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.
Best example of positive feedback is the release of oxytocin during childbirth. Oxytocin is a reproductive hormone in females. Though it is also secreted in males, its function is yet unclear. Secretion of oxytocin occurs in response to nervous stimulation of the hypothalamus. It stimulates and enhances labor contractions.