Page 113 - 86 human physiology part-2

Chapter 17

Amniotic Fluid

The amnion grows and begins to fill, mainly with water, around two weeks after fertilization. After
a further 10 weeks the liquid contains proteins, carbohydrates, lipids and phospholipids, urea and
electrolytes, all which aid in the growth of the fetus. In the late stages of gestation much of the amniotic
fluid consists of fetal urine.

The forewaters are released when the amnion ruptures, commonly known as when a woman's
"waters break" or "spontaneous rupture of membranes" (SROM). The majority of the hindwaters
remain inside the womb until the baby is born.

Endocrine Function of the Placenta

There are pituitary like hormones and steroid hormones secreted from the placenta. The pituitary
like hormones are hCG and hCS. hCG is similar to LH and helps maintain the mothers corpus luteum.
hCS is like prolactin and growth hormone and help aid in increasing fat breakdown that spares the use
of glucose from the mothers tissues. This effect leaves more glucose available to the placenta and the
fetus for necessary growth. The steroid hormone are progesterone and estrogen. Progesterone helps
maintain the endrometrium and supports the growth of mammary glands. Estrogen also helps maintain
the endrometrium and growth of mammary glands. It also inhibits prolactin secretion.

Developing Baby

The womb is expanding, the baby is growing and taking all the nourishment from the mother.
What once started as a microscopic two-celled egg, will be formed into a baby in just 12 weeks. The
baby develops from conception to term, in a month-to-month progress.

Overview of Developmental Milestones

WEEK CHANGES IN MOTHER DEVELOPMENT OF BABY
Pre-embryonic Development
Fertilization occurs, cell division begins and
1 week Ovulation Occurs
continues, chorion appears
Embryonic Development
Symptoms of early pregnancy
(nausea, breast swelling and Implantation occurs; amnion and yolk sac appear;
2 weeks
tenderness, fatigue); blood pregnancy embryo has tissue; placenta begins to form
tests may show positive
First period missed; urine pregnancy
3 weeks test may show positive; early Nervous system begins to develop; allantois and
pregnancy symptoms continue blood vessels are present and placenta is well formed
Limb buds form; heart is beating; nervous system
4 weeks further develops; embryo has tail; other systems are
forming

328 | Human Physiology