The Circulatory System

Arteries

Blood vessels that carry blood from the heart to tissues and organs in the body.

Veins

Blood vessels that carry blood to the heart from tissues and organs in the body.

Capillaries

Tiny blood vessels with thin walls where oxygen and nutrients are exchanged for carbon dioxide and waste.

Tunica externa

The outer layer of arteries and veins.

Tunica media

The middle layer of arteries and veins, which is thicker in arteries and contains smooth muscle.

Tunica interna

The inner layer of arteries and veins.

Valves

Structures found in veins that allow blood to flow towards the heart.

Superior vena cava

The large vein that carries deoxygenated blood from the upper body to the heart.

Common carotid artery

An artery that supplies blood to the neck and head, branching into internal and external carotid arteries.

Femoral artery

An artery that supplies blood to the thigh and is a continuation of the external iliac artery.

Great saphenous vein

The largest superficial vein in the body, located in the lower extremity.