Tag: respiratory system in humans

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Multiple choice zoology gas exchange and smoking gas exchange gas exchange in humans respiratory system in humans

Surfactant is?

  1. Protein produced by type II alveolar cells

  2. Excessive in many premature infants causing difficulty in breathing

  3. Decreases surface tension of fluid lining alveoli

  4. Lacking in individuals suffering from acute respiratory distress syndromes
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Pulmonary surfactant is a mixture of lipids and proteins that reduces the surface tension of the fluid lining the alveoli, preventing them from collapsing during expiration.

Multiple choice zoology gas exchange and smoking gas exchange gas exchange in humans respiratory system in humans

Partial pressures of oxygen and carbon dioxide in healthy human lung alveoli are respectively about.

  1. $104$ and $40$mm Hg
  2. $90$ and $20$mm Hg
  3. $40$ and $45$mm Hg
  4. $159$ and $0.3$mm Hg
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

In healthy human alveoli, the partial pressure of oxygen (pO2) is approximately 104 mm Hg and the partial pressure of carbon dioxide (pCO2) is approximately 40 mm Hg.

Multiple choice zoology gas exchange and smoking gas exchange gas exchange in humans respiratory system in humans

Lungs do not collapse between breaths and some air always remains in the lungs which can never be expelled because ____________________.

  1. There is a negative pressure in the lungs

  2. There is a negative intrapleural pressure pulling at the lung walls

  3. There is a positive intrapleural pressure

  4. Pressure in the lungs in higher than the atmospheric pressure
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

The intrapleural pressure within the pleural cavity is always negative relative to atmospheric pressure, acting as a partial vacuum that pulls outward on the lung walls and prevents the lungs from collapsing between breaths.