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.
Stress at moderate levels that produces positive results is called Eustress
Answer:
Explanation:
Gas exchange takes place in the millions of alveoli in the lungs and the capillaries that envelop them. As shown below, inhaled oxygen moves from the alveoli to the blood in the capillaries, and carbon dioxide moves from the blood in the capillaries to the air in the alveoli.
