Do Now
• What is the major function of the
respiratory system? Major Organs?
• What is the relationship between the
cardiovascular system and the respiratory
system?
Chapter 13
Respiratory System
• The trillions of cells in our body require an
abundant and continuous supply of
oxygen to carry out their vital functions.
• The cardiovascular system
and the respiratory system
share the responsibility for
supplying the body with
oxygen and disposing of
carbon dioxide.
• The respiratory system organs oversee
the gas exchanges that occur between the
blood and the external environment.
• Transportation of gases is carried out by
the cardiovascular system.
Functional Anatomy of the
Respiratory System
Organs of the Respiratory
system
•
•
•
•
•
•
•
Nose
Pharynx
Larynx
Trachea
Bronchi and their smaller branches
Lungs
BLT  PLT
• The lungs contain the alveoli which are
terminal air sacs.
• Gas exchange only occurs in the alveoli.
• Therefore all other organs of the
respiratory system are conducting
passageways that allow air to reach the
lungs.
The Organs of the
Respiratory System
Functions of the Conducting
Passageways
• Allows air to reach the lungs
1. Nose
• Air enters through the nostrils or external
nares.
• The nose contains two nasal cavities.
• Special ciliated cells in the upper reaches
of the nasal cavity act as odor receptors.
• Tear glands drain into the nasal
cavity.
• The palate separates the nasal
cavity from the oral cavity.
• Function – filter, warm and
moisten the air
2. Pharynx
• The pharynx is a muscular passageway
commonly called the throat.
• It is a common passageway for food and
air.
• The pharynx in superior to the larynx and
trachea.
• Tonsils are located in the pharynx.
3. Larynx
• The larynx is also known as
the voicebox.
• Function of the larynx:
sound production
• The epiglottis: a flap of
tissue that prevents food
from passing into the larynx
• Parts of the larynx form folds called the
vocal folds or the true vocal cords which:
vibrate with expelled air giving us the
ability to speak
• Glottis – opening to the larynx – epiglottis
covers
4. Trachea
• The trachea is also known as the
windpipe
• The trachea is lined with cilia. The cilia
beat in the direction opposite of the
incoming air.
• They propel mucus: loaded with dust
particles and other debris, away from the
lungs to the throat where it can be
swallowed or spat out
• The trachea is rigid because it has C
shaped cartilaginous rings
• Tracheotomy – when as incision is
made in the trachea to allow air to
pass around a blockage
5. Bronchi
• The trachea divides into the
right and left primary bronchi
• The bronchi laid into the lungs
• The bronchi branch into a
great number of smaller
passageways known
bronchioles
During an asthma attack:
• Smooth muscle lining the bronchioles
constricts and movement of air through
the narrowed tubes results in the
characteristic wheezing
By the time air has reached
the bronchi it is:
1. Warm
2. Cleansed of most impurities
3. Well humidified
6. Lungs
• The paired lungs are fairly large organs
• They occupy almost the entire thoracic cavity
• The primary bronchi go into the lungs where they
subdivide into smaller and smaller branches
(secondary and tertiary bronchi). They finally end
in the smallest of the conducting passageways
the bronchioles.
• The bronchioles end in alveoli or air sacs.
• The alveoli make up the respiratory zone
• The lungs are cone-shaped organs. The right
lung has three lobes and the left lung has 2
lobes. The left lung has 2 since the heart is on
that side and takes up some of the space.
Capillary Network Diagram
• Each alveolar sac is made up of simple
squamous epithelium surrounded by blood
capillaries. Gas exchange occurs in the
capillaries.
• This layer of tissue and the capillary net create
the respiratory membrane (air/blood barrier). Air
flows by one side and blood flows by on the other
side. Gas exchange occurs by simple diffusion.
• There are approximately 300 million
(alveoli). Their surface area is at least 40X
that of the skin.
• The lungs are mostly air spaces so they
are light and usually float in water – soft
and spongy
• Macrophages (WBC) wander in and out of
the alveoli picking up bacteria, carbon
particles and other debris.
