Which part of the respiratory system is composed of a single layer of epithelial tissues surrounded by a network of capillaries?

alveoli

trachea

bronchiole

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white blood cells or wbc s are mainly 2 types-

1.agranulocytes

2.granulocytes

the monocytes or macrophages of agranulocytes , dendritic cells which are accessory leucocytes, and b cells which is one type of lymphocytes   identify the antigens present on the pathogen's surface. these three cells are called antigen presenting cells(apc) which are phagocytes and destroy the antigens by secreting antitoxins. besides this leukocyte is always plays vital role in the immunity of the body.

six grader is what i am ssorry

the animal that would be cutest if scaled down to the size of a cat? elephant