Block 11 Flashcards

0
Q

What percentage of sperm makes it to the cervix?

A

1%

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1
Q

Where does fertilisation occur most frequently?

A

Ampullary region of uterine tube

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2
Q

What steps must occur before the oocyte can be fertilised?

A

Capacitation

Acrosome reaction

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3
Q

What is Capacitation?

A

Lasts 7 hours
Destabilising of sperm head by removal of cholesterol
Acrosomal membrane removed
Sperm plasma membrane hyper polarisation
Influx of HCO3, increased Camp, influx Ca and decrease pH
Hyperactive motility

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4
Q

What are the 3 phases of fertilisation?

A

Penetration of corona radiata
Penetration of zona pellucida
Fusion of oocyte and sperm cell membrane

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5
Q

During one ejaculation, how many sperm are released?

A

300 000 000

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6
Q

What is the function of ZP3 in fertilisation?

A

Causes the release of acrosomal enzymes like acrosin
Allows the sperm to penetrate the zona pellucida
Allows contact with oocyte membrane

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8
Q

What is the Acrosome reaction?

A

When the sperm contacts the oocyte membrane the permeability of the zona pellucida changes
Lysosomal enzymes are released from cortical granules that line the plasma membrane of oocyte
Zona reaction
Prevents sperm penetration and Inactivates receptors on surface

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9
Q

What is the second polar body?

A

It is one of the daughter cells produces when the oocyte finishes its 2nd meitotic division, it receives hardly any cytoplasm

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10
Q

What is the morula and when does it form?

A

3 days

16 cells in the same space as the initial zygote

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11
Q

What is a blastocyst?

A

It is the next stage after the morula and it forms a cavity to allow for nutrition to get to all cells - blastocyst cavity.

inner cell mass and outer cell mass

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12
Q

What is the bilaminar disc?

A

It is the stage after the blastocyst. It is when the inner cell mass subdivide into the epiblast and the hypoblast.

The cells continue to divide and as a result the epiblast cells need a cavity for nutrition (amniotic cavity). Initial cavity = primitive yolk sac

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13
Q

When does gastrulation occur? What is it?

A

day 12

Primitive node, primitive pit and primitive streak form in epiblast.

Cells in the primitive streak multiply and fold under the epiblast to form new layers.

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14
Q

What happens during week 1 of embryogenesis?

A

Division of cells to form a blastocyst cavity. Formation of hypoblast, epiblast and trophoblast

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15
Q

What happens during week 2 of embryogenesis?

A

Implantation and development of the primary yolk sac

Formation of the primitive streak and node

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16
Q

What happens during week 3 of embryogenesis?

A
Head and tail folding
Neuralation
Fore-mid-hind gut
Germ cells in allantois wall
Primitive vascular system - heart tube
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17
Q

What happens during week 4 of embryogenesis?

A
Pharyngeal arches
trachea and lung buds
thyroid and liver
urorectal septum
mesonephrus, mesonephric duct and uteric bud
indifferent gonads
septum primum forms
forelimb bud
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18
Q

What happens during week 5 of embryogenesis?

A
Optic cup and vesicle
primary bronchi
pharygeal pouches
pancreas
mullerian ducts
septation of ventricles
spleen
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19
Q

What happens during week 6 of embryogenesis?

A
upper lip and palate
anterior lobe of pituitary
rotation of stomach
major calyces
testis differentiating
external genitalia indifferent
forelimb digit rays
hindlimb bud
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20
Q

What happens during week 7 of embryogenesis?

A
posterior lobe of pituitary
membranous labyrinth
brochi division
midgut loop rotating
metanephric nephrons and minor calyces
septum secondum
cartilaginous part of skull
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21
Q

When does an embyro become a foetus?

A

8 weeks

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22
Q

What happens during week 8 of embryogenesis?

A

digits on hand
external ear
membranous part of skull

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23
Q

What components of the female reproductive system aid fertilsation?

A

Fluid current in tube from epithelial secretion
cilia beating towards uterus
weak contractions of fallopian tube

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24
Q

When does implantation occur?

A

1-3 days after fertilisation

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25
Q

Before implantation, where does the embryo get its nutrition?

A

uterine milk secreted from the endometrium

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26
Q

What hormones are secreted by the placenta?

A

human chorionic gonadatropin
oestrogens
progesterone
homan chorionic somatrotropin

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27
Q

Human chorionic gonadatropin - where is it secreted from?

A

synctial trophoblasts

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28
Q

Human chorionic gonadatropin - function?

A

Prevents menstruation and causes the persistence of the corpus luteum

Increases to a peak at 10-12 weeks then decreases, can be measured in blood 8-9 days after ovulation

Causes corpus luteum to secrete more sex hormones and causes decidual cells to swell.
It also causes males to secrete testosterone and differentiate

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29
Q

Oestrogen - where is it secreted from and what are its functions?

