Reproduction

Question 1

During ejaculation, _____ sperm are ejected into the vagina, but _____ due
to leakage, destruction, or inability to penetrate the mucus of the cervix.

Answer 1

several hundred million; most

are lost

Question 2

In order to be fertilized, the secondary oocyte must encounter a sperm within _____ of
ovulation. (Sperm can live in the female reproductive tract for up to _____.)

Answer 2

12 to 24 hours; 1 to 3 days

Question 3

The secondary oocyte is protected by two structures, a cluster of cells called the _____
and a clear glycoprotein coat called the _____.

Answer 3

corona radiata; zona pellucida

Question 4

To penetrate the egg, the acrosome of sperm must _____ to release _____. To prevent
early release, each sperm’s acrosome is inactive until _____.

Answer 4

rupture; digestive enzymes;

long after it enters the vagina

Question 5

The acrosomes of sperm cannot rupture until they are exposed for several hours to fluids
in the vagina, uterus, and fallopian tubes. This preparation of the acrosome for use is
called _____.

Answer 5

capacitation

Question 6

Only one sperm will actually fertilize the egg, but that one sperm needs the help of many
others in order to _____ so that it can reach the egg. Essentially, the egg’s defenses fail
when attacked by hundreds of sperm.

Answer 6

dissolve the zona pellucida

Question 7

The membrane covering the acrosome contains receptors which bind to proteins of the
zona pellucida. This binding triggers the _____, which causes the _____.

Answer 7

acrosomal reaction; release of

digestive enzymes

Question 8

The first sperm to penetrate the zona pellucida will bind to a receptor on the oocyte’s
membrane. This triggers two events: the first sperm _____, and other sperm are _____.

Answer 8

enters the oocyte’s cytoplasm;

blocked from entry

Question 9

There are two mechanisms which prevent more than one sperm from entering an oocyte.
The first is the _____, which occurs when the membrane of the _____ and prevents
similar binding by other sperm cells.

Answer 9

fast block to polyspermy;

oocyte depolarizes

Question 10

The _____ block to polyspermy results in the release of _____, which are specialized
vesicles. This leads to the denaturation of the zona pellucida’s proteins, including _____.

Answer 10

slow; cortical granules; the

receptors to which sperm bind

Question 11

The entry of the sperm into the oocyte causes the oocyte to activate. As a result, it _____,
becoming the _____ and producing a small, cytoplasm-free cell, the second polar body.
(Recall that the first one was produced during _____.)

Answer 11

finishes meiosis II; ovum;

oogenesis

Question 12

Inside the oocyte, the sperm’s head and tail separate. The sperm’s nucleus swells to form
the _____, and migrates to the center of the ovum where it joins with the _____ (which
was formed when the oocyte completed meiosis II).

Answer 12

male pronucleus; female

pronucleus

Question 13

It’s not until the male and female _____ fuse to form a diploid nucleus that the joined
sperm and egg can be called a(n) _____ (which means _____).

Answer 13

pronuclei; zygote; fertilized,

diploid egg

Question 14

Fertilization usually occurs in the _____ or _____ of the uterine tube; cell division begins
there, and continues until the growing mass of cells _____.

Answer 14

infundibulum; distal ampulla;
implants in the wall of the
uterus

Question 15

Almost immediately after fertilization, the zygote begins to _____; a small, berry like
structure called the _____ is formed by day 3, and a hollow ball of cells called the _____
has been formed by day 4.

Answer 15

divide rapidly; morula;

blastocyst

Question 16

The formation of the blastocyst is called _____.

Answer 16

blastulation

Question 17

During pre-embryonic development, mitosis and cytokinesis occur without _____. This
process is called _____. As a result, the entire blastocyst, which contains ~100 or so cells,
is roughly _____ .

Answer 17

growth between divisions;
cleavage; the same size that
the ovum was

Question 18

The blastocyst is a hollow ball. The outer wall is the _____, and the cluster of cells inside
is the _____.

Answer 18

trophoblast; inner cell mass

Question 19

The cells of the _____ are still pluripotent, and can form any tissue or even complete
individuals.

