Transcript Respiratory System Chapter 15

Respiratory System
Chapter 24
The main function of the respiratory system is to
supply oxygen to, & eliminate carbon dioxide
from the body
In order to accomplish this task, the respiratory
system must work in conjunction with the
cardiovascular system
“Respiration” refers to the overall exchange of
gases between the atmosphere, blood & cells
Respiration involves 3 processes
 Pulmonary ventilation
 External respiration
 Internal respiration
Anatomy Overview
Nasal cavity
Pharynx
Larynx
Trachea
Bronchi
The respiratory tract includes:
Nose (nasal cavity) Pharynx
(nasopharynx, oropharynx,
laryngopharynx) Larynx
Trachea Bronchi (primary,
secondary (lobar), tertiary
(segmental) Bronchioles
Terminal bronchioles Respiratory
bronchioles Alveolar ducts
Alveoli
Bronchioles
Respiratory
bronchioles
Right
Lung
Left
Lung
Alveolar duct
Alveoli
Histology
Respiratory Epithelium =
Pseudostratified Ciliated
Columnar (PSCC)
Nose (nasal cavity)
Air normally enters through external nares through nasal vestibule into nasal
cavity.
Nasal cavity divided by nasal septum and has a respiratory area with 3 nasal
conchae (superior, middle & inferior) projecting into the midline from each
lateral wall creating nasal meatuses between; and an olfactory area
Nasal cavity communicates
with the paranasal sinuses in
frontal, maxillary, ethmoid &
sphenoid bones
Functions of nasal cavity
include: warming,
moistening & filtering air;
olfaction
Pharynx
Air passes from nasal cavity, across internal nares into nasopharynx, past
oropharynx & through laryngopharynx to larynx
Nasopharynx lined with PSCC epithelium, but oro & laryngopharynx lined with
stratified squamous epithelium because they are also part of digestive system
Eustachian (auditory) tube – connects nasopharynx & middle ear cavity
Pharyngeal tonsil – lymphatic tissue embedded in wall of nasopharynx
Palatine tonsils - lymphatic tissue embedded in wall of oropharynx
Uvula – posterior tissue from soft palate; protects nasopharynx when
swallowing
Larynx
Air passageway made of 9 pieces of cartilage – (1) Thyroid cartilage, (1)
Epiglottis, (1) Cricoid cartilage, (2) Arytenoid, (2) Corniculate, (2)
Cuneiform
A.K.A your “voicebox” because it contains the vocal cords
Larynx
Thyroid cartilage –
protects anterior &
lateral walls of airway
 Epiglottis – leafshaped cartilage that
protects opening
(“glottis”) of airway
when swallowing
 Cricoid cartilage –
complete ring of
cartilage; protects
posterior wall of airway;
attaches to trachea
Larynx
 Arytenoid, corniculate
& cuneiform cartilages –
attach to upper
(vestibular) vocal folds &
lower (true) vocal cords
Trachea
Tough but flexible “windpipe”,
anterior to esophagus

 attached to cricoid cartilage (at
about C6 vertebral level) & ends
within mediastinum by branching
into left & right primary bronchi
(at T5 vertebral level)
 End of trachea known as Carina
Carina
Trachea
 Lined with
respiratory epithelium
 “C”-shaped pieces
of hyaline cartilage
protecting airway
while allowing for
swallowing
 Trachealis muscle
(smooth muscle) runs
across posterior wall
of trachea connecting
ends of tracheal
cartilage
Trachea
Low power
Medium power
High power
Bronchi
Carina
 Trachea splits into a left & right
primary bronchus which enters into
the hilus of each lung
 Within the lung, the primary
bronchi branch into secondary
(lobar) bronchi (3 in right lung/2 in
left lung)
 Secondary bronchi then branch
into 10 tertiary (segmental) bronchi
 Tertiary bronchi then continue to
branch into smaller & smaller
bronchi & then into very narrow
bronchioles
This branching patterns creates
the “bronchial tree”
Changes In Airway
As you go further down into the bronchial tree of each
lung, changes in the airway occur:
 increased number of airways (1 primary; 2 or 3
secondary; 10 tertiary bronchi; 6000 terminal bronchioles;
millions of alveolar ducts)
 decreased diameter of each airway
 decreased amount of cartilage in the airways (no
cartilage at all by terminal bronchioles)
 increased amount of smooth muscle (relative to
diameter)
 lining epithelium changes from PSCC  simple squamous
epithelium (in alveoli)
Lungs
Located within the thoracic cavity,
surrounded by the double-layered pleural
membrane –
parietal pleura – lines cavity wall
visceral pleura – covers the lungs
Lungs- Anatomical Features
Apex – extends 1” above clavicle
Hilum – at medial surface;
where primary bronchus,
pulmonary artery & veins
enter/exit lung
Superior
lobe
Horizontal
fissure
Middle lobe
Superior lobe
Right
lung
Left
lung
Oblique
fissure
Oblique fissure
Cardiac notch
Inferior
lobe
Inferior lobe
Base – rests on diaphragm
Lung – medial surface
Groove for
aorta
Hilum
Cardiac notch
of Lt. lung
Airways within Lungs
 Each lung has a
primary bronchus
entering at the hilus
 Each lobe of a lung
has a secondary (a.k.a.
lobar) bronchus
 Lobes are functionally
divided into
bronchopulmonary
segments & each
segment has a tertiary
(segmental) bronchus
 Segments are
functionally divided into
many lobules & each
lobule receives a
terminal bronchiole
Relationship of Airways &
Pulmonary Vessels
 As airways branch within
lungs, they are accompanied
by branches of the pulmonary
artery (carrying de-oxygenated
blood into the lungs), &
branches of the pulmonary
veins (carrying oxygenated
blood out of the lungs)
 As the alveolar ducts
expand to form alveoli,
pulmonary arterioles will
branch to form a network
of pulmonary capillaries,
surrounding the alveoli
Alveoli
 Alveoli are expanded
chambers of epithelial
tissue that are the
exchange surfaces of
the lungs
 There are about 150
million alveoli in each
lung
 Multiple alveoli
usually share a
common alveolar duct,
creating “alveolar sacs”
Alveoli
There are three types of
cells found within alveoli:
 Alveolar Squamous
epithelial (aka “type I”) cells
– primary cells making up
the wall of the alveoli
 Septal (aka “type II”)
cells – sectrete “surfactant”
to reduce surface tension
which prevents alveoli from
sticking together & allows
for easier gas exchange
 Alveolar macrophages
(aka “dust cells”) –
phagocytic cells that remove
dust, debris & pathogens
Gas “exchange” occurs across the Respiratory membrane – the
fused membranes of the alveolar epithelium & the pulmonary
capillary endothelium