Respiratory System Under Stress - Trachte

Question 1

What are the various adaptions of the Respiratory System to exercise?

(Hint: 10 adaptions)

Answer 1

1. O₂ consumption climbs (250mL → 3,000-6,000)
2. CO₂ production increases (200mL → 3,000)
3. Ventilation increases to accomplish #1 & #2
4. Respiratory quotient increases to 1 or higher
5. Diffusion capacity typically increases 3x
6. Cardiac output increases 3-4x
7. Systolic pressure increases (diastolic decreases or is unchanged)
8. P_O2 is usually unchanged/rises slightly
9. P_CO2 is usually decreased slightly
10. pH is usually decreased (lactic acid buildup)

Question 2

What is the impact of altitude on oxygen and carbon dioxide levels?

Answer 2

• Atmospheric pressure declines with altitude
  
  • @sea level: Total pressure = 760mmHg, P_O2 = 160
  • @1500m (DENVER): Total pressure is 620 mmHg, P_O2 = 130
• P_O2 declines with altitude
• Low P_O2 causes hyperventilation → reducing P_CO2 to as low as 8 mmHg

Question 3

What are the potential toxic effects of pure oxygen?

Answer 3

• Oxygen is damaging to tissues
• Breathing 100% O₂ chronically decreases vital capacity and can cause pulmonary edema
• Causes atelectasis
  
  • complete or partial collapse of a lung or lobe of a lung
  • enormous diffusion gradient for oxygen to move into blood → causes alveoli collapse

Question 4

What is the effect of diving on the respiratory system?

Answer 4

• Diving → increased pressure
  
  • pressure increases 760 mmHg every 10m
  • gas containing structures (ear, lungs) can compress on descent or expand on ascent
  • Nitrogen equilibrates with tissues at high pressures
    
    • decompression syndrome if N₂ escapes from blood too quickly

Question 5

How does diving increase the potential for nitrogen toxicity?

Answer 5

• Nitrogen is poorly soluble in blood, but high pressures force it into solution
• Nitrogen equilibrates with tissues at high pressures but is returned to the blood at low pressures
• If decompression is too quick → nitrogen escapes from the blood as bubbles
  
  • bubbles can deposit in tissues
  • causes pain & neurological damage if bubbles form in cranial circulation

Question 6

What are the therapeutic uses of hyperbaric oxygen?

Answer 6

• Useful in carbon monoxide poisoning
  
  • can increase oxygen content of blood to 6mL/dL by increasing pressure to 3 atmospheres
• Can be used to treat gas gangrene

Question 7

What are the adaptions of fetal lungs and circulation?

Answer 7

• The first breath requires enormous pressures to overcome suface tension and partially fluid filled lungs
• Enormous drop in pulmonary vascular resistance
  
  • probably caused by oxygenation of alveoli
• Dutus arteriosus should close
• Foramen ovale should be closed by increased pressure in the left atrium