Question

question 19
1 pts
according to the law of partial pressures, the partial pressure of gas in a mixture of gases is
directly related to the concentration of that gas in the mixture and to the total pressure of the mixture.
inversely proportional to the concentration of that gas in the mixture and to the total pressure of the mixture.
indirectly related to the concentration of gases in the total mixture.
inversely proportional to the volume of gases in the mixture.
question 20
1 pts
during inspiration, as the size of the thorax increases, the
intrapleural and alveolar pressures decrease.
intrapleural and alveolar pressures increase.
alveolar pressure increases and the intrapleural pressure decreases.
alveolar pressure decreases and the intrapleural pressure increases.

Explanation:

• Question 19:
• According to Dalton's law of partial pressures, \(P_i = X_i\times P_{total}\), where \(P_i\) is the partial pressure of gas \(i\), \(X_i\) is the mole - fraction (concentration in terms of amount) of gas \(i\) in the mixture, and \(P_{total}\) is the total pressure of the mixture.
• If \(X_i\) (concentration of gas \(i\)) increases, \(P_i\) increases (direct relationship). Also, if \(P_{total}\) increases, \(P_i\) increases (direct relationship).
• Question 20:
• During inspiration, the diaphragm contracts and the intercostal muscles contract, increasing the volume of the thorax.
• According to Boyle's law (\(P=\frac{nRT}{V}\), for a fixed amount of gas \(n\) and constant \(T\)), when the volume (\(V\)) of the thoracic cavity (which contains the lungs) increases, the intrapulmonary (alveolar) pressure (\(P\)) decreases.
• The intrapleural pressure (pressure in the pleural cavity) also decreases because the expansion of the thorax creates a more negative pressure in the pleural space.

Answer:

• Question 19: directly related to the concentration of that gas in the mixture and to the total pressure of the mixture.
• Question 20: intrapleural and alveolar pressures decrease.