Chapter 28

Question 1

Explain the events of capacitation

Answer 1

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.

Question 2

Explain the events of the acrosomal reaction

Answer 2

1. Sperm approaches and passes the granulosa cells protecting the oocyte
2. Sperm binds to zona receptors, causing calcium level to rise and releasing the acrosome enzymes which eat holes through the zona pellucida
3. Binding of the sperm membrane and oocyte receptors
4. Plasma membranes fuse and the sperm enters the oocyte

Question 3

Define: capacitation

Answer 3

The process of cholesterol being stripped from the acrosome to release its enzymes necessary for fertilization without spillage

Question 4

The time frame for which a woman is developing a fetus

Answer 4

Gestational period

Question 5

From fertilization to 8 weeks, the zygote is referred to as a ____, but after 9 weeks it is referred to a ____

Answer 5

embryo; fetus

Question 6

Describe the processes of cleavage and implementation

Answer 6

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

Question 7

Define: morula

Answer 7

Solid ball of cells that forms 3 days after fertilization

Question 8

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

Answer 8

Blastocyst

Question 9

Describe the hormonal changes during pregnancy

Answer 9

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

Question 10

Define: human chorionic gonadotropin (hCG)

Answer 10

Promotes secretion of progesterone and estrogen from the syncytiotrophoblast and prevents implantation rejection

Question 11

List the functions of the placenta

Answer 11

nutritive, respiratory, excretory, and endocrine functions

Question 12

Describe the vascular relationship in the placenta:

Answer 12

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.

Question 13

Identify the extraembryonic membranes and list their functions

Answer 13

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

Question 14

The 3 primary germ layers of gastrulation and the corresponding tissues formed

Answer 14

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.

Question 15

List the unique features of the fetal circulation

Answer 15

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

Question 16

Any factor that may cause severe congenital abnormalities or even fetal death if substance crosses placental barriers and enters fetal blood

Answer 16

Teratogen

Question 17

Dangerous complication of pregnancy that can result in hypertension and proteinuria

Answer 17

preeclampsia

Question 18

Describe the 3 stages of labor

Answer 18

1. Dilation: longest part of labor; Cervix effaces and dilates & Amnion ruptures
2. Expulsion: full dilation until delivery; Episiotomy (vaginal incision); strong contractions every 2–3 minutes (vertex or breech)
3. Placenta: Delivery of afterbirth (placenta and membranes) occurs within 30 minutes
   after birth

Question 19

Outline the events that start respiration and circulation, after birth:

Answer 19

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.

Question 20

Explain the feedback mechanism for lactation

Answer 20

1. Infant sucks and the mechanoreceptors in the nipple sends afferent impulses to the hypothalamus
2. Hypothalamus sends efferent impulses to the posterior pituitary where oxytocin is
3. Oxytocin stimulates contraction of the breast via myoepithelial cells
4. Milk is ejected through ducts in nipples, creating positive feedback.

Question 21

List some of the methods of contraception

Answer 21

Behavioral: pull out method
Barrier: condoms and diaphragm
Hormonal: OCP, injections, and implants

Question 22

List some of the methods of ART

Answer 22

• 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

Question 23

The neonatal period is described as the first __ (#) weeks after birth

Answer 23

4

Question 24

Define: physiological jaundice

Answer 24

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

Question 25

A pregnancy in which the embryo implants in any site other than the uterus; most often the site is a uterine tube

Answer 25

Ectopic Pregnancy