Labor is very stressful for the fetus. It is important for the intrapartum nurse to be know-ledgeable regarding the mechanisms that regulate the fetal heart rate and keep the brain well oxygenated

Question

When evaluating the client's progress, the nurse knows that four of the five fetal factors that interact to regulate the heart rate are the: a. Uterine activity.
b. Autonomic nervous system.
c. Baroreceptors.
d. Chemoreceptors.
e. Adrenal glands.

Answer 1

B, C, D, E
Correct: B, C, D, E. The sympathetic and parasympathetic branches of the autonomic nerv-ous system are balanced forces that regulate FHR. Sympathetic stimulation increases the heart rate, while parasympathetic responses, through stimulation of the vagus nerve, reduce the FHR and maintain variability. The baroreceptors stimulate the vagus nerve to slow the FHR and decrease the blood pressure. These are located in the carotid arch and major arteries. The chemoreceptors are cells that respond to changes in oxygen, carbon dioxide, and pH. They are found in the medulla oblongata and the aortic and carotid bodies. The adrenal me-dulla secretes epinephrine and norepinephrine in response to stress, causing an acceleration in FHR.
Incorrect: A. Hypertonic uterine activity can reduce the time available for exchange of oxygen and waste products; however, this is a maternal factor. The fifth fetal factor is the central nervous system. The fetal cerebral cortex causes the heart rate to increase during fetal movement and decrease when the fetus sleeps.