Loai Gaffer Functional Anatomy The respiratory system includes the lungs and a series of airways that connect the lungs to the external environment structures of the respiratory system are subdivided ID: 914171
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Slide1
Respiratory Physiology
Dr.
Loai Gaffer
Slide2Functional Anatomy
Slide3The respiratory system includes the lungs and a series of airways that connect the lungs to the external environment
structures of the respiratory system are subdivided
into
a conducting zone
a respiratory zone
Slide4Slide5The
conducting zone
includes the nose,
nasopharynx
, larynx, trachea, bronchi, bronchioles, and terminal bronchioles
bring air into and out.Warms
Humidifies
Filter
Slide6The walls of the conducting airways contain smooth muscle.
has both sympathetic and parasympathetic innervation, which have opposite effects on airway diameter:
What is the bronchial tone?
Slide7The
respiratory zone
: the respiratory bronchioles, the alveolar ducts, and the alveolar sacs.
Alveoli are the functional unit of the Lung
Slide8The alveoli are
pouch like
vaginations
of the walls
Each lung has a total of approximately 300 million alveoli. The alveolar walls are rimmed with elastic fibers and lined with epithelial cells, called
type I
and
type II
pneumocytes
(or alveolar cells).
The type II pneumocytes synthesize pulmonary
surfactant The alveoli contain phagocytic cells called alveolar macrophages
Slide9Slide10Slide111 lung
Slide12Pulmonary blood flow
Pulmonary blood flow is the cardiac output of the right heart.
It is ejected from the right ventricle and is delivered to the lungs via the
pulmonary artery .
The pulmonary arteries branch into increasingly smaller arteries and travel with the bronchi toward the respiratory zones. The smallest arteries divide into arterioles and then into the
pulmonary capillaries,
Slide13Slide14Atmospheric (Barometric) pressure & gas laws
Slide15Atmospheric (Barometric) pressure:
is the pressure exerted by the weight of the air in the atmosphere on objects on Earth’s surface.
Barometer:
use a Column of Hg.
1 atm
= 760 mm Hg
Slide16Composition of Air:
GAS
%
N
78.06
O₂
20.98
CO₂
0.04
Aragon & Helium
0.92
H₂O
0.50GAS%N74.09
O₂19.67CO₂0.04Aragon & Helium0.92H₂O6.20DRY
HUMIDIFIED
Slide17Why Air Humidification …
?
Why Do We Need Nitrogen in
Atmosphere …
?
Dampens the harsh effect of pure oxygen environment.
Makes the air thicker which is easy to breath.
Nitrogen is necessary for plant growth.
Nitrogen in the air is used by the human body to synthesize NO.
What About Aragon …
?
Fill light-bulb.
Protect metals from oxidation during welding.Cryosurgery. A dry alveolus impairs gas exchange.
Slide18GAS LAWS
Slide19Dalton’s Law
The pressure of a mixture of gases is equal to the sum of the pressures of all of the constituent gases alone.
Pressure
total
= Pressure
1
+ Pressure
2
+ ... +
Pressure
n
P = PN2 + PO2 + PCO2 + PAr + PHe
Slide20Pressure of one gas(P) = Total pressure × fraction of amount it represents.
PO
2
=
760 × 0.21 = 160 mm HgPN2 = 760 × 0.79 = 600 mm Hg
PCO
2
= 760 × 0.004 = 0.3 mm Hg
Slide21Henry’s Law
At
a constant temperature
, the amount of a given gas that dissolves in a given type and volume of liquid is directly proportional to the partial pressure of that gas in equilibrium with that liquid.
Slide22The solubility of a gas in a liquid is directly proportional to the pressure of the gas.
V =
sP
Slide23Boyle’s Law
The pressure exerted by a gas
at constant temperature
varies inversely with the volume of the gas.
P
α
1
V
Slide24Slide25Boyle’s law & Respiratory Mechanics
Slide26Atmospheric pressure diminishes with increasing altitude above sea level.
