placenta liquor

Question 1

what is the placenta

Answer 1

organ that is essential for transfer
of nutrients and gases from the
mother to the fetus and for removal
of fetal waste products.

Question 2

what is the endometrium

Answer 2

prepares for implantation during secretory phase of menstrual phase

Question 3

describe what happen in the decidual reaction

Answer 3

trophoblast secrete HCG to support corpus luteum . corpus luteum secretes progesterone until 20 weeks. progesterone and oestrogen trigger hypertrophy of epithelial and stromal cells
stromal cells store lipid and glycogen in the cytoplasm - becoming decidual cells , lining becomes more vascular . nutrient is supplied to endometrial tissues
endometrium is now decidua

Question 4

decidua basalis

Answer 4

site of implantation from maternal side maternal macrophages migrate here

Question 5

decidua peritallis

Answer 5

Rest of former endometrium, lining
the body of the uterus and fundus -
i.e. the side not occupied by the
embryo

Question 6

decidua capsularis

Answer 6

Decidua capsularis
Overlies embryo and chorionic
vesicle
Generally regresses

Question 7

what happens in fertilisation

Answer 7

sperm reaches oocyte and penetrates the zone pellucida. oocyte swells and becomes impenetrable to other sperms . each haploid nucleus transforms into a pronuclei

Question 8

what happens during implantation

Answer 8

Blastocyst progresses along fallopian tube
and into the uterus

Trophoblast cells meet the endometrium -
due to enzyme production and the
stickiness of endometrium, blastocyst
begins to implant

Endometrial folds around blastocyst swell
and epithelial cells multiply above,
forming a cover for the embedded
blastocyst

Trophoblast cells net to the endometrium
become multi-nucleated cells -
syncitiotrophoblast cells

Villi begin to form from syncitiotrophoblasts,
branching into the decidua - which contains
blood vessels

Syncitiotrophoblasts grow down into the basal
layer of the decidua

Lacunae fuse to develop the intervillous space, in
which maternal blood flows

Invading cords of trophoblasts form primary villi,
later branching out to form secondary villi

Corpus luteum gravidiatis continues to secrete
hormones

Question 9

what is the amnion

Answer 9

Inner membrane (closest to fetus)
Can be stripped back to insertion of cord
Derived from inner cell mass
Smooth, transparent
Tougher than chorion
Secretes liquo

Question 10

what is the chorion

Answer 10

Outer membrane (closest to mother)
Derived from trophoblast
Opaque, friable
Roughened by adherent decidua
Lines uterine cavity

Question 11

what is the umbilical cord

Answer 11

Differs to adult circulation in terms of vessels
2 arteries (deoxygenated blood)
1 vein (oxygenated blood)
Usually central insertion into placenta
Wharton’s jelly - protection
30 - 90cm long, 1 - 2cm diameter
Term blood flow usually 350ml/min

Question 12

what anomalies could be in the umbilical cord

Answer 12

Anomalies may include insertion site, false knots, hypercoiling, true knots, only 1 artery, 4 vessels, haematoma

Question 13

what is the maternal side of the placenta

Answer 13

aternal side
Fetal side
Decidua basalis
Darker colour
About 20 lobes - cotyledons
Each cotyledon has own blood supply
Sometimes gritty texture - lime salt deposits
Infarcts may be noted

Question 14

what is the fetal side of the placenta

Answer 14

Villous chorion
Amnion covers surface
White, shiney appearance
Branches of umbilical vessels visible
Cord insertion is on this side

Question 15

what happen in utero

Answer 15

ork?
Fetal side
Maternal blood delivered to decidua via
spiral arteries
Blood flows around intervillous spaces
Fetal blood (deoxygenated) pumped by
fetal heart through umbilical arteries to
capillaries of the chorionic villi
Deoxygenated blood becomes
oxygenated
Oxygenated blood travels through the
umbilical vein to fetus
Waste (i.e.) carbon dioxide drains back into
maternal uterine vein

Question 16

what is the function of the placental membrane

Answer 16

Structure to prevent mixing of fetal and maternal blood

Question 17

what are the 4 layers of placental membrane

Answer 17

4 layers;
Syncitiotrohopblast
Cytotrophoblast
Connective tissue
Endothelium of fetal capillaries

