__________ consist primarily of volunteers, usually drawn from other emergency services

When reading radiographs, density can be defined as

the amount of light transmitted through a film. clarity. sharpness. blurriness.

What definition best describes the concept of afterload?

A) Pressure that the left ventricle must pump blood against to open the aortic valve B) Ability of the heart to adequately contract and pump blood out of the pulmonic valve C) Amount of blood that a person has in the arteries at any given moment D) Amount of blood returned to the lungs for oxygenation by the right ventricle