Evolution by natural selection.
survival of the fittest=natural selection
In aplastic anemia, then lab result will be decreased in all blood component( white blood cells, red blood cells, and thrombocyte).
Aplastic anemia is caused by the bone marrow failure. Bone marrow is the place that produces blood cells, so the decrease wouldn't be in the red blood cell only, but in other blood cells too. There shouldn't be any iron deficiency or decreases in the mean corpuscular volume
Atria is a large part of the heart so too big for cells; arteries & veins lead away or to the heart.
Capillaries are the smallest vascular structures that allow materials to be exchanged easily between cells.
