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xB11W1 > PBL 1 > Flashcards

PBL 1 Flashcards

1
Q

How do sperm move?

A

a combination of their own motility and uterine contractions (oxytocin)

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2
Q

how does the cervix filter out any sperm with poor motility or morphology?

A

thick cervical mucus means only sperm with the best motility can enter

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3
Q

what are the 2 steps of capacitation?

A

destabilisation of the acrosomal sperm head membrane which allows it to penetrate the outer layer of the egg, and chemical changes in the tail that allow a greater mobility in the sperm.

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4
Q

what’s sperm hyper activation?

A

The sudden rise in calcium levels causes the flagellum to form deeper bends, propelling the sperm more forcefully through the viscous environment.

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5
Q

where does the sperm meet the egg?

A

at the ampulla isthmus junction of fallopian tubes

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6
Q

what are the layers of the egg’s membrane?

A

corona radiata, zona pellucida and vitelline membrane.

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7
Q

how does the sperm penetrate the corona radiata?

A

by releasing hyaluronidase from the acrosome which digests cumulus cells which are embedded in a gel-like substance made primarily of hyaluronic acid

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8
Q

how does sperm penetrate the zone pellucida?

A

it interacts wtith glycoproteins ZP2/3, triggering the acrosome reaction= release of Acrosin which can digest through

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9
Q

how do sperm enter oocyte?

A

after sperm has bound to ZP2/3 it goes through a process called fusion where the sperm binds to the plasma membrane and the nucleus and organelles are engulfed.

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10
Q

how does the oocyte prevent polyspermy?

A

calcium is released from zone pellucida. Elevation of calcium initiates the cortical reaction preventing more sperm from entering

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11
Q

what is the cortical reaction?

A

release of cortical granule contents into the perivitaline space modifying the extracellular matrix to make it impenetrable to sperm entry.

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12
Q

how does the cortical reaction make the extracellular matrix impenetrable to sperm?

A

Cortical granules within the egg’s cytoplasm release enzymes into the zona pellucida
These enzymes destroy sperm binding sites and also thicken and harden the glycoprotein matrix of the jelly coat - forms the hyaline layer
This prevents polyspermy

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13
Q

outline the activation of the oocyte?

A

sperm contribute phospholipase C zeta which cleaves PIP2 into IP3. IP3 then triggers calcium transience which reactivate the mitotic cycle through destruction of cyclin B = meiotic division

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14
Q

outline oogenesis?

A

oogonium undergoes mitosis to form primary oocyte. Meiosis 1 occurs to produce first polar body and secondary oocyte. If fertilisation occurs, meiosis 2 occurs to produce second polar body and ovum

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15
Q

what is syngamy?

A

the fusion of the 2 cell’s nuclei in reproduction.

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16
Q

what are blastomeres?

A

a cell formed by the cleavage of an ovum

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17
Q

at what stage does the ovum begin to make its own genes?

A

when it has cleaved into a 4 cell embryo

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18
Q

what is the morula?

A

solid mass of 16 blastomeres when we can no longer see individual blastomeres and tight junctions have begun to fall apart

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19
Q

what’s the significance of cleavage of ovum occurring within the zone pellucida?

A

the zygote doesnt get any bigger it just has more cells

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20
Q

what type of cells are the blastomeres within the morula?

A

totipotent

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21
Q

how does the morula differentiate?

A

cells on the outside will form trophectoderm cells and cells within the morula form the inner cell mass

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22
Q

where does the inner cell mass cluster within the zygote?

A

at the embryonic pole (one side)

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23
Q

what will the trophoblast cells become?

A

the large part of the placenta

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24
Q

what will the inner cell mass become?

A

the foetus

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25
Q

what is the blastocoel?

A

a cavity within the morula formed by Na+/K+ ATPase

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26
Q

when does the morula become the blastocyst?

A

5-6 days after fertilisation when cells begin to start differentiating

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27
Q

when does implantation begin?

A

8-9 days after fertilisation

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28
Q

when does the embryo hatch from the zone pellucida?

A

7-10 days after fertilisation

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29
Q

what is the ‘implantation window’?

A

The reception-ready phase of the endometrium of the uterus- lasts 4 days and usually occurs 6 days after peak LH levels

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30
Q

what is the ‘implantation window’ characterised by?

A

changes to the endometrium cells, which aid in the absorption of the uterine fluid. This brings the blastocyst nearer to the endometrium and immobilizes it.

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31
Q

what is predecidualization?

A

when the endometrium increases in thickness, becomes vascularised and glands grow - about 7 days after ovulation
Surface of endometrium produced decimal cells - this is what is shed if there is no pregnancy

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32
Q

what is decidualization?

A

the further development of uterine glands, zone compact and epithelium of decimal cells

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33
Q

what is the decider basalis?

A

the part of the decider located basolaterally to the embryo after implantation

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34
Q

what Is the decider capsularis

A

the part that grows over the embryo on the luminal side, enclosing it into the endometrium

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35
Q

what is decider parietalis?

A

all other decider on the uterine surface

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36
Q

what’s the receptor on embryo membrane that facilitates implantation?

A

L selectin

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37
Q

what happens once embryo has attached to the decider basalis?

A

trophoblast secretes enzymes that digest the extracellular matrix of endometrial tissue. The trophoblast cells then begin to intrude between the endometrial cells, attaching the blastocyst to the uterine surface.

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38
Q

what are the trophoblasts that proliferate into the wall known as?

A

synctiotrophoblast cells

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39
Q

what do trophoblast cells become?

A

outer layer of synctiotrophoblast cells and inner layer of cytotrophoblast cells

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40
Q

what’s the function of cytotrophoblasts?