(فمن يرد الله أن يهديه يشرح صدره للإسلام ومن يرد أن يضله يجعل صدره ضيقا حرجا
كأنما يصعد في السماء كذلك يجعل الله الرجس على الذين لا يعلمون
)
Slide27Slide28Lecture 2
Slide29Mechanics of Breathing
Slide30Important points to consider:
Both the
lungs and chest
are
elastic
structuresThere is a thin layer of fluid between the visceral (lungs) and parietal (chest) pleurae
The pressure in the space between the lungs and chest wall (
intrapleural
pressure)
is negative
(
subatmospheric)
Slide31Ventilation
Defined as the process of getting air into and out of the lungs during breathing.
Inspiration
Expiration
(Active process)
(Passive process)
Slide32Muscles of Inspiration:
The
diaphragm
is the most important muscle for inspiration.
external intercostal muscles
accessory muscles (
sternocledomastoid
and scalene)
Slide33Muscles of Expiration:
Expiration normally is a
passive
process
abdominal muscles
the internal intercostal muscles
Slide34Slide35External
intercostal
Diaphragm
Antero-posterior
Vertical
Transverse
Slide36Breathing cycle
the breathing cycle is divided into phases:
rest (the period between breaths)
inspiration
expiration
Slide37At rest
atm
= 0
Intra-alveolar
pressure
= 0
Intra-pleural pressure
- 4
Slide38During
Inspiration
atm
= 0
Intra-alveolar
pressure
= - 1
Intra-pleural pressure
- 6
According to Boyle’s law;
↑ volume → ↓ pressure
Slide39During
Expiration
atm
= 0
Intra-alveolar
pressure
= +1
Intra-pleural pressure
- 2.5
Slide40Intra-alveolar pressure changes
Intrapulmonary pressure
Phase of respiration ( with closed glottis)
-1 mmHg
End of normal inspiration
+1 mmHg
End of normal expiration
-30 mmHg
End of maximum inspiration
+50 mmHg
End of maximum expiration
Slide41Intrapleural
pressure changes
Intrapleural pressure
Phase of respiration ( with closed glottis)
-6 mmHg
End of normal inspiration
-2.5 mmHg
End of normal expiration
-30 mmHg
End of maximum inspiration
+50 mmHg
End of maximum expiration
Slide42Compliance
Lung elasticity:
is due to
elastin
&
collagen fibersElastin fibers are highly distensible and can be stretched to almost
double
their resting length
Slide43There are 3 terms used to assess the elastic properties of the lung:
Distensibility
:
the ease with which the lung can be inflated
Stiffness:
the ability to resist stretch
Elastic recoil:
the ability of the stretched lung to recoil back to its original position
Slide44Compliance: is measure of lung
distensibility
/
stretchability
/expandability.
Definition of Compliance:The volume change per unit pressure change (∆V/∆P)lung compliance
alone
is about
0.2L/cmH
2
O
C
α 1 E
Slide45Low compliance
indicates a
stiff lung
& means
more work is required
to bring in a normal volume of air.Ex; Lung fibrosisHigh compliant lung the elastic tissue has been
damaged
, there is
no problem inflating
the lungs but have
extreme difficulty exhaling
air.So that extra work is required to get air out of the lung.Ex; Emphysema
Restrictive lung diseaseObstructive lung disease
Slide46Surface Tension
the compliance of the lungs is affected by the surface tension
it arises because the
cohesive forces
between water molecules
attract each other tending to contract their surface and cause alveolar collapse.
Slide47Surfactant
Surfactant is a mixture of
dipalmitoylphosphatidylcholine
(DPPC), other lipids, and proteins.
Surfactant is produced by
type II alveolar epithelial cells .Secreted from the alveolar cell type II at
30 week
gestation.
It has a hydrophobic tail & a hydrophilic tail.
