Prenatal development Flashcards
(39 cards)
Fertilization:
When sperm penetrates egg while it is in the fallopian tube.
Fertilization process
The process of genetic transmission happens at the time of sexual intercourse. At this time, the man ejaculates 350 million sperm cells into the woman’s vagina.
The sperm swim through the fluid of the woman’s uterus to the fallopian tubes where one may penetrate a woman’s egg or ovum, if it is available for fertilization.
Penetration is called conception. Forms zygote.
In Vitro Fertilization
Conception outside the body. Plus *Artificial insemination
*Surrogate womb
Two ways to describe stages of prenatal period
trimesters. germinal (zygote), embryonic, fetal
germinal period
conception through 2 weeks.
From fertilization until the cell mass drifts out of the fallopian tubes and attaches itself to the uterine wall.
embryonic period
weeks 2-8
Fetal period
fetal 9 through 38
by the fourth day of the germinal period..
By the 4th day, 60 to 70 cells exist that form a hollow, fluid-filled ball called a blastocyst.
by days 8-10..
The embryonic Disk- The cells on the inside of the blastocyst, will become the new organism the outer ring will provide protective covering.
zygote has reached the uterus, mitosis has produced hundreds of cells!
between the seventh and ninth day..
Implantation – Occurs sometime between the seventh and the ninth day when the blastocyst burrows deep into the lining of the uterus.
The amnion
is a membrane that encloses the developing organism in amniotic fluid. The fluid functions as a cushion and temperature regulator.
The yolk sac
produces blood cells until the liver, spleen, and bone marrow mature enough to take over this function.
How many zygotes do not make it through the germinal phase?
30% do not make it to the embryonic stage
Embryo stage
he cell differentiates into different systems and organs. Begins with the attachment of the zygote to the uterine wall and continues for approximately 6 weeks.
This is most critical time. Major organs. Rapid growth. Critical time.
The most rapid prenatal changes take place during these six weeks as the groundwork for all body structures and internal organs is begun.
Abnormalities that occur at this embryonic stage may result in fatal dysfunction - heart, stomach. Spontaneous abortions.
Impact of maternal disease is greatest at this time.
neural tube
primitive spinal cord.
When can the baby move and respond?
By the end of the embryo stage, the embryo can move, and it responds to touch, especially the mouth area an on the soles of the feet.
Placenta:
Forms on the uterine wall at the point where the embryo and the uterus are attached. Placenta is the structure that exchanges oxygen, nutrients and other elements from the blood of the mother to the blood of the child. Exchange of excrements from child’s blood to mother’s. Semi-permeable
CEPHALOCAUDAL
Pertains the fact that neonatal development occurs earlier and more rapidly in the head and upper parts of the body than in lower parts of the body. (e.g., infant has a disproportionately large head)
When can the fetus live on it’s own
after 28 weeks
When have all the brains neuron’s been produced?
End of second trimester.
around five months..
fetus activity declines for brain regions to mature and cns undergoes refinement.
at six months
At six months. Very active. Sucking fingers, changing positions. Gains lots of weight.
Proximodistal Growth
Occurs earlier and more rapidly in the center of the body than in the extremities. For example, infants will gain control over their arms before they can use their fingers reliably.
Emotional conditions of mother
When a mother experiences fear and anxiety, blood supply increases to the brain and the heart and limbs, resulting in decreased blood supply to the uterus. Stress hormones also cross the placenta
