2. Component of respiratory system
structurally, the respiratory system
consists of two parts
upper respiratory system
and associated structures.
lower respiratory system
bronchi, and lungs.
3. Component of respiratory system
Functionally, the respiratory system also
consists of two parts
conducting zone consists
and terminal bronchioles
respiratory zone include
the respiratory bronchioles
to filter, warm, and moisten air and conduct it into the
Provide aconduit for passage of air
4. Nasal cavity
nose can be divided into
external and internal portions
external nose is the portion of
the nose visible on the face
two openings called the external
nares (NA ¯ -rez; singular is
naris) or nostrils.
warming, moistening, and
filtering incoming air
detecting olfactory stimuli; and (3)
5. Nasal cavity
Internal nose is a large cavity
beyond the nasal vestibule
Anteriorly, the internal nose
merges with the
external nose, and posteriorly it
communicates with the pharynx
through two openings called the
internal nares or choanae
Ducts from the paranasal
sinuses (which drain mucus)
open into the internal nose.
6. Nasal cavity
nasal septum-divides the
nasal cavity into two
• made up of
plate of ethmoid
– the vomer,
– the septal cartilage
Each half is referred to
as a nasal fossa.
is a funnel-shaped tube that starts
at the internal nares and extends
to the level of the cricoid
Its wall is composed of skeletal
muscles and is lined with a
• has 3 parts
– laryngeo pharynx.
9. larynx( voice box)
is a short passageway
that connects the
laryngopharynx with the
It lies in the midline of the neck
anterior to the esophagus and
the fourth through sixth
cervical vertebrae (C4–C6).
10. larynx( voice box)
is composed of nine pieces
This scaffold of cartilages is
held together and to the
hyoid bone by sheets of
dense connective tissue that
form the cricothyroid and
is a tubular passageway for air
It is about 12cm long and 2.5cm
It is found anterior to the
oesophagus as it extends into
the thoracic cavity.
A series of incomplete C-
shaped rings of hyaline cartilage
form the walls of the trachea.
The cartilages help to keep the
air way permanently open
• Respiratory epithelium of the trachea:
– The lumen of the trachea is lined by a ciliated
pseudostratified columnar epithelium.
– The epithelium is composed of 3 cell types:
1) ciliated columnar cells
2) goblet cells, and
At the superior border of the
fifth thoracic vertebra, the
trachea divides into
a right primary bronchus
a left primarybronchus
At the point where the
trachea divides into right and
left primary bronchi an
internal ridge called the
• A Bronchial tree
– This is composed of a series of respiratory tubes that
branch in to progressively narrow tubes as they extend
in to the lungs
– divides in to
• primary bronchus
• secondary bronchus
• tertiary bronchus
• Alveolar ducts
– are thin walled tubes from which numerous alveoli or
clusters of alveoli open around the circumference so that
the wall becomes little more than a succession of
– The alveolar ducts end in irregular spaces surrounded by
clusters of alveoli called alveolar sacs.
– are thin- walled, polyhedral structures that are open at
one side to allow air into their cavities.
– Adjacent alveoli are separated by a common
interalveolar septum, whose most conspicuous feature is
a rich network of capillaries that bulge the septal wall to
expose most of the capillary surface to alveolar air.
– Small openings in the septal wall, alveolar pores, permit
communication and equalization of air pressure
– On each side the alveolar wall is covered by an
attenuated epithelium beneath which is a basal lamina.
– The pleura are thin membranes made up of collagenous
and elastic fibers, covered by a single layer of
– The layer lining the wall of the thoracic cavity is the
parietal pleura, which reflects from the thoracic wall
onto the surface of the lungs, where it becomes the
– The pleura secrete a small amount of fluid between the
two layers to permit friction free movement
are paired cone-shaped organs
in the thoracic cavity.
Each lung is enclosed and
protected by a double-layered
called the pleural membrane
The lungs extend from the
diaphragm to just slightly
superior to the clavicles and lie
against the ribs anteriorly and
The broad inferior portion of
the lung, the base, is concave
and fits over the convex area
of the diaphragm.
The narrow superior portion
of the lung is the apex.
costal surfacethe lung lying
against the ribs, the
mediastinal (medial) surface
contains a region, the hilum,
through which bronchi,
pulmonary blood vessels,
lymphatic vessels, and nerves
enter and exit
– The left lung
• is some what smaller than the right
• has a cardiac notch (an indentation in its anterior border) to
accommodate the heart.
• divided into
– a superior lobe and
– an inferior lobe by an oblique fissure.
– The right lung
• is subdivided into three lobes;
• middle, and
• inferior lobes by a horizontal and an oblique fissure.
– Lobular divisions of the lungs make up specific bronchial
• The right lung contains ten bronchial segments and
• the left lung contains eight.