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OBGYN > Embryology & Pregnancy Physio > Flashcards

Embryology & Pregnancy Physio Flashcards

1
Q

How many days after fertilization is pituitary LH stimulating luteal cells to secrete progesterone & estrogen in preparation for implantation

A

10 days

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2
Q

What happens to the trophoblastic cells on day 5 of fertilization

A

they begin to secrete hCG which will take over for the luteal hormones completely by day 10

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3
Q

What does the B subunit of fetal hCG do

A

stimulates corpus luteum to secrete progesterone & estrogen

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4
Q

When does fetal hCG peak during pregnancy

A

in the first 3 mos

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5
Q

What is measured as an index of fetal well-being

A

estriol, th emain placental estrogen

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6
Q

What are the peripheral effects of hormonal changes during the 4th+ months of pregnancy

A
  • massive growth of the uterus (myometrium)
  • increased growth of all components of the breast
  • estrogen/progesterone primarily secreted by the placenta
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7
Q

What is measured as an index of placental well-being

A

hPL (human placental lactogen)
- increases maternal lipolysis & ketogenesis
- decreases maternal energy stores
- anti-insulin actions (gestational DM)

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8
Q

Which peptide hormone secreted by the ovaries during pregnancy is responsible for distention of the pubic symphysis, cervix, & vagina

A

Relaxin (non-essential: this will still happen in the absence of ovarian secretion)

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9
Q

Describe the role of oxytocin near the end of pregnancy

A
  • receptors in the myometrium increase in response to elevated plasma estrogens
  • elevated oxytocin causes uterine prostaglandin secretion to increase (which causes uterine contractions)
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10
Q

Describe the process by which a spontaneous abortion occurs in fetal demise

A

toxic products from the fetus increase prostaglandin release from the uterus which initiate contractions & spontaneous abortion

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11
Q

describe the interaction of estrogen in lactation

A
  • high estrogen increases prolactin secretion
  • estrogen blocks milk synthesis (estrogen drops during parturition/childbirth which withdraws the block on milk synthesis)
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12
Q

Describe how lactation is maintained

A
  • suckling stimulates nipple receptors & transmits to hypothalamus
  • oxytocin & PRL released & GnRH decreased (which decreases FSH & LH)
  • decreased FSH & LH lead to decreased estrogen
  • decreased estrogen leads to anovulation and amenorrhea
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13
Q

Define fertilization

A

Fusion of an ovum and spermatozoon to form a single cell/zygote
- occurs within 24 hrs after ovulation
- goals: restores diploid chromosomes, determines sex, initiates cleavage

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14
Q

List the gestational periods

A
  • Germinal period: 1st - 3rd weeks of development
  • Embryonic period: 4th - 8th weeks of development (most organ/tissues formed & 3 germ layers differentiate)
  • Fetal period: 9th week to term (rapid fetal growth, placental development completed)
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15
Q

What are the main components of the germinal period (1st-3rd weeks)

A
  • cleavage
  • morula formation (12-16 cell stage)
  • blastocyst formation
  • implantation
  • trophoblast & chorion differentiate
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16
Q

How many hours after fertilization does it take to reach the 16-cell stage of cleavage

A

96 hours after fertilization

17
Q

Describe the type of cell the zygote becomes at the 16-cell stage of cleavage

A

Morula
- Inner cells: embryo proper
- Outer cells: trophoblast
- Zona Pellucida: membrane surrounding oocyte, prevents polyspermia & ectopic implantation, disappears at the end of the 5th day of fertilization

18
Q

Describe implantation of the blastocyst

A

embeds in the anterior/posterior wall of uterus near the fundus in the functional layer of the endometrium
- end of 1st week
- during secretory phase (high progesterone)
- endometrium now known as decidua!!!

19
Q

Describe the divisions of the decidua

A
  • Decidua basalis
  • Decidua capsularis (ruptures during labor)
  • Decidua parietalis
20
Q

Summarize the 2nd week of development of a fetus/zygote

A

Week of 2s
- trophoblast differentiates into 2 layers (syn/cytotrophoblast)
- embryoblast forms 2 layers (epiblast & hypoblast)
- extraembryonic mesoderm splits into 2 layers (somatic & splanchnic layers)
- Formation of 3 cavities: amniotic, yolk sac, & chorionic cavities

21
Q

When does the primitive streak appear

A

at day 15
- caudal end of germ disc on epiblast
- groove containing pluripotent cells
- gastrulation = differentiation of cells in streak

22
Q

What is the source of all three germ layers

A

the epiblast
- gives rise to all tissues & organs of the embryo
- differentiates into buccopharyngeal membrane, cloacal membrane, notochord (neural tube)

23
Q

What happens if the allantois/allantoenteric diverticulum remains patent

A

Leakage of urine through the umbilicus

24
Q

Describe the pathophysiology of caudal dysgenesis aka sirenomelia aka mermaid syndrome

A

insufficient mesoderm in the caudal region

25
Q

Describe the pathophysiology of sacrococcygeal teratoma

A

remnants of primitive streak in the sacrococcygeal region forming a tumor of pluripotent cells that produce a teratoma

26
Q

Describe the pathophysiology of anencephaly

A

failure of closure of the neural tube at the cranial region

27
Q

Describe the pathophysiology of spina bifida

A

failure of closure of the neural tube at the cervical to caudal region

28
Q

List some derivatives of the ectoderm

A
  • nervous system
  • hypophysis
  • mammary & cutaneous glands
  • epidermis, hair, nails
  • sensory epithelium of eye, ear, nose
  • epithelium of sinuses, oral & nasal cavities
  • tooth enamel
  • intra oral glands
29
Q

What forms from the sclerotome

A
  • base of skull
  • vertebral column & ribs
  • most of the calvaria (skull vault)
30
Q

What forms from the dermatomyotomes

A
  • dermis of skin & back
  • muscles of back
  • body wall
  • some limb muscles
31
Q

What does the intra-embryonic coelom give rise to (from lateral plate mesoderm)

A

pericardial, pleural, peritoneal cavities

32
Q

The intermediate mesoderm differentiates into what system

A

urogenital system

33
Q

What does the primitive yolk sac from the endoderm differentiate into

A

primitive gut

34
Q

Describe the 5 major divisions of the primitive gut

A
  • pharyngeal gut = tympanic cavity, auditory tube, tonsils, thymus, mouth, tongue, pharynx, thyroid, parathyroid
  • foregut = esophagus, stomach, part of duodenum, liver, gallbladder, pancreas, lining epi of the trachea, bronchi, lung
  • midgut = duodenum, small intestine, appendix, ceacum, ascending colon, R 2/3 of transverse colon
  • hindgut = L 1/3 of transverse colon, descending & sigmoid colon, rectum
  • cloaca = rectum, anal canal, bladder except trigone, urethra, genital tracts

OBGYN (22 decks)

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