pulmonary capillaries
across the respiratory membrane
3. Internal (tissue) respiration: In this step the
blood loses O2 and gains CO2. Within cells, the
metabolic reactions that consume O2 and give off
CO2 during the production of ATP are termed
cellular respiration

COMPONENTS OF THE
RESPIRATORY SYSTEM
Structurally, the respiratory
system consists of
two parts:
(1) The upper respiratory
system includes the nose,
nasal cavity, pharynx, and
associated structures;
(2) the lower
respiratory system
includes the larynx,
trachea, bronchi, and
lungs.

Functions of the respiratory system
1. Provides for gas exchange: intake of O2 for
delivery to body cells and removal of CO2
produced by body cells.
2. Helps regulate blood pH.
3. Contains receptors for sense of smell, filters
inspired air, produces vocal sounds (phonation),
and excretes small amounts of water and heat.
4. Endocrine functions: releases ACE.

THE UPPER RESPIRATORY
SYSTEM
Nose:
• The nose is a specialized organ at the entrance of the respiratory
system that consists of a visible external nose(consists of a
supporting framework of bone and hyaline cartilage, covered with
muscle and skin and lined by a mucous membrane)
• frontal bone, nasal bones, and maxillae form the bony framework
of the external nose.
The interior structures of the external nose have three functions:
(1) warming, moistening, and filtering incoming air;
(2) detecting olfactory stimuli; and
(3) modifying speech vibrations as they pass through the large,
hollow resonating chambers.
Rhinoplasty : is a surgical procedure in which the shape of the external
nose is altered.

• Nasal cavity: it is lined with muscle and mucous
membrane. A vertical partition, the nasal
septum, divides the nasal cavity into right and left
sides.
• The bony and cartilaginous framework of the
nose help to keep the vestibule and nasal cavity
patent, The olfactory receptor cells, supporting
cells, and basal cells lie in the respiratory region,
which is near the superior nasal conchae and
adjacent septum. These cells make up the
olfactory epithelium. It contains cilia but no
goblet cells.
• Tonsillectomy: is surgical removal of the tonsils.

PHARYNX
• The pharynx lies just posterior to the nasal and oral
cavities, superior to the larynx, and just anterior to the
cervical vertebrae. Its wall is composed of skeletal muscles
and is lined with a mucous membrane.
• Relaxed skeletal muscles help keep the pharynx patent.
Contraction of the skeletal muscles assists in deglutition
(swallowing).
• The pharynx functions as a passageway for air and food,
provides a resonating chamber for speech sounds, and
houses the tonsils, which participate in immunological
reactions against foreign invaders.
• The pharynx can be divided into three anatomical regions:
(1) nasopharynx, (2) oropharynx, and (3) laryngopharynx.

The Lower Respiratory System
• The lower respiratory system includes the
larynx, trachea, bronchi, and lungs.
A) LARYNX
• The larynx, or voice box, is a short passageway
that connects the laryngopharynx with the
trachea. It lies in the midline of the neck
anterior to the esophagus and the fourth
through sixth cervical vertebrae (C4–C6)

THE STRUCTURES OF VOICE
PRODUCTION
• The mucous membrane of the larynx forms
two pairs of folds:
• a superior pair called the vestibular folds
(false vocal cords) and
• an inferior pair called the vocal folds (true
vocal cords).
• The space between the vestibular folds is
known as the rima vestibuli.

B) TRACHEA
• The trachea or windpipe, is a tubular passageway for
air that is about 12 cm (5 in.) long and 2.5 cm (1 in.) in
diameter. It is located anterior to the esophagus
• It extends from the larynx to the superior border of
the fifth thoracic vertebra (T5), where it divides into
right and left primary bronchi
• The layers of the tracheal wall, from deep to
superficial, are the (1) mucosa, (2) submucosa, (3)
hyaline cartilage, and (4) adventitia (composed of
areolar connective tissue).

C) BRONCHI
• At the superior border of the fifth thoracic vertebra,
the trachea divides into a right main (primary)
bronchus which goes into the right lung, and a left
main (primary) bronchus, which goes into the left lung
• The right main bronchus is more vertical, shorter, and
wider than the left . As a result, an aspirated object is
more likely to enter and lodge in the right main
bronchus than the left .
• Like the trachea, the main bronchi contain incomplete
rings of cartilage and are lined by ciliated
pseudostratified columnar epithelium.

