Question

what causes air to move into the lungs during inspiration?
multiple choice
muscle contraction of upper airways
concentration gradients for oxygen and carbon dioxide
pressure gradient between atomosphere and alveoli
partial pressure gradients for oxygen and carbon dioxide

Explanation:

During inspiration, the diaphragm and intercostal muscles contract, increasing the volume of the thoracic cavity. This leads to a decrease in intrapulmonary pressure below atmospheric pressure. As a result, a pressure gradient is created between the atmosphere (higher pressure) and the alveoli (lower pressure), causing air to move into the lungs. Muscle contraction of upper airways is not the main cause. Concentration gradients for oxygen and carbon dioxide are relevant for gas exchange in the alveoli (not for air movement into lungs during inspiration). Partial pressure gradients for oxygen and carbon dioxide are also for gas exchange (not for the bulk movement of air into lungs during inspiration).

Answer:

Pressure gradient between atmosphere and alveoli.