Chp 16: Part Iv: Pregnancy And Embryonic Development

Front 1

Pregnancy

Back 1

refers to events that occur from the time of fertilization (conception) until the infant is born.

Front 2

The pregnant woman's developing offspring is called the __________.

Back 2

conceptus

Front 3

Development occurs during the gestation period which is approximately_____days.

Back 3

280

Front 4

From fertilization through week 8, the embryonic period, the ______ is called an _______, and from week 9 through birth, the fetal period, the conceptus is called a _____, and at birth is called an ______.

Back 4

conceptus
embryo
fetus
infant

Front 5

For fertilization to occur, the sperm must reach the ovulated _________.

Back 5

secondary oocyte

Front 6

The oocyte is viable for ___ to ___ hours after it is cast out of the ovary, and sperm generally retain their fertilizing power within the female reproductive tract for ___ to ___ hours after ejaculation.

Back 6

12/24
24/48

Front 7

For fertilization to occur, sexual intercourse must occur no more than ____ days before ovulation and no later than ______ after.

Back 7

two
24 hours

Front 8

If sperm are deposited in a female's vagina at the approximate time of ovulation, they are attracted to the _______by chemicals allowing the sperm to locate the ________.

Back 8

oocyte
oocyte

Front 9

Only a few hundred to a few thousand of the millions of sperm deposited make it to the egg's vicinity. When the swarming sperm reach the oocyte, their cell surface enzymes break down the wall that the ________ radiate have around the oocyte.

Back 9

corona

Front 10

Once a path has been made, thousands of sperm undergo the _________ reaction in which the ________ membranes break down, releasing enzymes that digest holes in the oocyte membrane.

Back 10

acrosomal
acrosome

Front 11

Then, when the membrane is adequately weakened and a single sperm makes contact with the oocyte's membrane receptors, the head of the sperm is pulled into the _______ ______.

Back 11

oocyte cytoplasm

Front 12

__________ occurs at the moment the genetic material of a sperm combines with that of an ovum to form a fertilized egg, or _______.

Back 12

Fertilization
zygote

The zygote represents the first cell of the new individual.

Front 13

As the zygote journeys down the uterine tube it undergoes rapid mitotic cell divisions. This early stage of embryonic development is called _________.

Back 13

cleavage

Front 14

The embryo continues to develop until it has about ____ cells, and then it hollows out to form a structure called a _______or a __________ vesicle.

Back 14

100
blastocyst
chorionic

Front 15

The embryo now begins to secrete a hormone called ____________________________, which prods the corpus luteum of the ovary to continue produce its hormones.

Back 15

human chorionic gonadotropic (hCG)

Front 16

The _______ has two important functional areas: the __________, which forms the large fluid-filled sphere, and the _______________, a small cluster of cells on one side.

Back 16

blastocyst
trophoblast
inner cell mass

Front 17

Three primary germ layers are being formed from the inner cell mass including the _________ which becomes the nervous system and dermis of the skin, the __________ which forms mucosae and associated glands, and the __________ which becomes everything else.

Back 17

ectoderm
endoderm
mesoderm

Front 18

After it is securely implanted, the _________ part of the blastocyst develops elaborate projections, called ____________, which combine with tissues of the mother's uterus to form the ________.

Back 18

trophoblast
chorionic villi
placenta

Front 19

Once the placenta has formed, the embryonic body, now surrounded by a fluid-filled sac called the ________, is attached to the placenta by a blood vessel-containing stalk of tissue, the __________.

Back 19

amnion
umbilical cord

Front 20

By the end of the second month of pregnancy, the placenta has also become an endocrine organ and is producing _________, ________, and other hormones that help to maintain the pregnancy.

Back 20

estrogen
progesterone

Front 21

Beginning in the ninth week of development, the embryo is referred to as a ______.

Back 21

fetus

Front 22

From this point on the major activities are growth and organ specialization, accompanied by changes in body proportions. By approximately _____ days after fertilization, the fetus is ready to be born.

Back 22

270

Front 23

Pregnancy has many effects on the mother, both physical and _________.

