PSYC 2P12 Chapter Notes - Chapter 2: Neonatal Intensive Care Unit
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PSYC 2P12 Chapter 2 – Prenatal Development, Pregnancy, and Birth
•uterus – pear-shaped muscular organ lined with endometrium
•cervix – neck, or narrow lower portion, of the uterus which opens to the vagina
•fallopian tubes – pair of slim, pipe-like structures that connect the ovaries with the uterus
•ovary – almond shaped organ that contains a woman’s ova
•ova – eggs
Fertilization, the union of sperm and egg, begins with ovulation, the moment during a
woman’s cycle when an ovum is expelled from the ovary (usually around day 14). Hormones orchestrate
ovulation and pregnancy. The male sexual organs the testes are continually manufacturing sperm.
Chromosomes are threadlike strands of DNA located in the nucleus of every cell that carries the
genes, which transmit hereditary information. DNA is the material that makes up our genes and bears our
hereditary characteristics. Our genes contain a chemical blueprint for manufacturing proteins.
The germinal stage occurs during the first two weeks after fertilization. The fertilized ovum or
zygote makes its first division within 36 hours. Upon many cell divisions a blastocyst (hollow sphere of
cells) is formed and ready for implantation, when it becomes embedded in the uterine wall. At about
day 9 the blastocyst proliferates in the wall to form the placenta. During the six week long embryonic
stage, all of the major organs are formed. In the final period called the fetal stage, development occurs
at a leisurely pace and lasts about seven months. During this phase physical refinements, massive growth,
and brain development. The current age of viability (earliest point at which a baby can survive outside
the womb) is around 22 to 23 weeks.
Principles of Prenatal Development:
1. Growth follows the proximodistal sequence, from the most anterior (proximal) to the most
2. Development takes place according to the cephalocaudal sequence, from the top to the
3. The mass-to-specific sequence, or gross structures before smaller refinements
Threats to Developing Baby
Birth defects are physical or neurological problems that occur prenatally or at birth. A
teratogen is any substance that crosses the placenta and harms the fetus, and these are especially
damaging during the sensitive period.
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