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HAN 202 > Chapter 28: Pregnancy > Flashcards

Chapter 28: Pregnancy Flashcards

1
Q

Pregnancy

A

events that occur from fertilization until the infant is born

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2
Q

Conceptus

A

the developing offspring

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3
Q

Gestation period

A

time from the last menstrual period until birth (about 280 days)

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4
Q

embryo

A

conceptus from fertilization through week 8

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5
Q

fetus

A

conceptus from week 9 through birth

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6
Q

From egg to zygote

A
  • > The oocyte is viable for 12 to 24 hours
  • > sperm is viable 24 to 48 hours after ejaculation
  • > for fertilization to occur, coitus must occur no more than
  • 2 days before ovulation
  • 24 hours after ovulation
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7
Q

fertilization

A

when the sperms chromosomes combine with those of a secondary oocyte (immature egg) to form a fertilized egg (zygote)

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8
Q

sperm transport

A
  • > propelled by whiplike tail movements of their flagella
  • > Forceful uterine contractions which disperse them throughout uterine cavity
  • > Ejaculated sperm (40- 500 million):
  • Leak out of the vagina immediately after deposition
  • Are destroyed by the acidic vaginal environment
  • Fail to make it through the cervical mucus
  • Are dispersed in the uterine cavity or destroyed by phagocytes
  • Few (100 to a few thousand) reach the uterine tubes
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9
Q

accomplishing fertilization

A

-> sperm need to pass 2 layers (corona radiata and zona pellucida) to reach oocyte

  • > sperm must be capacitated before they can penetrate the oocyte
  • secretions of the female tract weaken acrosome membrane

*capacitation: sperm membranes become fragile so hydrolytic enzymes can be released

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10
Q

acrosomal reaction

A

sperm binds to zona pellucida, releases enzymes that digest holes in this layer

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11
Q

sperm penetration

A
  • > an acrosomal process forms and binds to receptors on oocyte’s plasma membrane
  • > sperm and oocyte membranes fuse
  • > nucleus is pulled into oocyte cytoplasm
  • > only 1 sperm is allowed to penetrate the oocyte (monospermy)
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12
Q

Once sperm enter oocyte

A
  • > waves of Ca+ are released into oocyte’s cytoplasm this activates:
    1. oocyte to prepare for 2nd meiotic division
    2. cortical reaction- Zonal inhibiting proteins (ZIPS) are released, this blocks other sperm from entering
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13
Q

embryonic development

A

Cleavage:

  • rapid mitotic divisions of zygote without increase in size (dosen’t get bigger bc still in fallopian tube so it still needs to be able to travel)
  • this increases surface area, increases # of cells
  • easier for uptake in nutrients, O2, and removal of wastes
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14
Q

cleavage

A

zygote -> blastomeres (36 hours) 2 to 8 cells -> morula (72 hours) 16 or more cells -> blastocyste (4-5 days) fluid filled hollow sphere, this reaches the uterus

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15
Q

Twins

A
  • Identical: one egg/ one sperm
  • fraternal: 2 eggs/ 2 sperm
  • conjoined: split occurs late
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16
Q

blastocyst

A
  • Trophoblast cells- single layer of flat cells
  • immunosuppressive
  • participate in placenta formation
  • Inner cell mass
  • becomes the embryonic disc
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17
Q

ectopic pregnancy

A

fertilized egg implants itself in fallopian tubes. usually winds up being miscarriage

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18
Q

implantation

A
  • blastocyst floats for 2-3 days
  • nourished by uterine secretions
  • implantation begins 6-7 days after ovulation
  • trophoblast adheres to the endometrium
  • secrete enzymes which irritate the endometrium
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19
Q

Which of the following stages is the true moment of fertilization?

A

Once the chromosomes of the male and female pronuclei are united

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20
Q

What happens if 2 sperm penetrate the egg?

A

The zygote would be non functional

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21
Q

Capacitation refers to changes occurring in ______.

A

sperm before fertilization

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22
Q

Hormonal changes during pregnancy

A

Human chorionic gonadotropin (hCG):
-secreted by trophoblast cells, later the chorion

  • prompts corpus luteum to continue secretion of progesterone and estrogen
  • hCG levels rise until the end of the second month, then decline as the placenta begins to secrete progesterone and estrogen
  • hCG levels are used in pregnancy tests
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23
Q

placentation

A

Formation of the placenta from embryonic and maternal tissues
1. embryonic tissues: the chorion (develop from the inner cell mass)… comes from baby

  1. Maternal tissue: decidua basalis… comes from mother

**mother and baby’s blood supply do not mix

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24
Q

After successful implantation has occurred, the corpus luteum is maintained by the hormone ______ secreted by the trophoblast cells.

A

hCG (human chorionic gonadotropin)

25
Q

Which of the following develops into the embryo?

A

Inner cell mass

26
Q

Gastrula to fetus

A

gastrulation:
-during implantation, the blastocyst starts to convert to a gastrula

  • inner cell mass develops into the embryonic disc (subdivides into epiblast and hypoblast)
  • the 3 primary germ layers and the extraembryonic membranes develop (week 3)
27
Q

extraembryonic membranes

A
  1. Amnion- forms amnionic sac
  2. yolk sac- forms part of digestive tube
  3. Allantois-unbilical cord
  4. chorion- helps form the placenta
    - all formed within the first 2-3 weeks of development
28
Q

gastrulation

A

embryonic disic (2 layer) becomes a 3-layered embryo (endoderm, mesoderm and ectoderm)

-appearance of primitive streak (dorsal groove)

  • Notochord:
  • mesoderm cells
  • form axial support
29
Q

ectoderm

A

nervous system and skin epidermis

30
Q

endoderm

A

epithelial linings of the digestive, respiratory, and urogenital

31
Q

mesoderm

A

forms all other tissues i.e: muscles

32
Q

endoderm and ectoderm are considered epithelia

A

true

33
Q

organogenesis

A

-formation of body organs and systems

  • at 8th week
  • all organ systems are recognizable
  • end of the embryonic period
34
Q

ectoderm

A

Neurulation:
-first major event of organogenesis

  • gives rise to brain and spinal cord
  • neural plate folds inward as a neural groove and fuse into neural tube
  • neural crest cells-> cranial, spinal, and sympathetic ganglia, and adrenal medulla
35
Q

Neural tube defects

A

Tx: folic acid

spina bifida

36
Q

Which of the following structures form the placenta?

