Week 3 - D - Physiology of pregnancy and lactation (placenta,hormones, matneral, nutrition, lactation)

Question 1

Where does the egg meet the sperm? What is this known as?

Answer 1

Fertilization occurs in the ampulla of the Fallopian Tube. This is known as fertilisation

Question 2

What does the zygote formed from fertilisation of the egg divide into to become the blastocyst? How many cells is this structure? What day is this structure formed by?

Answer 2

The zygote divides to become the morula - this is a 8-16 cell stage at around day 3/4 after ovulation

Question 3

What are the five major stages of embryonic development?

Answer 3

Gametogenesis Fertilisation Cleavage Gastrulation - formation of the germ layers Organogenesis

Question 4

What day is the blastocyst formed by? When is the earlies possible day of implantation? What is normally the day of implantation of the fertilised egg?

Answer 4

The blastocyst should be formed by day 5/6 after ovulation Earliest possible day of implantation is day 6 (hence why copper coil can be used for up to 5 days after the earliest expected date of ovulation - unethical to kill the implanted foetus)

Question 5

After implantation, if you look into the uterine cavity, can you see the blastocyst ? Once the egg is ovulated, what sweep it into the oviduct?

Answer 5

The egg is swept into the oviduct by the fimbriae - the fimbraie surround the ostium of the fallopian tube

Question 6

The blasocyst has an outer cell structure known as the trophoblast and an inner cell mass What is the inner cell mas known as and what does it go on to develop? What does the outer cell mass go on to develop?

Answer 6

The inner cell mass known as the embryoblast goes on to develop the embryo

The outer cell mass known as the trophoblast burrows into the endometrium and becomes the placenta

Question 7

The trophoblast has two layers - the cytotrophoblast and the syncytiotrophoblast

• Which is the inner layer?
• Which is the outer layer which actively invades the endometrium?

Which layer produces b-HCG and progesterone?

Answer 7

The inner layer of the trophoblast is the cytotrophoblast

The outer layer that invades the endometrium and produces b-HCG and prgesterone (which maintains the endometrium lining) is known as the syncytiotrophoblast

Question 8

* When the free-floating blastocyst adheres to the endometrial lining, cords of trophoblastic cells begin to penetrate the endometrium. * Advancing cords of trophoblastic cells tunnel deeper into endometrium, carving out a hole for the blastocyst. The boundaries between cells in the advancing trophoblastic tissue disintegrate.

What is the sac which covers the baby known as?

Answer 8

The amnion - covers the embryo The chorion covers the embryo+placenta (foetal portion of placenta is known as the chorion sometimes)

Question 9

When implantation is finished the blastocyst is completely buried in the endometrium By what day will the blastocyst be fully embedded in the endometrial wall? What are the structures that sprout from the chorion to provide maximum contact area with maternal blood known as?

Answer 9

The blastocyst will be fully embedded in the endometrial wall by day 12 after ovulation Chorionic villi sprout from the chorion to provide maximum contact area with maternal blood

Question 10

* Placenta is formed from embryo – True or false? * Placenta helps in nutrition of the growing embryo from fertilisation - True or false? * Placenta is fetal heart - True or false?

Answer 10

* Placenta is formed from the embryo - false as it is formed from both the embryo and the mother * Placenta helps in nutrition of the growing embryo from fertilisation - false as it is the yolk sac that in the early weeks of pregnancy, the embryo is attached to a tiny yolk sac that provides nourishment. A few weeks later, the placenta will be fully formed and will take over the transfer of nutrients to the embryo. * Placental is foetal heart - false it is foetal lung

Question 11

Placenta is formed from both trophoblast cells and decidual cells What are decidual cells? What are the trophoblastic cells that differentiate into multinucleate cells and invade the the decidua to break down cavites and form capillaries that fill with maternal blood?

Answer 11

The decidual cells are the uterine cells of the endometrium which form the maternal part of the placenta The syncytiotrophoblasts invade the decidua and form the foetal part of the placenta

Question 12

Developing embryo sends capillaries into the syncytiotrophoblast projections to form “placental villi” Each villus contains foetal capillaries separated from maternal blood by a thin layer of tissue – no direct contact between foetal & maternal blood What is the foetal part of the placenta known as? What is the placental part of the placenta known as?

