Blood is life

This week is "Blood" week at Maeflowers - each day will be a post on something blood related. Today - what is blood?

It's almost a cliche - "blood is life". But it's true. Blood carries the components necessary for cell function, and thus life, to every tissue of the body.

Red blood cells

Blood is actually a milieu - it has many components all mixed together but not combined (it's not like a chemical reaction where two substances mix to become one - blood components are separable and act on their own). Blood is made mostly of plasma, a water-based substance containing dissolved proteins, gases, and other molecules, like vitamins. The cells in blood come in two varieties - white and red. Red blood cells are what we think of when we think blood, because we see their coloration. Known scientifically as erythrocytes, red blood cells contain a protein (hemoglobin) that binds oxygen. White blood cells start out as lymphocytes - these become T cells, B cells, macrophages - the immune cells and maids of the body, cleaning up dead and broken cells and foreign material from the bloodstream and tissues.

Blood is capable of providing life because of the circulatory system - which you'll be able to read about tomorrow.