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Semester 1 > Pregnancy and delivery > Flashcards

Pregnancy and delivery Flashcards

1
Q

what happens with oocyte once released from ovary for fertilisation

A

= ovulation
fimbriae guide to fallopian tubes where meets sperm
sperm able to get to fallopian tubes because oestradiol has thinned cervical mucus

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2
Q

describe days 1 to 4 post fertilisation (include fertilisation)

A

oocyte fertilised by sperm into zygote

first divisions= cleavage divisions, embryo increases in cell number but not in size
cleavage divisions are asynchronous
cleavage divisions= 2 to 8 cells

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3
Q

describe the blastocyst stage post-fertilisation

A 
blastocyst forms days 4-5
blastocyst when 32-64 cells
first stage cell differentiation
has 2 regions
blastocyst hatches day 6-7 to allow implantation
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4
Q

the 2 regions of the blastocyst

A

inner cell mass: these cells become the embryo. pluripotent stem cells.

trophoblast: ring of cells around inner cell mass
form extraembryonic component of placenta
forms extraembryonic tissues

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5
Q

describe implantation of embryo

A

-embryo secretes proteases for deep invasion of uterine stroma
-embryo implants interstitially in endometrium
on anterior or posterior wall of uterus body
- synciotrophoblast sends out projections which erode maternal tissues
- blastocyst binds with endometrium then buries itself under
-overgrowth of endometrial surface over embryo so securely held

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6
Q

outline 1st trimester of pregnancy

A

1st trimester= 0-13 weeks,
rapid growth of placenta,
organogenesis week 3-10
riskiest period

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7
Q

outline 2nd trimester pregnancy

A

14-26 week

overall growth

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8
Q

outline 3rd trimester pregnancy

A

27-40 week
rapid fetal growth of 250 grams/week
placental growth slows but efficiency increased

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9
Q 
what are:
yolk sac
amnion
chorion
allantois
A

yolk sac: 1st site blood cell formation

amnion: surrounds embryo, makes amniotic fluid cavity
chorion: becomes principle part of placenta
allantois: bacomes vascular connection between embryo and placenta

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10
Q

label the embryo, yolk sac, amnion, chorion, allantois

A

b

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11
Q

what happens next with the inner cell mass

A

bilaminar embryonic disc, whereby the inner cell mass forms two layers, the epiblast and hypoblast

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12
Q

epiblast

A

lies above the hypoblast and gives rise to the 3 germ layers, amnion, allantois, part of the yolk sac
appears day 8

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13
Q

what does the ectoderm go on to form

A

skin, CNS, PNS, brain

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14
Q

what does the mesoderm go on to form

A

kidneys, repro organs, bones, muscles, vascular system

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15
Q

what does the endoderm go on to form

A

intestines, liver, lungs

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16
Q

what are the cephalic and caudal ends of the embryo

A 
cephalic= head
caudal= tail
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17
Q

when does gastrulation happen and why is it so important

A

day 14-16 post fertilisation
organs must be correct size and orientation w correct differentiated cell types
gastrulatioon allows cell movement to orientate and locate organs correctly

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18
Q

what is gastrulation

A

establishment of the 3 germ layers

induces shape changes in embryo

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19
Q

what is the 1st visible sign of gastrulation

A

an invagination occurs in caudal half of epiblast, formin primitive streak

cells migrate through primitive streak

this forms the mesoderm and changes embryo shape

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20
Q

first system to start developing after gastrulation?

