Chapter 28 Flashcards
Heredity
Explain the events of capacitation
As sperm move through the cervical mucus, uterus, and uterine tubes, secretions of the female tract remove some of their protective membrane proteins, as well as the cholesterol that keeps their acrosomal membranes “tough” and stable.
Explain the events of the acrosomal reaction
- Sperm approaches and passes the granulosa cells protecting the oocyte
- Sperm binds to zona receptors, causing calcium level to rise and releasing the acrosome enzymes which eat holes through the zona pellucida
- Binding of the sperm membrane and oocyte receptors
- Plasma membranes fuse and the sperm enters the oocyte
Define: capacitation
The process of cholesterol being stripped from the acrosome to release its enzymes necessary for fertilization without spillage
The time frame for which a woman is developing a fetus
Gestational period
From fertilization to 8 weeks, the zygote is referred to as a ____, but after 9 weeks it is referred to a ____
embryo; fetus
Describe the processes of cleavage and implementation
Cleavage: period of fairly rapid mitotic divisions of the zygote without intervening growth
Implementation: if the mucosa is receptive, cell adhesion molecules bind the trophoblast to the endometrial epithelium, and the blastocyst implants high in the uterus. If not, the blastocyst will drift lower and attach when able. The trophoblast then proliferates and forms two distinct layers: cytotrophoblast and syncytiotrophoblast
Define: morula
Solid ball of cells that forms 3 days after fertilization
Fluid-filled hollow sphere composed of a single layer of large, flattened cells called trophoblast cells and a small cluster of 20 to 30 rounded cells, called the embryoblast (or inner cell mass), clinging to the inside
Blastocyst
Describe the hormonal changes during pregnancy
HcG rises for the 1st two months of pregnancy, then by month 4 intensely declines as progesterone and estrogen are secreted by the corpus luteum increase
Define: human chorionic gonadotropin (hCG)
Promotes secretion of progesterone and estrogen from the syncytiotrophoblast and prevents implantation rejection
List the functions of the placenta
nutritive, respiratory, excretory, and endocrine functions
Describe the vascular relationship in the placenta:
Chorionic villi are invaded by newly forming blood vessels, which extend to the embryo as the umbilical arteries and vein. As the placenta forms, and the endometrium erodes - creating blood-filled lacunae that once soaked in maternal blood begin to form the decidua basalis portion of the placenta.
Identify the extraembryonic membranes and list their functions
amnion - protection from physical trauma and temperature regulation
yolk sac - forms digestive tube and source of earliest blood cells
allantois - structural base for the umbilical cord
chorion - forms placenta and encloses embryonic body
The 3 primary germ layers of gastrulation and the corresponding tissues formed
ectoderm: nervous system and epidermis
mesoderm: form bones, muscles, dermis, internal viscera
endoderm: epithelial linings of the digestive, respiratory, and urogenital systems, and associated glands.
List the unique features of the fetal circulation
Umbilical artery: carries blood from fetus to placenta
Umbilical vein: oxygenated blood from placenta to fetus
Ductus venosus: drains blood from umbilical vein
Foramen ovale: opening in interatrial septum
Ductus arteriosus: drains the pulmonary trunk
Any factor that may cause severe congenital abnormalities or even fetal death if substance crosses placental barriers and enters fetal blood
Teratogen
Dangerous complication of pregnancy that can result in hypertension and proteinuria
preeclampsia
Describe the 3 stages of labor
- Dilation: longest part of labor; Cervix effaces and dilates & Amnion ruptures
- Expulsion: full dilation until delivery; Episiotomy (vaginal incision); strong contractions every 2–3 minutes (vertex or breech)
- Placenta: Delivery of afterbirth (placenta and membranes) occurs within 30 minutes
after birth
Outline the events that start respiration and circulation, after birth:
Carbon dioxide builds up after birth because the placenta is no longer removing it (central acidosis). Stimulates respiratory control centers, which is difficult because airways are tiny and lungs are collapsed.
Explain the feedback mechanism for lactation
- Infant sucks and the mechanoreceptors in the nipple sends afferent impulses to the hypothalamus
- Hypothalamus sends efferent impulses to the posterior pituitary where oxytocin is
- Oxytocin stimulates contraction of the breast via myoepithelial cells
- Milk is ejected through ducts in nipples, creating positive feedback.
List some of the methods of contraception
Behavioral: pull out method
Barrier: condoms and diaphragm
Hormonal: OCP, injections, and implants
List some of the methods of ART
- Surgical removal and reimplantation of fertilized oocyte
- IVF: egg and sperm are incubated until the embryonic stage, then reinserted
- ZIFT: In vitro fertilized oocytes are transferred to uterine tubes, so natural implantation can occur
- GIFT: sperm and oocytes are transferred together into uterine tubes so natural fertilization to take place
The neonatal period is described as the first __ (#) weeks after birth
4
Define: physiological jaundice
When bilirubin is not broken down by the liver fast enough, causing an surplus in the blood which results in deposits of bilirubin in the blood
