OXYTOCICS AND ERGOT ALKALOIDS
Section I. OXYTOCICS
In previous lessons, the female reproductive system was discussed. Usually
females have little difficulty delivering the offspring. In some instances, however, the
physician may need to intervene in the birthing process. In these cases, the physician
may choose to use an oxytocic to speed up the birth process.
11-2. THE PROCESS OF BIRTH
During gestation (the time the fetus is in the uterus), the uterus is relatively quiet
in terms of muscle contraction. However, as the time draws near for the process of birth
to begin, the uterus begins to contract. These forceful contractions are necessary for
the fetus to be expelled from the uterus. Oxytocin is a hormone that causes the uterus
11-3. ACTION OF OXYTOCIN
Oxytocin directly stimulates contractions of the muscles of the uterus. In general,
the gravid uterus is much more responsive to oxytocic action than is the nongravid
uterus. In other words, the closer a woman is to giving birth to the child, the more
responsive her uterus will be to the effects of oxytocin.
11-4. ROLE OF OXYTOCIN IN THE BIRTH PROCESS
Oxytocin is produced in the neurohypophysis. Oxytocin is a substance that
causes the uterus to contract. Another hormone, relaxin, helps to relax some of the
ligaments attached to the pubic area. Together, these hormones act to produce
conditions favorable to the birth of the fetus. If it were not for the actions of relaxin, the
forceful uterine contractions produced by oxytocin would harm the fetus and the mother.
Oxytocin, therefore, serves to begin labor and to expel the afterbirth (placenta, etc.)
after the delivery of the infant.
11-5. THE STAGES OF LABOR
To understand the role of oxytocics in the delivery of a baby, the three stages of
labor must be understood (See figure 11-1). These stages and what happens in them
are presented below: