There are millions of alveoli in the lungs they provide a very large surface area why is a large surface area necessary?

Answer 1

By having millions of these tiny sacs, the surface area of the lungs is vastly increased. This adaprtation enables a greater volume of air to breathed in, in each breath. An increased surface area allows for more diffusion to take place between the lungs and the blood.

Answer 2

"Gas exchange is by diffusion from the gas contents in the lungs to the blood vessels in the pulmonary aveolus. The many indentations within the lung act to increase the surface area in the volume occupied by the lungs."

To improve on the previous answer, the larger the surface area compared to the volume (or size) of the cell, the faster the rate of diffusion through the cell membrane. So with a larger surface area, more particles can diffuse in and out of the cell and at a faster rate for the same volume of cell.

Answer 3

The alveoli have special adaptation that have made them very efficient for gas exchange.

• They are rounded, giving them a larger surface area than any other shape
• They are millions (150 million) of alveoli per lung to increase the total surface area for gas exchange
• The membrane between an alveolus and it neighbouring capillaries (called the respiratory membrane or alveoli-capillary membrane) is very thin, creating a very short diffusion distance for gases)
• The epithelium of alveoli contains a thin layer of moisture on the inside to allow for gases to first diffuse into the moisture and then pass through the membrane
• Each alveolar sac is surrounded by a dense network of capillaries

Gas exchange is by diffusion from the gas contents in the lungs to the blood vessels in the pulmonary aveolus. The many indentations within the lung act to increase the surface area in the volume occupied by the lungs.

Answer 4

The alveoli are essential for gas exchange in the lungs, and one of the adaptations for effective diffusion of gases is to have a large surface area. This means that by increasing the surface area, the more area the gas has to diffuse through, and therefore the more gas exchange that can take place.

Hope this helps - doing A -level Biology :)

Answer 5

The alveoli increase the surface area of the lungs so gases can diffuse across it faster for a quicker rate of respiration.