Explain how the body prevents particles in inspired air from reaching the gas
exchange surfaces.

Your respiratory system prevents harmful substances from entering the lungs by using: .Mucus produced in the trachea and bronchial tubes to keep air passages moist and aid in intercepting dust, bacteria and other substances; The sweeping motion of cilia (small hairs in the trachea) to keep air passages clean

what subject is this

thrombocytopenia, which is a deficiency in blood platelets, can cause bleeding and bruising in the dermis similar to senile purpura. other possible causes include: exposure to ultraviolet rays and aging skin are common causes of senile purpura. senile purpura may also be a sign of collagen loss in the skin and bones.