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 |
Development and Maturation of the Cardiopulmonary System
Cardiopulmonary Adjustments at Birth