Repro 8

Question 1

The human placenta is haemomonochorial, what does this mean?

Answer 1

There is only one layer of trophoblast separating maternal blood from foetal capillary wall

Question 2

What is placenta praevia?

Answer 2

Implantation in lower uterine segment, requires C-section and can cause haemorrhage

Question 3

How is the endometrium prepared for implantation?

Answer 3

“Pre-decidual” cells in preparation for decidualisation

Elaboration of spiral arterial supply

Question 4

What is decidualisation?

Answer 4

A reaction balancing the force of invasion of the trophoblast. can occur in ectopic pregnancy

Question 5

How are the spiral arteries remodelled?

Answer 5

Low resistance vascular bed created

Maintains high flow

Question 6

Describe the development of the foetal membranes?

Answer 6

Initially chorion has villi all round (wk5)
Villi are lost leaving them only in decidua basalis (wk12)
Amnion joins chorion to become one membrane

Question 7

What is twinning?

Answer 7

The degree to which membranes are shared in monozygotic twins

Question 8

What are the three degrees of twinning?

Answer 8

Share both amnion and chorion
Share neither
Share just chorion

Question 9

Describe the placenta in 1st trimester

Answer 9

Established
Barrier still thick
Complete cytotrophoblast layer beneath syncytiotrophoblast

Question 10

Describe the placenta at term

Answer 10

SA for exchange increased lots
Placental barrier thin
Cytotrophoblast layer lost

Question 11

How many umbilical arteries are there? What is their function?

Answer 11

2 - carry deoxygenated blood foetus -> placenta

Question 12

How many umbilical veins are there? What is their function?

Answer 12

1 - carries oxygenated blood placenta -> foetus

Question 13

What are the three main functions of the placenta?

Answer 13

Metabolism
Endocrine
Transport

Question 14

What are the metabolic functions of the placenta?

Answer 14

Synthesis of glycogen, cholesterol and FAs

Question 15

What are the endocrine functions of the placenta?

Answer 15

Production of; hCG, hC Somatomammotrophin, hC thyrotrophin, hC corticotrophin, progesterone and oestrogen

Question 16

What are the functions of human chorioni gonadotrophin?

Answer 16

Supports secretion by corpus luteum
Pregnancy specific and excreted in maternal urine so can be test
Reduces risk of trophoblast disease

Question 17

At what point does the corpus luteum stop producing progesterone and oestrogen? Why?

Answer 17

11th week - placenta takes over

Question 18

How do placental hormones influence maternal metabolism?

Answer 18

Progesterone increases appetite

hCS/hPL increase glucose availability to foetus

Question 19

How is gas exchange limited in the foetus?

Answer 19

Flow-limited i.e. foetal stores are small

Question 20

How is active transport carried out between foetus and mother?

Answer 20

“Transporters” expressed by syncytiotrophoblast; AAs, iron, vitamins

Question 21

How is passive immunity established initially in the foetus?

Answer 21

IgG only - conc. higher in foetal plasma than maternal circulation

Question 22

What is a teratogen?

Answer 22

An agent or factor causing malformation of an embryo

Question 23

List some common teratogens

Answer 23

Thalidomide
Alcohol
Cigarette smoke

Question 24

Why are teratogens significant to the placenta?

Answer 24

As it is not a “true” barrier they can access foetus through it

Question 25

List some infectious agents relevant to the placenta

Answer 25

Varicella zoster Cytomegalovirus Treponema pallidum Rubella

Question 26

How does the maternal cardiovasuclar system change during pregnancy?

Answer 26

Blood volume increase CO, SV and HR increase BP drops T1-2, normal in T3

Question 27

What caues low BP in pregnancy?

Answer 27

Progesterone reduces sytemic vascular resistance

Question 28

What casues the return to normal BP in T3 of pregnancy?

Answer 28

Aortocaval compression by gravid uterus

Question 29

what is the role of the endothelium in pregnancy?

Answer 29

Controls vascular permeability | Contributes to control of vascular tone

Question 30

What is pre-eclampsia?

Answer 30

A defect in placentation; vasoconstriction causing high BP with contracted plasma

Question 31

Which aspects of the maternal urinary system increase during pregnancy?

Answer 31

Renal plasma flow GFR Creatinine clearance Protein excretion

Question 32

Which aspects of the maternal urinary system decrease in pregnancy?

Answer 32

Urea Uric acid Bicarbonate Creatinine

Question 33

What are the consequences of changes to the maternal urinary system in pregnancy?

Answer 33

Progesterone causes hydroureter | Possible pyelonephritis

Question 34

What changes occur in the respiratory system of pregnant women?

Answer 34

``` Diaphragm displaced Diameters of thorax increase Increased ventilation Increased tidal volume Decreased functional residual capacity ```

Question 35

What problems can occur in the respiratory system of pregnant women?

Answer 35

Physiological hyperventialtion; increased CO2 production, progesterone increases respiratory drive

Question 36

How does pregnancy alter carbohydrate metabolism?

Answer 36

Increased maternal peripheral insulin resistance due to action of hPL, switch to alternative fuels

Question 37

What is gestational diabetes?

Answer 37

Carbohydrate intolerance first recognised in pregnancy but not persisting after delivery

Question 38

List some risk factors of gestational diabetes

Answer 38

Prediabetes Hypertension FH of it or type II DM

Question 39

How is lipid metabolism altered in pregnancy?

Answer 39

Increase in lipolysis from T2 | Increased plasma FFAs on fasting

Question 40

How is the thyroid gland alterd in pregnancy?

Answer 40

Thyroid binding globulin production increased T3&4 increased hCG directly affects TSH (can lower it)

Question 41

How does pregnancy alter the haematological state of the mother?

Answer 41

Pro-thrombotic state ++ fibrin at implantation site More fibrinogen & clotting factors Reduced fibrinolysis

Question 42

Why can warfarin not be used in thromboembolic disease during pregnancy?

Answer 42

Crosses the placenta and is teratogenic

Question 43

How can physiological anaemia occur in pregnancy?

Answer 43

Blood volume increase not met with sufficient red cell mass increase