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Semester 4 - Reproductive System > Session 8 - Preggers > Flashcards

Session 8 - Preggers Flashcards

1
Q

How long before blastocyst enters uterine cavity?

A

4-5 days

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2
Q

What does implantation involve, in terms of cell layers?

A

Interaction between trophoblast and epithelium of the uterus

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3
Q

What does trophoblast divide into?

A

Synctiotrophoblast and cytotrophoblast

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4
Q

What does haemomonochorial mean?

A

One layer of trophoblast separates maternal blood from foetal capillary wall

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5
Q

What happens to wall of placenta over time?

A

Placental membrane becomes progressively thinner as the needs of the foetus increase

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6
Q

What is the basic unit of exchange in a placenta?

A

Villi

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7
Q

Outline the development of the villi of the placenta overtime

A

o Primary villi
 Early, finger-like projections of trophoblast
o Secondary villi
 Invasion of mesenchyme into core
o Tertiary villi
 Invasion of mesenchyme core by fetal vessels

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8
Q

What are the three main aims of implantation?

A

Establish the basic unit of exchange
Anchor the placenta
Establish maternal blood flow within the placenta

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9
Q

How is the placenta anchored?

A

By the establishment of outermost cytotrophoblast shell

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10
Q

What are the two main changes in the endometriun which allows placental development ?

A

o Decidualisation

o Remodelling of Spiral Arteries

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11
Q

What is decidualisation

A

Decidual cells develop under the influence of progesterone in the endometrium.
Provides balancing force for the invasive force of the trophoblast

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12
Q

What occurs in remodelling of spiral arteries, and why does this happen?

A

 Creation of low resistance vascular bed

 Maintains the high flow required to meet fetal demand, particularly late in gestation

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13
Q

Name three implantation defects

A

Ectopic pregnancy
Placenta praevia
Incomplete invasion

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14
Q

Outline what occurs in ectopic pregnancy

A

 Implantation at site other than uterine body
 Most commonly fallopian tube
 Can be peritoneal or ovarian
 Can very quickly become a life-threatening emergency

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15
Q

Outline placenta praevia

A

 Implantation in the lower uterine segment
 Can cause haemorrhage in pregnancy
 Requires C-Section delivery

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16
Q

What occurs in incomplete invasion?

A

 Placental insufficiency

 Pre-Eclampsia

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17
Q

Outline the structure of the placenta (x4)

A 
1.	A fetal portion 
  o	Formed by the chorion frondsum
  o	Bordered by the chorionic plate
2.	A maternal portion
  o	Formed by the decidua basalis
  o	The decidual plate is most intimately incorporated into the placenta
18
Q

What exists between chorionic and decidual platers?

A

The intervillous spaces

19
Q

What forms in fourth and fifth months?

A

Decidual septa. which projects into the intervillous spaces but do not reach the chorionic plate

20
Q

What do the decidual septa divida the placenta into?

A

Cotyledons, or compasrtments

21
Q

Describe the first trimester placenta

A

o Placental ‘barrier’ to diffusion still relatively thick

o Complete cytotrophoblast layer beneath syncytiotrophoblast

22
Q

Describe the placenta at full term

A

o Surface area for exchange dramatically increased
o Placental ‘barrier’ is now thin
o Cytotrophoblast layer beneath syncytiotrophoblast lost

23
Q

What do the umbilical arteries and veins project into?

A

Tertiary villi

24
Q

Outline foetal blood vessels

A

Two Umbilical Arteries
o Deoxygenated blood Fetus  Placenta

One Umbilical Vein
o Oxygenated blood Placenta  Fetus

25
Q

How do cotyledons receive their blood?

A

80 – 100 spiral arteries that pierce the decidual plate

26
Q

Describe the factors influencing the passive diffusion of substances across the placenta

A

o Concentration Gradient
 The steeper the gradient, the more diffusion
o Barrier to diffusion
 Placental membrane gradually thins throughout pregnancy as the demand of the fetus increases
o Diffusion distance
 Haemomonochorial

27
Q

What crosses the placenta via simple diffusion?

A 
o	Water
o	Electrolytes
o	Urea and uric acid
o	Gases
   	Flow limited, not diffusion-limited
   	Fetal O2 stores are small – maintenance of adequate flow is essential
28
Q

What crosses the placenta via facilitated diffusion?

A

o Glucose

29
Q

What crosses the placenta via active transport?

A

Specific transporters are expressed by the syncytiotrophoblast
o Amino acids
o Iron
o Vitamins

30
Q

Name five teratogens which can damage foetus

A 
o	Thalidomide
o	Alcohol
o	Therapeutic drugs
o	Drugs of abuse
o	Maternal smoking
31
Q

Name five pathogens which can cross the placenta

A 
o	Varicella zoster
o	Cytomegalovirus
o	Treponema Pallidum
o	Toxoplasma gondii
o	Rubella
32
Q

What are the two types of hormones produced by placenta?

A

Protein hormones

Steroid hormones

33
Q

Name four protein hormones produced by the placenta

A

o Human Chorionic Gonadotrophin (hCG)
o Human Chorionic Somatommotrophin (hCS)
o Human Chorionic Thyrotrophin
o Human Chorionic Cortiotrophin

34
Q

Describe the production and role of hCG

A

 Produced during the first two months of pregnancy
 Supports the secretory function of the corpus luteum
 Produced by syncytiotrophoblast, therefore is pregnancy specific

35
Q

What is the role of hCS?

A

 Influences maternal metabolism, increasing the availability of glucose to the fetus

36
Q

What are the two steroid hormones produced by placenta?

A

Progesterone

Oestrogen

37
Q

What is the main role of placenta produced progesterone

A

 Placenta takes over production from the corpus luteum (Week 11)
 Influences maternal metabolism by increasing appetite

38
Q

Name three substances other than hormones synthesised by the placenta

A

Glycogen
Cholesterol
Fatty acids

39
Q

Describe the hormonal basis of testing for pregnancy

A

o Produced during the first two months of pregnancy
o Supports the secretory function of the corpus luteum
o Produced by syncytiotrophoblast, therefore is pregnancy specific
o Excreted in maternal urine, therefore is used as the basis for Pregnancy Testing

40
Q

What immunological component does the foetus produce by the end of the first trimester?

A

Complement

41
Q

What is the immune defence of the foetus provided by?

A

IgG from the mother, which is transported from mother to foetus at approximately 14 weeks. IgG is transported via receptor mediated pinocytosis.

42
Q

What is haemolytic disease of the newborn?

A

o Rhesus blood group incompatibility of mother and fetus
o Mother previously sensitised to rhesus antigen (e.g. previous pregnancy)
o IgG against rhesus crosses the placenta and attacked foetal RBCs
o Now uncommon because of prophylactic treatment
 Rhesus –‘ve mothers pregnant with Rhesus +’ve fetus given Rhesus specific IgG throughout pregnancy, to prevent sensitisation in the event of exposure to the antigen (The given IgG will bind to antigen before the mother’s immune system can mount a response)

Semester 4 - Reproductive System (30 decks)

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