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Structures: Part Deux > LEC55: Placenta > Flashcards

LEC55: Placenta Flashcards

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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
what readies endometrium for implantation? when does this occur?
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
26
cause of peeclampsia? clinical significance?
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
27
phases of chorionic villus
1o, 2o, 3o
28
structure of 1o chorionic villus?
2 layers - syncytiotrophoblastic shell, cytotrophoblastic core
29
structure of 2o chorionic villus?
3 layers: mesenchymal core, cytotrophoblastic layer, syncytiogrophoblastic shell
30
structure of 3o chorionic villus?
week 17/20-onward 4 components: syncytiotrophoblastic shell, cytotrophoblastic layer, mesenchymal core & fetal capillaries grow into villi
31
when is fetal capillary-venous network established?
tertiary chorionic villi stage
32
how does umbilical vein connect to placenta?
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
where do tertiary chorionic villi sit?
sinde of intravillus space
34
how does maternal blood \> fetal circulation?
blood pressure shoots maternal blood out of spiral arteries extruded maternal blood bathes fetal capillary beds
35
what is this network?
tertiary chorionic villus
36
what structure do chorionic villi cover?
chorionic sac
37
how much of chorionic sac do chorionic villi cover?
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
name of area where chorionic villi disappear?
chorion laevae, aka smooth chorion
39
area where chorionic villi remain? function?
chorion frondosum, aka villus chorion = area where placenta develops
40
name the structures
41
what occurs in intervillus space?
blood interpolates between villi
42
where is chorionic plate? function?
between fused amnion and chorion spikes of placental tissue grow toward chorionic plate
43
what are cotyledons
areas of intervillus space served by 2 or more chorionic villi
44
how does maternal blood \> fetal veins
blood injected into intervellus space blasted out of vessel bathes capillary beds \> venous system
45
what in maternal-fetal circulation system has highest oxygen content?
UMBILICAL VEIN! not umbilical artery!
46
what is placental membrane?
extrafetal tissues that separate maternal & fetal blood site where placental exchange occurs
47
structure of placental membrane prior to 20 weeks?
syncytiotrophoblast cytotrophoblast villus connective tissue (tertiary) fetal capillary endothelium
48
placental membrane structure \>20 weeks?
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
umbilical vein fxn?
carries oxygenated blood TO fetus
50
umbilical arteries' function?
carry deoxygenated blood FROM fetus
51
composition of umbilical cord?
1 umbilical vein, 2 umbilical arteries
52
wharton's jelly location, function?
mucoid connective tissue protects, cushions maternal blood vessels against compression amt of wharton's jelly decreases as pregnancy progresses
53
incidence of 1 umbilical artery? risks?
1/50, 2% pregnancies increased risk of cardiac defects & of poor growth later in pregnancy
54
what is amnion
aka membranes, bag of waters, or amniotic sac
55
describe growth of amniotic cavity
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
what is the bag of water that breaks?
chorio-amniotic membrane, where amnion and chorionic cavity fuse
57
what must occur to do an amniocentesis?
amnion-chorion must be fused
58
where in endometrium does embryo implant?
decidua basalis
59
what is decidua capsularis
capsule surrounding fetus
60
what is decidua parietalis
most external part of decidua will fuse w/ decidua basalis, allow embryo to fill entire uterine cavity
61
where does amniotic fluid come from?
early, derived form diffusion of fluid from decidua (surrounding tissues) through amnion \> 12 weeks, FETAL URINE!! & excreted lung fluid (\<20%)
62
when does volume of amniotic fluid peak? amount?
36 weeks 1 liter
63
function of amniotic fluid?
provides fluid filled space for fetus to grow provides protection, cushion for baby allows room for lungs to expand
64
amniotic fluid composition?
99% water also desquamated fetal skin cells, carbohydrates, fats, enzymes, hormones, salts (electrolytes, urea)
65
how does amniocentesis work?
draw 20-30cc fluid from amniotic cavity, put in culture desquamated skin cells from fetus grow in culture \> test
66
does mature placenta produce luteotrophic hormone?
LH - no! that's what triggers ovulation
67
uteroplacental circulation
68
describe process of utero-placental circulation

Structures: Part Deux (36 decks)

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