LEC55: Placenta Flashcards Preview

Structures: Part Deux > LEC55: Placenta > Flashcards

Flashcards in LEC55: Placenta Deck (68):
1

functions of placenta

1) respiration

2) nutrition

3) endocrine

4) excretion

5) protection

2

respiratory function of placenta?

materal oxygen - fetal CO2 exchange

3

nutrition provided via placenta?

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

4

excretory products from placenta?

fetal waste products, include: 

urea, uric acid, CO2

5

what is placenta's protective function?

prevents passage of some microorganisms, allows passage of protective antibodies 

6

methods of placental transfer?

1) simple diffusion

2) facilitated diffusion 

3) active transport

4) pinocytosis

7

what passes thru placental via simple diffusion?

oxygen, CO2, water

8

what passes thru placenta via facilitated diffusion?

glucose, some electrolytes

9

what passes thru placenta via active transport?

some hormones ie estrogen, progesterone; also iron 

requires energy, usually ATP 

10

what is pinocytosis? what does pinocytosis for placenta?

phagocytic action 

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

11

main types of placental hormones

1) steroid hormones 

2) protein hormones

12

placental steroid hormones?

1) progesterone 

2) estriol* 

*only place in body woman has estrogen as estriol, usually it's estradiol 

13

placental protein hormones?

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

14

fxn of hCG?

pregnancy test hormone

"tells" corpus luteum to maintain progesterone production

15

fxn of hCS?

promotes fetal growth, growth of body

16

fxn of hPL?

early insulin-like hormone for fetus 

helps placenta deal w/ sugar

17

fxn of hCT?

functions as fetus's thyroid

18

fxn of hCACTH?

does job til fetal adrenal glands develop

stimulates cortisol production

19

size of placenta, at term?

500 grams or 1 lb

20

2 parts of the placenta?

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

21

when do trophoblasts invade into endometrium?

week 2

22

composition, function of syncytiotrophoblasts in invasion of endometrium

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

under hCG 

invades decida 

engulfs endometrial glands, maternal blood vessels 

23

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

actively dividing 

gives rise to syncytiotrophoblast layer

24

when does chorionic villi form?

as outer cell mass invades trophoblasts via cytotrophoblasts & syncytiotrophoblasts 

week 2

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 

 

A image thumb
29

structure of 2o chorionic villus?

3 layers: mesenchymal core, cytotrophoblastic layer, syncytiogrophoblastic shell 

 

A image thumb
30

structure of 3o chorionic villus? 

week 17/20-onward 

4 components: 

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

 

A image thumb
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?

 

Q image thumb

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 

Q image thumb

A image thumb
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

A image thumb
68

describe process of utero-placental circulation

A image thumb