Respiratory physiology I. - u-szeged.hu · Respiratory physiology I. prof. Gyula Sáry Respiratory...
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2019.10.11. 1 1 Respiratory physiology I. prof. Gyula Sáry Respiratory mechanics, ventilation Learning objectives: 25-26. 2 • Respiratory muscles and movements • Lung volumes • Compliance of the lung and chest • Surface tension in the airways • Pressure changes during respiration • Airway resistance • Dead space of ventilation • Respiratory minute volume
Transcript of Respiratory physiology I. - u-szeged.hu · Respiratory physiology I. prof. Gyula Sáry Respiratory...
2019.10.11.
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Respiratory physiology I.
prof. Gyula Sáry
Respiratory mechanics, ventilation
Learning objectives: 25-26.
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• Respiratory muscles and movements
• Lung volumes
• Compliance of the lung and chest
• Surface tension in the airways
• Pressure changes during respiration
• Airway resistance
• Dead space of ventilation
• Respiratory minute volume
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anoxia
begins
symptom free
period
functional
problems begin
survival time
reanimation time
total
paresis
irreversible
damage
cellular death
+ CO2 accumulation (CO2retention)!
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ventilation
transport/perfusion
diffusion
distribution
Respiration: main phases
ventilation
alveolar diffusion
transport
in the bloodstream
tissue diffusion
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Muscles of inspiraton and (active) expiration
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maximal expiration
maximal inspiration
diaphragma
intercostal muscles
chest movements
inspiration
expiration
external
internal
turning
axis
Respiratory movements
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diaphragma: vertical movements
chest: antero-posterior and sideways movements
Volume changes during respiration
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The principle of spirometry, measuring lung volumes
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The normal spirogram
Exp. reserve volume
Insp. reserve volume
capacity= volume1+volume2+volume3+….
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Lung volumes that can not be determined
directly by spirometry
Exp. reserve volume
Insp. reserve volume
RV= V0 xCe
Ca-CeV0= spirometer volume
Ca and Ce helium concentration at beginning and after equibrium
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Pulmonary volumes and age
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Pulmonary volumes and age
age (years)
vital capacity
total lung
capacity
residual
volume
functional
residual
capacity
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Changes in volume and pressure during respiration
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A distensibility of the lung (compliance)
Volume changes per pressure units (L/cm H2O)
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Elastic forces in the lung and in the chest during breathing
end of
normal
expiration
end of
forced
expiration
end of
forced
inspiration
equilibrium
for chest
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pressure
pressure
lun
g v
olu
me
(L)
maximal expiration
resting state
of the chest
resting state
of the resp. syst.
relaxation pressure curve
Thorax
Thorax + lung
Lung
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Summary
• Functional residual capacity (end of normal expiration) is
determined by the interaction between lung tissue and
chest.
• Total lung capacity (end of forced inspiration) is
detemined by the balance between chest-lung recoil and
the force of inspiratory muscles.
• Residual volumen (end of forced expiration) is determined
by the interaction between expiratory muscles and the
elasticty of the chest.
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abdominal
respiration
thoracal
respiration
diaphragma
The role of the negative intrapleural pressure;
pneumothorax
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Positive pressure ventilation (anesthesia)
• volume controlled
• pressure controlled
•
•
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Negative pressure ventilation (the „iron lung”)
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Elasticity of the lung
Determined by:
elastic fibres of the lung
surface tension and surfactant
interdependency of the alveoli
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Distensibility of the lung
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Surfactant, surface tension
Surface tension: why do falling water drops have a spherical shape?
Type II. alveolar cells: production of surfactant
Surfactant:
surface tension drops to 1/10 of the original value
prevents edema
Premature babies:
infant respiratory distress syndrom (IRDS)
atelectasis (no air in the alveoli)
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Production of surfactant
•produced by type II. alveolar cells
•LB= lamellar bodies
•exocytosis (stimulus: distension of the lung)
•formes a thin film
•surface tension drops to 1/10
•phosphatidilcholine, albumin, IgA, apoproteins
•removed by phagocitosis (recycling!)
•produced from the 6.-7. intrauterine month
•premature babies:
infant respiratory distress syndrome (IRDS)
atelectasis
glycocorticoids stimulate
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Interdependence of the alveoli
vessel
bronchuslung tissue
smooth muscle
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Pressure changes during respiration
intapulmonar
intrapleural
respiratory volume
time (s)
time (s)
time (s)
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Resistance of the lung against change in volume
elastic resistance:
chest and lung elasticity
viscous (non elastic) resistance:
most importantly against airflow
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Reynolds number
v= flow velocity
ρ= density
d= diameter
η= viscosity
velocity x density x diameter
viscosity
Pressure
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Resistance against airflow
lung volume
Air
wa
y r
esi
sta
mce
To
tal l
un
g c
ap
aci
ty
Re
stin
g p
osi
tio
n
Re
sid
ua
l vo
lum
en
3.
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Resistance against airflow
individual diameter > individual diameter
total cross section area << total cross section area
airway resistance > airway resistance
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Dead space of respiration
no gas exchange
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Dead space of respiration
• Anatomical and physiological dead space
• Respiratory rate
• Respiratory minute volume
• Dead space ventilation
• Alveolar minute volume
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Spirogram: dynamic components
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Timed vital capacity
Time (s)
FEV1
Volume
Vc
Tiffeneau index=FEV1/Vc