Back 23

physiological

Front 24

Starting as a fist sized organ, the uterus grows to occupy most of the pelvic cavity by __ weeks.

Back 24

16

Front 25

As birth nears, the uterus reaches the level of the __________ and occupies the bulk of the abdominal cavity.

Back 25

xiphoid process

The crowded abdominal organs press superiorly against the diaphragm, which intrudes on the thoracic cavity.

Front 26

Gastrointestinal system:

Back 26

Many women suffer nausea, or morning sickness, during the first few months of pregnancy, until their system adjusts to the elevated levels of progesterone and estrogens. Heartburn and constipation are also common.

Front 27

Urinary system:

Back 27

The kidneys have the additional burden of disposing of fetal metabolic wastes, and they produce more urine during pregnancy. The uterus also compresses the bladder, and urination becomes more frequent and urgent.

Front 28

Respiratory system:

Back 28

The nasal mucosa responds to estrogen by becoming swollen and congested; thus, nasal stuffiness and occasional nosebleeds may occur. Vital capacity and respiratory rate increase during pregnancy, but residual volume declines, and many women exhibit dyspnea during the later stages of pregnancy.

Front 29

Cardiovascular system:

Back 29

Total body water rises, and blood volume increases by 25% to 40% to accommodate the additional needs of the fetus. The rise in blood volume also acts as a safeguard against blood loss during birth. Blood pressure and pulse typically rise and increase cardiac output by 20% to 40%; this helps propel the greater blood volume around the body. Because the uterus presses on the pelvic blood vessels, venous return from the lower limbs may be impaired resulting in varicose veins.

Front 30

Childbirth, or _________, usually occurs within 15 days of the calculated due date.

Back 30

parturition

Front 31

The series of events that expel the infant from the uterus is referred to as ______.

Back 31

labor

Several events trigger labor.

Front 32

During the last few weeks of pregnancy, _______ reach their highest levels in the mother's blood.

Back 32

estrogens

This has two important consequences. It causes the myometrium to form abundant oxytocin receptors, and it interferes with progesterone's quieting influence on the uterine muscle.

Front 33

Weak, irregular uterine contractions begin to occur. These contractions are called ___________________ or false labor.

Back 33

Braxton Hicks contractions

Front 34

As birth nears, two more chemical signals cooperate to convert these false labor pains into real contractions. Certain cells of the fetus begin to produce _______, which in turn stimulates the placenta to release _________.

Back 34

oxytocin
prostaglandins

Both hormones stimulate more frequent and powerful contractions of the uterus. The increasing emotional and physical stresses activate the mother's hypothalamus, which signals for more oxytocin release by the posterior pituitary.

Front 35

The combined effects of rising levels of _______ and __________ initiate the rhythmic, expulsive contractions of _______.

Back 35

oxytocin
prostaglandins
true labor

Front 36

Once the hypothalamus is involved, a __________ ________ _____________ is propelled into action.

Back 36

positive feedback mechanism

Stronger contractions cause the release of more oxytocin, which causes even more vigorous contractions, forcing the baby ever deeper into the mother's pelvis.

Front 37

The process of labor is divided into ____ stages.

Back 37

three

Front 38

Stage 1: The ________ stage is...

Back 38

Dilation

the time from the appearance of true contractions until the cervix is fully dilated by the baby's head. The dilation stage is the longest part of labor and usually lasts for 6 to 12 hours or more.

Front 39

Stage 2: The _____ stage is...

Back 39

expulsion

the time from full dilation of the cervix to delivery of the infant. In this stage, the infant passes through the cervix and vagina to the outside of the body. During this stage, a mother experiencing natural childbirth has an increasing urge to push, or bear down, with the abdominal muscles.

Front 40

Stage 3: The _________ stage is...

Back 40

placental

the delivery of the placenta and is usually accomplished within 15 minutes after birth of the infant. The strong uterine contractions that continue after birth compress uterine blood vessels, limit bleeding, and cause the placenta to detach from the uterine wall. The placenta and its attached fetal membranes, the afterbirth, are then easily removed by a slight tug on the umbilical cord.