Macrophages are ________.

The words “antigen” and “virus” are interchangeable?

The valves of the heart are part of which layer?

Match each term/event with the correct initiator.

Which of the following is a function of erythrocytes (red blood cells)?

   Which event of the cardiac cycle occurs when systolic blood pressure is measured?

A primary reason for needing a new vaccine for influenza each year is that _____.

Innate immunity _______ .

An antigen ____________ .

Bone cells that maintain existing bone are called _____.