A

nervous system, at 3 weeks post fertilisation
neural plate in cephalic region will be brain
neural tube along dorsal region will be spine

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21
Q

outline neural tube closure

A 
neural tube starts as neural plate
folds to form neural groove
folds further to form nerual fold
rolls into neural tube
spinal region closes first, cephalic and caudal neuropores still open, then they close
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22
Q

why is it so important neural tube closes

A

if cephalic neuropore left open= exencephaly

if spine of tube left open= spina bifida

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23
Q

neural crest formation

A

once spinal tube closes
neural crest cells form at boundary with ectoderm in dorsal region
neural crest cells migrate out of dorsal neural tube
become incorporated in a vairety of tissues

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24
Q

somite development

A

blocks of mesoderm tissue in pairs along neural tube
develop in succession, anterior to posterior
44 pairs total
produce muscle and ribs

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25
Q

sensory organ development

A

sensory organs develop from placodes- visible ectodermal thickening on surface

otic placodes visible from week 4, disappear week 5 forming inner ear

optic placodes also visible week 4, form the lenses

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26
Q

limb development

A

limbs develop from limb buds, external structures visible from week 4
forelimb develops first (for both arms)
then hindlimb develops (for both legs)
patterning is important to specify

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27
Q

hands, feet, finger development

A

limb buds undergrow outgrowth,
hands and feet vivible week 7
condensation of cartilage show precursors of digits, then apoptosis between digits seperates

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28
Q

heart development

A 
visible on ventral surface
heartbeat begins day 22
circulation begins 28 days
first organ to function
required for embryonic and foetal growth
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29
Q

lung development

A

through branching morphogenesis
endoderm and mesoderm alveoli
mesoderm for musculoskeletal, ectoderm for neural

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30
Q

kidney development

A

kidneys develop in close association with genitals in the urogenital ridge
develop through branching morphogenesis
in stages:
pronephros, mesonephros, metanephros

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31
Q

what is branching morphogenesis

A

generates epithelial trees

large subvessels become divided into smaller vessels

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32
Q

GI system development

A

GI system develops in different cavities

foregut: oral cavity, oesophagus, trachea, stomach
midgut: small intestine, pancreas
hindgut: colon

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33
Q

what is special about midgut development

A

intestines develop through herniation
undergoes series of rotations to package smaller into adult morphology
ventral abdominal wall will close around the midgut

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34
Q

what are the 3 types of causes of birth defects

A

genetic- inherited or de novo mutations

environmental- exposure to teratogens

infectious- maternal disease

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35
Q

how common are birth defects in england

A

1 in 47 live and still births

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36
Q

how does timing to exposure of teratogen in embryo/foetus influence outcome

A

organs developing in window of time exposure occurs will be most affected

so depends on when as to which organ system and how early on

the later it occurs, the better the outcome

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37
Q

what do the trophoblast cells produce

A

trophoblast cells produce hCG (human chorionic gonadotrophin hormone) around day 8

hCG ensures corpus luteum continues to make oestrogen and progesterone to maintain pregnancy and prevents other follicles developing

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38
Q

what would hapen in hCG didn’t rise

A

corpus luteum would shrivel day 10 and oestrogen and progesterone would fall, endometrium would slough off as period taking embryo with

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39
Q

why is the corpus luteum so important in first trimester

A

corpus luteum produces oestrogen and progesterone

progesterone maintains pregnancy, if don’t have triggers labour/miscarriage

40
Q

what happens with hCG and corpus luteum week 9

A

at 9 weeks hCG levels peak then drop off, corpus luteum shrivels
placenta takes over hormone production, done by syncytiotrophoblasts

41
Q

mother and fetal circulation are?

A

completely seperate. placenta is the barrier.

42
Q

what is the placenta formed of

A

chorionic villi, which are projections from fetal tissue, consist of 2 layers-

syncytiotrophoblast- the outer layer
cytotrophoblast- the inner layer

uterine capillaries break down so chorionic villi are bathing in mothers blood

43
Q

what happens as the chorionic villi mature

A

cytotrohoblasts reduces to produce single layer of syncytiotrophoblast so there is closer contact of maternal and fetal blood and v high SA

44
Q

what do the syncytiotrophoblasts do

A

in direct contact with maternal blood in intervillous space

hormone production of oestrogen/progesterone/hPL

45
Q

how do O2/CO2/nutrients get from placenta to foetus

A

umbilical veins bring O2 and nutrients to foetus
umbilical arteries carry deoxygenated blood/CO2 away from foetus to placenta
CO2/O2 diffuse in/out of veins/arteries through the bathing of chorionic villi in intervillous space