After 20 weeks, the cytotrophoblastic cells disappear & the placental membrane will then only consist of 3 layers

Question 18

what may influence placental blood flow

Answer 18

contractions
hypotension
hypotension

Question 19

what are the function of placenta (respiration )

Answer 19

Deoxygenated fetal blood flowing through the placenta absorbs oxygen
Deoxygenated fetal blood expels carbon dioxide
Removal of waste products

Question 20

what are the function of placenta (nutrition)

Answer 20

mino acids for cell building
Glucose for energy
Calcium & phosphorus for bones & teeth
Iron for blood
Fats cross the placenta less easily
Stores glycogen, which can be converted to
glucose when required

Question 21

what are the function of the placenta (endocrine)

Answer 21

wave footer ornament
Hormone testosterone molecular structural formula
HCG - Large amounts at first to encourage corpus luteum
gravidiatis to continue secreting progesterone and oestrogen.
Reduces as pregnancy progresses

Oestrogen - Secreted in large quantities & takes over from
corpus luteum gravidiatis by 12 weeks

Progesterone - Takes over from corpus luteum gravidiatis by
12 weeks. Levels drop immediately before labour.

Human Placental Lactogen - Growth promoter – rises when
HCG falls.

Question 22

what is the function of the placenta (protection)

Answer 22

Serves as a radiator – 85% fetal heat production
transmitted to mother via placenta

Protects from rejection by mother

Protection from pathogens

Though some (i.e. syphilis & TB) can cross
placenta

Passage of maternal antibodies (IgG) in third
trimester

Question 23

placenta anomalies name them

Answer 23

ACRETA , INCRETA , PERCETA

Question 24

placenta accreta

Answer 24

General term - describes any placenta that is
abnormally adherent to myometrium

Question 25

placenta increta

Answer 25

villi invade myometrium

Question 26

placenta percreta

Answer 26

Villi penetrate myometrial wall & into
surrounding structures such as the bladder
Often occurs when decidua formation is
defective – i.e. implantation over uterine
scars or in lower segment.
Fetal side

Question 27

succentruitate lobe

Answer 27

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Succenturiate Lobe
Fetal side
Small portion of placental lobe
separated from main body

Attached to main placenta through
vessels passing through membrane

Could be retained inutero following
birth, increasing risk of haemorrhage
or sepsis

Question 28

bipartite placenta

Answer 28

Placenta divided into 2 main lobes

Vessels branch off from cord

Also referred to as a ‘bi-lobed’
placenta

Question 29

velamentous insertion

Answer 29

Vessels of the cord break up and run
through the membrane before
reaching the placenta

Can be linked to other conditions
such as vasa praevia

Question 30

vasa pravia

Answer 30

fetal vessels run within membrane in close proximity to the internal os

Question 31

circumvillate

Answer 31

chorion Is not attached to the edge of the placenta . fetal surface is same distance from edge . thickened ring seen on fetal surface

Question 32

battledore

Answer 32

cord insertion is on the edge of the placenta

Question 33

liquor composition

Answer 33

Also known as amniotic fluid
98% water
1-2% organic & inorganic substances
Alkaline
Clear/pale/straw colour
Contains proteins, carbohydrates, lipids & hormones
Vernix & lanugo
Fetus drinks & excretes
Volume around 700-1000ml at term

Question 34

what are the function of the placenta

Answer 34

Cushioning
Temperature
Lubrication
Aid musculoskeletal development
Fluids
Maintain even pressure
Prevent amnion adherence
Barrier to infection

Question 35

what is placental formation

Answer 35

Amnioblasts (cells of amnion) initially actively secrete liquor into
developing amniotic sac

Then, liquor is derived from maternal tissues, through process of
diffusion across membranes and decidua parietalis

Until 20 weeks, liquor passes freely into fetal tissues - until skin then
becomes keratinised

Some of the fluid also comes from fetal urine (from 11 weeks)

Fetal urine, lung secretions will then continue to help maintain the
volume

Question 36

excess fluid in placenta is known as

Answer 36

polyhydramnios

Question 37

reduced amount of amniotic fluid

Answer 37

oligohydramnios