Download Respiratory System PPT File

The respiratory system
Structures
Organs of the respiratory system
Larynx
Trachea
Rib cage
Bronchus
Mediastinum
Lung
Right or
Left Lung?
Diaphragm
• Passage for air from nasal cavity to
trachea
• Trachea
• Carries air to & from lungs. Lined with
mucous membrane and cilia
• Rib Cage
• Forms the framework of the chest.
Providing protection to organs inside
• Mediastinum
• Area where heart fits between lungs
• Covered by a pleural membrane that
• Lungs
lines lungs and the inside of the chest
wall (two layers – visceral & parietal).
Pleural fluid fills in between layers to
hold in place.
• Muscle contracts and relaxes to change
• Diaphragm
the chest volume during breathing
• Larynx
The head (LS)
Nasal cavity
Soft palate
Pharynx
Epiglottis
Larynx
Trachea
Section through the head
Nasal cavity
Palate
Teeth
Tongue
Pharynx
Epiglottis
Hyoid bone
Vocal cords
Larynx
Esophagus
The Miles Kelly Art library, Wellcome Images
The nose (nasal cavity)
• Air enters and leaves the body
through the nose
• Here it is cleaned (filtered),
warmed and moistened before
entering the body
• The nasal secretions contain an
anti-bacterial enzyme - lysozyme
More functions
• Epiglottis - Flap of tissue which, when
swallowing, closes off the trachea to
prevent food and liquid from entering the
lungs
• Larynx – the organ of voice. Air going to
and from the lungs passes through the
larynx. It contains vocal cords which
vibrate to make sound. Vocal cords can
change the pitch and volume.
The mucous lining
• The nasal cavity and upper airways
have a mucous lining
• The epithelial lining contains goblet
cells which secrete a clear, sticky
mucus
• The function of mucus is to trap dirt
particles and microbes before they
enter the lungs
Cilia
• Cilia – microscopic hair-like structures
that beat back and forth to help move
mucus along and trap the particles.
The bronchial tree
Larynx
Trachea
Bronchus
Bronchiole
The Sourcebook of Medical Illustration (The Parthenon Publishing Group, P. Cull, ed., 1989)
Trachea & bronchi
• The trachea & bronchi are
reinforced with C-shaped rings of
cartilage. These prevent the tubes
collapsing during inhalation.
The bronchi
Cartilage
rings
Muscular
wall
Mucous
lining
The Miles Kelly Art library, Wellcome Images
• The upper airways are lined
with a ciliated mucous
membrane
–The sticky mucus traps dirt &
microbes
–The cilia sweep the dirty mucus
up the trachea and into the throat
The ciliated lining tissue
Mucussecreting
goblet cells
Cilia
G. Meyer, ANHB-UWA,
Alveoli
Alveoli
• The bronchioles terminate in microscopic
clusters of air sacs called the alveoli. These
make up most of the lung
• Gas exchange takes place in the alveoli
The alveoli (air sacs)
Alveoli are wellsupplied with blood
capillaries =
increasing
efficiency of Gas
exchange (taking
in O2 around the
body, and
removing CO2)
Section through a lung showing alveoli
and blood supply
M I Walker, Wellcome Images
Muscles
• Diaphragm and
Intercostals (rib muscles)
• These muscles are
involved in contracting
and relaxing during
inspiration and expiration
to change the volume of
the thoracic cavity, and
therefore changing the
volume of lungs.
Pleura
• Double layered – 2 layers: Visceral and
Parietal
• These linings lubricate chest
movements, and help to keep lungs in
position. Contains a pleural cavity
between layers filled of pleural fluid which
lubricates the surfaces and allows the
layers to slide against each other easily
during respiration.
The respiratory system
Gas exchange
Exchange surfaces
• Like all exchange surfaces, the alveoli
are well suited because they:
– are very thin (only 1 layer of cells)
– have a large surface area – due to the
millions of alveoli
– have a rich blood supply – network of
capillaries so close
– are moist – because only gases can
diffuse into & out of the blood only
when they are dissolved in fluid.
Terms
You need to understand the
difference between the
terms BREATHING (aka
VENTILATION) and
RESPIRATION
Breathing
• Breathing (sometimes referred to
as ventilation) is the process of
moving air into and out of the
lungs.
• The purpose of breathing is to
exchanged oxygen and carbon
dioxide between the lungs and
the air .
Respiration
• Respiration is the transport of
oxygen from the air to the
tissues and the transport of
carbon dioxide in the opposite
direction.
[not to be confused with the process of
cellular respiration discussed earlier]
External respiration vs.
Internal respiration
• External respiration is the
movement of O2 and CO2 between
the lungs and the bloodstream.
• Internal respiration is the
exchange of O2 and CO2 between
the blood and the tissues that
need it.
Thoracic volume
Rib cage relaxes
Diaphragm domed
Rib cage raised
Diaphragm flattens
Inspiration vs. Expiration
• Air flows from areas of higher
pressure to areas of lower
pressure.
• INSPIRATION – taking air into the
lungs
• EXPIRATION – breathing out.
Opposite to inspiration
INSPIRATION
• Pressure of air in the lungs is less than outside.
• Low pressure inside is achieved by increasing
the volume of the lungs.
• Diaphragm and external intercostals muscles
contract – becomes flatter and rib cage moves
outwards
• Air flows in until the pressure becomes equal.
• During normal breathing mainly diaphragm
involved. Heavier inspiration, movements of the
rib cage become more important.
Expiration
• Diaphragm and external intercostals relax.
