upâ¢stream. 1. toward or in the higher part of a stream; against the current. 2. directed or situated upstream. 3. against or opposite to the direction of transcription, translation, or synthesis of a DNA, RNA, or protein molecule.dv. 1. Toward or closer to the source of a stream; in the direction opposite to that of the current: paddling upstream. 2. At an earlier point in a production process or supply chain. adj.
Positive feedback mechanisms. A positive feedback mechanism is the exact opposite of a negative feedback mechanism. With negative feedback, the output reduces the original effect of the stimulus. In a positive feedback system, the output enhances the original stimulus.
â the changing conditons of the external environment. â the changing conditons of the internal environment. Homeostasis is a self-adjustng mechanism involving feedback where the response to a stmulus alters the. internal conditons and may become a new stmulus.