Mechanisms of Breathing
• Respiration: the complete process of
supplying oxygen to body cells for aerobic
cellular respiration and the reverse
process of ridding the body of oxygen
Respiration includes the
following components:
1. Breathing
•
•
Inspiration – entrance of air into the
lungs
Expiration – exit of air from the lungs
2. External Respiration
• Exchange of the gases oxygen and
carbon dioxide between air and blood
• Occurs in the lungs
3. Internal Respiration
• Exchange of the gases oxygen and
carbon dioxide between blood and tissue
fluid
• Occurs in the body cells
4. Cellular Respiration
• Production of ATP in cells
Mechanics of Breathing
• Breathing is a completely mechanical
process that depends on volume changes
occurring in the thoracic cavity
• Volume changes lead to pressure
changes, which lead to the flow of gases
to equalize the pressure
Ventilation
• The manner in which air enters and exits
the lungs
To understand ventilation it
is necessary to:
1. There is a continuous column of air from
the pharynx to the alveoli of the lungs
2. The lungs lie within the sealed-off
thoracic cavity. The rib cage forms the
top and sides. The diaphragm forms the
floor of the thoracic cavity.
3. The lungs are enclosed by 2 serous
membranes called pleural membranes.
One layer is attached to the rib cage and
diaphragm and the other layer is attached
to the lungs. The two layers are very
close and are only separated by a little
fluid. The pressure in the pleural space is
lower than atmospheric pressure.
Inspiration is Active
• Inspiration is triggered by the respiratory
center. Impulses are sent by way of the
nerves to the diaphragm and the muscles
of the rib cage known as intercoastals.
• When relaxed the diaphragm is domed
shaped but when it contracts it lowers.
• Nerves also stimulate the intercostal
muscles to contract causing the rib cage
to move upward and outward
• When the diaphragm contracts and the rib
cage moves up and out, the thoracic
cavity increases in size. This causes the
lungs to expand and air to move in from
the nose or mouth.
Expiration is usually
passive
• When the nerves stop sending signals, the
diaphragm relaxes and resumes its dome
shape.
• The abdominal organs press up against
the diaphragm and the rib cage moves
down and inward
• This causes the elastic lungs to recoil and
air to be pushed out.
External and Internal
Respiration
• The principles of diffusion alone govern
whether oxygen or carbon dioxide enters
or leaves the blood
External Respiration
cleanses the blood
• External respiration refers to the
exchange of gases between air in the
alveoli and blood in the pulmonary
capillaries
External Respiration
occurs in the lungs.
• Carbon dioxide diffuses out of the blood in
the lungs.
• Oxygen diffuses into the blood in the
lungs.
Internal respiration
cleanses tissue fluid
• Internal respiration occurs in the body
cells
• Oxygen diffuses out of the blood and into
the tissues.
• Carbon dioxide diffuses out the tissues
and into the blood
Respiratory Sounds
• As air flows in and out of the
respiratory passageways it produces
two recognizable sounds that can be
picked up with a stethoscope.
1. Bronchial Sounds – produced by air
rushing through the large respiratory
passageways
2. Vesicular sounds – as air fills the alveoli
• Diseased respiratory tissue, mucus or pus
can produce abnormal sounds such as
rales (a rasping sound) or wheezing (a
whistling sound)
Respiration and Health
Bronchitis: Acute and
Chronic
Acute
• Caused by: secondary
bacteria infection
• Results in: heavy mucous
discharge with much
coughing
• Treatment: antibiotics
Chronic
• Caused by: smoking – second hand
smoke – irritation to the lining of the
bronchi
• Results in: frequent coughing, increased
risk of respiratory infections
• Treatment - none
Pneumonia
• Caused by: bacteria or virus infection of
the lungs
• Results in: lobes fill with fluid become
non-functional
• Treatment - antibiotics
Pulmonary Tuberculosis
• Caused by: Tubercle bacillus – bacteria
• Results in: cysts in the lungs, alveoli burst
and replace by inelastic connective tissue
• Treatment: antibiotics – some strains are
now resistant
Emphysema
• Caused by:
destruction of lung
tissue – damage and
collapse of lung tissue
• Results in: ballooning
or inflation of the
lungs due to trapped
air, breathless cough,
surface for gas
exchange decreases,
not enough oxygen to
hear and body
• Treatment: none
Smoker's Lung - tar coated, causing emphysema
Lung Cancer
• Caused by: smoking
• Results in: thickening
of bronchi cells, loss of
cilia, dust and bacteria
enter
• Treatment: removal of
lung piece
The End