Answer 19

inner cell mass

Question 20

The trophoblast will eventually develop into the _____, while the inner cell mass will
eventually form one or more _____.

Answer 20

placenta and supporting

structures; embryos

Question 21

The _____ reaches the uterus around four days after ovulation. It remains there as the
_____ breaks up, during which time it is nourished by uterine secretions.

Answer 21

blastocyst; zona pellucida

Question 22

Implantation begins about 6–7 days after ovulation; in this process, the cells of the
trophoblast which are closest to the inner cell mass _____. This process continues until
the blastocyst is _____, and takes several days.

Answer 22

digest their way into the
endometrium; completely
embedded

Question 23

To prevent menstruation, the cells of the blastocyst release _____ for the first _____
months of pregnancy. This promotes the survival of the corpus luteum until the placenta is
mature enough to produce large amounts of _____ and _____.

Answer 23

human chorionic gonadotropin
(hCG); four; progesterone;
estrogen

Question 24

High levels of estrogen and progesterone can cause an unpleasant side effect in the early
months of pregnancy: _____.

Answer 24

morning sickness

Question 25

The placenta is a temporary organ which forms in the uterus to allow the blood of the mother and the unborn child to _____. It also acts as a(n) _____ to shield the fetus from at least some harmful substances.

Answer 25

exchange chemicals and gases | without mixing; filter

Question 26

Before implantation, the boundary between the inside of the blastocyst and the outside is a single layer of cells called the _____. Eventually, cell division and differentiation lead to a more complex boundary called the _____.

Answer 26

trophoblast; chorion

Question 27

After implantation, trophoblast cells divide rapidly and the outermost cells _____. _____ grow from the surface, and become _____ as surrounding blood vessels are dissolved. This is the very early _____.

Answer 27

fuse to form a syncytium; Villi; bathed in maternal blood; chorion

Question 28

The placenta forms from the _____ and the _____ which lie between the embryo and the wall of the uterus. The _____ in other regions deteriorate, forming the smooth chorion.

Answer 28

endometrium; chorionic villi; | chorionic villi

Question 29

The placenta is fully functional by _____ .

Answer 29

the 3rd month after fertilization

Question 30

The _____ connects the developing embryo to the placenta until birth.

Answer 30

umbilical cord

Question 31

The _____ channels blood from the umbilical cord past the fetal liver, directly to the vena cava.

Answer 31

ductus venosus

Question 32

Together, the foramen ovale, ductus arteriosus, and ductus venosus are known as the _____.

Answer 32

vascular shunts

Question 33

The development of ectoderm, mesoderm, and endoderm from the _____ is called _____, and the embryo is referred to as a(n) _____. All three layers are present roughly _____ after conception.

Answer 33

inner cell mass; gastrulation; | gastrula; 16 days

Question 34

Early in gastrulation, a two-chambered ball of cells on a connecting stalk forms. One chamber is the _____, and the other the _____: the wall between them is the _____, and will actually form the embryo.

Answer 34

amnion; yolk sac; embryonic | disk

Question 35

The _____ is a fluid-filled sac which will eventually surround the fetus. At first the fluid is derived directly from the _____, but by birth much of its volume is _____. It provides cushioning and support, and _____, during development.

Answer 35

amnion; maternal blood; fetal | urine; room to move

Question 36

Cells of the yolk sac form the earliest _____, contribute the formation of the _____, and become the _____ or _____ of the fetus.

Answer 36

blood cells; gut; | spermatogonia; oogonia

Question 37

A projection formed by the yolk sac, the _____, eventually helps to form the umbilical cord and its base becomes the _____.

Answer 37

allantois; urinary bladder

Question 38

The brain and spinal cord begin to form within two weeks of fertilization, a process called _____.

Answer 38

neurulation

Question 39

The cerebrum and other brain regions become recognizable roughly _____ after fertilization, although its development is far from complete - the central sulcus, for example, does not appear until roughly _____ after fertilization.

Answer 39

eight weeks; twenty weeks

Question 40

A rudimentary circulatory system and a beating heart are present by the start of the _____ after fertilization.

Answer 40

4th week

Question 41

Organogenesis is the formation of organs and organ systems; by the end of the _____, all organ systems are recognizable.