• On entering the lungs, the main bronchi divide to form smaller
bronchi—the lobar (secondary) bronchi, one for each lobe of
the lung. (The right lung has three lobes; the left lung has two.)
The lobar bronchi continue to branch, forming still smaller
bronchi, called segmental (tertiary) bronchi that supply the
specific bronchopulmonary segments within the lobes.
• The segmental bronchi then divide into bronchioles. Bronchioles
in turn branch repeatedly, and the smallest ones branch into
even smaller tubes called terminal bronchioles.
• These bronchioles contain club (Clara) cells, columnar,
nonciliated cells interspersed among the epithelial cells. Club
cells may protect against harmful effects of inhaled toxins and
carcinogens, produce surfactant and function as stem cells
(reserve cells), which give rise to various cells of the epithelium.
• The terminal bronchioles represent the end of the conducting
zone of the respiratory system. This extensive branching from
the trachea through the terminal bronchioles resembles an
inverted tree and is commonly referred to as the bronchial tree

THE LUNGS
• A pulmonologist is a specialist in the diagnosis
and treatment of lung diseases.
• The lungs are paired cone-shaped organs in
the thoracic cavity, They are separated from
each other by the heart and other structures
of the mediastinum, which divides the
thoracic cavity into two anatomically distinct
chambers. As a result, if trauma causes one
lung to collapse, the other may remain
expanded.

• Each lung is enclosed and protected by a
double-layered serous membrane called the
pleural membrane or pleura.
1. The superficial layer, called the parietal
pleura thoracic cavity
2. the deep layer, the visceral pleura, covers the
lungs themselves

• The lungs extend from the diaphragm to just
slightly superior to the clavicles and lie against
the ribs anteriorly and posteriorly.
• The broad inferior portion of the lung, the
base, is concave and fits over the convex area
of diaphram

Lobes, Fissures, and Lobules
• One or two fissures divide each lung
into sections called lobes.
• Both lungs have an oblique fissure, which extends
inferiorly and anteriorly; the right lung also has a
horizontal fissure. The oblique fissure in the left lung
separates the superior lobe from the inferior lobe.
• In the right lung, the superior part of the oblique
fissure separates the superior lobe from the inferior
lobe; the inferior part of the oblique fissure separates
the inferior lobe from the middle lobe, which is
bordered superiorly by the horizontal fissure.

• Each lobe receives its own lobar bronchus.
Thus, the right main bronchus gives rise to
three lobar bronchi called the superior,
middle, and inferior lobar bronchi.
• and the left main bronchus gives rise to
superior and inferior lobar bronchi

• Each lobe of the lungs has many small
compartments called lobules; each lobule is
wrapped in elastic connective tissue and
contains a lymphatic vessel, an arteriole, a
venule, and a branch from a terminal
bronchiole
• Terminal bronchioles and lobule subdivide
into microscopic branches called respiratory
bronchioles

Respiratory
bronchioles
Alveolar
ducts
Alveolar
sacs

Alveolar Sacs and Alveoli
• Each alveolar sac is composed of
outpouchings called alveoli

• The wall of each alveolus (singular) consists of two types of
alveolar epithelial cells.
• The more numerous type I alveolar (squamous pulmonary
epithelial) cells are simple squamous epithelial cells that form
a nearly continuous lining of the alveolar wall.
• Type II alveolar cells, also called septal cells, are fewer in
number and are found between type I alveolar cells.

• Type II alveolar cells, rounded or cuboidal
epithelial cells with free surfaces containing
microvilli, secrete alveolar fluid, which keeps
the surface between the cells and the air
moist. Included in the alveolar fluid is
surfactant

Inhalation
• Breathing in is called inhalation (inspiration). Just
before each inhalation, the air pressure inside the
lungs is equal to the air pressure of the
atmosphere, which at sea level is about 760
millimeters of mercury (mmHg), or 1 atmosphere
(atm).
• For air to flow into the lungs, the pressure inside
the alveoli must become lower than the
atmospheric pressure. This condition is achieved
by increasing the size of the lungs.

