A note on Proteins
Next up: Protein in the Body
The three major sources of body protein are blood plasma, visceral tissue, and muscle. There are, however, no body stores or “reservoirs” of this macro-nuitrient because all protein is part of tissue structures or exists as vital constituents of metabolic, transport, and hormonal systems.
Protein makes up generally between 12-15% of the body mass, but there is considerable variability in the protein content of different cells. A brain cell is only about 10% protein; red blood cells and muscle cells contain as much as 20% of their total weight as protein. The protein content of skeletal muscle, which represents about 65% of the body’s total protein, increases with the systematic application of resistance training.