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):
1

What are the four basic components of Respiratory Physiology?

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

2

How do gasses move across the blood-gas interface?

Diffusion

(high pressure → low pressure)

3

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

4

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

5

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

6

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

7

What are the conducting airways composed of?

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

8

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

150 mL

9

What is the volume of a normal breath?

500 mL

10

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

Intubated patient

tube → increases dead space

11

What is the respiratory zone?

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

12

What is airflow initiated by?

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

13

Where does dust settle in the respiratory tract if inhaled?

Terminal bronchioles

(not alveoli)

14

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)

15

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

15%

(this is why COPD patients get so tired)

16

What is the path of blood flow in the lungs?

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

17

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!

18

How long do RBCs spend in the pulmonary capillaries?

less than a second

19

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

20

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)