5: Physiology of pregnancy and the peurperium

Question 1

After fertilisation, zygotes divide into a ___ and then a ___.

Answer 1

morula

blastocyst

Question 2

What part of the blastocyst

a) implants in the uterus and becomes the placenta
b) becomes the foetus itself?

Answer 2

a) Trophoblast layer

b) Inner cell mass

Question 3

Where does fertilisation occur?

Answer 3

Ampulla of the uterine tubes

Question 4

Where does implantation occur?

Answer 4

Body of the uterus

Question 5

Which layer of the uterus is invaded by trophoblasts?

Answer 5

Endometrium

Question 6

What are the outer cells of the blastocyst called?

Answer 6

Trophoblasts

Question 7

Why do trophoblasts invade the endometrium?

Answer 7

To make space for the blastocyst

Question 8

While the trophoblasts carve out a space in the endometrium for the blastocyst, what develops in the inner cell mass?

Answer 8

Amniotic cavity

where the foetus itself will develop

Question 9

What is the decidua?

Answer 9

Endometrium during pregnancy

Question 10

What is the chorion?

Answer 10

Outer layer of the embryo

whatever that’s called at the time

Question 11

Which cells break down maternal capillaries to form cavities filled with maternal blood?

Answer 11

Syncytiotrophoblasts

Question 12

What structures extend from the placenta into the endometrium to exchange gas and nutrients with the maternal blood?

Answer 12

Chorionic / placental villi

Question 13

What is another name for placental villi?

Answer 13

Chorionic villi

sampled for genetic analysis

Question 14

What stops foetal and maternal blood from coming into direct contact?

Answer 14

Thin membrane of chorionic villi

Question 15

By which week in development are the placenta and foetal heart functional?

Answer 15

Week 5

Question 16

The framework of the placenta i.e foetal/maternal gas and nutrient exchange via chorionic villi is in place by Week 5.

How does the embryo survive before this?

Answer 16

Trophoblasts have invaded the endometrium

Endometrium is highly concentrated with protein, glycogen and lipids

Question 17

Which hormone, released by the corpus luteum, stimulates the endometrium to concentrate glycogen, protein and lipids?

Answer 17

Progesterone

Question 18

Which structure extends projections into the endometrium to supply the foetus with nutrients and oxygen?

Answer 18

Placenta

Question 19

During development, the foetus’ lungs are deflated.

Which structure plays the role of the lungs?

Answer 19

Placenta

Question 20

What are the relative oxygen concentrations of the maternal and foetal blood?

Answer 20

Maternal blood - greater oxygen concentration

Foetal blood - less oxygen because arterial and venous blood mixes in the placenta

So diffusion occurs from mother to child

Question 21

What are the relative carbon dioxide concentrations of the maternal and foetal blood?

Answer 21

Maternal blood - less carbon dioxide

Foetal blood - more carbon dioxide

So diffusion occurs from foetus to mother

Question 22

What blood vessels are contained in the umbilical cord?

Answer 22

2 umbilical arteries

1 umbilical vein

Question 23

Why does the umbilical cord have two arteries?

Answer 23

Unknown

deal with it

Question 24

Which vessel carries oxygen-rich blood from the placenta to the foetus via the umbilical cord?

Answer 24

Umbilical vein

Question 25

Which **vessels** carry poorly oxygenated blood from the **foetus** to the **placenta** via the **umbilical cord**?

Answer 25

**Umbilical arteries** just like the pulmonary arteries and veins, it's the opposite of normal

Question 26

Once **poorly oxygenated blood** has returned to the mother FROM the foetus via the **umbilical arteries**, which vessels carry it to the maternal IVC?