Answer 12

Foetal part of the placenta is known as the chorion Placental part is known as the decidua basalis

Question 13

What is the structure that separates the foetal blood and maternal blood known as?

Answer 13

Placental membrane or barrier

Question 14

2 way exchange of respiratory gases, nutrients, metabolites etc between mother and foetus, largely down diffusion gradient By what week of pregnancy are the placenta (and foetal heart) functional? (not complete but functional)

Answer 14

They are functional by the 5th week of pregnancy

Question 15

• * Early nutrition of the embryo is due to - invasion of trophoblastic cells into the decidua
• * Human chorionic gonadotropin (HCG) signals the corpus luteum to continue secreting progesterone stimulates decidual cells to concentrate glycogen, proteins and lipids
• * Blood vessels from embryo develop in the villi. A thin membrane separates the embryo’s blood in villi from mother’s blood in the intervillous space

How is the circulation in the intervillous space described?

Answer 15

It is described as an arteriovenous shunt - takes the deoxygenated blood from the foetus and provides the foetus with oxygenated blood from the placenta

Question 16

The placenta plays the role of the “Fetal Lungs” The respiratory function of the placenta makes supply of oxygen and removal of carbon dioxide possible. The exchange takes place between maternal (oxygen-rich) blood and the umbilical blood (mixing of arterial and venous blood, oxygen-poor).

What carries the oxygenated blood from placenta to growing foetus?

Answer 16

The umbilical vein carries the oxygen rich blood of the mother from placenta to foetus

Question 17

What are the veins that carry the deoxygenated blood back from foetus to mother?

Answer 17

These are the uterine veins

Question 18

The supply of the fetus with oxygen is facilitated by three factors:

• Foetal Hb
• Higher Hb
• Bohr effect

Describe all three?

At normal partial pressures of oxygen - higher % of oxyhaemoglobin in foetus than in adult

Answer 18

• Foetal Hb has a higher affinity for oxygen than adult haemoglobin
• There is an increased haemoglobin concentration in the foetus (50%more than in adults)
• Bohr effect - foetal haemoglobin can carry more oxygen in low CO2 levels than in high CO2 levels (shifts oxygen dissociation curve to the left) (for some reason lecturer put this in - this is legit the haldane effect)

Question 19

Why is it that foetal haemoglobin has a higher affinity for oxygen than adult haemglobin?

Answer 19

• Foetal haemoglobin - 2alpha subunits, 2 beta subunits
• Adult haemglogbin - 2alpha subunits, 2 beta subunits

The γ subunit has fewer positive charges than the (adult) β subunit, 2,3-BPG is less electrostatically bound to fetal hemoglobin compared to adult hemoglobin.- this shifts oxygen disocciate curve to the left as foetal haemoglobin therefore has a higher affintiy (2,3-BPG basically non-competitively inhibits oxygen on beta subunits)

Question 20

The placental exchange processes occur via classic membranous transport mechanisms: Passive transport (without energy consumption) Simple diffusion Osmosis Simplified transport (facilitated transport) Active transport Electrolytes follow water via osmotic gradient Which two electrolytes can only go from mother to child?

Answer 20

Iron and Ca2+ can only go from mother to child irrespective of the osmotic gradient

Question 21

How does glucose cross the placenta? It is the foetus’ main source of energy

Answer 21

Glucose crosses the placenta via facilitated transport - ie it is freely diffusible

Question 22

drugs can also cross the placental barrier - teratogens: They account for 3% of all congenital malformations not including alcohol Name 4 drugs which can cross?

Answer 22

Heroine, nicotine, caffeine, carbamezapine, sodium valproate, ACEandARBs

Question 23

A pregnant women is in the following state – T/F? Diabetic? Coagulopathic? Hyperparathyroid? Hyperthyroid? Hyper motility in gut Hyper oestrogenic? Hyper progestrogenic?

