Brainscape's Knowledge GenomeTM


Top Flashcards (Certified)
All Flashcards

BRS Ageing and Development > placentation and parturition > Flashcards

placentation and parturition Flashcards

1
Q

What form of embryonic nutrition leads to the breakdown of maternal endometrial
capillaries to form trophoblastic lacunae?

A

histiotrophic

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

haemotrophic nutrition

A

start of 2nd trimester

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

what type of placenta do humans have?

A

haemochorial

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

histiotrophic

A

Histotroph is the nutritional material accumulated in spaces between the maternal and fetal tissues, derived from the maternal endometrium and the uterine glands. This nutritional material is absorbed by phagocytosis initially by blastocyst trophectoderm and then by trophoblast of the placenta

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

hemotrophic nutrition

A

hemotrophic nutrition is the exchange of blood-borne materials between the maternal and fetal circulations

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Trophoblastic lacunae

A

Large spaces filled with maternal blood formed by breakdown of maternal capillaries and uterine glands
Become intervillous spaces aka maternal blood spaces

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

what is the chorion?

A

The chorion is a double-layered membrane formed by the trophoblast and the extra-embryonic mesoderm

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

what is the difference between the amnion and the chorion

A

The amnion is found on the innermost part of the placenta. It lines the amniotic cavity and holds the amniotic fluid and the developing embryo. … The chorion, on the other hand, is the outer membrane that surrounds the amnion

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

formation of amnion

A

ballon analogy
arises from epiblast
Forms a closed, avascular sac with the developing embryo at one end
Begins to secrete amniotic fluid from 5th week – forms a fluid filled sac that encapsulates and protects the fetus

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

chorion

A

formed from yolk sac derivatives
highly vascularised
gives rise to chorionic villi

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

what is the umbilical chord formed from?

A

allantois
outgrowths of yolk sac
connecting stalk from embryo to chorion
once coated in mesoderm and vascularised becomes umbilical chord

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

chorionic villus formation

A 
Cytotrophoblast forms
finger-like projections 
through 
syncitiotrophoblast layer
Into maternal
endometrium

only cytotrophoblasts have ability to proliferate

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

villus microstructure

A

convulated know of vessels
slow blood flow: enabling exchange
coated in trophoblast

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

what changes occur to terminal villus over pregnancy?

effect of these changes?

A

1 - thins out to 40um diameter (from 200)

2 - trophoblastic covering also thins to only 1-2um separation from maternal blood

enable a rapidly growing embryo in later stages which requires a lot more oxygen, blood flow, nutrients
distance of diffusion reduces

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

maternal blood supply

A

ovarian artery > arcuate> radial> basal> spiral

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

ovarian artery > _____> radial>_____>_______

A

ovarian artery > arcuate> radial> basal> spiral

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

_____ > arcuate>____> ___l> spiral

A

ovarian artery > arcuate> radial> basal> spiral

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

endovascular EVT formation

A

Extra-villus trophoblast (EVT) cells which coat villi invade down
the spiral arteries
form endovascular extra-villus trophoblast cells

this replaces maternal endothelium, smooth muscle

evt coats inside of the vessel

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

what is conversion?

A

maternal spiral arteries invaded by villus trophoblast, replaced by endovascular EVT
conduit for maternal blood flow

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

calcium exchange across placenta

A

Calcium: actively transported against a concentration gradient by magnesium ATPase calcium pump

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

maternal changes

A

Maternal blood volume increases to 40% (near term (20-30% erythrocytes, 30-60% plasma

cardiac output increased by 30%: stroke volume / rate

Pulmonary ventilation increases 40%

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

placenta/ fetus oxygen exchange

A

Placenta consumes 40-60% glucose and O2 supplied

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

why is the fetus able to consume 40-60% of oxygen?

this is a sickening fact!

A

fetal / embryonic haemoglobin has a higher affinity for o2 than maternal

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

what forms chorionic villus and what is its function?

A

invasion of chorionic cytrophoblast cells into maternal endometrium
surface for exchange

