7. STEPS OF RESPIRATION
• PULMONARY VENTILATION
• EXTERNAL RESPIRATION OR PULMONARY
RESPIRATION
• TRANSPORT OF GASES IN BLOOD
• INTERNAL RESPIRATION OR TISSUE
RESPIRATION
9. MECHANICS OF BREATHING
• 2 PROCESSES-
• Inspiration-Inlow of atmospheric air into lungs.
• Expiration-Outflow of air from lungs into
atmosphere.
10. Important Pressures
• Atmospheric Pressure –Pressure exerted by the air
surrounding the body i.e 0cm water pressure
• Intrapulmonary Pressure /intraalveolar pressure–pressure
exerted by the air within the lungs
• Intrapleural Pressure /intrathoracic pressure-pressure within
the pleural cavity exerted by pleural fluid.
• Transpulmonary Pressure/recoil pressure
11. MUSCLE OF INSPIRATION
• Muscle of normal tidal inspiration-
• Diaphragm
• External intercostal
• Accessory Muscle of inspiration-
i. Sternocleidomastoid
ii. Scalene
iii. Serratus Anterior
iv. Pectoralis major and minor
• Laryngeal muscle
12. MUSCLE OF EXPIRATION
• Internal intercostal
• Abdominal muscles include-
i. Abdominal Rectii
ii. Transversus Abdominis
iii. Internal oblique
21. BOYLE’S LAW
• Pressure of gas is inversely proportional to
volume of thoracic cavity.
• Normal size
• Gas molecules strike wall and exert pressure.
22. • If volume increases,less
pressure is exerted
• If volume decreases,more
pressure is exerted
23.
24.
25.
26.
27. COMPLIANCE
Ease with which lungs can be stretched.
Compliance of lung is determined by-
•Elastic forces of lung tissue.
•Alveolar surface tension.
28. COMPLIANCE
Low compliance
• Supine position
• High standing diaphragm
• Pulmonary fibrosis
• Surgical intervention
• Hydrothorax
• Pneumothorax
High compliance
• Emphysema
• Old age
29. SURFACE TENSION IN LUNGS
• Thin layer fluid lines alveoli.
• Surface tension due to attraction between water
molecule.
• Surface tension=force for alveoli to collapse or resist
expansion
30.
31. SURFACE TENSION
• Increase tendency of alveoli to collapse.
• Increase work of breathing.
• Causes pulmonary oedema.
• Alveolar instability.
32. TO OVERCOME SURFACE TENSION
• Surfactant secreted from type II cells.
• Important components-
• Dipalmitoylphosphatidylcholine
• Surfactant apoproteins
• Calcium ions
33. WORK OF BREATHING
• INCREASE IN –
• Exercise
• Obstructive lung diseases
• Restrictive lung diseases
