O M G i just did that one on Plato
well anyway i think the answer was the the skin because any thing that invades the body is a threat to the immune system.
It is normal to start anywhere between 11 and 17 years old.
Shortness of breath after moderate physical activity most likely indicates limitations in cardiovascular fitness.
When performing physical activity, heart rate increases. And when heart rate increases, you must also take in more oxygen. Thus, if you are short of breath after moderate physical activity, then you have limitations in cardiovascular fitness.
Hope this helps!! :)
