• Created by: libsd
  • Created on: 23-01-19 20:20
What are the measurements of a placenta
20cm diameter, 3cm thick, 1/6 babies weight
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What is a placenta
A unique human haemochorial villous circular organ that nourishes and mantains the foetus through the umbilical cord by transferring nutrients and gases from the mother and removes waste
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Maternal side of the placenta
Basal plate, dark red in colour- maternal blood partial seperation of basal decidua, 20/40 cotyledons seperated by sulci on surface and the decidua dips to form septa, cotyledons are made of lobes containing single villus with brances,sometimes lime
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Fetal surface of the placenta
Shiny surface due to amnion covering, branches of umbilical vein and arteries are visible spreading out from the insertion, amnion can be pulled off, chorion cannot be seperated as it is made from the same thromboblastic layer as placenta
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When does the umbilical cord develop
5 weeks
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Where does the umbilical cord come from
The fetal surface to umbilical area of fetus. Originates from duct that lies between the amniotic and yolk sac which transmits the umbilical blood vessles
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What does the umbilical cord do
Transports oxygen and nutrients, removes waste
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Length of umbilical cord
Max length at 30 weeks, between 40-70cm, average 55-60cm, minimum 32cm
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Whats in an umbilical cord
Two arteries, one vein
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What is whartons jelly
Gelatinous substance formed of primary mesoderm, protects blood vessels and gives cord tone
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What is amnion
Inner thin but tough translucent membrane that is rich in collagen and has tensile strength. It is continuous with covering of placenta and slides against chorion. It is a reservoir for arachoidonic acid and is involved in protein synthesis/ secretio
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How thick is amnion
1 layer 0.08-0.12mm
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What is chorion
Outer thick opaque membrane which is continous with chorionic plate that contains blood vessels. Synthesises renin and prostaglandin. Reservoir for progesterone
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Amnion and Chorion
200ml amniotic fluid if not fused, metabolically active, initiation of labour, rich source of enzymes required for prostaglandin production
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What are the functions of amniotic fluid
Provide space for growth and movement, maintain constant temp and pressure, antibacterial, protects foetus
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Amniotic fluid production
Appears at 3 weeks, 7ml at 8 weeks, 10-20ml at 10 weeks, 200ml by 16 weeks, 50ml+ a week to 32 weeks at 700-800ml
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What causes fluid turnover
1000ml/day due to swallowing urine and lung fluid
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What is in amniotic fluid
98-99% water and remainder electrocytes, creatine, bile pigements, renin, glucose, hormones, skin, lanugo and vernix
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Storage function of the placenta
Acts as the liver- stores glucose and glycogen and reconverts, sometimes stores iron and fat soluble vitamins
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Endocrine function of the placenta
Day three after conception. hCG, hPL, hCACTH, progesterone, oestrogen, relacin, lh, essential for fetal growth
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Respiration function of placenta
Gaseous exchange, fetal haemoglobin has a higher afinity to oxygen
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Protection function of placenta
Filter, contains immunoglobins, infection barrier, prevents rejection, lg protects against illnesses mum has had for three months
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Excretion function of placenta
Removal of CO2
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Nutrition function of the placenta
amino acids, selects nutrients, obtains water/vitamins/minerals, broken down nutrients, uses similar amounts of oxygen and glucose as brain, synthesises glycogen/cholesterol/fatty acids/enzymes
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What day does implantation occur
7 days after ovulation and takes 10 days. loss of zona pellucida and rapid proliferation of the trophectoderm from the trophoblast cell mass, adherence of the blastocyst to endometrial surface, erosion of the epithelium of the endometrium
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Trophoblast division
Inner cytotrophoblast, junctional anchoring trophoblast, extravillous invasive trophoblast, outer synciytiotropoblast
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What occurs after implantation
Decidualization, villi erode maternal blood vessels forming lacunae and fill with a nutritional substance from endometrial glands, lacunae fuse to form intervillous spaces
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Tertiary villi
Mesenchyme differentiates into blood vessels to form arteriocapillary netweork and fuse with placental vessels developing in connecting stalks
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What are the 4 layers that seperate blood
Synciytiotropoblast, cytotrophoblast, villi/fetal connective tissue, fetal capillary endothelium
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Succient lobe
extra love away from the main body attached by vesels which run through the membranes
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Circumvallate placenta
Opaque ring on fetal surface
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Battledore insertion
Umbilical cord inserts at edge of placenta
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Velamentous insertion
Cord inserted into membranes, blood vessels run into placenta
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Bipartite placenta
Two distinct lobes
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Card 2


What is a placenta


A unique human haemochorial villous circular organ that nourishes and mantains the foetus through the umbilical cord by transferring nutrients and gases from the mother and removes waste

Card 3


Maternal side of the placenta


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Card 4


Fetal surface of the placenta


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Card 5


When does the umbilical cord develop


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