A

Placenta

Causes enlargement of uterus, breasts, breast ducts, external genitalia and relaxation of pelvic ligaments

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30
Q

Progesterone - where is it secreted from and what are its functions?

A

Placenta - concentration increases over time

Causes decidual cells to develop and nurish early embryo, decreases contractility of uterus (preventing spontaneous abortion), increases secretions of fallopian tubes for nutrition, helps oestrogen prepare breasts for lactation

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31
Q

Human Chroionic somatomammotropin - where is it secreted from and what are its functions?

A

Placenta after 5th week

Decreases insulin sensitivity, decreases use of glucose by the mother to provide more for the baby. Promotes the release of free fatty acids, can promote growth

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32
Q

Changes in mother during pregnancy?

A
Increased uterine blood flow
Increased cardiac output
increased blood volume
increased BMR
weight gain
increased urine production
increased GFR
Increased blood pressure
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33
Q

What is the normal weight gain during pregnancy?

A

24 pounds - most in the last trimester

7lb foetus
4lb amniotic fluid
2lb uterus
2lb breast
9lb other
34
Q

What are the 3 antibody preparations used in pregnancy testing?

A

Reaction zone - monoclonal anti-HCG Ab-enzyme conjugate
Test zone - immobilised polyclonal anti-HCG antibodies +dye
Control zone - immobilised goat anti-mouse antibodies +dye

35
Q

What are the foods to avoid during pregnancy?

A
Vitamin A - liver
Pate (listeria)
Soft cheese
Unpasteurised milk
Raw egg (salmonella)
Rare meat (toxoplasmosis)
tuna (mercury)
raw shellfish
caffeine
36
Q

How many antenatal appointments for a nulliparous woman?

A

10

37
Q

How many antenatal appointments for parous woman?

A

7

38
Q

When are the antenatal appointments and what happens at each?

A

12 weeks - lifestyle advice, screening
16 weeks - review test and offer iron if anaemic
19 weeks - testing for foetal structural abnormalities
25 weeks NP - routine checks
28 weeks - routine checks, antiD prophylaxis for rhesus negative. pertussis vaccination
31 weeks NP - routine checks and review of screening
36 weeks - routine checks, checking of foetal position with external cephalic version offered if breech
38 weeks - routine checks
40 weeks - routine
41 weeks - membrane sweep and or labour induction

39
Q

What are the normal routine checks carried out during an antenatal appointment?

A

BP check
Proteinuria screening
Symphysis fundal height + plotting

40
Q

What diseases are screened for in pregnancy?

A
anaemia
HIV
hep B
rubella
syphilis
sickle cell
thalassaemia
Downs
41
Q

What are the dangers of alcohol in pregnancy?

A
Damages brain and affects childs behaviour
Slow growth, development delay
mental retardation
foetal alcohol syndrome
miscarriage risk
42
Q

What are the signs of foetal alcohol syndrome?

A

facial deformities
slow and retarded development
brain and neurological problems

43
Q

What are the dangers of smoking in pregnancy?

A
Still birth
Premature delivery
Low birth weight
Stunted growth and development
Under developed lungs
Sudden infant death syndrome
Learning disorders
44
Q

What is ovulation induction and what are the risks?

A

Medications are used to stimulate the follicles in the ovaries to produce more than one egg per cycle

Clomiphene citrate
SERM
gonadotropins

Increase the chance of multiple births and of developing ovarian cysts
Ovarian hyperstimulation syndrome

45
Q

What are the stages of IVF?

A
  1. Down Regulation - Switching off normal female hormone production
  2. Stimulation of follicle production
  3. Egg maturation
  4. Preparing womb to receive embryos
  5. Egg collection - oocyte capture
  6. Embryo transfer
46
Q

What is used for down regulation in IVF?

A

Gonadotropin-releasing hormone analogues

Buserelin
Goserelin

47
Q

What is used for egg maturation in IVF?

A

Pregnyl - works like hCG
Prepares them for collection
Given 36 hours before

48
Q

What is used for preparing the womb in IVF?

A

Utrogestran - works like progesterone to keep lining thick

49
Q

What are the rules for embryo transfer in under 37s?

A

1st cycle - 1 embryo
2nd cycle - 1 embryo unless not top quality
3rd - 2 embryo maximum

50
Q

What are the rules for embryo transfer between 37-39?

A

1st and 2nd cycle - one unless not top quality

3rd - 2 embryos maximum

51
Q

What are the rules for embryo transfer between 40-42?

A

Double egg transfer

52
Q

What are the criteria for IVF referral?

