How is backflow of blood from the right ventricle into the right atrium prevented?

Is it considered muscles' ennervation if the sympathetic fibers innervate vessels within the muscle ? (vasomotricity)

James is sitting at his desk on the ground floor of an office building when the entire room starts shaking. which action is most appropriate in this situation? a. standing near a window b.running out of the building c.holding up a bookshelf d.preparing for aftershocks

Marijuana is an example of a(n) drug