46
Q

what are the functions of the placenta

A

exchange of gases
metabolic transfer
endocrine function
immunological transfer

47
Q

exchange of gases in placenta

A

occurs via passive diffusion in chorionic villi
Bohr and Haldene effects faciliate O2 release and CO2 removal
foetal haemoglobin has greater affinity for O2 than adult so further enhanced

48
Q

metabolic transfer in placenta

A

glucose transferred from maternal blood via facilitated diffusion
fatty acids, amino acids, water, Na, K, Ca, Fe vitamins

49
Q

metabolic transfer in placenta

A

glucose transferred from maternal blood via facilitated diffusion
fatty acids, amino acids, water, Na, K, Ca, Fe vitamins

50
Q

endocrine function of placenta

A

produces hCG to maintain corpus luteum in 1st trimester so that it will make oestrogen and progesterone
produces oestrogen and progesterone and hPL from week 9
produces human growth hormone

51
Q

hPL

A

human placental lactogen-
encourages insulin resistance in mother, thereby increases her blood glucose levels and accumulation of fat, ensures glucose availability for foetus

52
Q

human growth hormone in pregnancy

A

stimulates gluconeogenesis so energy for foetus

53
Q

immunological transfer in placenta

A

IgG antibodies transfer and give passive immunity

rest of immunoglobulins too large

placental transfer most be considered when prescribing

54
Q

discuss changes in fundal height of uterus in pregnancy

A

uterus grows into abdomen.
20 weeks at umbilicus
36 weeks at xiphoid process
fundal height is distance from syphysis pubis to fundus of uterus

55
Q

how can fundal height be used to estimate gestational age

A

plus/minus a couple cm, fundal height in cm= week

ie 36cm= 36 week

56
Q

what does the mothers cardiovascular system do in pregnancy

A

must expand to accommodate growing foetus and prepare for loss of blood at delivery

high volume state
physiological anaemia of pregnancy
heart rate rises by 20bpm
bp falls

57
Q

explain why pregnancy is a high volume state

A

circulating blood volume increases by 30-50%, ie 5L to 7.5L in 3rd trimester

58
Q

what is physiological anaemia of pregnancy

A

RBC increases a bit but plasma volume increases a lot, so haemocrit (% of RBCs) goes down

59
Q

why does bp fall in pregnancy

A

progesterone causes vessels to dilate

60
Q

why may we see varicose veins in pregnancy

A

uterus presses against pelvic veins, leads to varicose veins and swelling in lower legs/ankles

61
Q

what does increased cardiac output mean for the kidneys in pregnant mother

A

more fluid passing through kidneys=
increased glomerular filtration rate and urinary output, uterus also puts pressure on bladder=
greater urinary frequency

62
Q

how do kidneys compensate for additional workload in pregnancy

A

increase size, calcyes and renal pelvis dilate, leads to physiological hydronephrosis

increased size ureters leads to physiological hydroureter, progesterone causes hypomobility of ureters
- leads to incr capacity store urine and hypomobility of ureters leads to urinary stasis= increased risk upper UTI

63
Q

why and how do the lungs compensate for growing uterus

A

uterus pushes up on diaghragm so harder to breathe comfy

so progesterone relaxes ligaments in thorax= increases transvaers diameter of rib cage= increases tidal volume

64
Q

what effect does oestrogen have on respiratory system

A

causes increased vascularisation and capillary engorgement in upper respiratory tract

may cause stuffy nose, congestion, nosebleeds

65
Q

how does pregnancy affect gait of woman

A

progesterone and relaxin loosen ligaments around sacroiliac joints and symphysis pubis to prep for fetal passage
causes waddling gat, maybe pain in other joints

66
Q

changes to breats in pregnancy

A

oestrogen and progesterone promote breast development and milk producing machinery

incr blood flow to breasts and budding of breast tissue

oestrogen stimulates production of prolactin, but high progesterone inhibits until after birth