A

Women under 40 who have not conceived after 2 years of regular unprotected intercourse

OR - 12 cycles of artificial insemination
= 3 IVF cycles

If 40-42 years = 1 IVF cycle

53
Q

What are the limitations of ART?

A
High cost of treatment
Age of female partner
Religious complications
Access is limited
Side effects of drugs
Increased ectopic pregnancy
54
Q

What are the success rates of artificial reproduction techniques?

A

41 = 12%

55
Q

Describe the blood supply to the placenta

A

2 umbilical arteries (from the internal iliac arteries)

drained by 1 umbilical vein

56
Q

Describe the flow of blood through the placenta

A
  • Placental villus required for maternal exchange
  • Umbilical arteries enter placenta
  • Divide into many branches
  • Small arteries branch into placental villi
  • Foetal capillaries bring in foetal blood from umbilical arteries
  • Blood leaves through sinusoidal capillaries to venous
  • Mother forms a reservoir so blood envelopes placental villus
57
Q

What are the 2 layers of the placental villus?

A

Syncytiotrophoblast (outermost)

Cytotrophoblast

58
Q

What is the syncytiotrophoblast?

A

Outermost layer of placental villus
Exchange via passive diffusion, facilitated diffusion and active transport and occurs through fully differentiated epithelial cels

59
Q

What is the cytotrophoblast?

A

Less differentiated but can become syncytiotrophoblasts if required.

As syncytiotrophoblast cells die they form synctial knots which eventually break off into mothers blood

60
Q

Outline placenta formation

A
  • Blastocyst escapes from zona pellucida
  • Trophoblast adheres to endometrium
  • Endometrium undergoes decidualisation
  • Decidual reaction as blastocyst implants
  • Trophoblast cells release proteases to invade endometrium
  • Trophoblasts differentiate into cytotrophoblasts surrounded by syncytiotrophoblasts
61
Q

What happens in the decidual reaction?

A

Dilation of blood vessels
Increased capillary permeability
Oedema
Increased proliferation of glandular and epithelial cells

62
Q

Define pre-eclampsia

A

Systemic syndrome characterised by widespread maternal endothelial dysfunction presenting clinically with oedema, hypertension and proteinuria

63
Q

When does pre-eclampsia occur?

A

3-5% of pregnancies
Last trimester
More common in first pregnancy

64
Q

What is HELLP syndrome/

A

Haemolysis
Elevated liver enzymes
Low platelets

65
Q

Define congenital defect

A

Any abnormality, structural or functional, identified at any age, which began before birth or the cause of which was present before birth

66
Q

What is the incidence of congential physical defects?

A

2-3% of live born infants

Leading cause of peri-natal death (20-25%)

67
Q

What are common single primary defects?

A
DDH
Talipes
Cleft lip/palate
Cardiac septal defects
Neural tube defects
68
Q

How can single primary defects be categorised?

A

Malformation
Disruption
Deformation
Sequence

69
Q

What is a malformation?

A

Abnormal initial formation of embryo

Result of genetic and or environmental factors during organogenesis

e.g. neural tube defect

70
Q

Describe the position of the breast

A

Sternal edge to midaxillary line

2nd to 6th rib

71
Q

What is a disruption?

A

A destructive process which alters normal structures after their formation

Amniotic bands - limb amputations
Cardiovascular events - e.g. Poland anomaly

72
Q

How is the breast of the skin attached to the dermis?

A

Suspensory ligaments of Cooper

73
Q

What is the clinical importance of ligaments of cooper in breast cancer?

A

With cancer and fibrosis it causes a dimpling of the overlying skin

Pitting of the oedematous skin (lymphatic)

74
Q

What is a deformation?

A

Moulding of a body part that has differentiated normally by mechanical forces usually over a long period of time

e.g. DDH, talipes

75
Q

What is talipes?

A

1/ 1000
Club foot
Foot turned inwards and upwards
Short Achilles tendon - fixed flexion

76
Q

What is DDH?

A
Development dysplasia of the hip
1-3%
Screened
Females and breech birth are risk factors
Swaddling
77
Q

What is a sequence?

A

Pattern of multiple anomalies that occurs early and produces a cascade of 2y and 3y error in morphogenesis

Pierre Robin Sequence

78
Q

Define teratogen

A

An environmental agent that causes abnormalities of form or function in an exposed embryo or foetus

Sufficient amounts
Appropriate time
Susceptible individual

79
Q

Give examples of teratogens

A
CMV
Herpes
Toxoplasmosis
Alcohol
Thalidomide
Drugs
Ionising radiation
80
Q

What prevention and screening is available in pregnancy to reduce birth defects?

A
Oral folate supplementation
Rubella vaccination
Avoidance of risk factors
Genetic counselling 
Donor gametes
Antenatal screening (ultrasound)