Ventilation and Airflow Flashcards
What is the difference between internal and external respiration?
- INTERNAL - Energy production as ATP
- EXTERNAL - Receiving oxygen from atmosphere, removal of CO2
What are the 4 stages of external respiration?
- VENTILATION (INHALATION OF OXYGEN, EXHALATION OF CO2)
- ALVEOLAR GAS EXCHANGE
- GAS TRANSPORT BETWEEN LUNG AND TISSUES
- GAS EXCHANGE BETWEEN BLOOD AND TISSUES
What does Boyle’s Law state?
- Pressure inversely proportional to volume
What would occur if the volume of a container containing gaseous particles, is reduced?
- Greater collision of particles with vessel wall
- Greater pressure
Describe how Boyle’s Law is applied in ventilation.
- When lungs relaxed, alveolar pressure = atmospheric pressure
- During inspiration, lung volume increases. Pressure decreases
- Alveolar pressure > atmospheric pressure. Air moves down pressure gradient
What occurs when the intercostal muscles and diaphragm contract?
- INTERCOSTAL - lifting of ribcage. Expansion of thoracic cavity
- DIAPHRAGM - lower portion of thoracic cavity pulled down
- Increased thoracic cavity volume - causes increase in lung volume (lungs adhered to inner thoracic wall). Pressure decreases.
Describe expiration.
- Passive process
- Relaxation of intercostal and diaphragm muscles
- Increased alveolar pressure. Expulsion of air
Describe the following ventilation volumes:
- TIDAL VOLUME
- INSPIRATORY RESERVE VOLUME
- EXPIRATORY VOLUME VOLUME
- RESIDUAL VOLUME
- Volume of air entering with each breath
- Extra volume that can be inspired/expired above tidal volume
- Air remaining in lungs following maximal exhalation - prevents lung collapse
The alveolar linings are covered in water. What problems can this cause and what is the main mechanism that prevents these problems?
- During expiration, as alveoli relax, polar water molecules attracted to one another
- Can cause alveolar collapse
- Prevented by surfactant from type II pneumocytes
Define the following lung capacities:
- INSPIRATORY CAPACITY
- FUNCTIONAL RESIDUAL CAPACITY
- VITAL CAPACITY
- TOTAL LUNG CAPACITY
- Tidal volume + IRV
- ERV + RV - Volume remaining after normal expiration
- IRV + TV + ERV - Maximal exhalation following maximal inhalation
- Sum of all volumes.
How does surfactant work?
Reduces surface tension of water
- Prevents alveolar collapse
Describe neonatal respiratory distress syndrome.
- Reduced or no surfactant production in neonates
- More prone to alveolar collapse
- Provided with artificial surfactant
What factors is airflow directly and inversely proportional to?
- DIRECTLY - Pressure gradient and airway radius(clinically most important)
- INVERSELY - Viscosity and airway length
- REVERSE for resistance to airflow (i.e airway length directly proportional/radius inversely pproportional)
Outline Poiseuille’s Law.
𝑅= 8𝐿𝜂/(𝜋𝑟^4 )
What is the effect of the beta-2 receptors on the smooth muscle of airway bronchioles?
BRONCHIOLE DILATION
- Smooth muscle relaxation
- Clinical target for drugs such as salbutamol
