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PHYSIOLOGY OF RESPIRATION |FINDYOURSELF
Respiratory Physiology
Functions of
Respiratory System
•
Exchange
of gases between atmosphere and the blood
•
Homeostatic
regulation of body pH
•
Protection
from inhaled pathogens and irritating substances
•
Lungs
contain lymphocytes, plasma cells and macrophages
•
Vocalization
•
Loss
of water and heat from body
•
It
enhances venous return ( Respiratory pump)
•
The
nose as a part of respiratory system, serves as the organ of smell
•
Lungs
synthesize certain prostaglandins, histamine, heparin and kallekrein
•
Pulmonary capillary endothelial cells contain
Angiotensin converting enzyme
•
Lungs
act as reservoir of blood
•
Lungs
synthesize surfactant
•
Pulmonary
vessels can trap fat cells, small clots and detached cancer cells and thus
prevent their entry into systemic circulation
External
Respiration
1.
Movement
of air from environment / atmosphere to lungs/ alveoli
2.
From
alveoli to blood
3.
Transport
in the blood
4.
From
blood into cells
5.
Regulation
of respiration
Functional
anatomy of respiratory system
Nose or
Mouth -- Pharynx -- Larynx --
Trachea --
Bronchi -- Smaller Bronchi --
Terminal
Bronchioles -- Respiratory Bronchioles -- Alveolar Ducts -- Alveolar sacs -- Alveoli
•
Alveoli
are thin-walled, Inflatable, grapelike sacs at the terminal branches of
conducting airways
•
Each
contain single layer of epithelial cells
•
Epithelial
cells are two types
(a) Type I cells --
for gas exchange, large and occupy 95% of alveolar surface area
(Pneumocyte type I )
(b) Type II cells --
Secrete surfactant ( small cells)
(Pneumocyte type II )
q Alveolar macrophages
Pleural sacs
•
It
is a double- walled closed sac that separates each lung from the thoracic wall
and other surrounding structures
Two types:
(1) Visceral Pleura
(2) Parietal Pleura
Gas Laws
1.
The
total Pressure of a mixture of gases is the sum of the pressures of the
individual gases (Dalton’s Law).
2.
Gases,
singly or in a mixture, move from areas of higher pressure to areas of lower
pressure.
3.
If
the volume of a container of gas changes, the pressure of the gas will change
in an inverse manner ( Boyle’s Law)
4.
The
amount of a gas that will dissolve in a liquid is determined by the partial
pressure of the gas and the gas’s solubility in the liquid
Pulmonary
Ventilation
Pulmonary ventilation is defined as inflow &
outflow of air between the atmosphere & the lung alveoli
Inflow
à
Inspiration
Outflow à
Expiration
Muscles
of Inspiration
•
External
Intercostals
•
Sternocleidomastoid
•
Anterior
serrati
•
Scaleni
Muscle of
Expiration
•
Abdominal
Recti
•
Internal
Intercostals
•
Other
Abdominal Muscles