Answer 26

**Uterine veins --\> Internal iliac veins --\> Common iliac veins --\> IVC**

Question 27

Once **deoxygenated blood** has passed from the **foetus to the** **mother** via the **umbilical arteries --\> placenta**, **which blood vessels carry it to the maternal heart?**

Answer 27

**Uterine veins --\> Internal iliac veins --\> Common iliac veins --\> IVC**

Question 28

What is the main difference between **foetal** and **maternal haemoglobin?**

Answer 28

**Foetal Hb** has a **greater oxygen affinity** than **adult Hb**

Question 29

Why does **foetal Hb** have a greater oxygen affinity than **adult Hb?**

Answer 29

**Foetal haemoglobin interacts less with 2,3-diphosphoglycerate** (2,3-DPG) 2,3-DPG shifts the oxygen-Hb dissociation curve to the RIGHT i.e less affinity So less interaction with 2,3-DPG shifts the curve to the LEFT i.e greater affinity

Question 30

**Foetal blood** has an **(increased / decreased)** concentration of Hb compared to **adult blood.**

Answer 30

**increased concentration of Hb**

Question 31

What is the **Bohr effect**?

Answer 31

**CO2 displaces oxygen from Hb** So increased concentrations of CO2 means decreased affinity of Hb for oxygen

Question 32

In relation to pregnancy, what is the **double Bohr effect?**

Answer 32

Remember that increased CO2 conc. = decreased affinity of Hb for oxygen **Foetus exchanges CO2 with mother via placenta** - **foetal Hb has GREATER affinity for O2 due to decreased CO2 conc.** **Mother accepts CO2 from foetus via placenta down concentration gradient - adult Hb has REDUCED affinity for O2 due to increased CO2 conc** The displaced oxygen from adult Hb is exchanged with the foetus via placenta **Double Bohr effect**

Question 33

What **three factors re: Hb** allow for **oxygenation of the foetus** during pregnancy?

Answer 33

**1. Foetal Hb oxygen affinity \> Adult Hb oxygen affinity** (reduced interaction with 2,3-DPG, shifts curve to the left) ## Footnote **2. [Foetal Hb] \> [Adult Hb]** **3. Double Bohr effect**

Question 34

The **foetus** obtains all the nutrients it requires from the mother via the **placenta**. Toxic substances can also cross the placenta - what are some examples?

Answer 34

**Drugs** e.g thalidomide, tetracycline, anti-epileptics ## Footnote **Alcohol, nicotine, caffeine...**

Question 35

Which **hormone** prevents the degeneration of the **corpus luteum**?

Answer 35

**hCG** Also the hormone used in the pregnancy test

Question 36

Which hormone has important functions re: growth and contributes to **gestational diabetes**?

Answer 36

**hCS** human chorionic somatomammotropin

Question 37

Which hormone is produced by the corpus luteum and allows the endometrium to proliferate?

Answer 37

**Progesterone**

Question 38

Which hormone, released by **theca** cells, allows the **uterus to enlarge** and the **breasts to develop** during pregnancy?

Answer 38

**Oestrogen** which is a group of different hormones

Question 39

Why can **hyperthyroidism** occur in pregnancy?

Answer 39

**hCG levels increase in pregnancy** **hCG has a very similar structure to TSH**; binds to thyroid receptors producing a (mild) effect **\> HYPERTHYROIDISM**

Question 40

In pregnancy, the **oxygen demand** of the mother and foetus increase due to the new foetal circulation. What **cardiovascular adaptions** does the body make to account for this?

Answer 40

**Blood volume --\> Cardiac output _increases_** **Heart rate _increases_** **Blood pressure _decreases_**

Question 41

What supplement do **some** pregnant women, and definitely those with **multiple pregnancy**, require?

Answer 41

**Iron**

Question 42

What is **pre-eclampsia**?

Answer 42

**Pregnancy-induced hypertension, proteinuria and oedema** Caused by compression of the spiral arteries during pregnancy

Question 43

What is the **triad of signs** seen in **pre-eclampsia?**

Answer 43

**Hypertension** **Proteinuria** **Oedema** (esp. hands and feet)

Question 44

If untreated, what does **pre-eclampsia** progress to? What are the signs and symptoms?

