I think the answer is molars
The correct answer is microglia.
<span>Microglia is glial cells found in the central nervous system with the protective role. Because they are the resident macrophage cells, they act as the first and main form of active immune defense. Microglia is constantly cleaning the CNS for plaques, damaged or unnecessary neurons, and infectious agents, like viruses or other microorganisms.</span>
Scientific Theory change but not thrown away because scientist
continue looking for possibilities and exact proportion to prove such theory,
though it is change because they always conducted hypnosis in every theory and
once it proves something different they conduct another hypothesis for more
actual evidence.
The respiratory and circulatory systems bring oxygen and nutrients to the cells. The respiratory and circulatory systems work together to maintain homeostasis. The respiratory system moves gases into and out of the blood.