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Animal Science > Pregnancy and Parturition > Flashcards

Pregnancy and Parturition Flashcards

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Biology 101 flashcards
1
Q

What is pregnancy?

A

The condition when the female animal develops offspring in the uterus

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2
Q

What is gestation

A

The period from fertilization to parturition that occurs in four main phases

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3
Q

What are the four phases of gestation?

A

1.) Fertilization and early embryonic development

2.) Implantation of the embryo to the uterine wall

3.) Placentation/development of the placenta

4.) Fetal growth

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4
Q

Where does the first step of gestation (fertilization and early embryonic development) occur?

A

Lumen of the female reproductive tract

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5
Q

What does the second step of gestation (implantation of the embryo to the uterine wall) require?

A

Appropriate development/thickening of the endometrial layer

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6
Q

What does the third step of gestation (placentation, or development of the placenta) involve?

A

Development of fetal membranes

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7
Q

When do spermatozoa become motile?

A

After ejaculation

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8
Q

What is the fate of the first arriving spermatozoa?

A

They typically aren’t the ones to accomplish fertilization

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9
Q

What can result in oxytocin release in natural and artificial insemination?

A

Tactile stimulation of the female reproductive tract

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10
Q

What is oxytocin release a result of and what does oxytocin do?

A

It’s released as a result of a neural reflex and it promotes contraction of smooth muscle in the female tubular genitalia to help transport spermatozoa

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11
Q

Nontactile stimuli can release oxytocin from what location?

A

Posterior pituitary gland

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12
Q

What can release and effects of oxytocin be dampened by?

A

Stressors that increase sympathetic tone (sympathetic impulses = fight or flight)

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13
Q

What does presence of semen in the female reproductive tract result in?

A

An immunologic reaction and inflammation

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14
Q

Why is an immunologic reaction present when sperm is in the reproductive tract?

A

To clear the remaining debris as the sperm become nonviable

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15
Q

What is the timeframe for viability and survival times of spermatozoa under normal conditions?

A

They are only viable for a matter of hours and are correlated to the period of sexual receptivity of the female

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16
Q

When does insemination most often occur and why?

A

It most often occurs prior to ovulation so the viable sperm are present when the ova arrive for fertilization

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17
Q

What does the zona pellucida surround?

A

Vitelline membrane (cell membrane/plasma membrane of the ovum)

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18
Q

What is the number of granulosa cells surrounding the zona pellucida called?

A

Cumulus oophorous

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19
Q

How many haploid spermatozoa does the male produce for every stem cell?

A

4

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20
Q

How many mature gametes does the female develop per cycle?

A

1

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21
Q

What is the genetic material that is discarded during ova maturation called?

A

Polar body

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22
Q

What is the zona pellucida?

A

A semipermeable membrane made of glycoproteins

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23
Q

What does the zona pellucida contain?

A

Receptor sites for attachment of sperm and Zona Protein 3 (ZP3)

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24
Q

What does the sperm do after binding to the zona pellucida?

A

The acrosome reaction occurs, which releases enzymes that break down the zona pellucida and allow the passage of sperm to the vitelline membrane

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25
Q

What does the sperm do after penetrating the zona pellucida?

A

The cell membrane of the sperm that will accomplish fertilization fuses with the vitelline membrane of the ovum

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26
Q

What does the fusing of the sperm and the vitelline membrane cause and what does it form?

A

The initiation of the second meiotic division of the ovum, which forms the second polar body

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27
Q

What is polyspermy?

A

Entry of more than one spermatozoon into the ovum

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28
Q

Fusion of the gametes stimulates what?

A

The ovum releases cytoplasmic granules, which depolarizes the plasma membrane of the egg

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29
Q

What is a fast block and what is an example?

A

A fast block stops more sperm from fertilizing as soon as the first sperm attachment

An example is the depolarizing of the plasma membrane

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30
Q

What is an example of a fast and a slow block?

A

An example of a fast block is depolarizing the vitelline membrane to prevent further attachment

An example of a slow block is when depolarization also stimulates an increase in Calcium, which causes vesicles to move toward the cell surface, which causes the release of cytoplasmic granules and ZP3 to become inactive

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31
Q

What is the typical result of polyspermic fertilization?

A

Early embryonic death

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32
Q

What are the three layers of the uterus

A

Perimetrium, myometrium, and endometrium

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33
Q

Where is the perimetrium found?

A

Outside the uterus, but covered by the visceral peritoneum

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34
Q

What is the myometrium and what is it made of?

A

It’s the middle muscular layer of the uterus and it’s made of smooth muscle wall that grows with the fetus

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35
Q

Why are ovary hormones important to the myometrium?

A

It is responsive to ovary hormones. It decreases tone and relaxes with progesterone and increases tone and contracts with estrogen

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36
Q

What does contraction of the myometrium allow?

