1 adj Social means relating to society or to the way society is organized. ADJ n. ...the worst effects of unemployment, low pay and other social problems., ...long-term social change., ...changing social attitudes., ...the tightly woven social fabric of small towns., ...research into housing and social policy.
The human circulatory system (simplified). Red indicates oxygenated blood carried in arteries, blue indicates deoxygenated blood carried in veins. Capillaries, which join the arteries and veins, and the lymphatic vessels are not shown.
Three sets of vessels comprise the circulatory system: arteries, lymphatics, and veins. Arteries bring oxygen-carrying blood from the heart to the tissues. In the normal course of blood circulation, small amounts of fluid and protein leak from arteries and veins. Lymphatic vessels bring this protein-rich fluid back into the circulation. The third type of blood vessel is the vein. Veins bring oxygen-depleted blood from the organs and tissues to the heart and lungs, where it is re-oxygenated. Blood return to the heart tends to be passive and is enabled by muscle contraction in the arms and legs.