Intro to Respiratory Physiology - Trachte Flashcards Preview

CRRAB II Week 5 - WLB > Intro to Respiratory Physiology - Trachte > Flashcards

Flashcards in Intro to Respiratory Physiology - Trachte Deck (20):

What are the four basic components of Respiratory Physiology?

  1. Ventilation
  2. Perfusion
  3. Diffusion
  4. Exchange


How do gasses move across the blood-gas interface?


(high pressure → low pressure)


What is the driving force of oxygen in diffusion?

  • Partial pressure air > Partial pressure blood
    • Air = 150 mmHg (humidified)
    • Venous blood = 40 mmHg
    • Moves from AIR → BLOOD via diffusion


What is the driving force of carbon dioxide in diffusion?

  • Partial pressure blood > Partial pressure air
    • Venous Blood = 46 mmHg
    • Air = 0 mmHg
    • Moves from BLOOD → AIR by diffusion


Gases move across the capillary/alveolar barrier depending on what?

  • Cross-sectional area of the barrier (50-100 m2)
    • tons of blood vessels surrounding alveoli
    • greater surface area → greater potential for diffusion
    • more vasculature → more efficient exchange
  • Inversely proportional to the thickness of barrier
    • thicker barrier → less diffusion
    • thinner barrier → more permeable
      • CO2 is more permeable than O2


What are conducting airways?

  • Branched tubes that conduct air but are not involved in gas exchange
  • They comprise anatomic "dead space"
    • have gas concentrations similar to atmosphere, except that air is humidified


What are the conducting airways composed of?

  • Trachea
  • Right & Left bronchi
  • Lobar bronchi
  • Segmental bronchi
  • Eventually → Terminal bronchioles
    • smallest airways without alveoli


What is the typical volume of air that the conducting airways hold?

150 mL


What is the volume of a normal breath?

500 mL


Can you think of clinical examples that are the equivalent of a longer neck?

Intubated patient

tube → increases dead space


What is the respiratory zone?

  • Acinus
    • terminal bronchioles divide into → respiratory bronchioles
      • occasional alveoli
    • respiratory bronchioles lead to → alveolar ducts
      • completely lined with alveoli


What is airflow initiated by?

  • Expansion of thoracic cavity
    • Diaphragm contracts (moves downward)
    • Intercostals contract (raises ribs)


Where does dust settle in the respiratory tract if inhaled?

Terminal bronchioles

(not alveoli)


Why is the lung so easy to expand?

Very compliant!

  • Lungs are balanced between chest wall
    • helps with compliance to volume change
  • Compliance = change in volume/change in pressure)


How much of the body's total metabolic work is spent on breathing?


(this is why COPD patients get so tired)


What is the path of blood flow in the lungs?

  • Pulmonary artery (O2 poor) →
  • Capillaries →
  • Pulmonary Vein (O2 rich)


Because the capillaries in the lungs have extremely thin walls, they are at increased susceptibility to damage from what processes?

  • Increasing capillary pressure
    • e.g. pulmonary HTN
  • Increasing alveolar pressure
    • e.g. tension pneumothorax

***The capillaries have the same amount of flow through them as the pulmonary artery/vein, but with much less resistance!


How long do RBCs spend in the pulmonary capillaries?

less than a second


Alveoli are 500 million bubbles and surface tension should make them want to collapse when they are small, but a really important mechanism keeps them from doing so. What is it?

Lung surfactant

  • reduces surface tension and prevents alveolar collapse
    • Surfactant = nonpolar tail + polar head
      • prevents water molecules from attracting each other → decreases Tension
    • develops at 7 months gestation


What are the three mechanisms to eliminate unwanted inhaled particles?

  1. Can be filtered (nose)
  2. Can be moved toward the mouth by a mucous-ciliary elevator (inhibited by cigarrete smoke)
  3. Can be engulfed by macrophages (typically in alveoli)