Considering the left ventricle, why does isovolumetric ventricular contraction occur during ventricular systole?

Blood collected from the subclavian and jugular veins goes into the:

Which of the following components of blood are responsible for protecting the body against invaders/immune system?   

Which of the following organs would have the capillaries with the greatest permeability.

Of the following events involved in hemostasis, which occurs first?

A monocyte:

The Bundle of His is:

How does blood get back to the heart from the legs?

Which vessel is blood forced through during ventricular systole?

Which layer of the wall of the heart is the deepest?