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Obs and Gynae > fertilisation + implantation > Flashcards

fertilisation + implantation Flashcards

1
Q

what do sperm infiltrate in feritlization?

A

zona pellucida

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2
Q

what is the ovary called once sperm have fertilized it- day 1?

A

zygote

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3
Q

is zygote haploid or diploid

A

diploid

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4
Q

what occurs once a zygote is formed (day 1-day4)

A

cleavage
- cells within zona pellucida undergo meiosis, dividing and multiplying in number
-the cells increase in number but not in size

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5
Q

what occurs on day 4 of fertilization?

A

Merula is formed

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6
Q

how many cells is a merula

A

16 cells

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7
Q

what days is the merula/ blastocyst transported into the uterine body?

A

days 3-4

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8
Q

how many cells is a blastocyst?

A

32+ cells

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9
Q

what days does a blastocyst implant in the uterus?

A

days 5-8

(think earliest can actually detect pregnancy is 1 week)

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10
Q

describe process of fertilizartion and implantation from when sperm meets ovum - implantation in uterine wall

A

day 1- sperm infiltrates zona pellucida of ovum creating a ZYGOTE (diploid cell)

cleavage occurs causing increase in number of cella (meiosis within zona pellucida)

day 4- MORULA (16 cells)

BLASTOCYST- 32+ cells

days 3-5 the blastocyst is taken to uterine body
days 5-8 the blastocyst attaches to the uterine lining

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11
Q

what are the cells on the outer layer of blastocyst called?

A

trophoblasts

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12
Q

what are the trophoblasts (cells on outer later of blastocyst) destined to become?

A

placenta

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13
Q

what are the inner cells of the blastocyst destined to become?

A

fetus

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14
Q

what is syncytiotrophoblast?

A

-trophoblasts differentiate into syncytiotrophoblasts

-syncytiotrophoblasts invade decidua and break down capillaries to form cavities filled with maternal blood

-developing embryos send capillaries into the syncytiotrophoblast projections to form placental villi

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15
Q

explain out blastocyst implants once it has reached the uterus body

A

blastocyst (32+ cells) reaches uterine body on days 5-8

-cells of trophoblast (outer layer of blastocyst) undergo adhesion to stroma of endometrium
-syncytiotrophoblast (outer later of trophoblast) forms progections into the stroma
-cells of stroma convert into a tissue called decidua (specialised in providing nutrients to trophoblast)
-when blastocyst implants, the syncytiotrophoblast starts to produce HCG

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16
Q

what is decidua?

A

-specialised tissue that provides nutrients to the trophoblast (outer layer of the blastocyst)

-it is formed when the blastocyst implants and the synctiotrophoblast (outer layer of trophoblasts) forms prodjections into endometrial stroma

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17
Q

explain the formation of placental villi

A

trophoblasts differentiate into syncytrophoblasts

-syncytrophoblasts invade decidua and break down capillaries to form cavities filled with maternal blood

-developing embryos send capillaries into these cavities of maternal blood (syncytiotrophoblast projections) to form placental villi

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18
Q

what does each placental villi contain?

A

-fetal capillaries seperated from maternal blood by a thin layer of tissue

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19
Q

is there any direct contact between fetal and maternal blood in the placental villi

A

-no direct contact between fetal and maternal blood

placental villi- contain fetal capillaries and maternal blood SEPERATED by a thin layer of tissue

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20
Q

which way does gas exchange work in the placental villi?

A

2 way exchange
-of respiratory gases, nutrients, metabolites between mother and foetus

-largely down diffusion gradient

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21
Q

what what week is the placenta functional?

A

5th week

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22
Q

how is oxygen transported to the feotus?

A

placental plays the role of ‘foetal lungs’

-oxygen diffuses from maternal blood (pool of blood within placental villi) and into the fetal circulation system

-oxygen saturated blood returns to the fetus via the UMBILICAL VEIN

-maternal oxygen poor blood flows black into the UTERINE VEIN

23
Q

what transports fetal oxygen rich blood to fetus?

A

Umbilical vein

24
Q

what transports maternal oxygen poor blood back to the body?

A

uterine vein

25
Q

what factors facilitate O2 exchange from mother - foetus?

A

3 factors:
-fetal Hb
-Higher Hb concentration
-Bohr affect (CADET right)

26
Q

explain how water gets from mother to foetus?

