Answer:
inner and outer sells help lot they are help a lot through out your body they allow the body to process right and it tells your body that can go in and what can go out so if a sickness enters your body then it will alert your body and tell it to fight the sickness then if they succeed then your all better and no longer are sick.
Step-by-step explanation:
the person above me did a good job and got it correct with this explanation.