Definition is a rhetorical mode that can be used in something smaller or shorter than a full paper. You can use extended definition for several paragraphs only in a paper of much greater length. You also can add to a paper a one-paragraph definition--like a brief encyclopedia definition.
Immunodeficiency: Therapies include thymus transplantation and adoptive transfer of mature T cells (ATMTC) for individuals with complete DiGeorge syndrome and appropriate prophylaxis measures and monitoring autoimmune complications for incomplete or partial DiGeorge syndrome.
How does digoxin work? Digoxin acts by inhibiting cell membrane sodium/potassium ATPase which leads to reversal of the usual sodium/calcium exchange. An increased intracellular calcium level results which, in myocardial muscle, has the effect of enhancing the strength of contraction (positive inotropism).