Final answer:
During the early postpartum period, one should expect a decrease in blood volume due to the loss of the placenta and reduced vascular resistance. Positive feedback in physiology includes the release of oxytocin during childbirth, and an example of negative feedback is the regulation of blood glucose levels after a meal.
Step-by-step explanation:
The physiologic response that a nurse should expect during the early postpartum period is decreased blood volume. After childbirth, the loss of the placenta and reduced vascular resistance lead to a decrease in blood volume. Uterine contractions are not decreased; in fact, they continue to occur to help the uterus return to its pre-pregnancy size and prevent hemorrhage (involution). As for the options provided by the student, regarding physiology and hormonal feedback mechanisms, the positive feedback example is the role of oxytocin in childbirth. Oxytocin levels increase in response to cervical dilation, leading to stronger uterine contractions which, in turn, cause more oxytocin to be released. This process continues until the baby is delivered. Moreover, negative feedback is exemplified by the lowering of blood glucose levels after a meal, where the secretion of insulin by the pancreas is regulated to reduce blood glucose concentration, returning it to normal levels.