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anatomy > Ch. 29 - Pregnancy selections > Flashcards

Ch. 29 - Pregnancy selections Flashcards

1
Q

describe each trimester in pregnancy

A

First trimester:
* First 3 months of pregnancy
* Zygote becoming embryo and then early fetus

Second trimester:
* Months 4 to 6 of pregnancy
* Growth of fetus and expansion of maternal tissues

Third trimester:
* Months 7 to 9 of pregnancy
* Fetus growing most rapidly
* Mother’s body preparing for labor and delivery

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2
Q

what is the prenatal period 2

A
  • Begins with fertilization and ends 38 weeks later with birth
  • Composed of three shorter periods: Pre-embryonic period, Embryonic period, and Fetal period
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3
Q

describe the pre-embryonic period 3

A
  • first 2 weeks after fertilization
  • Zygote becomes spherical multicellular structured blastocyst
  • Ends when blastocyst implants in uterine lining
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4
Q

describe the embryonic period 3

A
  • weeks 3-8 of development
  • undeveloped versions of major organs appear
  • Now called an embryo
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5
Q

describe the fetal period 3

A
  • Remaining 30 weeks prior to birth
  • Organism is now called a fetus
  • Continues to grow and increase in complexity
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6
Q

How are sperm attracted to the ovulated oocyte? Give examples

A
  • via chemoattractants
  • progesterone: chemokines released from an oocyte
  • allurin: released from the fallopian tubes
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7
Q

what happens WHILE the sperm acrosome pierces the zona pellucida during fertilization

A

After penetration of the secondary oocyte there is Immediate hardening of zona pellucida which prevents other sperm from entering this layer. This ensures only one sperm fertilizes the oocyte.

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8
Q

what is polyspermy

A

when two sperm enter simultaneously; Immediately fatal with 23 triplets of chromosomes

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9
Q

what happens AFTER the sperm penetrates 3

A
  • sperm and oocyte membranes fuse; sperm nucleus enters oocyte
  • Secondary oocyte completing second meiotic division > Forms an ovum
  • sperm and ovum, haploid cells, fuse to form a diploid zygote
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10
Q

describe the 3 phases of fertilization

A

phase 1: sperm penetrates corona radiata.

phase 2: sperm undergoes acrosome reaction and penetrates zona pellucida

phase 3: sperm and oocyte plasma membranes fuse; pronuclei of ovum and sperm fuse

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11
Q

what is the cleavage phase 4

A
  • Series of mitotic divisions of a zygote
  • Increases cell number but not the overall size of the structure; Size only increases after implantation in the uterine wall
  • Zygote divisions start to be named at the 16-cell stage, known as the MORULA > Cells of the morula continue to divide; Develop a fluid-filled cavity (blastocyst cavity)
  • At this stage, the pre-embryo is a blastocyst > (it contains specialized proper cells)
    ->Trophoblast, outer ring of cells surrounding cavity; Will form the chorion
    -> Embryoblast, packed cells within one side of blastocyst; Will form embryo proper; Cells are pluripotent, able to develop into any tissue
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12
Q

describe the process of implantation 5

A
  • Blastocyst enters lumen of uterus by end
    of first week
  • Zona pellucida around blastocyst breaks
    down
  • Blastocyst burrows into the endometrium (implantation)
  • Begins by about day 7
  • By day 9, the blastocyst is completely burrowed into uterine wall; Contacts nutrients in uterine glands
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13
Q

A blastocyst produces Human chorionic gonadotropin (hCG), what is it and why? 4

A
  • hormone that signals reproductive system that implantation occurred
  • Promotes maintenance of corpus luteum mimicking effects of LH. corpus luteum produces estrogen and progesterone to maintain uterine lining
  • Detected in urine by end of 2nd week; Basis of most pregnancy tests
  • Levels high for first 3 months of pregnancy; Then decline, causing corpus luteum degeneration; By then placenta producing own estrogen to maintain pregnancy
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14
Q

when do embryonic membranes develop

what is the yolk sac

what is the amnion

what is the chorion

A

-develop by day 8
Yolk sac:
- 1st extraembryonic membrane; Does not store yolk; site for early blood cell and blood vessel formation

Amnion:
- Eventually encloses entire embryo in amniotic cavity; Protects membrane from drying out; Specialized to secrete amniotic fluid bathing embryo

Chorion:
- Outermost extraembryonic membrane; Cells blend with functional layer of endometrium; Eventually form placenta; Site of nutrient exchange between embryo and mother

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15
Q

functions of the placenta 3

when does it form

A
  • Highly vascular structure
  • Functions: Site of exchange of nutrients, wastes, and respiratory gases between maternal and fetal blood; Transmits maternal antibodies to developing embryo or fetus; Produces estrogen and progesterone to maintain and build the uterine lining
  • Begins to form during 2nd week, is not fully developed until after 3 months
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16
Q

On the placenta, what are Chorionic Villi? 4

A
  • Fingerlike structures formed from chorion > site of nutrient and gas exchange
  • Contain branches of umbilical vessels
  • Maternal blood does not mix with fetal blood > Bloodstreams are so close that nutrients and gases mix
  • O2 diffuses from maternal blood to fetal
    blood > CO2 diffuses from fetal to maternal blood
16
Q

what is gastrulation 3

A
  • occurs during third week
  • Epiblast forms three primary germ layers: Ectoderm, mesoderm, endoderm
  • Three-layered structure called an embryo
17
Q

cells of the embryo: what are endoderm, mesoderm, and ectoderm cells

A

Endoderm: “Internal organs” Epithelial lining of the respiratory tract, GI tract, urinary tract, reproductive tract, tympanic cavity, auditory tube. EX: Liver, gallbladder, pancreas, palatine tonsils, thyroid gland, thymus.