A

Expulsion of the fetus

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37
Q

What is the endometrium?

A

The innermost mucosal layer of the uterus

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38
Q

What is unique about the endometrium?

A

It thickens and changes under the influence of hormones and provides the attachment site for placental membranes

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39
Q

What are the three stages of the spermatozoa in the fertilization process?

A

Epididymal, Ejaculated, and Capacitated

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40
Q

What does the sperm look like in the epididymal stage?

A

The plasma membrane contains surface proteins and carbohydrates

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41
Q

What does the sperm look like in the ejaculated stage?

A

The surface proteins and carbohydrates from the epididymal stage are coated in seminal plasma proteins that mask parts of the proteins and carbohydrates on the surface

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42
Q

What does the sperm look like in the capacitated stage?

A

The seminal plasma coatings and parts of the surface proteins and carbohydrates are released when in the female tract, exposing the parts of the surface proteins and carbohydrates that can bond to the zona pellucida

43
Q

What stage of the spermatozoa is not understood very well?

A

The capacitated stage

44
Q

What do sperm have to do before they are capable of fertilization?

A

Remain in the female reproductive tract for a period of time after ejaculation

45
Q

What is capacitation?

A

The physiologic process that conveys the capacity to fertilize the ovum by changing or removing parts of the outer acrosome

46
Q

What are the 6 steps of fertilization through the generalized acrosomal process?

A

1.) Sperm makes contact with the egg at the Zona Protein 3

2.) The acrosome reacts with the zone pellucida to break it down with hydrolytic enzymes

3.) The acrosome reacts with the perivitelline space through protein receptors

4.) Plasma membrane of sperm and egg fuse

5.) Sperm nucleus enters the gg

6.) Cortical granules in the egg fuse with the egg’s plasma membrane which makes the vitelline layer impenetrable to sperm

47
Q

What is implantation?

A

Attachment of the blastula to the uterine epithelium and penetration of the epithelium by embryonic tissue

48
Q

What happens before implantation?

A

The ovulated and then fertilized ovum migrates through the lumen of the uterine tubes

49
Q

What does migration through the uterine tubes permit in litter-bearing animals and how is this achieved?

A

Spacing of embryos so each has enough space for development and the insurance that each uterine horn has some embryos

This is achieved through contact or paracrine communication between embryos

50
Q

Implantation is not ________

A

Invasive

51
Q

What is formed during implantation?

A

Cell-to-cell junctions between embryonic tissues and uterine epithelium

52
Q

What is involved in implantation between the mother and the embryo?

A

Binding of membrane proteins in embryonic tissues to receptors on maternal epithelium

53
Q

After fertilization, when does attachment occur in the sow, ewe, cow, and mare?

A

Sow- 11 days
Ewe- 16 days
Cow- 35 days
Mare- 55 days

54
Q

What is placentation?

A

The development of the extraembryonic membranes, called the placenta

55
Q

What is shed along with the placenta at parturition (birth) in some species?

A

A portion of the endometrium

56
Q

What allows for the exchange of nutrients between the fetus and the mother?

A

Areas of attachment between the dam and the fetus

57
Q

What is the relation between fetal and maternal blood vessels?

A

They are separated, but in close proximity

58
Q

What are the three layers of the placenta?

A

Amnion, allantois, and chorion

59
Q

What does the amnion consist of?

A

The amniotic sac surrounding the fetus

60
Q

What does the allantois consist of?

A

The allantoic sac

61
Q

What does the chorion consist of?

A

The outer layer of the placenta that attaches to the lining of the uterus

62
Q

What is the chorion?

A

The outermost placental membrane that is in contact with the maternal uterine endometrium

63
Q

What is the allantois?

A

The middle placental membrane that is a continuous layer that encloses a sac (similar to the pleural and cardiac potential spaces), which is called the allantoic cavity

64
Q

What is the amnion?

A

The innermost membrane that is closest to the fetus. It is a fluid filled cavity that contains the fetus and is fused with the inner layer of the allantois

65
Q

What are the first and second water bag?

A

Fetal membranes at the time of parturition. The allantoic sac is expelled first, so it’s the first bag, and the amniotic sac is expelled second, so it’s the second bag

66
Q

After the embryo reaches the uterus, about how long does it take for attachment to occur?

A

Around 5-7 days

67
Q

What type of placenta do cows have and how does it attach?

A

Cows have a cotyledonary placenta that attaches through button like structures called placentomes.

68
Q

What is the fetal side of the cotyledonary placenta attachment called and what is the maternal side called?

A

The fetal side is called the cotyledon and the maternal side is called the caruncle

69
Q

What type of placenta do horses and pigs have and how does it attach?

