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Structures: Part Deux > LEC55: Placenta > Flashcards

LEC55: Placenta Flashcards

1
Q

functions of placenta

A

1) respiration
2) nutrition
3) endocrine
4) excretion
5) protection

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2
Q

respiratory function of placenta?

A

materal oxygen - fetal CO2 exchange

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3
Q

nutrition provided via placenta?

A

glucose, amino acids from mother, thru placenta, so baby can build proteins

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4
Q

excretory products from placenta?

A

fetal waste products, include:

urea, uric acid, CO2

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5
Q

what is placenta’s protective function?

A

prevents passage of some microorganisms, allows passage of protective antibodies

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6
Q

methods of placental transfer?

A

1) simple diffusion
2) facilitated diffusion
3) active transport
4) pinocytosis

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7
Q

what passes thru placental via simple diffusion?

A

oxygen, CO2, water

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8
Q

what passes thru placenta via facilitated diffusion?

A

glucose, some electrolytes

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9
Q

what passes thru placenta via active transport?

A

some hormones ie estrogen, progesterone; also iron

requires energy, usually ATP

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10
Q

what is pinocytosis? what does pinocytosis for placenta?

A

phagocytic action

immunoglobulins - early immune system, from mother - transfer to fetus

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11
Q

main types of placental hormones

A

1) steroid hormones
2) protein hormones

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12
Q

placental steroid hormones?

A

1) progesterone
2) estriol*
* *only place in body woman has estrogen as estriol, usually it’s estradiol *

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13
Q

placental protein hormones?

A

1) hCG, human chorionic gonadotropin
2) hCS, human chorionic somatotropin
3) hPL, human placental lactogen
4) hCT, human chorionic thyrotropin
5) hCACTH, human chorionic corticotropin

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14
Q

fxn of hCG?

A

pregnancy test hormone

“tells” corpus luteum to maintain progesterone production

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15
Q

fxn of hCS?

A

promotes fetal growth, growth of body

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16
Q

fxn of hPL?

A

early insulin-like hormone for fetus

helps placenta deal w/ sugar

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17
Q

fxn of hCT?

A

functions as fetus’s thyroid

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18
Q

fxn of hCACTH?

A

does job til fetal adrenal glands develop

stimulates cortisol production

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19
Q

size of placenta, at term?

A

500 grams or 1 lb

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20
Q

2 parts of the placenta?

A

1) fetal part, chorionic villi, from cytotrophoblast & synciciotrophoblast
2) maternal part, decidua basalis, endometrium that has become rich, lush, ready for implantation; enriched w/ glycogen under progesterone influence, transforms endometrium > decidua

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21
Q

when do trophoblasts invade into endometrium?

A

week 2

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22
Q

composition, function of syncytiotrophoblasts in invasion of endometrium

A

finger-like projections that’re made of mass of cytotrophoblastic material

under hCG

invades decida

engulfs endometrial glands, maternal blood vessels

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23
Q

what do cytotrophoblasts do, what does it give rise to?

A

actively dividing

gives rise to syncytiotrophoblast layer

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24
Q

when does chorionic villi form?

A

as outer cell mass invades trophoblasts via cytotrophoblasts & syncytiotrophoblasts

week 2

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25
Q

what readies endometrium for implantation? when does this occur?

A

during secretory phase:

1) hCG and progesterone cause endometrium to secrete glycogen via uterine glands
2) spiral arteries form - maternal blood surges through, causes spiraling shape of vessels

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26
Q

cause of peeclampsia? clinical significance?

A

if remodeling of blood vessels from straight > spiral does not occur, > preeclampsia

elevated maternal BP, protein spillage in urine, taking on fluid all over body

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27
Q

phases of chorionic villus

A

1o, 2o, 3o

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28
Q

structure of 1o chorionic villus?

A

2 layers - syncytiotrophoblastic shell, cytotrophoblastic core

29
Q

structure of 2o chorionic villus?

A

3 layers: mesenchymal core, cytotrophoblastic layer, syncytiogrophoblastic shell

30
Q

structure of 3o chorionic villus?

A

week 17/20-onward

4 components:

syncytiotrophoblastic shell, cytotrophoblastic layer, mesenchymal core & fetal capillaries grow into villi

31
Q

when is fetal capillary-venous network established?

A

tertiary chorionic villi stage

32
Q

how does umbilical vein connect to placenta?

A

umbilical vein connects to veins of the tertiary villus; veins connected w/ fetal capillary beds hook up to arteries, join w/ arteries in umbilical cord

33
Q

where do tertiary chorionic villi sit?

