Narrowing of a blood vessel is known as _______________.

The veins have valves that allow blood to flow toward the heart but prevent it from flowing away from the heart.

The combining form ather/o means _______________.

Paralysis of the lower part of the body.

Means lacking normal muscle tone or strength.

The membranous sac that surrounds the heart is the ____________.

The thick muscular layer of the heart is called the

Hardening and narrowing of the arteries due to a buildup of cholesterol plaques.

______________ play an important role in the clotting of blood.

The right ventricle ___________________________.