Question

How air enters from our mouth to toe?

Answer 1

When you breath in air through your mouth (or through your nose, but this question is asking about your mouth) it goes into your lungs. This oxygen then goes to various places round your body, one of these places being your blood stream. When the oxygen enters your blood stream, the blood could travel to your toe. This is how air would enter your mouth and get to your toe.

Answer 2

When we breath air, it enters our trachea, which is the main passageway to our lungs. The lungs have something called bronchioles, which put that oxygen into tiny sacs and that air is delivered all across your body through arteries and veins! Vains reach to your toes, hands, and head, so they distribute oxygen everywhere.

In terms of the image below, the box on the top right is the example of the sacs of air in the bronchioles. The larger part of the image to the left is the overall respiratory system, and the arteries on the sacs of air are what deliver the air throughout the body.