A

Chorion and decidua basalis

37
Q

Embryonic ectoderm gives rise to the ________ in the adult organism.

A

skin and nervous tissue

38
Q

Which of the following is the first major event in organogenesis?

A

Neurulation

39
Q

what tissue does the heart come from

A

mesoderm

40
Q

development of fetal circulation

A
  • first blood cells arise in the yolk sac
  • by the end of the third week
  • embryo has a system of paired vessels
  • can hear baby’s heart beat
  • unique vascular modifications
  • ** umbilical arteries (deoxygenated blood)
  • **umbilical vein (oxygenated blood)
41
Q

Relaxin (placenta)

A
  • causes pelvic ligaments and the pubic symphysis to relax to ease birth passage
  • increase in lordosis
  • reproductive organs become engorged with blood
  • pigmentation may increase
42
Q

physiological changes: GI TRACT

A

Morning sickness due to elevated levels of estrogen and progesterone

43
Q

physiological changes: URINARY SYSTEM

A

increased in Urine production due to increased metabolism and fetal wastes, Stress incontinence

44
Q

physiological changes: RESPIRATORY SYSTEM

A

Tidal volume increases; Dyspnea (difficult breathing) may occur later in pregnancy.

45
Q

physiological changes: CARDIOVASCULAR SYSTEM

A

Blood volume increases 25–40%; Blood pressure and pulse rise; Venous return from lower limbs may be impaired

46
Q

Teratogens

A
  • Harmful substances that can cross placental barriers and enter the fetal blood which may cause congenital abnormalities or even death:
  • Alc- mental retardation
  • nicotine- hinders O2 delivery
  • medications-sedatives, antihypert
  • thalidomide: sedative of 1960s to prevent morning sickness
47
Q

parturition

A
  • Parturition giving birth to the baby
  • Labor events that expel the infant from the uterus
  • Stages of labor:
    1. dilation
    2. expulsion
    3. placental
48
Q

Initiation of labor

A

During the last few weeks of pregnancy:

  • Fetal secretion of cortisol stimulates the placenta to secrete more estrogen
  • causes production of oxytocin receptors
  • antagonizes calming effects of progesterone, leading to Braxton Hicks contractions (weak irregular contractions) in uterus- false labor
49
Q

Initiation of labor

A

Surfactant protein A:
-from fetal lungs causes softening of the cervix

Fetal oxytocin:
-causes the placenta to produce prostaglandins

  • > maternal emotional and physical stress
  • activates the hypothalamus, causing oxytocin release, causing powerful uterine contractions
  • positive feedback mechanism occurs
50
Q

Stages of labor

A
  1. Dilation
    - longest stage can last 6-12 hours or more
  2. expulsion
    - lasts about 30 min
  3. Placental-afterbirth. occurs about 30 min later
51
Q

stages of labor: dilation stage

A
  • Initial weak contractions:
  • 15-30 min apart, 10-30 seconds long
  • become more vigorous and rapid
  • cervix dilates fully to 10 cm
  • amnion ruptures, releasing amniotic fluid- “water breaking”
  • engagement occurs: head enters the true pelvis
52
Q

Stages of labor: expulsion stage

A
  • strong contractions every 2-3 min, about 1 min long
  • urge to push increases (in absence of local anesthesia)
  • crowning occurs when the largest dimension of the head distends vulva
  • lasts about 30-50 min
  • delivery of infant
53
Q

stages of labor: placental stage

A
  • strong contractions continue, causing detachment of the placenta
  • delivery of the afterbirth (placenta and membranes) occurs about 30 min after birth
  • all placenta fragments must be removed to prevent postpartum bleeding
54
Q

placenta previa

A
  • placenta formation adjacent to uterus

- presents a problem when uterus and cervix stretch may cause separation of placenta

55
Q

Neonatal period

A

4-week period immediately after birth

-physical status is assessed 1-5 minutes after birth

  • apgar score: 0-2 points each for
  • heart rate
  • respiration
  • color
  • muscle tone
  • reflexes
56
Q

First breath

A

increase in CO2-> central acidosis -> stimulates respiratory control centers to trigger the first inspiration
*Surfactant in alveolar fluid helps reduce surface tension

Respiratory rate: ~45 per minute for first two weeks, then declines
*Premies usually put on respirators, lungs still immature

57
Q

Lactation

A
  • production of milk by the mammary glands
  • anterior pituitary releases prolactin

-oxytocin causes the letdown reflex-actual ejection of milk from mammary glands

  • colostrum:
  • yellowish secretion rich vitamin A, protein, minerals, and IgA antibodies
  • released the first 2-3 days
58
Q

what is the definition of cleavage

A

A period of fairly rapid mitotic divisions of the zygote without intervening growth

59
Q

Which does not occur during gastrulation?

A

Zygote formation

HAN 202 (13 decks)

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