Medical Physiology, 3rd Edition

CHAPTER 57. Fetal and Neonatal Physiology

George Lister, Ervin E. Jones

Fetal development is a highly organized process. The most rapid phase of growth transpires in at a degree of hypoxemia that mimics ascent to Mount Everest, while nutrients reach the fetus indirectly, from the maternal circulation. The transition to the extrauterine environment occurs abruptly and is likewise extraordinarily well orchestrated. Indeed, within a matter of seconds, the breathing infant can supply sufficient oxygen to the tissues because of gas exchange in the previously fluid-filled newborn lung and rapid redirection of blood flow from fetal to adult pathways. Finally, the newborn must acclimate to its new milieu, where numerous homeostatic challenges confront the newly autonomous organs. Accordingly, the subchapters here address the growth of the fetus, the development of the cardiopulmonary system, the transition to the extrauterine environment, and early neonatal functions.

LESION

REFLEXOGENIC ERECTION

PSYCHOGENIC ERECTION

EFFECT ON EJACULATION

Upper motor neuron

Present

Absent

Significantly impaired

Lower motor neuron

Absent

Present

Less impaired

Biology of Fetal Growth

Development and Maturation of the Cardiopulmonary System

Cardiopulmonary Adjustments at Birth

Neonatal Physiology

References