RESPIRATION II
THE HUMAN ORGANISM
ANNOUNCEMENTS
• Exam 3 is Monday, Dec. 14th
• Practice Exam will be posted next week
• Office hours TBA
• Final Exam is Wednesday, Dec 16th
• Same format as hourly exams
• Cumulative
• May NOT be dropped
• No Practice Final
• Study material from previous exams
THE RESPIRATORY SYSTEM:
MECHANICS OF VENTILATION
Ventilation is the Result of:
• Behavior of Gases
• Gas laws explain movement of
gases in respiratory system
• Mechanical events
• Muscle contraction and relaxation
Behavior of Gases:
• Atmosphere is composed of a mix
of gases:
• The presence of a gas in mixture is
expressed as partial pressure (Px)
GAS
BEHAVIOR
Dalton’s Law:
GAS BEHAVIOR
GAS BEHAVIOR
Boyle’s Law:
THE RESPIRATORY SYSTEM:
MECHANICS OF VENTILATION
• Atmospheric Pressure (ATM):
• Intrapulmonary Pressure:
THE RESPIRATORY SYSTEM:
MECHANICS
OF VENTILATION
Mechanics of Ventilation:
• Lungs stuck to thoracic cavity
wall
• When thoracic cavity expands or
recoils, so do lungs
MECHANICS OF VENTILATION
INHALATION:
MECHANICS OF VENTILATION
EXHALATION:
THE RESPIRATORY SYSTEM:
MECHANICS OF VENTILATION
RESPIRATORY SYSTEM:
AIR FLOW IN LUNGS
Factors Effecting Air Flow:
– Pressure gradients
– Resistance to flow (which is influenced by:)
» Length of airways (constant)
» Viscosity of air (constant)
THE RESPIRATORY SYSTEM:
AIR FLOW IN LUNGS
Factors Effecting Air Flow:
• Trachea and Bronchi:
– Rigid structures
– Approx. 90% of airway resistance
– Constant sources of resistance
Factors Effecting Air Flow:
• Bronchioles:
– Approx. 10% of resistance
– Source of variable resistance
since airways don’t have fixed
diameter
THE
RESPIRATORY
SYSTEM:
AIR FLOW
IN LUNGS