Anatomy & Physiology Respiratory #13


Which process is responsible for gas exchange which is a function of the respiratory system?


  1. Osmosis
    • Rationale:

      Osmosis is a type of passive transport that moves water across a semipermeable membrane. It occurs in the opposite direction to the diffusion of ions and does not play a role in gas exchange.

  2. Diffusion
    • Rationale:

      Diffusion is responsible for the gas exchange that occurs in the lungs and other tissues of the body. It moves oxygen and carbon dioxide from areas of high concentration to areas of lower concentration to maintain homeostasis.

  3. Active transport
    • Rationale:

      Active transport, which requires energy from the cell, occurs when substances move from areas of lower to higher concentration. This is often the mode of transport required when very large molecules are shifted; this form of transport does not play a role in gas exchange.

  4. Facilitated diffusion
    • Rationale:

      Facilitated diffusion is a form of spontaneous transport of molecules, or ions, across a biological membrane. An exchange of facilitated diffusion is the movement of glucose into the cell, where it is used to make ATP (adenosine triphosphate).


The respiratory system is responsible for the gas exchange, particularly oxygen and carbon dioxide.


Learning Outcomes

Gas exchange takes place in the alveoli, a structure located within the lungs. The alveoli have moist, thin walls which are surrounded by capillaries. Oxygen is transported into the blood by diffusion via the walls of the alveoli and capillaries.

Test Taking Tip

Consider the structure and function required for gas exchange to determine the correct answer choice for this question.

Video Rationale