Gas Exchange

Understanding Gas Exchange

• The process of gas exchange involves the movement of oxygen into organisms to be used for respiration and carbon dioxide being expelled as a waste product.
• It happens in alveoli of the lungs, gills in fish, and leaf surfaces in plants.
• It occurs down a concentration gradient.
• The process is facilitated by a large surface area, thin epithelial layers and high concentration gradients.

Adaptations for Efficient gas exchange

• In mammalian lungs, the alveoli are tiny sacs with extremely thin walls and a large total surface area to increase

  efficiency.

• In fish, gills have a large surface area and a countercurrent system to maintain a large concentration difference.
• In plants, stomata open to allow CO2 in and O2 out, while a waxy cuticle minimises water loss.

Fick’s Law of Diffusion

• Fick’s law of diffusion describes how the rate of gas exchange can be affected by surface area,

  difference in concentration and thickness of membrane.

• Rate of diffusion is proportional to surface area times concentration difference divided by membrane thickness.

Role in Homeostasis

• Gas exchange plays a vital role in homeostasis. It ensures that the body gets enough oxygen for

  various processes and rids itself of waste carbon dioxide.

• Respiratory centres in the brain control the rate and depth of breathing to maintain gas concentrations.

Gas exchange and Health Concerns

• Conditions like COPD (chronic obstructive pulmonary disease) and asthma affect the airways and

  hamper gas exchange.

• Smoking can cause tar build-up and emphysema, both of which can cause long-term damage to lungs, decreasing

  the efficiency of gas exchange.

• Altitude sickness is a result of inadequate oxygen availability at high altitudes leading to complications in gas

  exchange.