respiratory physiology and lung capacity. inhalation diaphragm contracts ribs move up and out, chest...
TRANSCRIPT
Respiratory Physiology and
Lung Capacity
Inhalation
• Diaphragm contracts
• Ribs move up and out, chest cavity enlarges and pressure decreases
• Air rushes in from higher pressure environment
Exhalation
• Diaphragm relaxes
• Ribs compress, chest cavity gets smaller and pressure increases
• Air escapes to lower pressure environment
Breathing
• Involuntary inhalation and exhalation
• Delivers O2 to alveoli and removes CO2
• Medulla oblongata– Brain region that controls
breathing
Gas Exchange
Control of Breathing
• Chemoreceptors detect change in blood pH
– Blood high in CO2 has lower than normal pH
• Drop in pH causes medulla oblongata to stimulate breathing
Breathing is aNegative Feedback
Loop
Human Lung Capacity
• Influenced by many factors:– Age– Gender– Body position– Strength of diaphragm– Strength of chest muscles– Illness / disease
• The average human breathes 12-20 times per minute.
Measurements
Tidal Volume (TV): the amount of air inhaled and exhaled in a normal breath.
Inspiratory Reserve Volume (IRV): the amount of air that can be inhaled after a normal inhalation.
Expiratory Reserve Volume (ERV): the amount of air that can be forcefully exhaled after a normal exhalation.
Vital Capacity (VC): the maximum amount of air that can be exhaled. (VC = TV + IRV + ERV)
Residual Volume (RV): the amount of air remaining in the lungs after a forceful exhalation.
Without this “leftover” air in our lungs, they would collapse!
Average Lung Volumes for Young Adult Males
Measuring Lung Capacity
• Displacement Method
– Air is breathed through a tube into a bottle of water.
– Air displaces the water (water leaves the bottle into the surrounding tub).
– Litres of air are measured from markings on side of bottle.
Measuring Lung Capacity
• Balloon Method– Air is breathed into
balloon.– Circumference (C) of
balloon is measured.– Volume is calculated
with the following formula:
€
V =1
6×1
π 2×C3
Measuring Lung Capacity
• Spirometer– Air is breathed into the
mouthpiece of the spirometer.
– The spirometer’s gauge needle moves.
– The gauge’s measurement is read in mL.
Comparing Average Lung Capacities
• Males tend to have larger vital capacities than females.
• Athletes and musicians tend to have larger VC.
• Smokers tend to have a smaller VC.
How do we measure up to other mammals?