How do elastic fibres in the alveoli contribute to exhalation?

Elastic fibres in the alveoli shrink and recoil back to their original shape when the thoracic cavity volume decreases.


This increases the pulmonary pressure and helps push air out of the lungs.

Answer in your head, out loud, or on paper, then tap the card to flip.

Describe the key stages of expiration, including changes in thoracic cavity volume and pressure.

  1. The internal intercostal muscles contract
  2. The ribs move down and in, decreasing the thoracic cavity volume
  3. The diaphragm relaxes and expands, decreasing the thoracic cavity volume
  4. Decreased thoracic cavity volume increases the thoracic cavity pressure relative to the atmospheric pressure
  5. Air moves down a pressure gradient from the lungs into the atmosphere

Answer in your head, out loud, or on paper, then tap the card to flip.

Describe the key stages of inspiration, including changes in thoracic cavity volume and pressure.

  1. The external intercostal muscles contract
  2. The ribs move up and out, increasing thoracic cavity volume
  3. The diaphragm contracts and flattens, increasing thoracic cavity volume
  4. Increased thoracic cavity volume decreases the thoracic cavity pressure relative to the atmospheric pressure
  5. Air moves down a pressure gradient from the atmosphere into the lungs

Answer in your head, out loud, or on paper, then tap the card to flip.

Which muscles are involved in ventilation in the human gas exchange system?

  1. Diaphragm
  2. Internal intercostal muscles
  3. External intercostal muscles

Answer in your head, out loud, or on paper, then tap the card to flip.

What is ventilation?

Ventilation is the constant movement of air into and out of the lungs.


It is also called breathing.

Answer in your head, out loud, or on paper, then tap the card to flip.

Are inspiration and expiration active or passive processes?

Inspiration is an active process (it requires energy).


Expiration is a mostly passive process (it does not require much energy).

Answer in your head, out loud, or on paper, then tap the card to flip.