Answer 23

Diabetic - True Coagulopathic - True Hyperparathyroid - True Hyperthyroid - True Hyper motility in the gut - True Hyper oestrogenic - True Hyper progestogenic - True

Question 24

What does the corpus luteum become if fertilisation doesnt occur? What hormone produced by the placenta prevents this? What does the corpus luteum prodcue?

Answer 24

If fertilisation doesnt occur the coprus luteum (yellow) will become the corpus albicans beta-human chorionic gonadotrophin prevents the involution of the coprus luteum and therefore the corpus luteum continues to produce progesterone (and oestrogen) which maintains the endometrium

Question 25

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Answer 25

B - Doubles by 50% in 48 hours - (can check HCG twice over 48 hours to check to see if the levels have in fact doubled - if not can be a sign of miscarriage or ectopic pregnnacy)

Question 26

* produced from ~ week 5 of pregnancy (from syncytiotrophoblasts) * growth hormone-like effects: protein tissue formation. * decreases insulin sensitivity in mother: more glucose for the fetus What hormone is this?

Answer 26

This is human placental lactogen

Question 27

What is human placental lactogen also known as? (remember has growth hormone like effects)

Answer 27

It is also known as human chorionic somatomammotropin

Question 28

What is human chorionic somatomammortropin (human placental lactogen) (HPLorHCS) involved in the development of?

Answer 28

Human chorionic somatomammotropin is invloved in breast development in a female

Question 29

What is the function of progesterone produced by the coprus luteum throughout pregnancy?

Answer 29

Function is to decrease uterine contractility Causes secretions to welcome the implantation of the fertilised egg

Question 30

The placenta also produces other hormones eg CRH (corticotropin releasing hormone) HC thyrotopin (human chorionicc thyrotropin) and Has an increased calcium demand What does the increased levels of CRH produced by the placenta cause? (think about aldosterone and cortisol)

Answer 30

CRH causes the mother to have an increased ACTH ACTH stimulates the adrenal glands to produce cortisol and aldosterone INcreased aldosterone leads to hypertension INcreased cortisol leads to oedema and an increased isnulin resistance in the mother which is what can cause gestational diabetes

Question 31

What does the human chorionic thyrotropin produced by the placenta and the increased calcium demand cause in the mother?

Answer 31

HC thyrotropin - this basically acts like TSH (thyroid stimulating hormone) therefore making the thyroid gland stimulated - mother becomes hyperthyroid INcreased calcium demand causes the mother to become hyperparathyorid also

Question 32

Why is a pregnant women Diabetic? Hyperparathyroid? Hyperthyroid?

Answer 32

Placenta produces CRH - this causes increased ACTH production which increase aldosterone (causes hypertension) and cortisol levels - cortisol increases blood sugar levels leading to increased insulin and causing incsulin resistance - gestational diabetes Also HCS decreaes insulin snsitivuty Placenta produces HC Thyrotopin - overactive thyorid INcreased calcium demand due to doetus - hyperparathyroid

Question 33

What does oestrogen increase cause to the mother?

Answer 33

Oestogen makes the mother a coagulopath as it contains some clotting facotrs

Question 34

MATERNAL ADAPTATIONS TO PREGNANCY Increase in Cardiac Output (CO) during pregnancy is due to demands of the uteroplacental circulation. How much does the cardiac ouptut increase during pregnancy in the mother?

Answer 34

The cardiac ouput increases by 30-50% during pregnancy

Question 35

At what week of pregnancy will the cardiac output increase in the mother and at what week does it peak?

Answer 35

The CO output increases by week 6 and peaks around week 24 of pregnancy

Question 36

Due to the growing uterus the cardiac ouput decreases in the last 8 weeks of pregnancy as a vessel is compressed by the uterus What vessel is this? It carries part of the preload to the right atrium of the heart

Answer 36

The uterus compresses the vena cava as it grows - therefore after the cardiac ouput peaks at roughly 24 weeks of pregnancy (30-50% above normal remember), the uterus will compress the vena cava and the CO becomes ensitive to body position resulting in the decrease during the last 8 weeks of pregnancy

Question 37

Why does the heart rate increase to 90bpm in the pregnant women?

