Cytoplasm. The cytoplasm is the part of the cell which does all the work. Different cells do different jobs, however whatever the job is it will require energy in the form of a chemical called ATP. This energy containing chemical is produced by tiny organelles in the cell called mitochondria. Muscle cells contain two very special chemicals called actin and myosin.
Definition of TREPHINATION. : an act or instance of perforating the skull with a surgical instrument. ADVERTISEMENT.efinition of TREPHINATION. : an act or instance of perforating the skull with a surgical instrument. ADVERTISEMENT.
a small circular saw with a center pin mounted on a strong hollow metal shaft to which is attached a transverse handle: used in surgery to remove circular disks of bone from the skull. verb (used with object), trephined, trephining. 2. to operate upon with a trephine. Origin of trephine.