Lung Volumes and Lung Capacities Quiz

Lung Volumes and Capacities

• Average total lung capacity of an adult human male is about 6 liters of air.
• Tidal breathing is normal, resting breathing; the tidal volume (TV) is the volume of air inhaled or exhaled in a single breath, which is approximately 500 ml.
• Average human respiratory rate (RR) is 30-60 breaths per minute at birth, decreasing to 12-20 breaths per minute in adults.
• Ventilation is calculated by multiplying respiratory rate (RR) by tidal volume (TV).

Factors Affecting Lung Volumes

• Lung volumes vary with different people, including:
  • Taller people having larger volumes
  • Shorter people having smaller volumes
  • People living at higher altitudes having larger volumes
  • People living at lower altitudes having smaller volumes
  • Fit people having larger volumes
  • Obese people having smaller volumes
• People living at high altitudes have larger lung capacities due to lower partial pressure of oxygen.
• Living at high altitudes can lead to altitude sickness due to inadequate oxygen intake.

Lung Function Development and Air Pollution

• Lung function development is reduced in children who grow up near motorways.
• Air pollution exposure affects FEV1 in asthmatics and FVC and FEV1 in healthy adults, even at low concentrations.

Pregnancy and Lung Volumes

• Functional residual capacity drops by 18-20% during pregnancy due to diaphragm compression by the uterus.
• Total lung capacity decreases by 5%, and expiratory reserve volume decreases by 20%.
• Tidal volume increases by 30-40%, and minute ventilation increases by 30-40% to meet the increased oxygen requirement of the body.

Average Lung Volumes in Healthy Adults

• Inspiratory reserve volume: 3.3 liters in men, 1.9 liters in women
• Tidal volume: 0.5 liters in both men and women
• Expiratory reserve volume: 1.1 liters in men, 0.7 liters in women
• Residual volume: 1.1 liters in men, 1.2 liters in women
• Lung capacities:
  • Vital capacity: 4.8 liters in men, 3.1 liters in women
  • Inspiratory capacity: 3.8 liters in men, 2.4 liters in women
  • Functional residual capacity: 2.4 liters in men, 1.8 liters in women
  • Total lung capacity: 6.0 liters in men, 4.2 liters in women