Respiratory movements Flashcards
Structure and function of the respiratory system Basic gas laws and partial pressure Mechanics of breathing, alveolar ventilation, and ventilation-perfusion matching
What is the purpose of alveoli?
Permit gas transfer and allow O2 pass from the lungs to the blood
What are the 2 parts of the respiratory tree?
Conducting system
Exchange surface
What is the makeup of the conducting system? (4)
Trachea
Primary bronchi
Small bronchi
Bronchioles
What is the makeup of the exchange surface and what is special about it compared to the conducting system?
Bronchioles
Alveoli
- special: large SA, compact and compressed
What are the 4 gas laws respiration is dependent on?
Volume of lungs
Pressure of lungs and atmosphere
Temperature - physiological
Movement of O2 and CO2
What is the kinetic theory of gases? (2)
Correlation between pressure and movement of molecules.
The more frequent and harder the collisions, the higher the pressure
What is Boyle’s law? (2)
P = 1/V
Pressure is inversely proportional to volume at a constant temperature
What is the significance of water vapour in the respiratory system? (4)
All respiratory surfaces are moist
O2 comes into contact with the moisture
O2 is diluted from 21kPa to 19.9kPa O2
Lung O2 is 13.3kPa - general dilution
What is Dalton’s law of partial pressure? (2)
Pressure exerted by each gas in a mixture of gases is INDEPENDENT of the other gases present
Total pressure of a mixture of gases is EQUAL TO THE SUM of the individual gas pressures
What are the main changes of pressure at sea level and altitude?
Barometric pressure: 101kPa -> 33.7kPa
Partial pressure: 19.9kPa -> 5.8kPa
What is the diffusion pathway of O2 in the alveoli? (5)
Air: 21.2kPa Respiratory: 19.9kPa (moved down) Alveoli: 13.3kPa (move down) Venous blood in: 5.8kPa (move down) Venous blood out: 13.3kPa
What is the diffusion pathway of CO2 out of the blood? (4)
Venous blood in: 6.0kPa
Venous blood out: 5.3kPa
Alveoli: 5.3kPa
Air: 0kPa
What happens when we inspire? (5)
Rib cage: expands Lungs: stretch Diaphragm: move downward Alveolar pressure: reduced Air drawn into the lungs
What happens when we expire? (5)
Rib cage: contracts Lungs: contract Diaphragm: moves upwards Alveolar pressure: increased Air is pushed out of the lungs
What is pulmonary ventilation rate?
Frequency x tidal volume
12 x 0.5
What is alveolar ventilation rate (Va)?
The actual amount of air that reaches the alveoli
What is perfusion?
Deoxygenated blood passing through the lungs and becoming re-oxygenated
What is the ventilation - perfusion ratio?
Va / Q
What happens when perfusion is impaired?
Dead space occurs
What is dead space? (3)
Normal ventilation, no perfusion
No capacity to take O2 away or bring CO2 to alveoli
No gas exchange between alveoli and blood
What happens when the alveolar ventilation rate is impaired?
A shunt occurs
What happens when a shunt occurs? (2)
No ventilation, normal perfusion
No new O2 into the system, alveoli equilibrates with venous blood
What happens where there is low O2? (2)
Constriction of pulmonary arterioles
Hypoxia
What happens when there is high O2? (2)
Dilates pulmonary arterioles
Foetus
What happens when there is low CO2? (2)
Bronchioles constrict
Hypocapnia
What happens when there is high CO2? (2)
Bronchioles dilate
Lung disease