Answer 41

embryonic period

Question 42

The medical community assumes that the mother will not know which sexual act led to conception, and calculates fetal age based on the time that has passed since _____. Developmental biologists, however, calculate age based on the time since _____.

Answer 42

the last menstrual period; | fertilization

Question 43

From the beginning of the _____ after conception, when organ systems are _____, the developing child is no longer an embryo, but is instead called a(n) _____.

Answer 43

9th week; present but not yet | fully functional; fetus

Question 44

Survival of the fetus outside the mother is not possible until at least _____ weeks after fertilization, a time referred to as the edge of viability. At this point, major _____ will be required, and lifelong _____ may result even if the child survives.

Answer 44

22; medical intervention; | disability

Question 45

Even late in pregnancy, chemicals and disease affecting the mother can still cause _____: the brain, for example, continues to develop even _____. Chemicals that cause developmental abnormalities in the developing embryo or fetus are ______.

Answer 45

birth defects; after birth; | teratogens

Question 46

The last two months of _____ ('before birth') development include the production of _____ by the lungs, to allow breathing, and the storage of _____ for use as energy and insulation.

Answer 46

prenatal; surfactant; | subcutaneous fat

Question 47

During pregnancy, the uterus enlarges dramatically: the woman’s center of gravity _____ and an accentuated _____ often results.

Answer 47

shifts forward; lumbar curvature | lordosis

Question 48

Heartburn and constipation may result due to _____ and _____ of the GI tract.

Answer 48

displacement; decreased | mobility

Question 49

Upward pressure of the abdominal organs against the diaphragm as pregnancy reaches its final stages causes many women to suffer from _____.

Answer 49

difficult breathing OR dyspnea

Question 50

Near the end of pregnancy, placental production of the hormone relaxin causes _____ and _____ to soften and relax. A side-effect is that _____ of the body also respond.

Answer 50

pelvic ligaments; the pubic | symphysis; other ligaments

Question 51

The placenta produces _____, which helps to promote the maturation of the breasts for lactation and shifts the mother's metabolism to burn more fat, sparing glucose for the fetus.

Answer 51

human placental lactogen (hPL)

Question 52

Metabolic wastes are transferred from the fetal blood to the mother's and so the mother's _____ to cope.

Answer 52

kidneys must produce more | urine

Question 53

_____ during pregnancy can cause difficulties ranging from discomfort to incontinence.

Answer 53

Uterine pressure on the bladder

Question 54

Blood volume increases to accommodate the needs of the fetus, leading to increases in the mother's _____.

Answer 54

blood pressure and heart rate

Question 55

Parturition is the process of giving birth, and usually occurs between _____ and _____ days after the last menstrual period (LMP).

Answer 55

265; 295

Question 56

During the last few weeks of pregnancy, estrogen levels rise, stimulating myometrial cells of the uterus to form _____, and antagonizing progesterone's inhibition of _____.

Answer 56

oxytocin receptors; uterine | contractions

Question 57

As the time of birth approaches, the fetus usually changes position until _____.

Answer 57

the head is below the feet

Question 58

Labor is thought to be triggered by the release of _____ by the fetal adrenals, which causes the placenta to produce _____ which _____, leading to contractions.

Answer 58

corticosteroids; prostaglandins; | irritate the wall of the uterus

Question 59

Contraction of the uterus pushes the fetus against the cervix. _____ signals the posterior pituitary to release _____, which further increases uterine contractions.

Answer 59

Stretching of the cervix; | oxytocin

Question 60

Labor is divided into three stages: the _____, _____ and _____ stages.

Answer 60

dilation; expulsion; placental

Question 61

The dilation stage of labor extends from onset of labor to the time when _____.

Answer 61

the cervix is fully dilated (about | 10 cm in diameter)

Question 62

At some time during the dilation stage, the amniotic sac will _____ (or a medical care worker will see that it happens when dilation is nearly complete, if necessary). This is known as the _____.

Answer 62

rupture; water breaking

Question 63

Uterine contractions lasting ~ 10 to 30 seconds each generally occur _____ early in the dilation stage of labor.