Mesoderm: “Muscle” Dermis of the skin. Epithelial lining of blood vessels, lymph vessels, and serous membranes. EX: muscle tissue, connective tissue, adrenal cortex, heart, kidneys, ureters, internal reproductive organs, spleen.

Ectoderm: “Outside” Epidermis of skin and epidermal derivatives (hair, nails, sweat glands, mammary glands). EX: nervous tissue, sense organs, pituitary gland, adrenal gland, adrenal medulla, the enamel of teeth, the lens of the eye.

18
Q

what is organogenesis 4

A
  • Organ development
  • Begins once layers have formed and cell folding complete
  • By week 8: Upper/lower limbs have adult shape and most organ systems have a rudimentary form
  • sensitive to teratogens: Substances causing birth defects or death such as alcohol, tobacco, drugs, and some viruses
19
Q

describe the fetal period 4

A
  • from month 3 til birth (weeks 9-38)
  • maturation of tissues and organs
  • rapid body growth 2.5 cm > 53 cm
  • Weight increase most striking during last
    two months
20
Q

describe labor 4

A
  • Physical expulsion of fetus and placenta from uterus
  • Typically at 38 weeks for full-term pregnancy
  • Not all uterine contractions lead to true labor
  • Contractions are weak and irregular at first then become more intense and frequent with increasing estrogen and oxytocin
21
Q

what is premature labor 2

A
  • Labor prior to 38 weeks
  • Undesirable; infant’s body system is not fully
    developed
22
Q

define false labor

A

uterine contractions not resulting in 3 stages of labor

23
Q

what are Braxton-Hicks contractions 5

A
  • Irregularly spaced contractions and do not become more frequent
  • Relatively weak and do not increase in intensity
  • Pain limited to the lower abdomen and pelvic region
  • Pain sometimes stops with movement
  • Do not lead to cervical changes
24
Q

describe true labor 3

A
  • Uterine contractions that increase in intensity and regularity, resulting in changes to the cervix
  • Mother AND fetus hypothalamus secretes increasing levels of oxytocin
  • oxytocin stimulates placenta to secrete prostaglandins that stimulate uterine contraction and dilate the cervix
25
Q

the first stage of true labor is the dilation stage, describe it 3

A
  • Begins with onset of regular uterine contractions and ends when cervix is dilated to 10 cm
  • Longest of 3 stages: Nulliparous women experience a longer dilation stage (8 to 24 hours). Parous women average 4 to 12 hours
  • Rupture of amniotic sac and release of amniotic fluid: “Water breaking”; Manually ruptured if necessary
26
Q

describe the expulsion stage of true labor 6

A
  • Begins with complete dilation of the cervix and Ends with expulsion of fetus
  • Usually 30 min to several hours (Nulliparous women with longer stage)
  • Uterine contractions help push fetus through vagina > Facilitated if woman “bears down”
  • Crowning: When first part of baby’s calvarium distends vagina; Head followed by rest of the body
  • Episiotomy sometimes necessary: Perineal muscles surgically incised; Creates wider opening for body
  • Umbilical cord clamped and tied off
27
Q

what is the placental stage of true labor 2

A
  • Occurs after baby is expelled
  • Uterus contracts to displaces placenta from uterine wall
28
Q

what is afterbirth

A
  • Placenta and remaining fetal membranes
  • Expulsion completed within 30 minutes
  • Carefully examined to make sure all
    expelled > Complications may occur if fragments are left
29
Q

describe newborn breathing 5

A
  • Respiratory changes in the neonate > caused by central nervous system reactions to change in environment
  • Fetal lungs are not fully inflated prior to birth
  • Takes breath within 10 seconds of birth
  • Surfactant keeps alveoli open
  • If born earlier than 28 weeks, surfactant
    insufficient: need ventilator until lungs mature
30
Q

what is lactation

A

Production and release of breast milk from
mammary glands

31
Q

where is prolactin produced?
function?
inhibited by?
what hormone does it work with; what do they do

A
  • Produced by anterior pituitary
  • Responsible for milk production
  • inhibited by dopamine
  • Increased by high levels of estrogen
  • Both hormones cause acini proliferation/branching of
    lactiferous ducts
32
Q

what is colostrum 5

A
  • Produced by mammary glands during late pregnancy and the first few days after birth
  • Watery, milk-like substance
  • Lower concentration of fat than true breast milk
  • Rich in immunoglobulins, especially IgA: Infant acquiring passive immunity from the mother
  • Laxative effect, facilitating infant’s first bowel movement
33
Q

what is breast milk 4

A
  • Starts to be produced a few days postpartum
  • Higher fat content than colostrum
  • Has essential fatty acids, enzymes for digestion, and immunoglobulins
  • More easily digestible than breast milk substitutes
34
Q

describe the postive feedback mechanism for milk letdown 4

A
  1. With suckling, stimulates breast mechanoreceptors
  2. Send signals to the hypothalamus to produce oxytocin (posterior pituitary)
  3. Myoepithelial cells in mammary acini contract and release breast milk
  4. infant continues to nurse > Facilitates further milk release

anatomy (17 decks)

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