Respiratory system Flashcards
What is the main function of the respiratory system?
To maintain arterial blood-gas homeostasis
What separates the upper and lower respiratory system?
Epiglottis
Name the lung membranes - outer to inner
- Parietal pleura
- Visceral pleura
Why is interpleural pressure lower than atmospheric pressure?
To prevent alveoli from collapsing
Identify the types of alveoli
- T1 - approx. 95% responsible for gas exchange
- T2 - releases surfactant to reduce surface tension
What factors contribute to an ideal gas exchange surface?
- Short diffusion distance
- One cell thick
- Large surface area
How many layers must a gas pass to enter the blood?
- Plasma
- Capillary endothelial
- Interstitial fluid
- Alveolar epithelium
- Surfactant
What happens to inspiration and expiration pressure after a marathon?
Respiratory muscle fatigue - both pressures decrease
What mechanism is in place to ensure that the respiratory muscles do not fatigue?
The metaboreflex - blood is redistributed from skeletal muscles to respiratory muscles
What characterises exercise induced asthma? (3)
- Reduced maximal expiration
- Greater airway resistance - narrow airway
- Decreased time to fatigue
Define anatomical dead space
The amount of air that remains in the conducting airway per breath and is not used in gas exchange
What is the typical value for dead space, and how do you calculate alveolar ventilation?
Approx. 150ml
Va = TV - Td
What characterises obstructive airway disorder?
FVC <0.7
Does not respond to bronchodilators
What is hyperpnea?
The regulation of PaCO2 is directly proportional to alveolar ventilation and metabolic rate
Where is the RCC located and name the 3 groups
Pontine and medulla
1. VRG - initiates inspiration and expiration
2. DRG - initiates inspiration only
3. PRG - modulates output