Answer 63

every 15 to 30 minutes

Question 64

The dilation stage of labor varies greatly in length, but the average is _____ .

Answer 64

6 - 12 hours

Question 65

Thinning out and softening of the cervix is called _____ and must occur before or in conjunction with dilation.

Answer 65

effacement

Question 66

The expulsion stage extends from _____ until the time the infant is delivered. As this stage approaches, the urge to assist the labor process with _____ becomes intense. (This urge varies depending on which method is chosen for pain reduction.)

Answer 66

full dilation; the abdominal | muscles

Question 67

Normally, the head is delivered first. Deliveries in which the baby is in another position may require interventions ranging from _____ to _____.

Answer 67

repositioning; surgical delivery

Question 68

Surgical deliveries (_____) are sometimes needed (although it is argued by many that they are not needed nearly so often as they are performed) to ensure that the blood flow to the fetus is not _____.

Answer 68

Cesarean sections; interrupted | during delivery

Question 69

_____ occurs when the infant's head enters the _____ early in the dilation stage of labor.

Answer 69

Engagement; true pelvis

Question 70

Uterine contractions lasting ~ 1 minute each generally occur _____ during the expulsion stage of labor.

Answer 70

every 2 to 3 minutes

Question 71

The expulsion stage of labor is typically_____ in length.

Answer 71

30 minutes to 2 hours

Question 72

_____ refers to the point in time at which the widest part of the infant's head enters the _____ during the expulsion stage of labor.

Answer 72

Crowning; vulva

Question 73

The third and final stage of labor is the _____, in which the placenta and attached fetal membranes, no longer needed, are expelled.

Answer 73

placental stage

Question 74

The newborn baby is called a(n) '_____.'

Answer 74

neonate

Question 75

The placental stage of labor occurs _____ following the birth of the neonate.

Answer 75

within the half hour

Question 76

Within the first few seconds of postnatal life, _____ will cause it to take the first breath, inflating the lungs.

Answer 76

rising carbon dioxide levels in | the neonate's blood

Question 77

Within five minutes of birth in a medical environment, the Apgar score is used to assess the infant’s physiological status based on _____, _____, _____, _____ and _____.

Answer 77

Appearance; Pulse rate; Grimacing reflex; Activity; Respiration

Question 78

Within a half an hour after birth, the umbilical arteries and veins close and begin to fibrose; eventually all that will remain are _____

Answer 78

ligaments

Question 79

A flap of tissue covers the foramen ovale: _____, it is sealed to become the _____.

Answer 79

within a year; fossa ovalis

Question 80

Blood flow through the ductus arteriosus stops within a half hour of birth, and it eventually becomes the _____.

Answer 80

ligamentum arteriosus

Question 81

During pregnancy, high hormonal levels stimulate the growth of the _____ and _____ of the breasts. In addition, the _____ , presumably to make them easy for the infant to find.

Answer 81

glandular structure; adipose tissue; areolae darken and enlarge

Question 82

Prolactin, as its name suggests, promotes _____.

Answer 82

milk production

Question 83

Prolactin production by the anterior pituitary begins before birth, but milk production is limited until _____ after birth.

Answer 83

estrogen and progesterone fall

Question 84

The baby's suckling stimulates the nipples to send signals to the hypothalamus, which responds by causing the posterior pituitary to release _____, and the anterior pituitary to release _____.

Answer 84

oxytocin; prolactin

Question 85

Oxytocin causes the _____ reflex, resulting in the _____ by both breasts.

Answer 85

let-down; expulsion of milk

Question 86

For the first few days after birth, the breasts secrete _____ instead of true milk. This fluid is rich in protein, vitamin A, and protective antibodies which escape digestion in the newborn's stomach and thus offer protection.

Answer 86

colostrum

Question 87

Nursing partially disrupts the _____. However, if nursing is continued, it eventually resumes (although the timing may initially be irregular).

Answer 87

ovarian cycle

Question 88

Although the amniotic fluid and GI tract of the developing newborn contain solid waste, defecation does not normally occur until _____. The first bowel movement consists of this material, called _____; its rapid elimination is promoted by breast milk.

Answer 88

after birth; meconium