Answer 37

This is to increase the cardiac ouput

Question 38

Blood pressure (BP) drops during 2nd trimester (uteroplacental circulation expands & peripheral resistance decreases) What is the mainr esistant vessel?

Answer 38

This is the arterioles - hormones during pregnancy and the uteroplacental circulation expansion cause the blood vessels to dilate

Question 39

What is the recommended supplements during pregnancy by NICE guidleines?

Answer 39

Recommended women take 400micrograms of folic acid supplements before and during pregnancy up until the 12th weeks of birth Recommended women take 10micrograms of vitamin D for all pregnant and breast feeding women daily and 7micrograms for children after 6 months

Question 40

Lung function of the mother changes occur partly due to progesterone increases and partly because the enlarging uterus interferes with lung function. What does the increasing progesterone in the mother cause to affect lung function?

Answer 40

Progesterone signals the brain to lower CO2 levlels - it does this by increasing the CO2 sensitivity in the respiratory centres and therefore the mother is actually ‘forced’ to blow off more CO2

Question 41

Where is the respiratory centre located?

Answer 41

The respiratory centre is located in the medulla oblangata of the brainstem There is a pontine respiratory cente that affects the medulla DIVE - dorsal neurons - inspiration Ventral neurons- expiration (Active)

Question 42

Apart from respiratory changes due to the production of progesterone affecting the respiratory centres and causing more CO2 to be exhaled, the enlarging foetus also has an increase oxygen demand What do both these changes cause to the respiratory rate of the mother? What are the other changes in the mother?

Answer 42

The respiratory rate of the mother increases Increased tidal volume and minute volume of the mother Vital capacity and PO2 dont change Respiratory minute volume (or minute ventilation or minute volume) is the volume of gas inhaled (inhaled minute volume) or exhaled (exhaled minute volume) from a person’s lungs per minute.

Question 43

The kidney function also increases during pregnancy - increased GFR and renal plasma flow and therefore increased re-absorption of ions Posutral changes have an effect on renal functions INcrease or decrease: Sitting in upright position? Supine position? LAteral position during sleep?

Answer 43

Sitting in upright position - this decreases the rate of renal fucntions Supine position - increases the rate LAteral position during sleep - greatly increases the renal function Increased renal function means an increased rate of urine production

Question 44

pregnancy induced hypertension + proteinuria What is this?

Answer 44

This is pre-eclampsia

Question 45

What week of pregnancy does pre-eclampsia develop from? When does it usually resolve?

Answer 45

Pre-eclampsia develops after week 20 in pregnancy and usually will resolve by 10 days after delivery

Question 46

What causes pre eclampsia?

Answer 46

It is caused by a failure of trophoblastic invasion of the spira larteries neaning they cant form capillaries that fill with blood from the mother This causes a poor maternal blood flow which is attempted to be overcome by increasing the BP which is what is pre-eclampsia

Question 47

What is the single most significant risk factor for pre-eclampsia?

Answer 47

previously having pre-eclampsia – there’s an approximately 16% chance you’ll develop the condition again in later pregnancies

Question 48

Pre-eclampsia is more common in women with pre-existing hypertension, diabetes, autoimmune diseases (eg lupus), renal disease, a family history of pre-eclampsia, obesity and women with a multiple gestation (twins or multiple birth). What pregnancy is pre-eclampsia most likely to happen in?

Answer 48

Pre-eclampsia is most likely to happen in the first pregnancy - when the mother is nullparous

Question 49

What is the medication license for use to treat HBP in pregnancy? (other medications are also used but this is main one)

Answer 49

Labetalol is specifically licensed for use in pregnant women with high blood pressure.

Question 50

If a patient presents with risk factors for pre-eclampsia, what is the advise treatment?

Answer 50

Pregnant women at increased risk of pre-eclampsia at the booking appointment are offered a prescription of 75 mg of aspirin to take daily from 12 weeks until birth

Question 51

There is maternal weight gain during pregnancy due to both foetal and maternal weight Name some factors contributing to the foetal weight gain? How much weight is gained? Name some factors contributing to the maternal weight gain? How much weight is gained?