Answer 44

**Eclampsia** **Hypertension, seizures, coma** Lethal to both mother and baby

Question 45

How is **pre-eclampsia** managed?

Answer 45

**Regular monitoring of BP, hepatic and renal function, foetal growth** **Anti-hypertensive medication** - labetalol **Early delivery** - 36-38 weeks, can be vaginal or caesarean section

Question 46

How is **labetalol** administered?

Answer 46

**IV** in hospital **PO** otherwise

Question 47

What is the only **definitive treatment** for (pre)eclampsia?

Answer 47

**Delivery**

Question 48

**Pregnant women** (gain / lose) **weight.**

Answer 48

**gain weight**

Question 49

Do **pregnant women** need to "eat for two"?

Answer 49

**No** 250-300kcal extra per day is sufficient

Question 50

Which **hormones** increase **insulin resistance** in pregnant women and may cause **gestational diabetes**?

Answer 50

**Human chorionic somatomammotropin (hCS)** **Cortisol** **GH**

Question 51

Which supplement is given to **pregnant women** to prevent **neural tube defects**?

Answer 51

**Folic acid**

Question 52

**What dose of folic acid is recommended for most pregnant women?**

Answer 52

**400 micrograms**

Question 53

What dose of folic acid is recommended for pregnant women at **increased risk** of delivering babies with neural tube defects?

Answer 53

**5 milligrams**

Question 54

Which **vitamin supplement** is advised for all pregnant women?

Answer 54

**Vitamin D** 40 micrograms / day

Question 55

Which **supplement** is advised in some pregnant women, e.g multiple pregnancy, to prevent anaemia?

Answer 55

**Iron**

Question 56

Which specific **gland** secretes **oxytocin?**

Answer 56

**Posterior pituitary gland**

Question 57

Which hormone **reduces** uterine contractility?

Answer 57

**Progesterone**

Question 58

Which hormones **increase** uterine contractility?

Answer 58

**Oestrogen** **Oxytocin**

Question 59

What **physical stimulus** increases uterine contractility? What does this mean for multiple pregnancy?

Answer 59

**Stretching of the uterus** Twins/triplets/multiples take up more space, increasing the chances of early labour

Question 60

What are **Braxton Hicks**? When in pregnancy do they begin?

Answer 60

**Small contractions** **2nd trimester**

Question 61

Which **chemicals** are involved in the **induction of labour?**

Answer 61

**Prostaglandins**

Question 62

Which a) **hormone** b) **hormone-like chemical** c) **muscle actions** are involved in labour and childbirth?

Answer 62

**a) Oxytocin** **b) Prostaglandins** **c) Uterine contractions**

Question 63

Which **structure** follows the baby after birth?

Answer 63

**Placenta w/ umbilical cord** needs snipped

Question 64

High levels of which hormones **inhibit milk production** during pregnancy?

Answer 64

**Oestrogen and progesterone**

Question 65

Once childbirth has occurred and the levels of **oestrogen and progesterone** drop, which **hormone** can stimulate milk production?

Answer 65

**Prolactin**

Question 66

Which structures produce **a) oestrogen** **b) progesterone** **c) prolactin** **d) oxytocin?**

Answer 66

**a) Theca cells** **b) Corpus luteum** **c) Anterior pituitary gland** **d) Posterior pituitary gland**

Question 67

In terms of breastfeeding, which hormones trigger the a) **production** b) **'let down'** of the milk?

Answer 67

**a) Prolactin** - milk production **b)** **Oxytocin** - milk 'let-down'

Question 68

Which hormone is responsible for the **milk let-down reflex?** What social process is it also responsible for?

Answer 68

**Oxytocin** **Love / bonding** so breastfeeding and birth release floods of oxytocin, encouraging mother-child bonding

Question 69

What is **colostrum**?

Answer 69

**First breast milk produced by mammals post birth** High in protein and immunoglobulins Low in fat (in humans)

Question 70

What is **parturition**?

Answer 70

**Childbirth**