In your body, you have only two types of bone tissue: cortical and cancellous bone. In this lesson, we will learn about the structure and function of cancellous bone, which plays a crucial role in producing blood cells and stem cells and is the primary tissue affected by osteoporosis.
balaclava (plural balaclavas) 1  A warm cap shielding the neck and head, often made out of wool. ( 2 chiefly Canada) A ski mask with holes for the eyes and, sometimes, the nose and mouth, which may be rolled up and worn like a toque or pulled over the face for greater protection.
A respirator is a safety device that covers the nose and mouth and helps protect the wearer from breathing in some hazardous substances. An N95 dust mask is a disposable respirator that protects you from breathing in small particles in the air such as dust and mold. It is designed to filter out at least 95% of the dust and mold in the air.