Diffusion

Definition

Diffusion is the passive movement of particles from an area of higher concentration to an area of lower concentration, driven by the concentration gradient. This process is essential for the exchange of gases in the lungs, allowing oxygen to enter the bloodstream while carbon dioxide is expelled. The efficiency of diffusion is influenced by factors like surface area, distance, and the properties of the gas molecules involved.

5 Must Know Facts For Your Next Test

1. Diffusion allows for rapid gas exchange in the alveoli due to the large surface area and thin walls that minimize distance.
2. The rate of diffusion is affected by factors such as temperature, molecular weight of the gases, and the thickness of the membrane through which gases diffuse.
3. Oxygen typically diffuses into the blood due to its higher partial pressure in the alveoli compared to that in deoxygenated blood.
4. Carbon dioxide moves out of the blood and into the alveoli through diffusion because it has a higher partial pressure in the blood compared to the air in the alveoli.
5. In conditions like pneumonia or pulmonary edema, diffusion can be impaired due to fluid buildup in the alveoli, reducing gas exchange efficiency.

Review Questions

• How does diffusion facilitate gas exchange in the lungs, and what factors affect its efficiency?
  • Diffusion facilitates gas exchange in the lungs by allowing oxygen to move from areas of high concentration in the alveoli to areas of low concentration in deoxygenated blood. Factors affecting this process include surface area available for diffusion, distance that gases must travel through membranes, and characteristics of the gases themselves. Increased surface area in conditions like healthy lungs enhances diffusion efficiency, while thickened membranes or reduced surface area can hinder this vital process.
• Discuss how partial pressure gradients influence the process of diffusion during respiration.
  • Partial pressure gradients are crucial for driving diffusion during respiration. Oxygen diffuses into the bloodstream because its partial pressure is higher in the alveoli than in deoxygenated blood. Conversely, carbon dioxide diffuses from blood into the alveoli as its partial pressure is higher there compared to alveolar air. This difference ensures effective gas exchange and is vital for maintaining proper levels of oxygen and carbon dioxide in the body.
• Evaluate how conditions such as pneumonia can impact diffusion and overall respiratory function.
  • Conditions like pneumonia can severely impair diffusion by causing fluid accumulation in the alveoli, leading to thicker barriers for gas exchange. This results in reduced surface area available for oxygen and carbon dioxide movement. Consequently, patients may experience difficulty breathing and lowered oxygen levels in their bloodstream. Understanding how these pathologies affect diffusion is essential for developing treatment strategies that restore efficient respiratory function.

Related terms

Partial Pressure: The pressure exerted by a single type of gas in a mixture of gases, playing a crucial role in gas exchange during diffusion.

Alveoli: Tiny air sacs in the lungs where gas exchange occurs, facilitating the diffusion of oxygen and carbon dioxide.

Concentration Gradient: A difference in the concentration of a substance across a space, which drives the movement of particles during diffusion.