A

water diffuses into placenta along its osmotic gradient

-exchange increasing during pregnancy up to the 35th week

27
Q

explain how electrolytes get from mother to foetus

A

electrolytes follow water down its osmotic gradient

-iron and calcium can only go from mother to child

-glucose passes placenta via simplified transport

there is a free diffusion of fatty acids

28
Q

explain how fatty acids are transported from mother to feotus

A

through free diffusion (do not need gradient)

29
Q

what drugs can pass placental barrier

A

-Thalidomide (the one with all the birth defects a while ago)
-Carbamazepine
-Coumarins e.g. Warfarin
-Tetracyclins
-Aclohol, nicotine, heroin, cocaine + caffeine

30
Q

can methotrexate be given in pregnancy?

A

no- can lead to skeletal abnormalities

31
Q

can lithium be given in pregnancy?

A

no- can cause CVS defects

32
Q

can ACEI/ARBs be given in pregnancy?

A

no- can cause renal hypoplasia (underdevelopment of kidneys)

33
Q

what hormones are increased in anterior pituitary in pregnancy?

A

-ACTH increases
-prolactin increases
-melanocyte stimulating hormone increases

34
Q

what does an increase in ACTH in pregnancy lead to

A

-increase in ACTH from anterior pituitary in pregnancy leads to increase in cortisol and aldosterone

-this leads to increase risk of diabetes and infections

35
Q

what does an increase in prolactin in pregnancy lead to?

A

-increase in prolactin from anterior pituitary in pregnancy leads to suppression of FSH and LH

-reduced FSH and LH

36
Q

what does an increase in melanocyte stimulating hormone lead to?

A

-increase in melanocyte stimulating hormone in pregnancy leads to increased pigmentation of skin, linea nigra and melasma

37
Q

why might T3 and T4 increase in pregnancy?

A

HCG levels rise, doubling every 46 hours until around 3 months, then gradually start to fall

-HCG can bind to TSH receptors stimulating release of T3 and T4 causing symptoms of hyperthyroidism

38
Q

how long does the corpus luteum produce progesterone before the placenta takes over?

A

-until about 10 weeks in pregnancy

39
Q

what occurs to plasma + blood volume during pregnancy?

A

during pregnancy plasma volume and blood volume increase

40
Q

what occurs to cardiac output in pregnancy?

A

there is an increased cardiac output
-increased HR
-increased SV

CO= HR x SV

41
Q

what occurs to systemic vascular resistance in pregnancy?

A

-systemic vascular resistance decreases and so BP decreases in first + middle of pregnancy

42
Q

what can occur due to vasodilation and decrease in systemic vascular resistance?

A

-varicose veins can occur due to peripheral vasodilation and obstruction of inferior vena cava (by the uterus)

-peripheral vasodilation can cause hot flushes and sweats

43
Q

explain what occurs to lung volumes in pregnancy?

A

Tidal volume increase to meet O2 needs

-diaphragm is pushed up due to enlarged uterus
-decrease in residual volume and functional residual capacity

44
Q

what occurs to RR in pregnancy?

A

RR increases- to meet the new O2 needs

45
Q

what are the renal changes that occuring during pregnancy?

A

-increase in blood volume to kidneys (makes sense because increase in blood volume, plasma volume + CO)
-increase in GFR
-increase in aldosterone
-increase protein excretion from kidneys (also normal to have a trace of glucose)
-dilatation of ureters and collecting system

46
Q

why are pregnant women more likely to be iron, folate or B12 deficient?

A

-during pregnancy there is an increase RBC production leading to higher iron, folate and B12 requirements

47
Q

why do pregnant women not seem to have a higher than normal Hb even though they are producing more RBC?

A

-there is an increase in RBC during pregnancy
however
-there is also increase in plasma volume

plasma volume increases MORE than RBC volume, leading to a lower concentration of RBC

48
Q

why are pregnant women hypercoagulable?

A

as there is an increase in clotting factors
-fibrinogen
-factor VII, VIII and X

49
Q

what occurs to WBC in pregnancy

A

increase

50
Q

what occurs to platelets in pregnancy?

A

decrease platelets

51
Q

what occurs to ALP during pregnancy?

A

Increase ALP (secreted by placenta)

4x increase

52
Q

what occurs to albumin in pregnancy?

A

-decrease in albumin

because increase in GFR leads to more protein loss

53
Q

what effect does a decrease in protein have when takin meds?

A

decrease in protein (albumin) means that theres a decrease in protein binding to drugs

-increases the amount of free drug in the body

54
Q

what occurs to calcium in pregnancy?

A

-calcium requirements increase but so does calcium absorption in the gut

-so calcium remains stable

Obs and Gynae (61 decks)

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