Biology - Gas Exchange and Lungs

Structure of the Lungs and Gas Exchange

• Function of lungs:

  • Facilitate the process of cellular respiration by providing oxygen to the bloodstream.

  • Remove carbon dioxide from the body.

Pathway of Air

• Inhalation Process:

  • Air enters through the mouth or nose.

  • Travels down the trachea (windpipe).

  • Divides into two bronchi, which branch into smaller bronchioles.

  • Finally, reaches the alveoli, the sites of gas exchange.

Alveoli: The Site of Gas Exchange

• Alveolus Structure:

  • Composed of a single layer of very thin cells (similar to blood capillaries).

  • Short diffusion pathway increases the rate of gas exchange.

• Surface Area:

  • Adults possess hundreds of millions of alveoli, significantly increasing surface area.

  • If spread out, they could cover half a tennis court.

• Moist Walls:

  • Walls are moist, allowing gases to dissolve and enhancing diffusion rates.

Gas Exchange Process

• Oxygen Diffusion:

  • Oxygen concentration in alveoli is high compared to deoxygenated blood returning to the lungs (illustrated as blue blood).

  • Oxygen diffuses from the alveoli into the blood due to a favorable concentration gradient.

• Carbon Dioxide Diffusion:

  • Carbon dioxide concentration is higher in the blood than in the alveoli, enabling easy diffusion into the alveoli to be expelled during exhalation.

  • Carbon dioxide is primarily dissolved in blood plasma rather than being carried by red blood cells.

Continuous Nature of Gas Exchange

• The entire process is ongoing:

  • Deoxygenated blood consistently entering the capillaries.

  • Oxygenated blood continuously leaving post gas exchange.

Breathing Rate during Exercise

• Breathing rate can be calculated as:

  • Breathing Rate = Number of Breaths / Time (in minutes).

  • Example: 42 breaths in 3 minutes yields a rate of 14 breaths per minute.

Conclusion

• Recap of the significance of understanding lung function and gas exchange.

• The process is vital for maintaining efficient cellular respiration.