If your immune system attacks your own body parts, then it's called 'autoimmune disease'.
Autoimmune disease can happen at many times due to many problems the body can have. If one thing goes wrong with your body, it can go to another.
<span>living things ................</span>
<span>A. The nebula contracts and shrinks instead of expanding
</span><span>Nebula is the cloud of interstellar dust and gas that forms a star. It is collborately shaped during colliding and collapsing of the interstellar mediums this is influenced by the gravitational attraction of the atoms and particles in the entites. Hence, there are three types of nebular namely, are classical nebula, diffuse nebula, planetary nebular and supernova remnants.</span>
Answer:
look below
Explanation:
1) keep toxic substances out of the cell
2) allows certain minerals in that are needed and keeps others out and uses reciptors to do so
3) they separate vital but incompatible metabolic processes conducted within organelles