A

sinde of intravillus space

34
Q

how does maternal blood > fetal circulation?

A

blood pressure shoots maternal blood out of spiral arteries

extruded maternal blood bathes fetal capillary beds

35
Q

what is this network?

A

tertiary chorionic villus

36
Q

what structure do chorionic villi cover?

A

chorionic sac

37
Q

how much of chorionic sac do chorionic villi cover?

A

initially, villi cover entire outer surface of embryo

as embryo expands, villi degenerate - that area = chorion laevae (smooth chorion)

develop into placenta over chorion frondosum (villus chorion)

38
Q

name of area where chorionic villi disappear?

A

chorion laevae, aka smooth chorion

39
Q

area where chorionic villi remain? function?

A

chorion frondosum, aka villus chorion

= area where placenta develops

40
Q

name the structures

A
41
Q

what occurs in intervillus space?

A

blood interpolates between villi

42
Q

where is chorionic plate? function?

A

between fused amnion and chorion

spikes of placental tissue grow toward chorionic plate

43
Q

what are cotyledons

A

areas of intervillus space served by 2 or more chorionic villi

44
Q

how does maternal blood > fetal veins

A

blood injected into intervellus space

blasted out of vessel

bathes capillary beds

> venous system

45
Q

what in maternal-fetal circulation system has highest oxygen content?

A

UMBILICAL VEIN! not umbilical artery!

46
Q

what is placental membrane?

A

extrafetal tissues that separate maternal & fetal blood

site where placental exchange occurs

47
Q

structure of placental membrane prior to 20 weeks?

A

syncytiotrophoblast

cytotrophoblast

villus connective tissue (tertiary)

fetal capillary endothelium

48
Q

placental membrane structure >20 weeks?

A

cytotrohpoblasts disappear (attenuated)

fetal capillaries in intervillus space b/c growing toward syncytiotrophoblast

vasculosyncytial placental membrane of syncytiotrophoblast, villous connective tissue, fetal capillary endothelium remains

mesoderm in some areas

49
Q

umbilical vein fxn?

A

carries oxygenated blood TO fetus

50
Q

umbilical arteries’ function?

A

carry deoxygenated blood FROM fetus

51
Q

composition of umbilical cord?

A

1 umbilical vein, 2 umbilical arteries

52
Q

wharton’s jelly location, function?

A

mucoid connective tissue

protects, cushions maternal blood vessels against compression

amt of wharton’s jelly decreases as pregnancy progresses

53
Q

incidence of 1 umbilical artery? risks?

A

1/50, 2% pregnancies

increased risk of cardiac defects & of poor growth later in pregnancy

54
Q

what is amnion

A

aka membranes, bag of waters, or amniotic sac

55
Q

describe growth of amniotic cavity

A

forms during bilaminar embryo stage

grows as embryo grows

forms “C” around embryo

tightly opposes umbilical cord

eventually, fuses w/ chorion, completely obliterates chorionic cavity

56
Q

what is the bag of water that breaks?

A

chorio-amniotic membrane, where amnion and chorionic cavity fuse

57
Q

what must occur to do an amniocentesis?

A

amnion-chorion must be fused

58
Q

where in endometrium does embryo implant?

A

decidua basalis

59
Q

what is decidua capsularis

A

capsule surrounding fetus

60
Q

what is decidua parietalis

A

most external part of decidua

will fuse w/ decidua basalis, allow embryo to fill entire uterine cavity

61
Q

where does amniotic fluid come from?

A

early, derived form diffusion of fluid from decidua (surrounding tissues) through amnion

> 12 weeks, FETAL URINE!! & excreted lung fluid (<20%)

62
Q

when does volume of amniotic fluid peak? amount?

A

36 weeks

1 liter

63
Q

function of amniotic fluid?

A

provides fluid filled space for fetus to grow

provides protection, cushion for baby

allows room for lungs to expand

64
Q

amniotic fluid composition?

A

99% water

also desquamated fetal skin cells, carbohydrates, fats, enzymes, hormones, salts (electrolytes, urea)

65
Q

how does amniocentesis work?

A

draw 20-30cc fluid from amniotic cavity, put in culture

desquamated skin cells from fetus grow in culture > test

66
Q

does mature placenta produce luteotrophic hormone?

A

LH - no! that’s what triggers ovulation

67
Q

uteroplacental circulation

A
68
Q

describe process of utero-placental circulation

A

Structures: Part Deux (36 decks)

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