Childbirth (Oxytocin): During childbirth, oxytocin hormone causes contractions that become stronger and stronger – an example of positive feedback loop.
Blood clotting: When an injury occurs and bleeding begins, platelets start sticking together at wound site forming a clot – another example of positive feedback loop.
Lactation: The production and secretion of milk by mammary glands for feeding infants – also regulated by positive feedback mechanism.