How gaseous exchange take place in the alveoli?

Answer 1

We have followed the path of the air and of the oxygen into the bloodstream. But breathing is a two-way street: we breathe in and then we breathe out. When we breathe in, or inhale, oxygen is removed from the air. Breathing also removes waste from the lungs and from our noses and mouths. How does this waste material get into the air that we breathe out, or exhale?

The thin walls of the alveoli actually have two purposes. When we breathe in, oxygen passes through the walls of the alveoli and into the blood. Carbon dioxide and water vapor then travel the opposite direction. They are the main waste products that pass from the blood vessels (arteries) in the lungs, into the alveoli, through the windpipe and out the nose and mouth.

Answer 2

Gaseous exchange in our lungs take place by diffusion.which enters our lungs have lower concentration of oxygen but higher concentration of carbondioxide than atmospheric air entering the alveoli in the lungs.A concentration gradient for the two gases is set up b/w blood and alveolar air.Oxygen diffuse from the alveolar air into blood capillaries,carbondioxide diffuse in opposie direction.

Answer 3

There are about 168 million alveoli in your lungs. They are lined by single layer of flat cells. They are in contact with the blood capillaries. Blood capillaries also have single layer of flat cells. Through these very thin walls, the gaseous exchange takes place, very easily. The surface area of the lungs is about 1100 square feet or 100 square meters. The gases are exchanged in fraction of second. The oxygen goes in the blood from the alveoli and carbon bi oxide comes out of blood to alveloi. This happens by concentration gradient. You may like to think that all the amount of gases is transported like this. But it is not true. You can give up to fifty percent of gases only, by this mechanism. But that is enough.