Mechanics of Breathing Flashcards
What are the four key functions of the respiratory system?
- Pulmonary ventilation
- External respiration
- Transport of gases
- Internal respiration
What is external respiration?
Exchange of gases between the alveoli and the blood in pulmonary capillaries
What causes air to move during breathing?
A pressure gradient between the atmosphere and the alveoli
What are the three key pressure in the lungs?
- Atmospheric
- Intra alveolar
- Intrapleural
What is transmural pressure and why is it important?
The difference between intra alveolar and intrapleural pressure which keeps the lungs expanded
Which muscle are involved in inspiration?
The diaphragm and external intercostal muscles
Is quiet expiration an active or passive process?
Passive
What happens to intra alveolar and intrapleural pressures during inspiration?
Both decreases
What is the effect of sympathetic stimulation on the airways?
It causes bronchodilation
What is the effect of parasympathetic stimulation on airways?
Causes bronchodilation
What is lung compliance?
The ease with which the lungs can expands
When does air enter the lungs?
Intra alveolar pressure < atmospheric pressure
When does air leave the lungs?
Intra alveolar pressure > atmospheric pressure
What law explains the relationship between pressure and volume?
Boyle’s law - pressure is inversely proportional to volume
What happens to the diaphragm during inspiration?
- Contracts and flattens
- Increase thoracic volume
What is the role of the external intercostals in inspiration?
- Contract to lift the ribs
- Increase thoracic volume
What muscles are used in forced expiration?
- Internal intercostals
- Abdominal muscles
What determines air flow rate in the airways?
- Pressure gradient
- Airway resistance
What is elastic recoil?
The lungs ability to return to their original shape after being stretched
Why is water important in the alveoli?
Oxygen must dissolve in water before diffusing into the blood
What happens if surface tension is too high in the lungs?
The alveoli may collapse and gas exchange becomes imparied
How is surface tension regulated?
By pulmonary surfactant
What produces pulmonary surfactant?
Type II alveolar cells
What is the tidal volume of a normal breath?
500mL