A

They have a diffuse placenta that attaches uniformly throughout the placenta and uterus

70
Q

What type of placenta do dogs have and how does it attach?

A

They have a zonary placenta that attaches through a banded region

71
Q

What type of placenta do primates have and how does it attach?

A

They have a discoidal placenta that attaches via a distinct disc shaped region

72
Q

What are the three functions of progesterone during pregnancy?

A

1.) Providing negative feedback to the hypothalamus to inhibit further estrous cycles

2.) Inhibiting smooth muscles in the uterus to permit attachment and development of the fetus

3.) Assisting with the maintenance of the contractility of the cervix to protect the uterine environment

73
Q

When is relaxin present?

A

The last stages of pregnancy

74
Q

What does relaxin do?

A

Stimulates the mammary glands and relaxes the cervix and ligaments to help with birth

75
Q

What type of hormone is relaxin?

A

A protein hormone

76
Q

What species secrete relaxin from what locations?

A

The cow and the sow secrete it from the corpus luteum and the bitch and the mare secrete it from the placenta

77
Q

What is the primary function of relaxin?

A

To prepare for parturition and ultimately lactation by relaxing the ligaments between bones around the birth canal

78
Q

How does relaxin relate to the cervix and birth canal?

A

It contributes to the opening of the cervix and the relaxing of the muscles and ligaments in the birth canal to allow the fetus to pass through

79
Q

When does peak secretion of relaxin occur in some species?

A

Just before parturition

80
Q

What does a gradual increase of relaxin during late gestation do?

A

Facilitates mammary gland development to prepare for lactation

81
Q

What is parturition?

A

The act of giving birth to young that marks the end of a successful pregnancy

82
Q

What are the three steps of parturition?

A

1.) Uterine contractions

2.) Delivery of the newborn

3.) Delivery of the placenta

83
Q

What happens during the uterine contractions stage of parturition

A

Myometrium of the uterus contracts as the cervix relaxes, which presses the fetus into the cervix and causes the cervix to dilate

84
Q

What happens during the delivery of the newborn stage of parturition?

A

In the first stages there are strong uterine contractions and when very close to birth there are strong abdominal contractions

85
Q

What happens to contractions as time proceeds?

A

The increase in frequency and strength, which causes the water bags to rupture

86
Q

What happens during the delivery of the placenta stage of parturition?

A

The placenta separates from the wall of the uterus and is expelled by weaker uterine contractions

87
Q

What happens if the placenta stays in?

A

It causes infection

88
Q

Plasma levels of what type of hormone increase shortly before parturition?

A

Glucocorticoids

89
Q

What types of glucocorticoids are secreted from what organs?

A

Cortisol is secreted from the fetal adrenal cortex and ACTH is secreted from the fetal anterior pituitary gland

90
Q

What do glucocorticoids do?

A

Affect the placenta and the maternal uterus by causing changes to the uterine smooth muscle

They also increase estrogen production by the placenta so estrogen increases relative to progesterone

91
Q

What do glucocorticoids and estrogen act together to do?

A

Promote uterins synthesis and secretion of PGF2a

92
Q

What does PGF2a do?

A

In species where the corpus luteum remains, it causes leutolysis to remove this source of progesterone

93
Q

Why does progesterone need to be removed for parturition?

A

It suppresses activity of uterine smooth muscle, which prevents the fetus from being expelled

94
Q

Besides leutolysis, what else does PGF2a do?

A

Stimulates contraction of uterine smooth muscles to move the fetus to the birth canal, where it promotes dilation of the cervix

95
Q

How do hormones in the blood contribute to a positive feedback regulation loop?

A

Rising blood concentrations of a hormone produce increased release of that hormone

96
Q

What is a positive feedback loop not designed to do?

A

Maintain homeostasis

97
Q

What are the steps of cervix dilation and oxytocin relations during parturition

A

1.) Oxytocin is secreted, which causes uterine contraction

2.) The baby is pushed toward the cervix

3.) Fetal movement and pressure increase cervix dilation

4.) Increased cervix dilation sends nerve impulses to the brain

5.) These nerve impulses stimulate the pituitary gland to release more oxytocin

98
Q

What is uterine involution?

A

The shrinking and contraction of the uterus

99
Q

When does uterine involution begin?

A

Immediately after parturition

100
Q

What helps decrease blood loss after parturition?

A

Myometrium contraction

101
Q

After parturition, what happens at the former placental attachment sites?

A

The endometrium dies, detaches, and sloughs into the lumen of the uterus

102
Q

How long does complete uterine involution take?

A

Weeks to a month

103
Q

When is peak lactation?

A

A month to 3 months after parturition

104
Q

What is hypocalcemia associated with?

A

Decreased uterine involution and a retained placenta

Animal Science (12 decks)

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