Introduction
• Responsible for the exchange of gases between the
body and the external environment.
The Respiratory System
Chapter 15
– Cells need a supply of O2 and to eliminate CO2
– 3 basic processes
• Breathing
• External respiration
• Internal respiration
• Two systems supply O2 & eliminate CO2
– Respiratory system
– Cardiovascular system
Human Anatomy, 3rd edition
Prentice Hall, © 2001
The Respiratory Tract
The Respiratory Tract
• Upper respiratory
system
• Passageways
through which
air will move
• Terminate in
the alveoli
– Superior to the
larynx
– Functions – intake,
moistening, filtering,
sensing
• Lower respiratory
system
– Larynx and below
– Functions – sound
production, transport
of air, gas exchange
Human Anatomy, 3rd edition
Prentice Hall, © 2001
The Respiratory Epithelium
Human Anatomy, 3rd edition
Prentice Hall, © 2001
Surface View of the Epithelium
• Lines the upper
respiratory system
• Pseudostratified
ciliated columnar
epithelium with goblet
cells
– Entraps & removes
dust
– Moistens incoming air
– Olfactory sensation
• Capillaries warm
incoming air
• The common cold
Human Anatomy, 3rd edition
Prentice Hall, © 2001
Human Anatomy, 3rd edition
Prentice Hall, © 2001
1
The Nose
The Nasal Cavity
• Nasal septum
• Primary entrance
to the respiratory
system
– Divides into left and
right sides
• Hard & soft palate
form the floor
• Nasal conchae cause
turbulence through
nasal cavity
• Internal nares lead to
the pharynx
– Bone & cartilage
– External nares
Human Anatomy, 3rd edition
Prentice Hall, © 2001
Human Anatomy, 3rd edition
Prentice Hall, © 2001
Paranasal Sinuses
• Cavities in cranial
bones
• Functions
The Pharynx
• Area from the internal
nares to the larynx
• Shared between the
respiratory and
digestive systems
– Lighten skull bones
– Produce mucus
– Resonate during
sound production
Human Anatomy, 3rd edition
Prentice Hall, © 2001
Human Anatomy, 3rd edition
Prentice Hall, © 2001
The Larynx
The Larynx
• Connects the pharynx
to the trachea
• Lined by mucusproducing columnar
epithelium
• Functions
• Formed by 9
cartilages
– Thyroid cartilage
• Adam’s apple
– Epiglottis
– Produces sound
• Vocal folds
– Keeps food from
entering the airways
• Vestibular folds
• Epiglottis
• Closes glottis
Human Anatomy, 3rd edition
Prentice Hall, © 2001
Human Anatomy, 3rd edition
Prentice Hall, © 2001
2
The Larynx
Voice Production
• Ligaments lie under
mucous membrane
• Muscles attached to
the cartilages
– Control vocal
ligament tension
• Sound production
– Air flowing over
vocal folds (through
the glottis) produces
sound waves
http://www.entdocsonline.com/images/larynx.jpg
• Resonating chambers
Human Anatomy, 3rd edition
Prentice Hall, © 2001
Bronchi, Bronchioles, & Alveoli
The Trachea
• Trachea divides into
• Primary bronchii divide
• Extends from larynx
to primary bronchi
• The “windpipe”
• Structure
into
• Secondary bronchi divide
into
• Tertiary bronchi divide into
• Bronchioles divide into
• Terminal bronchioles
– Incomplete
cartilaginous rings
• Lined by mucusproducing epithelium
• Function –
passageway for air
divide into
• Respiratory bronchioles
divide into
• Alveolar ducts end in
• Alveoli
Human Anatomy, 3rd edition
Prentice Hall, © 2001
Human Anatomy, 3rd edition
Prentice Hall, © 2001
The Respiratory Tree
Changes as the Respiratory Tree
Branches
• As branching of
bronchi becomes more
extensive
– Rings of cartilage
become plates
– Smooth muscle
increases
– Columnar epithelium
becomes cuboidal,
then squamous (in
alveoli)
• Asthma
Human Anatomy, 3rd edition
Prentice Hall, © 2001
Human Anatomy, 3rd edition
Prentice Hall, © 2001
3
The Alveoli
Alveoli
Human Anatomy, 3rd edition
Prentice Hall, © 2001
Human Anatomy, 3rd edition
Prentice Hall, © 2001
The Alveoli
The Lungs
• Site of gas exchange
with the blood
• Closely associated
with capillaries
• Wall of the alveolus
+ wall of capillary
– Respiratory
membrane
• Gas exchange occurs
by diffusion
• Alveolar epithelium
contains:
– Alveolar Type 1 cells
• Gas exchange
• Emphysema
– Alveolar Type 2 cells
• Secrete surfactant
• Respiratory
Distress Syndrome
• Soft, spongy,
cone-shaped
• Right lung
– 3 lobes
• Left lung
– 2 lobes
• Macrophages
Human Anatomy, 3rd edition
Prentice Hall, © 2001
Blood Supply to the Lungs
– Pulmonary arteries, pulmonary veins
Human Anatomy, 3rd edition
Prentice Hall, © 2001
Breathing
• Lungs are prevented from collapsing
– Pressure in the pleural cavity is always slightly lower than
the pressure in lungs
Human Anatomy, 3rd edition
Prentice Hall, © 2001
Human Anatomy, 3rd edition
Prentice Hall, © 2001
4
Inhaling is Active Work
• Diaphragm
• Intercostals contract
• Other muscles in
thorax contract
• Thoracic cage expands
• Lung volume
increases
• Pressure in lungs
drops below
atmospheric pressure
• Air rushes in
Human Anatomy, 3rd edition
Prentice Hall, © 2001
Exhaling is Passive
• Diaphragm relaxes
• Intercostal muscles
relax
• Thoracic cage drops
• Lung volume
decreases
• Pressure in lungs
increases above
atmospheric pressure
• Air rushes out
Human Anatomy, 3rd edition
Prentice Hall, © 2001
5