67
Q

how do pregnancy tests work

A

hCG is secreted from day 8 post fertilisation so should only be present in pregnant urine

  1. urine sample deposited on reaction zone
  2. if hCG present it binds to complementary antibodes that are associated with an enzyme that activates dye molecules in reaction zone
  3. moves up through capillary action to test zone, hCG- antibody complex will bind with immobilised antibodies associated with dye molecule
  4. dye-activating antibody enzyme will bind with them to release colour, indicating pregnancy
  5. at control zone are other antibodies that will bind with first antibodies regardless of hCG presence
68
Q

clinical dating in pregnancy

A

pregnancy dated from first day of last menstrual period (LMP)
expected date of delivery (EDD) is 40 weeks from LMP

69
Q

when should labour start and what is labour

A

starts spontaneously between 37 and 42 weeks gestation, 40 weeks avg

labour= regular uerine contractions causing cervical dilation

70
Q

what are the 3 stages of labour

A

stage 1: cervical dilation from 0-10cm
stage 2: descent and delivery of baby
stage 3: delivery of placenta and membranes

71
Q

what type of contractions are required for delivery of placenta and why

A

sustained contraction rather than intermittent to prevent haemorrage

72
Q

role of oxytocin in labour/delivery

how produced

A

stimulates contractions

oxytocin is a peptide hormone secreted in pulses by pituitary, under hypothalmic ocntrol
pulsatility increases in labour and is also prodced by uterus
acts via myometrial receptors

73
Q

role of prostaglandin in labour/delivery

how produced

A

prostaglandin- PGF2alpha

stimulates action potentials and calcium channels of smooth muscle, stimulating contractions

synthesised by COX enzymes

produce by decidua and fetal membranes

74
Q

role of oestrogen in labour/delivery

A

involved in activation of myometrium by:
increasing oxytocin receptor expression
increasing prostaglanding and oxytocin levels

there is an increase in oestrogen production and increased oestrogen receptor expression in myometrium prior to birth

at end of pregnancy, oestrogen becomes dominant over porgesterone

75
Q

role of progesterone in labour/delivery

A

progesterone has a suppressive effect on myometrium throughout pregnancy

it is thought there is a functional progesterone withdrawal before birth- ie progesterone levels remain high but unable to act as usual

evidence:
blocking progesterone induces delviery- mifeprestone drug used to terminate pregnancy
before birth myometrium less responsive to progesterone

76
Q

role of placenta in labour/delivery

A

placental clock, dictates timing of delivery
placenta triggers fetal HPA axis by synthesising cortisol releasing hormone
placenta converts DHEA from fetal HPA axis to oestrogen

77
Q

role of foetus in labour/ delivery

A

foetal HPA axis matures before birth, triggered by placenta,
produces cortisol and DHEA
foetal cortisol upregulates COX enzymes, causing increased prostaglandin synthesis= contractions
DHEA converted to oestrogen by placenta, causes oestrogen surge

78
Q

summarise how the hormones work together in labour and delivery

A

placenta triggers foetal HPA axis by making cortisol releasing hormone

foetal HPA axis then makes cortisol and DHEA

cortisol upregulates COX enzymes so increased prostaglandin= contractions

DHEA from foetal HPA axis converted by placenta to oestrogen

oestrogen becomes dominant to progesterone, progesterone sensitivity reduced, myometrial contractions no longer suppressed

oestrogen increased oxytocin levels and receptors, oxytocin pulsatility increaes= contractions

oestroged increases prostaglanding levles, stimulate action potentials and calcium channels of smooth muscle of myometirum= contractions

79
Q

cervical changes in labour and delivery

A 
cervix is 85% connective tissue
remains closed until onset of labour
undergoes:
- ripening
- softening
- effacing (shortening)
- dilation

occurs due to mechanical stmulation and pressure of baby’s head, stimulated by inflamm mediators

80
Q

how is the myometrium controlled in pregnancy and what is it

A

myometrium is the middle muscular layer of uterine wall

under influence oestrogen, myometrium grows and expands for foetal growth in pregnancy

myometrial contraction suppressed by progesterone in rpegnancy

before birth, sensitised to effects of oxytocin and prostaglandins, less sensitive to progesterone

