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A&P Exam 4 > Reproduction > Flashcards

Flashcards in Reproduction Deck (88):
1

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

several hundred million; most
are lost

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 _____.)

12 to 24 hours; 1 to 3 days

3

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

corona radiata; zona pellucida

4

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

rupture; digestive enzymes;
long after it enters the vagina

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 _____.

capacitation

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.

dissolve the zona pellucida

7

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

acrosomal reaction; release of
digestive enzymes

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 _____.

enters the oocyte's cytoplasm;
blocked from entry

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.

fast block to polyspermy;
oocyte depolarizes

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 _____.

slow; cortical granules; the
receptors to which sperm bind

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 _____.)

finishes meiosis II; ovum;
oogenesis

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).

male pronucleus; female
pronucleus

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 _____).

pronuclei; zygote; fertilized,
diploid egg

14

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

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

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.

divide rapidly; morula;
blastocyst

16

The formation of the blastocyst is called _____.

blastulation

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 _____ .

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

18

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

trophoblast; inner cell mass

19

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

inner cell mass

20

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

placenta and supporting
structures; embryos

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.

blastocyst; zona pellucida

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.

digest their way into the
endometrium; completely
embedded

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 _____.

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

24

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

morning sickness

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.

exchange chemicals and gases
without mixing; filter

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 _____.

trophoblast; chorion

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 _____.

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

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.

endometrium; chorionic villi;
chorionic villi

29

The placenta is fully functional by _____ .

the 3rd month after fertilization

30

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

umbilical cord

31

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

ductus venosus

32

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

vascular shunts

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.

inner cell mass; gastrulation;
gastrula; 16 days

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.

amnion; yolk sac; embryonic
disk

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.

amnion; maternal blood; fetal
urine; room to move

36

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

blood cells; gut;
spermatogonia; oogonia

37

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

allantois; urinary bladder

38

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

neurulation

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.

eight weeks; twenty weeks

40

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

4th week

41

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

embryonic period

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 _____.

the last menstrual period;
fertilization

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) _____.

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

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.

22; medical intervention;
disability

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 ______.

birth defects; after birth;
teratogens

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.

prenatal; surfactant;
subcutaneous fat

47

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

shifts forward; lumbar curvature
(lordosis)

48

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

displacement; decreased
mobility

49

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

difficult breathing OR dyspnea

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.

pelvic ligaments; the pubic
symphysis; other ligaments

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.

human placental lactogen (hPL)

52

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

kidneys must produce more
urine

53

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

Uterine pressure on the bladder

54

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

blood pressure and heart rate

55

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

265; 295

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 _____.

oxytocin receptors; uterine
contractions

57

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

the head is below the feet

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.

corticosteroids; prostaglandins;
irritate the wall of the uterus

59

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

Stretching of the cervix;
oxytocin

60

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

dilation; expulsion; placental

61

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

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

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 _____.

rupture; water breaking

63

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

every 15 to 30 minutes

64

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

6 - 12 hours

65

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

effacement

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.)

full dilation; the abdominal
muscles

67

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

repositioning; surgical delivery

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 _____.

Cesarean sections; interrupted
during delivery

69

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

Engagement; true pelvis

70

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

every 2 to 3 minutes

71

The expulsion stage of labor is typically_____ in length.

30 minutes to 2 hours

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.

Crowning; vulva

73

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

placental stage

74

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

neonate

75

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

within the half hour

76

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

rising carbon dioxide levels in
the neonate's blood

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 _____.

Appearance; Pulse rate;
Grimacing reflex; Activity;
Respiration

78

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

ligaments

79

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

within a year; fossa ovalis

80

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

ligamentum arteriosus

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.

glandular structure; adipose
tissue; areolae darken and
enlarge

82

Prolactin, as its name suggests, promotes _____.

milk production

83

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

estrogen and progesterone fall

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 _____.

oxytocin; prolactin

85

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

let-down; expulsion of milk

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.

colostrum

87

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

ovarian cycle

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.

after birth; meconium