ANATOMY

Detailed explanation-1: -Gas exchange during respiration occurs primarily through diffusion. Diffusion is a process in which transport is driven by a concentration gradient. Gas molecules move from a region of high concentration to a region of low concentration.

Detailed explanation-2: -This is a process by which particles move naturally from a region where they are in high concentration to a region where they are in lower concentration. They move down a concentration gradient: the steeper the gradient, the faster the rate of diffusion.

Detailed explanation-3: -A large diffusion gradient-breathing ensures that the oxygen concentration in the alveoli is higher than in the capillaries so oxygen moves from the alveoli to the blood. Carbon dioxide diffuses in the opposite direction.

Detailed explanation-4: -The walls of the alveoli share a membrane with the capillaries. That’s how close they are. This lets oxygen and carbon dioxide diffuse, or move freely, between the respiratory system and the bloodstream. Oxygen molecules attach to red blood cells, which travel back to the heart.

Detailed explanation-5: -Breathing in and out (a ventilation mechanisms) maintains a steep concentration gradient between the oxygen (and carbon dioxide) in the alveoli and the blood so that the rate of diffusion is faster.