Mechanism of Respiration
By Prof. Dr. R. R. Deshpande
• This PPT has following Imp Contents – 1) Mechanism of Respiration 2) 2 Stages of Respiration 3) Muscles of Respiration 4) Bucket Handle movement of ribs 5) Pump Handle movement of Sternum 6) Role of Expiratory Muscles 7) Role of Accessory Muscles 8) Respiration & Ayurved
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3. Contents of PPT
• 1) Mechanism of Respiration
• 2) 2 Stages of Respiration
• 3) Muscles of Respiration
• 4) Bucket Handle movement of ribs
• 5) Pump Handle movement of Sternum
• 6) Role of Expiratory Muscles
• 7) Role of Accessory Muscles
• 8) Respiration & Ayurved
4. Mechanism of Respiration
• This includes Many Principles of Physics
applicable to act of Respiration
• 1) Mechanism of Respiration
• 2) Role of Various Pressures
• 3) Role of Surfactant
• 4) Lung Compliance
• 5) Elastic Recoil
• 6) Work of Breathing
5. Mechanism of Respiration
• 2 Stages of Respiration –
• i) Inspiration = Intake of Atmosphere air
• ii) Expiration = Giving out of Alveolar air
• RR = 14 to 18 / min .This is brought about by
Muscles of Respiration
11. Inspiration & Expiration
• During quiet respiration ,Inspiration is active (
Due to contraction of muscles of Respiration)
• Expiration is Passive ( Due to Relaxation of
Muscles of Respiration )
• In quiet breathing – Expiratory muscles &
Accessory muscles have No role ( They work
only during Exercise –when Ventilation is to be
increased )
12. Diaphragm
• Chief Muscle of Respiration
• Membranous muscle ,which separates
abdomen & thorax
• Originates from Xiphisternum ,Costal
cartilages & Vertebrae .Inserted in Central
tendon .Supplied by Phrenic Nerves
13. Diaphragm –Action
• Dome shaped muscle .When it contracts
,dome is lowered .Verticle diameter of chest
increases – Volume of chest increases – Intra
Thoracic Pressure falls – Inspiration takes
place ( Air moves from Higher Pressure to
Lower pressure )
• When Diaphragm relaxes ,Expiration occurs
passively
14. Tidal Volume
• Diaphragm has a large surface area ( 250 to
350 sq cm) &
• Moves through a distance of 1.5 cm ------
• So volume changes ,brought about by it’s
movement = 350 x 1.5 = 500 ml ( Tidal
Volume)
16. b) External Intercostal Muscles
• Present outer side of ribs ,directed downward
,forward & medially
• Supplied by Intercostal nerves
• When they contract – bring about 2 types of
movements as follows –
• i) Bucket Handle Movement of Ribs
• ii) Pump handle movement of Sternum
22. 3) Role of Accessory Muscles
• Most of these muscles are attached to Inlet of
chest
• When they contract – Upper ribs & clavicle is
elevated + Nostrils also open widely ---
Ventilation is enhanced
• Note – Expiratory & Accessory muscles work
only during Exercise