Pulmonary Ventilation
(inhalation and exhalation)
INTRODUCTION:
Pulmonary ventilation, or breathing, is the flow of
air into and out of the lungs.
In pulmonary ventilation, air flows between the
atmosphere and the alveoli of the lungs because of
alternating pressure differences created by
contraction and relaxation of respiratory muscles.
The rate of airflow and the amount of effort needed
for breathing are also influenced by alveolar surface
tension, compliance of the lungs, and airway
resistance.

Exhalation
• Exhalation is Breathing out, called expiration, is also
due to a pressure gradient, but in this case the gradient
is in the opposite direction: The pressure in the lungs is
greater than the pressure of the atmosphere.
• Normal exhalation during quiet breathing, unlike
inhalation, is a passive process because no muscular
contractions are involved. Instead, exhalation results
from elastic recoil of the chest wall and lungs, both of
which have a natural tendency to spring back after they
have been stretched.

Exchange of Oxygen and Carbon
Dioxide
EXTERNAL RESPIRATION:
• External respiration or pulmonary gas
exchange is the diffusion of O2 from air in the
alveoli of the lungs to blood in pulmonary
capillaries and the diffusion of CO2 in the
opposite direction

Internal Respiration
The left ventricle pumps
oxygenated blood into the
aorta and through
the systemic arteries to
systemic capillaries.
The exchange of O2 and CO2
between systemic capillaries
and tissue cells is called
internalrespiration or systemic
gas exchange

Transport of Oxygen and Carbon
Dioxide
Oxygen Transport:
Oxygen does not dissolve easily in water, so only
about 1.5% of inhaled O2 is dissolved in blood
plasma, which is mostly water.
About 98.5% of blood O2 is bound to
hemoglobin in red blood cells
Each 100 mL of oxygenated blood contains the
equivalent of 20 mL of gaseous O2

• The heme portion of hemoglobin contains
four atoms of iron, each capable of binding to
a molecule of O2.
• Oxygen and hemoglobin bind in an easily
reversible reaction to form oxyhemoglobin:

Regulation of respiratory system

HYPOXIA
• Hypoxia : is a deficiency of O2 at the tissue level. Based on the
cause, we can classify hypoxia into four types
• 1. Hypoxic hypoxia is caused by a low PO2 in arterial blood as a
result of high altitude, airway obstruction, or fluid in the lungs.
• 2. In anemic hypoxia, too little functioning hemoglobin is present in
the blood, which reduces O2 transport to tissue cells. Among the
causes are hemorrhage, anemia, and failure of hemoglobin to carry
its normal complement of O2, as in carbon monoxide poisoning.
• 3. In ischemic hypoxia, blood flow to a tissue is so reduced that too
little O2 is delivered to it, even though PO2 and oxyhemoglobin
levels are normal.
• 4. In histotoxic hypoxia, the blood delivers adequate O2 to tissues,
but the tissues are unable to use it properly because of the action
of some toxic agent. One cause is cyanide poisoning, in which
cyanide blocks an enzyme required for the use of O2 during ATP
synthesis.

Asphyxia
• Asphyxia or asphyxiation is a condition of
deficient supply of oxygen to the body that arises
from abnormal breathing.
• Asphyxia causes generalized hypoxia, which
affects primarily the tissues and organs. There are
many circumstances that can induce asphyxia, all
of which are characterized by the inability of a
person to acquire sufficient oxygen through
breathing for an extended period of time.
Asphyxia can cause coma or death.

• Dysbarism refers to medical conditions resulting from
changes in ambient pressure.
• Various activities are associated with pressure
changes. Underwater diving is the most frequently
cited example, but pressure changes also affect
people who work in other pressurized environments
and people who move between different altitudes

Oxygen therapy and resuscitation

Disorders: Homeostatic Imbalances
1. Asthma
2. Chronic Obstructive Pulmonary Disease
A. Emphysema: is a disorder characterized by destruction of
the walls of the alveoli, producing abnormally large air spaces
that remain filled with air during exhalation
B. Chronic bronchitis: is a disorder characterized by excessive
secretion of bronchial mucus accompanied by a productive
cough
3. Lung Cancer
4. Pneumonia
5. Tuberculosis
6. Pulmonary Edema
7. Sudden Infant Death Syndrome
8. Sudden Infant Death Syndrome

8. respiratory system

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