During life in utero,oxygenation of the fetus occurs through transplacental gas exchange.When birth occurs,four factors combine to stimulate the respiratory center in the medulla.The initiation of respiration then follows.Which is not one of these essential factors?
A)Chemical
B)Mechanical
C)Thermal
D)Psychologic

Question

Quizplus · Accepted Answer

This is not a factor in the initiation of breathing;rather it is sensory factors that contribute.These factors include handling by the health care provider,drying by the nurse,lights,smells,and sounds.Chemical factors are essential to initiate breathing.During labor decreased levels of oxygen and increased levels of carbon dioxide seem to have a cumulative effect that is involved in the initiation of breathing.Clamping the cord may also contribute to the start of respirations.Prostaglandins are known to inhibit breathing.Clamping the cord results in a drop in the level of prostaglandins.Mechanical factors also are necessary to initiate respirations.As the infant passes through the birth canal,the chest is compressed.With birth,the chest is relaxed,which allows for negative intrathoracic pressure that encourages air to flow into the lungs.The profound change in temperature between intrauterine and extrauterine life stimulates receptors in the skin to communicate with the receptors in the medulla.This also contributes to the initiation of breathing.

During Life in Utero,oxygenation of the Fetus Occurs Through Transplacental