Surfactant molecules are responsible for
reducing the surface tension
forces that oppose lung inflation.
Slide48H
₂O
H
₂O
H
₂O
H
₂O
H
₂O
Surfactant
Hydrophobic tail
Hydrophilic tail
Alveoli collapsed
↓ Surface tension
Inflation
Slide49Surfactant effects are mainly exerted on
small alveoli
especially
during expiration
.this is because small alveoli have higher tendency to collapse
which can be explained by the law of Laplace :P=2T/rP=pressure inside the alveolus
T=tension
R=radius of an alveolus.
Slide50Surfactant deficiency:
Surfactant deficiency is an important cause of
infant respiratory distress syndrome
(IRDS) also known as (hyaline membrane disease).
IRDS develops in infants born
before their surfactant system is functional
Surface tension in the lungs of these infants
is high
, and the
alveoli are
collapsed
Slide51Work of breathing
During normal tidal breathing the inspiratory muscles do all work & expiration is passive
Slide52Inspiratory muscle do work against:
Elastic forces 65% stored as potential energy
Frictional forces (non elastic work) 35% of work:
airway resistance work (28%)
tissue resistance work (7%)
Slide53Factors that ↑ the work of breathing :-
Reduction of the respiratory compliance
Deficient secretion of surfactant
Disease that ↑ the resistance to air outflow e.g. asthma & emphysema
Slide54What are the factors favoring collapse of the lungs?
Lung recoil
Surface tension
How are these force counteracted?
Transmural
pressure
TMP = IAP - IPP
Surfactant
Slide55Clinical Applied Physiology
Pneumothorax
is an abnormal collection of air or gas in the pleural space.
Pneumothorax can be caused by:
physical trauma to the chest (tension pneumothorax)
Rupture of a lung bullae (spontaneous pneumothorax)
Slide56Slide57Slide58Slide59Lecture 3
Slide60Pulmonary function tests
Slide61Types
Volume measuring spirometers
Flow measuring spirometers
Slide62Volume measuring spirometers
Slide63Flow measuring spirometers
Slide64Small Hand-held Spirometers
Slide65Parameters
FEV
₁
(Forced expiratory volume in one second)
:
The volume of air expired in the first second of the blow
FVC
(Forced vital capacity)
:
The total volume of air that can be forcibly exhaled in one breath
FEV
₁/FVC ratio: The fraction of air exhaled in the first second relative to the total volume exhaled
Slide66Factors affecting vital capacity
Age
Gender
Height
Ethnicity
Posture
Physical condition
Slide67Tests of mechanical properties
Lung volumes & capacities:
By Benedict Roth spirometer
Slide68Slide69Spirogram
Patterns
Normal
Obstructive
Restrictive
Mixed Obstructive and Restrictive
Slide70Normal Trace Showing FEV
₁
and FVC
FVC = 5 L
FEV
₁ = 4 L
FEV₁/FVC ratio = 0.8
Slide71Obstructive vs. restrictive
Obstructive
Restrictive
Pathology
Airway Narrowing
Fibrotic
tissue deposition
Elasticity
↓↓
↑↑
Compliance
↑↑↓↓sizeLarge SmallParameter affectedFEV
₁FVC
Slide72Slide73Bronchospasm, e.g. Asthma
• Inflammation and swelling of bronchial mucosa,
e.g. bronchitis
• Physical obstruction in the airways, e.g.
tumour
• C.O.P.D• External compression of the airways,e.g. tumour
Slide74Slide75Lung Parenchyma, e.g. Pulmonary Fibrosis
• Chest wall disorders, e.g. Scoliosis
• Neuromuscular disorders, e.g.
Guillan
Barre Syndrome• Pleural Disease, e.g. Pneumothorax orPleural Effusion• Cardiac, e.g. Congestive Heart Failure
• Others, e.g. Obesity, Ascites or Pregnancy
Slide76Slide77Thank you for listening