81
Q

outline fetal adaptations at birth

A

lungs inflate + surfactant
foramen ovale closes
ductus arteriosus closes

82
Q

adaptations in lungs at birth

A

in womb gas exchange occurs across the placenta, at birth lungs filled with fluid and not inflated

at birth, aspirate mucus, first breath within 10 secs
baby often blue at birth
baby first cry inflates lungs and forces absorption of remaining fluid

83
Q

role of surfactant at birth

A

surge of production at 34 weeks
role: reduce surface tension of alveoli in lungs so they can expand and prevents them collapsing at exhale
after first breath, surfactant thins alveolar membrane and increases alveolar SA

84
Q

where does oxygenated blood flow in fetus in womb

A 
oxygenated blood goes from, to:
placenta
umbilical vein
fetus
shunted to ductus venosus
inferior vena cava
right atrium
shunted via foramen ovale
left atrium
ascending aorta
body
85
Q

where does deoxygenated blood flow in fetus in womb

A 
doxygenated blood flows from, to:
body
right atrium
right ventricle
pulmonary artery
shunted to ductus arteriosus
descending aorta
umbilical artery
placenta
86
Q

umbilical vein and artery carry de/oxy blood in which direction

A

umbilical vein carries oxygenated blood placenta to fetus

umbilical artery carries deoxygenated blood away from fetus to placenta

87
Q

how does the blood travel from placenta to body of foetus t

A

oxygenated blood via umbilical vein to fetus, shunted into ductus venosus which shortcuts to the heart. enters right heart via inferior vena cava into right atrium
blood flows from right atrium to left atrium via foramen ovale
pumped into ascending aorta to body

88
Q

how does blood travel from body of foetus to placenta

A

deoxygaenated blood returns to right atrium into right ventricle
pumped into pulmonary artery but shunted into descending aorta via ductus arteriosus
descending aorta joins umbilical artery to placenta

thereby bypasses the lungs

89
Q

where is there high pressure in the heart in the womb

A

right side (right atrium)

90
Q

what 2 things change in fetal circulation at birth

A

foramen ovale closes

ductus arteriosus closes

91
Q

why does the foramen ovale close

A

umbilical cord is occluded so blood flow through ductus venosus stops

baby also takes first breath, aerating lungs

both combined cause pressure in right atrium to fall so foramen ovale closes

92
Q

why/when does ductus arteriosus close

A

rising O2 levels over next few days cause ductus arteriosus to close

93
Q

why do babies look blue at birth

A

in womb have lower O2 level than adults so look blue until circulation closes

sats go 65 to 95 %

94
Q

importance of skin to skin

A

important to leave on mothers bare chest for an hour/ up to after first feed

clams/relaxes both
regulates baby hr and breathing
stimulates digestion and interest in feeding
enables colonisation with mums friendly bacteria
stimulates release of hormones in mum for breastfeeding

95
Q

how are contraceptive methods classified

A

tier 1: most effective, <1 preg/100 women/year, long active reversible contraception (Larc) (IUDs, implants) and vasectomies and bilateral tube ligation

tier 2: 4-7/100/year contraceptive pills, patches, injections

tier 3: least effective, >13/100/year, condoms, diaphagms, cervical cups

96
Q

how do oral contraceptives work

A

combined oral contraceptives have both oestrogen and progestin

inhibit secretion of GnRH and so fsh and lh
FSH inhibition= follicles don’t develop
LH inhibition= ovulation doesn’t happen

progestin thins endometrial lining so implantation can’t occur
thickens cervical mucus so harder for sperm

97
Q

issues with oral contraceptives

A

contraindications: risk of DVT and cardiovascular events, highest in smokers and those over 35

hormonal contraceptives interact with other meds and may decrease contraceptive efficiency- antibiotics, anti seixure, HIV protease inhibitors

Semester 1 (18 decks)

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