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Respiratory system
Nose , pharynx ,larynx
,trachea ,bronchi , and the
lungs.
Nose
The nostril is the external nose opening.
Nasal cavity is divided by nasal septum.
The olfactory receptors are found in superior
part of nasal cavity just below ethmoid bone
Respiratory nasal mucosa rest on a rich
network of thin walled veins, that warms the
air as it flow past
Epistaxis is common and profuse
Sticky mucus produced by mucosal glands,
moistened and trap bacteria air posteriorly
The rest is ciliated respiratory mucosa, cilia
moves contaminated mucus to pharynx
The lateral wall has three bony
projections the chonchae.
It increase the surface area of mucosa
exposed to air, and cause air
turbulence to trap foreign particles
The nose is separated from the mouth
by the palate, the anterior part is
bony, posterior part is fleshy.
paranasal sinuses
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Surround nasal cavity
Amplify sounds we speak
Make bone of skull lighter
Mucosal lining of sinuses is continuous with
nasal passages and throat, so infection
spread to them sinusitis
• Headache and upper jaw pain is usual
result
Pharynx
Is muscular passage 13 cm in length?
It is divided in to
Nasopharynx Oropharynx
Laryngopharynx
Auditory tube opens into naso- pharynx.
Tonsil is a cluster of lymphoid tissue.
Otitis media result from spread of
infection from naso-pharynx
Pharyngeal tonsil is located high in
nasopharynx called adenoids
The palatine tonsils located in
Oropharynx, lingual tonsil at base of
the tongue.
Larynx
Is the voice box, below
pharynx?
It is formed of nine
cartilages, the largest
are thyroid, cricoid,
and the leaf like which
cover the laryngeal
opening, the epiglottis
The true vocal cords
are ligaments
covered by mucous
membrane.
They vibrate with
expelled air
Glottis is the slit like
pathway between
vocal cords
The lower part of larynx
and upper part of
trachea.
Trachea
Is 10-12 cm in length?
Begins at lower border of cricoid cartilage.
Ends at level of T4-5, at Sternal angle.
The trachea has C shaped cartilaginous rings,
to keep it open, and allow food to pass to
esophagus.
Lined by ciliated epithelium moves upward
Tracheostomy is life saving open in trachea
Tracheostomy and T tube
Primary bronchi
Start at angle of Lewis,
by division of trachea
RT is wider, shorter and
more in line with
trachea.
Foreign bodies usually
enter right bronchus
Continue
The primary bronchi enter lung ,divide into
secondary and tertiary bronchi
Smallest of conducting passages is
bronchioles
This is called respiratory tree
Respiratory bronchioles, alveolar duct and
alveolar sacs and alveoli are site of gas
exchange
Rest are conducting zone structure
Lungs
Occupy most of thoracic cavity except,
the central part called the mediastinum
(heart, big vessels).
Lung has apex below the clavicle, base
rest on diaphragm.
Divided by fissures into lobes, RT has
three lobes, LT has two lobes.
The lung is covered by glistening
membrane the pleura which has parietal
and visceral layer
Pleurisy inflammation of pleura
Alveoli
• the functional units of the lungs are the air sacs called
alveoli.
• There are millions of alveoli in each lung, and their
total surface area is estimated to be 700 to 800 square
feet.
• Each alveolus is surrounded by a network of
pulmonary capillaries.
• there are only two cells between the air in the alveoli
and the blood in the pulm.capillaries.
The respiratory membrane
• The respiratory membrane consists of the alveolar and capillary walls. Gas
exchange occurs across this membrane.
 Characteristics of this membrane :
..Type I cells are thin, squamous epithelial cells that constitute the primary
cell type of the alveolar wall. Oxygen diffusion occurs across these cells.
..Type II cells are cuboidal epithelial cells that are interspersed among the
type I cells. Type II cells secrete pulmonary surfactant (a phospholipid bound
to a protein) that reduces the surface tension of the moisture that covers the
alveolar walls.
..Alveolar macrophage (dust cells) wander among the other cells of the
alveolar wall removing debris and microorganisms.
..A thin epithelial basement membrane forms the outer layer of the alveolar
wall.
..A dense network of capillaries surrounds each alveolus. The capillary walls
consist of endothelial cells surrounded by a thin basement membrane. The
basement membranes of the alveolus and the capillary are often so close
that they fuse.
Cont,
• Respiratory membrane consists of
1. Alveolar type 1 epithelium
2. Fused basement membrane of both alveolar and
endothelial cells
3. Endothelial cells of capillaries
PSEUDOSTRATIEIED EPITHELIUM
• CILIATED
• This epithelium
may be ciliate with
goblet cells
• Example:
• Trachea
• Larger bronchi