Accepts electrons from cytochrome c, ultimately transferring them to oxygen, forming H2O. in the process, 2 protons are pumped across the membrane. Complex IV is a terminal oxidoreductase, meaning that it transferes the elctrons to the terminal electron acceptor, which, in this case, is O2.
White blood cells called lymphocytes originate in the bone marrow but migrate to parts of the lymphatic system such as the lymph nodes, spleen, and thymus. There are two main types of lymphatic cells, T cells and B cells.
Millions of different T cells are present in the lymphatic tissue. Each is poised to rapidly reproduce if triggered by the right molecular signal. The signal is presented by a special cell called the antigen-presenting cell (APC). The APC carries a foreign antigen, a piece of protein from an invader.