LECTURE NO (-)
Respiratory Physiology
Kamal Mohammad
Lecturer Of Physiology
Introduction
to
physiology
Dept.Of Physiology
Function of respiratory system
1.
2.
3.
4.
5.
Provide oxygen to the tissues and to remove carbon
dioxide (main function)
Play main role in regulation PH
Endocrine function (lung contain enzyme ACE
which convert ang I to ang II) the ang II play role in
regulation the arterial blood pressure
Participate in regulate body temp.
Defense mechanism (hair nose, mucus, ciliated
columnar epithelium, coughing, sneezing reflex,
and alveolar macrophage)
Introduction
◼
The goals of respiration are to provide oxygen to the
tissues and to remove carbon dioxide.
◼
To achieve these goals
◼
Respiration can be divided into four major functions:
1.
Pulmonary ventilation
2.
Gas exchange
3.
Gas transport
4.
Regulation of ventilation
Pulmonary ventilation
Regulation of ventilation
CO2
tissue
Gas exchange
O2
Gas transport
Structure & function
➢ Divisions :
The respiratory system is divided anatomically into:
➢ Upper respiratory tract:
◼ Include structures outside the thoracic cavity
◼ The nasal cavity, pharynx, larynx & upper part of
the trachea
◼
➢ Lower respiratory tract:
Include structure inside the thoracic cavity.
◼ The lower part of the trachea, bronchi, bronchioles,
alveolar ducts & alveoli.
◼
Respiratory system is divided physiologically into:
➢ Conducting zone:
◼ For conduction of air to the lower zone
◼ Includes the nasal cavity, pharynx, larynx, trachea,
bronchi & bronchioles.
◼
Conducting Zone
➢ Respiratory zone:
◼
For gas exchange. Includes the respiratory
bronchioles, alveolar duct , alveolar sacs & alveoli.
Functional anatomy of respiratory system
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◼
1.
2.
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◼
1.
2.
3.
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1.
2.
3.
Consist of Chest and lungs
Chest consist of ribs and diaphragm between ribs there are
muscles :inspiratory muscles (external intercostal muscles)
expiratory muscles (internal intercostal muscles)
Air Passages :The airways divide 23 times (trachea…. alveolar sacs ) consist of
conducting zone
The first 16 generations of passages
transports gas from and to the exterior
Bronchi+ bronchioles+ terminal bronchioles
Respiratory zones
remaining seven generations
Site of gas exchange occurs
respiratory bronchioles + alveolar ducts + alveoli
Functional anatomy of respiratory
system
◼
1.
2.
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Purpose from multiple divisions of airways
increase the total cross-sectional area of the
airways, from 2.5 cm2 in the trachea to 11,800 cm2
in the alveoli
The velocity of air flow in the small airways
declines to very low values.
Lungs: functional unit of lung is alveoli where the
gas exchange take place
Surround by pleural sac is divide into (visceral
pleura and parietal pleura
Visceral pleura
Interpleural space
lung
lung
Parietal pleura
◼
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◼
◼
➢
➢
Between parietal and visceral pleura there is space
called intrapleural space
Intrapleural pressure
is the pressure within the pleural sac
The pressure in interplural space is negative
pressure (subatmospheric pressure)
intrapleural fluid
resist separation between lung and chest wall
Allow the lungs slide easily on the chest wall
interplural space
Lung
chest
Chest
interpleural fuid
lung
◼
Causes of sup atmospheric pressure or
negative interplural pressure
1. Chest :- tends to move outward
2. Lungs :- tends to move inward due to elastic
recoil (tend to collapse )
3. Pleural capillaries and lymphatic's :- tend to
absorb fluid from the pleural space
Distribution of pulmonary Ventilation
◼
◼
1.
2.
Definition of pulmonary Ventilation is movement of air
in and out the lungs per minute
The inspired air is distribute into two compartments
In conducting system include (mouth nose and
terminal bronchioles ) this part is called anatomical dead
space because there is no gas exchange take place
The rest air occupies distal to terminal bronchioles
include (alveolar duct alveoli and alveolar sac ) this area
called (respiratory bronchioles) because these is gas
exchange take place
◼ Pulmonary
ventilation
= respiratory rate X tidal volume
=
12 /min
X
500ml = 6000ml/min
◼ anatomical
Dead space ventilation
= dead space volume X respiratory rate
= (1/3X 500ml ) X 12 = 2000 ml/min
◼ Alveolar
ventilation
( tidal volume – anatomical dead space volume) X
respiratory rate
= {500 - (1/3X 500ml) } X 12 =
={ 500ml -167ml} X12 =4000ml/min