positive feedback systems Flashcards
When are positive feedback systems useful?
When a rapid change with a particular objective is required by enhancing the effects of stimuli
How does a positive feedback system work to solve blood clotting?
Blood clotting damages the blood vessels and when this occurs the smooth muscles around the blood vessels tend to constrict which is a response designed to reduce the amount of blood loss but it also moves the exposed collagen closer to the blood vessel which brings the damaged area into closer contact with the blood meaning the platelet is more likely to bind with the damaged site. Once this happens the platelet releases chemicals that begin the process of aeration fro the platelets and draws more of them to the site. In this way the initial stimulus, the first platelets, causes a response that increases the amount of platelets binding to the damaged site.
When does the process of blood vessels grouping stop?
A cut-off point occurs when the damaged area if blood vessels is entirely covered.
How does a positive feedback system work with giving birth?
The uterine contractions leading up to partition begin when the uterus starts to push the neonate into the cervix causing a stretch in the cervix wall which stimulates the baroreceptor in the cervix. The brain then responds by releasing oxytocin which has the main effect of stimulating the contraction of the uterine muscles and stretches the uterus even further . The stimulus/baroreceptors then causes an increase in the muscular action that produces further stretching.
What is the cutoff point for uterine contractions?
Once the stretching stops manic the neonate has been born.