• Diaphragm moves back up into the chest
cavity and rib cage moves downwards.
• Lung volume reduces and air is greater
inside = thus air flows out until pressures
are equal.
• At rest, expiration is a passive process.
During forceful expiration, the intercostals
muscles contract to actively lower the rib
cage
Gas Exchange
• Concentration gradients again!
• The blood in the capillaries around the
alveoli has a low oxygen concentration
(as it has already delivered all the oxygen
to the cells and returning to the lungs)
• the air outside (in the alveoli) is high in
oxygen concentration.
• Oxygen will move from high to low
concentration = from the alveoli to the
blood capillaries.
• Oxygen dissolves in the moisture on
the inside of the alveolus and diffuses
through the membrane, through the
walls of the capillaries and into the
blood.
• The blood in capillaries around the
alveoli are high in Carbon Dioxide (has
come from the cells and picked up the
wastes)
• Carbon dioxide diffuses out of the
blood and into the air in the alveolus.
• Thus the expired air contains less
oxygen, and more carbon dioxide, than
inspired air.
External respiration
Partial pressure (mmHg)
Alveolar air
Deoxygenated
blood
Oxygenated
blood
Oxygen
100
40
100
Carbon
Dioxide
40
44
40
Breathing maintains the correct
concentration of gases in the lungs
Concentration
gradient
Transport of Oxygen and
Carbon Dioxide
% of Gases
• Inspired Air:
 20.95% Oxygen
 0.04% Carbon dioxide
• Expired Air
 15.8% Oxygen
 4.3% Carbon dioxide
• The other 79% is mainly made up of nitrogen,
with varying amounts of water vapour
Concentration gradients
• The concentration gradient for oxygen
and carbon dioxide is maintained by:
– Constant flow of blood through the
capillaries. Always replaced by more blood
pumping around the body. The new blood
is low in O2 and high in CO2.
– The continual movement of air in and out
of the alveoli as we breathe in and out.
‘New’ air is low in CO2 and high in O2.
• Blood is the major transport medium
for oxygen and carbon dioxide
• Both oxygen and carbon dioxide gases
are transported in the blood – but in
different ways
Oxygen
• Is carried by:
– 3% carried in solution in the blood plasma
(as not very soluble in water)
– 97% carried in combination with
haemoglobin (found in Red Blood Cells)
Oxygen transport
• Oxygen combines with haemoglobin in
RBCs to form oxyhaemoglobin
Hb + O2 = HbO2
Hb + O2 = HbO2
• Oxygen combines with haemoglobin where the
oxygen concentration is high (capillaries in the
lungs). Oxyhaemoglobin breaks down into O2
and Hb where oxygen concentrations are low (at
the cells which need the oxygen)
• Oxygenated blood is blood with a high
proportion of oxyhaemoglobin.
• Oxyhaemoglobin is bright red in colour, so the
blood in the arteries (except pulmonary arteries)
is bright red. Haemoglobin is dark red or
purplish in colour. The deoxygenated blood in
the veins (except pulmonary veins) is therefore
dark red.
Carbon Dioxide
• Is carried by:
– 7-8% carried in solution in the blood plasma
– 22% combines with the globin part of the
haemoglobin molecule to form a compound
called carbaminohaemoglobin
– 70% carried in plasma as bicarbonate ions,
HCO3-
Carbon dioxide transport
-
• Most CO2 is transported in the plasma
as dissolved bicarbonate ions
Carbon Dioxide
• Blood in the capillaries – most CO2 reacts
with water to form carbonic acid (H2CO3).
• Carbonic Acid then dissolves into
hydrogen ions and bicarbonate ions
CO2 + H2O = H2CO3 = H+ + HCO3-
Gas Percentages
OYXGEN
CARBON DIOXIDE
3% dissolved in
plasma
8% dissolved in plasma
97% as
oxyhaemoglobin
22% as
carbaminohaemoglobin
70% as bicarbonate ions
Oxygen saturation
Disorders of the Respiratory
System
Disorders / Complications
•
•
•
•
•
•
•
Asthma
Emphysema
Lung Cancer
Laryngitis
Bronchitis
Pneumonia
High Altitudes – tissues do not get enough
O2
Diseased lung tissue
B
A
CDC
C
Photo by Pöllö
A. healthy lung tissue
B. Smoker’s lung
C. Emphysema
Some Respiratory Disorders
Asthma:
• an allergic response to foreign substances
that enter the body (dust, pollen, animal
fur). These trigger an ‘attack’ where the
muscles surrounding the bronchioles
spasm – causing a narrowing o the air
passages making it difficult to breath
Asthma
Emphysema
• Caused by long term exposure to
irritating particles in the air. E.g.
Smokers inhale tobacco smoke, those
who work in situations where a lot o
dust or asbestos
• The irritating particles cause damage
to the alveoli. They lose their elasticity
and may break down – reducing the
internal surface area of the lungs.
• Due to loss of elasticity – lungs are
constantly inflated and expiration
requires voluntary effort.
• Inadequate S.A. for gas exchange.
Smoking Effects
The effects of tobacco smoke on the respiratory
system include:
• Irritation of the trachea and larynx
• Reduced lung function and breathlessness due to
swelling and narrowing of the lung airways and excess
mucus in the lung passages
• Impairment of the lungs’ clearance system, leading to
the build-up of poisonous substances, which results in
lung irritation and damage
• Increased risk of lung infection and symptoms such as
coughing and wheezing
• Permanent damage to the alveoli of the lungs.
Smoking