Positive feedback system
This system tends to strengthen or reinforce a change in one of the body's controlled condition. A change in the homeostatic condition is detected by receptors and the information is transmitted to the control center. The control center activates effectors which generate a response which increases the stimulus further reinforcing the initial change.
An example of positive feedback is the action of the hormone oxytoxin on the uterus during birth. During normal conditions the uterine muscle is passive and not contracting. Dilation of the cervix triggers stretch receptors which transmit nerve impulses to the Brain (hypothalamus). Stimulation of the hypothalamus results in oxytoxin (OT) being released from the posterior pituitary. Oxytocin is carried by the blood to the uterus where it causes uterine contractions. During the birth process dilation of the cervix initiates the release of OT which causes uterine muscle contractions. …
