In the given question, after the arm of the person got scrapped by the concrete which injured the skin of the person.
For the body, the scrapping of the body could have allowed the microorganism to invade and the immune system could have been activated. The immune cells which continuously flows in the lymph and blood are the white blood cells which are or five types.
When the smear of the blood is observed then the cells with large nucleus were observed which are the neutrophils, the most abundant white blood cells in the body.
Through the process of respiration , in lung the carbon dioxide from the blood is exchanged with oxygen.
The smallest dunctional unit if the lung is the alveoli
At this level the gases are exchange through the capillaries present close to the alveoli.
The concentration gradient ,meaning the greater amount of oxygen present in the lungs and greater amount of carbon dioxide in the blood creates a gradient that allow the movment of oxygen into the blood and carbon dioxide in the alveoli through the membrane .
Partial pressure created allows the easy movement .The carbon dioxide get into the trachea and expelled through nose and mouth.