Answer 51

Foetal weight gain - Foetus, placenta, amniotic fluid Foetal weight gain accounts for 5kg Maternal wight gain - Uterus+Breasts, extracellular fluid, blood,, Other tissue Maternal wight gain accounts for 6kg Total of average of 11kg weight gain during pregnancy - 24pounds

Question 52

Mothers are required to eat more during pregnancy to accompany for feotal metabolism and some is stored as maternal fat There are two phases of maternal-fetal metabolism in pregnancy Maternal anabolic phase and maternal catobolic phase How long does each phase last?

Answer 52

Maternal anabolic phase lasts from 0-20 weeks of pregnancy Maternal catabolic phase lasts from 21-40 weeks of the trimester

Question 53

In the maternal anabolic (anabolism is the build up of molecules into larger ones - ie glucose into glycgoen) phase there is a smaller nuritional demand What happens to insulin sensitivity in this phase?

Answer 53

In this phase there is normal or increased insulin sensitivity to meet the glyocgen storage required for the maternal catabolic phase

Question 54

What is the maternal catabolic phase also known as? (and why)

Answer 54

It is also known as the accelerated starvation of the mother

This is because the mothers glyocgen stores are converted to glucose and lipolysis occurs so that there is increased transport of nutrients through the placental membrane for the foetus to recieve

Question 55

What three hormones cause insulin resistance in the mother?

Answer 55

Human chorionic somatomammotropin (HCS) (aka human placental lactogen) Cortisol - causes increased glucose and therefore leads to insulin resistance Growth hormone Both cortisol and glucose act against the action of insulin and raise the blood sugar

Question 56

When is HCS produced? What does it cause?

Answer 56

Causes growth hormone like effects - protein formation Decreases insulin sensitivity in the mother theerefore more glucose for foetus INvolved in breast development It is produced from week 5 of pregnancy

Question 57

Toward the end of pregnancy, uterus becomes progressively more excitable. Estrogen:Progesterone ratio alters increasing excitability:- progesterone inhibits contractility while estrogen increases contractility. What other hormone causes increased uterine contractions?

Answer 57

Oxytocin also causes increased uterine production

Question 58

Oxytocin (from maternal posterior pituitary gland): increases contractions and excitability WHat happens to the cervix to cause increased contractibility of the uterus?

Answer 58

Increased cervical stretch by foetal head increases the uterine contractibility via a positive feedback mechanism Cervical stretching also causes further oxytocin release

Question 59

Strong uterine contraction and pain from the birth canal cause neurogenic reflexes from spinal cord that induce intense abdominal muscle contractions How does oestrogen from the ovaries increases uterine contraction?

Answer 59

It does this by inducing oxytocin receptors on the uterus which stimulates the uterine contractions and excitability

Question 60

What does oxytocin stimulate the placenta to make and what does this cause?

Answer 60

Oxyctocin stimulates the placenta to make prostogllandins which stimulates further contractions

Question 61

For lactation to occur The ductile system in the breast needs to form The development of the lobule–alveolar system also needs to form Which hormone does thse?

Answer 61

Oestrogen forms the ductile system in the breast Progesterone forms the lobule alveloar system in the breast Both oestrogen and progesterone inhibit milk production. At birth sudden drop in these hormones which means prolactin levels rise

Question 62

What does prolactin cause? What does the sucking stimulus of the baby cause?

Answer 62

Prolactin stimulates the production of milk The suckling stimulus of the baby causes the release of oxytocin from the posterior pituitary gland to regulate smooth muscle contraction in the breast causing milk ejection

Question 63

When prolactin stimulates the breatst to produce milk, where is the milk poduced? (What hormone causes the development of this system?) What hormone cuses the development of the system that carries the milk produced to the nipple?

Answer 63

The milk is produced in the lobules (Mammary alveoli cluster into groups called lobules - dveelopment is due to progesterone) and the milk drains in the lactiferous ducts (formed due to hormone oestrogen)

Question 64

What is the reflex known as for the milk production and release?

Answer 64

This is known as the milk let down reflex