3.5 Physiology Respiratory System

I Made Muliarta
Gambar 4. Beberapa Jenis Spirometer

Anatomy Pulmonary
Review Ventilation
Respiratory System
Gas Respiration
Exchange Control
Gas Transport
RESPIRATORY SYSTEM
Ventilation Diffusion Perfusion
Boyle’s law
Muscles involvement Dalton’s Law
Pressure Changes Henry’s law Not all regions ventilated equally
(intrapulmonary and intrapleura)
Pulmonary and bronchial response
V/Q matching
Lung compliance Factors influence

Surface tension
Surfactant gas exchange
Airway resistance
Lung Function Measurement

Some volumes can be measured
Lung capacities
Patern of the lung function
INTRODUCTION
• Our cells need oxygen & produce
carbondioxide
• The respiratory system brings the needed O2
into and eliminate CO2
• The blood transport these gases
• Pulmonary Ventilation
• Air entering adjusted to body temp., filtered,
almost completely humidified
(Silverthorn, 2001)
INTRODUCTION
• The lung provide gas exchange surface
separating blood from the surrounding
alveolar gaseous environment
• Oxygen transfer simultaneously
• Adult’s lung: ±1 kg, 4-6 L, if spread out:
50-100 m2 (badminton court)
• More than 300 million alveoli
INTRODUCTION
• Alveoli:
• Elastic thin walled
• Membranous sacs
• ± 0,3 mm in diameter
• Millions of short, thin walled
capillaries and alveoli lie side by side
• Gases diffuse across the extremely (Silverthorn, 2001)
thin barrier (0,3µm)
(Cumings, 2003)
VENTILATION
• Ventilation????
• The function of ventilation: to maintain
blood gases at their optimum level
• The Ventilation occurs due to pressure
differences
–  respiratory muscles
– lung elasticity, resistance
• Two lungs shaped
balloons
• Each lung sorrounded:
serous membrane
(visceralis and parietalis
pleurae)
• Ventilatory system:
– Conducting zone (conduct,
humidification, warming,
filtration, vocalization, Ig
secretion)
– Respiratory zone (gas
exchange)
• Inspired air held within conducting zone
referred to as dead air (dead space)
• Anatomical Dead space (VD) is usually
about 150 ml
• Wasted ventilation:
– Anatomical dead space
– Alveolar dead space
Minute Ventilation/Minute Volume/Pulmonary
Ventilation
• Gas moved in-out of the lungs 1 minute

• Calculate: respiration rate per minute,
volume each breath (VT)
Alveolar Ventilation
• Not all air inspired reaches the alveoli
• Therefore, two values:
– VE
– VA
Alveolar Volume = VT – VD
VA = (VT - VD)f
• Ventilatory system:
– Conducting zone (conduct,
humidification, warming,
filtration, vocalization, Ig
secretion)
– Respiratory zone (gas
exchange)
• VT = 500 ml
• VD = 150 ml
• f = 12 x/mnt
• VA = 350 x 12
= 4200 ml/mnt
Mechanics of Breathing
• Including:
– The pressure differences that generate air flow
– The respiratory muscles that effect these
pressure differences
– Tissue properties that influence how easily the
lungs expand
Mechanics of Breathing
• Breathing: air moves into and out of the

lung
• It travels from regions of high air pressure
to low air pressure
• Relationship between Boyle’s law and
ventilation
• Lung volume is changed by muscles
contraction and relaxation
• During quiet breathing: inspiration is an
active process, expiration is a passive
process
• Forced expiration and inspiration involve
additional muscles
Diaphragm and ext. int. m. contr.
Increasing the volume of thoracic cavity
Intrapleural pressure becomes more negative
Lung expand
Intrapulmonary pressure becomes negative
Air flows into the lung

Diaphragm and ext. int. m. relax
Decreases Thoracic cavity volume
Intrapleural pressure becomes less negative
Lung recoils
Intraplulmonary pressure rises above atm. pressure
Air flows out of the lung

SPIROMETRY
• To assess lung function
Lung Volumes and Capacities
• Some of these volumes can be measured using spirometry
• Typical trace spirometer
Patterns of Lung Function
Pattern Grade %FEV1/FVC %FVC
Normal ≥ 70 % ≥ 80 %
Mild 61-69% ≥ 80 %
Obstructive Moderate 45-60% ≥ 80 %
Severe ≤ 45% ≥ 80 %
Mild ≥ 70 % 66-79%
Restrictive Moderate ≥ 70 % 51-65%
Severe ≥ 70 % ≤ 50%
Combination < 70% < 80%

Gaseous Exchange in The Lungs
• Gas exchange between alveoli and blood
takes place by diffusion
• Diffusion occurs:
– High concentration to low
– Until the concentration is equalized
– Across respiratory membrane
The rate of diffusion across
• Factors (Fick’s law): membrane is inversely
proportional to the membrane
– The large of surface area thickness
– The thickness of the membrane

– Partial pressure gradient
– Solubility of the gas
Gaseous Exchange in The Lungs
• Gas exchange between alveoli and blood
takes place by diffusion
• Diffusion occurs:
– High concentration to low
– Until the concentration is equalized
– Across respiratory membrane
Learning task
• What is the sequence of event during quiet
inspiration (muscle involvement, pressure
changes (intrapulmonary and intrapleura),
volume changes)
• What is pulmonary ventilation and alveolar
ventilation means?
• Describe Lung volumes and lung capacities
• Describe the Dalton’s Law!
• Describe the factors that influence oxygen
diffusion from alveoli into the blood!

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I Made Muliarta

Gambar 4. Beberapa Jenis Spirometer

Ventilation Diffusion Perfusion

Lung compliance Factors influence

Lung Function Measurement

thin barrier (0,3µm)

• Gas moved in-out of the lungs 1 minute

• Breathing: air moves into and out of the

Increasing the volume of thoracic cavity

Intrapleural pressure becomes more negative

Intrapulmonary pressure becomes negative

Air flows into the lung

Decreases Thoracic cavity volume

Intrapleural pressure becomes less negative

Intraplulmonary pressure rises above atm. pressure

Air flows out of the lung

Combination < 70% < 80%

– The thickness of the membrane

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