Positive Feedback Control of Labor

Positive Feedback Control of Labor To complete this worksheet, select: Module: Foundations Activity: Animations Title: Positive Feedback Control of Labor Introduction 1. What starts the positive feedback loop of childbirth labor? This cycle begins when the child enters the cervix and stretches the muscle wall.. 2. Describe the positive feedback loop between cervical stretch receptors, neurosecretory cells in the hypothalamus, Oxytocin, and the uterine smooth muscle. When the child enters the cervix it stretches, or dilates, and labor begins. Pressure sensitive receptor cells of the cervix detect the stretch and send impulses to the brain. These impulses go to the neurosecretory cells of the brain where a hormone called oxytocin is released into the capillaries of the pituitary gland. The blood then carries the hormone to the uterine tissue. Oxytocin causes the smooth muscle tissue of the uterine wall to contract more forcefully and pushes the child further into the cervix. This stretches the cervical wall further and sends more impulses to the hypothalamus. The cycle is continued with greater speed until the cervix is fully dilated and the child is born. 3. How is this positive feedback loop terminated? The birth of the child reduces and eliminates the stimuli to the pressure sensitive receptor cells. Without any stimuli impulses cease to the hypothalamus and there is no longer a production of Oxytocin.