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
why does the fetus make rapid respiratory movements when it doesnt need to?
perhaps to practise breathing reflex to aid diaphragm development
26
circulatory system
Placenta acts as site of gas exchange for fetus Ventricles act in parallel rather than series vascular shunts bypass pulmonary & hepatic circulation -> close at birth
27
Gastrointestinal | System
Endocrine pancreas functional from start of 2T, insulin from mid-2T Liver glycogen progressively deposited – accelerates towards term Large amounts of amniotic fluid swallowed –debris and bile acids form meconium (1st poo lining baby's intestines during pregnancy)
28
nervous system
Fetal movements begin late 1T, detectable by mother from ~14 weeks Stress responses from 18 weeks, thalamus-cortex connections form by 24 weeks Fetus does not show conscious wakefulness – mostly in slow-wave or REM sleep
29
resp system
Primitive air sacs form in lungs around 20 weeks, vascularization from 28 weeks Surfactant production begins around week 20, upregulated towards term Fetus spends 1-4h/day making rapid respiratory movements during REM sleep
30
3 aims of labour?
Safe expulsion of the fetus at the correct time Expulsion of the placenta and fetal membranes Resolution/healing to permit future reproductive events
31
role of prostaglandins during labour
Immune cell infiltration Inflammatory cytokine and prostaglandin secretion all aid in labour which has characteristics of a pro - inflammatory reaction
32
first stage of labour
contractions start latent phase: slow dilation of cervis 2/3 cm active phase - rapid dilation 10cm
33
second stage
delivery of fetus | maximal myometrial contractions
34
third stage
Explusion of placenta and fetal membranes | Post-partum repair
35
cervix remodelling
Changes to collagen bundle structure underlie softening, but mechanism unclear from rigid, stretch resistant to softening Ripening : Monocyte infiltration and IL-6 and IL-8 secretion Hylaluron deposition Dilation : Increased hyaluronidase expression -> HA breakdown MMPs decrease collagen content post partum repair recovery of tissue integrity and competency
36
what is MMPs?
matrix mellano proteases
37
Initiation of labour - how does it start?
fetus determines as there are changes in the fetal HPA axis- CRH levels rise exponentially decrease in CRH bidning protein levels so more bioavailable CRH
38
what is CRH?
corticotrophin releasing hormone
39
what is the role of CRH? | 3 things it does
1) promotes fetal ACTH and cortisol release 2) drives placental prodcution of CRH - POSITIVE feedback loop 3) stimulates DHEAS production by fetal adrenal cortex
40
what is a substrate for oestrogen production and is produced by the fetal adrenal cortex this substrates production is stimulated by CRH
``` DHEAS Dehydroepiandrosterone sulphate (DHEAS) is an androgen primarily produced by the adrenal cortex ```
41
what maintains uterine relaxation throughout pregnancy?
HIGH progesterone
42
describe functional progesterone withdrawal
term approaches shift from activating signalling progesterone isoform A to progesterone B, C isoforms. These are repressive isoforms expressed in uterus and cause the uterus to become blind to progesterone action simultaneous rise in estrogen receptor alpha expression
43
summarise progesterone withdrawal as term approaches
PR-A switch to PR-B, PR-C; from activating receptors to repressive receptors suppression of alpha oestrogen receptor expression is also removed Estrogen can then act to transform the myometrium to a contractile phenotype
44
what is ferguson reflex?
The Ferguson reflex is a neuroendocrine reflex in which the fetal distension of the cervix stimulates a series of neuroendocrine responses, leading to oxytocin production
45
what increases oxytocin production
Uterine oxytocin production increases sharply at onset of labour Expression increase is driven by increase in estrogen levels. Release promoted by stretch receptors -> Ferguson reflex
46
what is the oxytocin signalling?
Signals through G-coupled oxytocin receptor (OTR / OXTR)
47
what inhibits oxytocin signalling pre labour?
Pre-labour: progesterone inhibits OXTR expression -> uterus relaxed
48
what promotes uterine OXTR expression?
Rise in estrogen promotes large increase in uterine OXTR expression
49
3 functions of oxytocin
Increases connectivity of myocytes in myometrium (syncytium) Destabilise membrane potentials to lower threshold for contraction Enhances liberation of intracellular Ca2+ ion stores
50
what is relevance of liberation of Ca2+ ion stores by oxytocin?
aids myometrial contraction
51
Primary Prostaglandins synthesized during labour? are PGE2, PGF2alpha and PGI2
PGE2, PGF2alpha PGI2
52
what drives prostaglandin action?
Rising estrogen levels
53
2 ways | rising estrogen levels drives prostaglandin action?
. Rising estrogen activates phospholipase A2 enzyme, generating more arachidonic acid for PG synthesis 2. Estrogen stimulation of oxytocin receptor expression promotes PG release.
54
action of PGE2
cervix re-modelling IL8 release collagen bundle re-modelling leukocyte infiltration into cervix
55
PGF2 alpha action
. destabalises membrane potentials | promotes connectivity of myocytes
56
PGI2
myometrium | between contraction and relaxation allows for myometrial smooth muscle relaxation of lower uterine segment
57
what factors implicated in cervix re-modelling other than prostaglandin
peptide hormone relaxin | nitric oxide
58
what forms a syncytium
myometrial muscle cells - extensive gap junctions | contraction start at fondus
59
what does brachystatic mean? muscle contractions in fetal expulsions are like this what does it do?
Muscle contractions are brachystatic –fibres do not return to full length on relaxation This causes lower segment and cervix to be pulled up forming birth canal
60
what causes area of contact of placenta with endometrium to shrink?
Rapid shrinkage of the uterus after fetal delivery
61
uterine shrinkage causes what two things?
folding of fetal membranes | area of contact of placenta with endometrium to shrink
62
clamping of umbilical cord after birth does what?
stops fetal blood flow to placenta - villi collapse Hematoma formation between decidua and placenta Contractions expel placenta and fetal tissues
63
uterine incolution and cervix repair restore to what?
Shielding uterus from commensural bacteria | Restore endometrial cyclicity in response to hormones
64
what facilitates uterine vessel thrombosis
uterus remaining contracted

BRS Ageing and Development (3 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2025 Bold Learning Solutions. Terms and Conditions