In early years of the game the football was made of . vinyl
pigskin
plastic
leather

Astructural difference between the trachea and esophagus that prevents the trachea from collapsing is the presence of: a) smooth muscle b) skeletal muscle c) respiratory cilia d) rings of cartilage

What kind of wound occurred when the skin scrapes against a hard surface and tiny blood vessels break in the outer layer of skin

Bloodborn pathogens are infectious microorganisms carried by what?