A

they invade the syncytiotrophoblast matrix and forms early chorionic villi.

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41
Q

how do uterine arteries react to progesterone?

A

they become large and coiled, engorging the endometrial layer with blood

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42
Q

what is the decidual reaction and when does it occur?

A

high progesterone levels cause decidual cells to become enlarged and coated in a sugar rich fatty fluid which can be absorbed by the syncytiotrophoblast and this helps sustain the embryo early on
happens by day 12

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43
Q

what is spiral artery remodelling?

A

Modification of the arteries from low-flow, high-resistance to high-flow, low-resistance vessels capable of meeting the demands of the developing foetus

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44
Q

what is the chorion?

A

the embryonic derived portion of the placenta

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45
Q

what are chorionic villi?

A

vill that sprout from the chorion after their rapid proliferation in order to give a maximum area of contact with the maternal blood.

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46
Q

what is the intervillous space?

A

the part of the placenta that surrounds chorionic villi and contains maternal blood

47
Q

what does the inner cell mass differentiate into?

A

the bilaminar disc- hypoblast and epiblast

48
Q

what will the hypoblast become?

A

the yolk sac

49
Q

what does the yolk sac give rise to?

A

primordial germ cells, which develop in the embryo and eventually become ovaries or testes in the fetus.

50
Q

what will the epiblast become?

A

the primary germ layers - ectoderm, mesoderm and endoderm

51
Q

what happens as the syncitiotrophoblast expands?

A

lucanae begin to form. by day 12 they fuse to form lacunae network
capillaries here dilate to form maternal sinusoids. enzymes begin to erode the lining of the sinusoids and uterine glands, allowing maternal blood and uterine secretions into the lacunae= allowing exchange of gases and metabolites

52
Q

how is the bilaminar disc connected to the trophoblast cells in the second week of development?

A

the connecting stalk- this is the future umbilical cord

53
Q

what is gastrulation?

A

the process whereby the bilaminar embryonic dis undergoes reorganisation to form the trilamincr disc

54
Q

outline gastrulation

A

at day 15 the primitive streak forms near the caudal end of the bilaminar embryonic disc = defines axis of body

at cranial end, primitive streak expands to form the primitive pit

this pit continues towards the caudal end of the streak, forming a primitive groove

cells of epiblast migrate inwards towards streak and invaginate into the hypoblast

by day 16 the majority of the hypoblast cells are eventually completely replaced by definitive endoderm

remaining cells of epiblast are referred to as ectoderm which forms the most exterior, distal layer.

some invaginated epiblast cells remain between ectoderm and endoderm = mesoderm

55
Q

when does neurolation occur?

A

in the 4th week

56
Q

where is human chorionic gonadotropin formed from?

A

syncitiotrophoblast cells

57
Q

why is hCG important?

A

it binds to LH receptors on the ovaries, maintaining thr corpus luteum = maintaining progesterone output and avoiding menses

58
Q

how do hCG levels change throughout pregnancy?

A

they rise during the first 6-8 weeks and then the levels start to fall

59
Q

why does the placenta produce human placental lactose?

A

it counters the effects of maternal insulin to ensure there is plenty of glucose available to the baby

60
Q

what is an ectopic pregnancy?

A

a pregnancy that occurs somewhere other than the uterine cavity

61
Q

what is a heterotopic pregnancy?

A

the presence if multiple gestations with one being present in the uterine cavity and the other outside the uterus

62
Q

outline what happens for an ectopic pregnancy to occur?

A

the fertilised egg comes to rest somewhere other than the endometrium but the surface has to have a rich enough blood supply to support the developing embryo

63
Q

what’s the most common place for an egg to implant in an ectopic pregnancy?

A

the Fallopian tube

64
Q

outline the pathophysiology of an ectopic pregnancy within a Fallopian tube?

A

as it grows it eventually runs out of space and the growing pregnancy stretches nerve fibres in the wall of the tube causing lower abdominal pain. Eventually the expansion causes damage to the wall of the ampulla, potentially rupturing the Fallopian tube

65
Q

what happens if the Fallopian tube ruptures?

A

you may experience massive haemorrhaging in the abdominal cavity and this blood can irritate the peritoneum which can cause referred pain to the shoulder

66
Q

why can an ectopic pregnancy cause referred pain to the shoulder?

A

the bleeding irritates the phrenic nerve

67
Q

what are some causes of ectopic pregnancies?

A

-inflammation and scarring of the fallopian tubes from a previous
- medical condition/infection/surgery.
hormonal factors.
-genetic abnormalities.
-birth defects.
-medical conditions that affect the shape and condition of the fallopian tubes and reproductive organs.

68
Q

what are some risk factors for ectopic pregnancies?

A 
history of pelvic inflammatory disease
C-section history
endometriosis
chlamidia/gonorrhoea
congenital abnormalities
smoking
IVF
IUD
previous ectopic pregnancy
69
Q

how does age affect chance of ectopic pregnancy?

A

The incidence of ectopic pregnancy showed a steady increase with increasing maternal age

70
Q

what are symptoms of ectopic pregnancy?

A

amenorrhea, pelvic pain and vaginal bleeding

you may also get normal early pregnancy discomforts e.g. nausea and breast tenderness

71
Q

when would symptoms for ectopic pregnancies come on?

A

6-8 weeks if its within the Fallopian tube ampulla but if its somewhere with more space, the symptoms may take much longer to appear

72
Q

what are symptoms of Fallopian tube rupture?

A

severe abdominal pain which may refer to the shoulder

haemodynamic instability e.g. feeling faint, tachycardia, hypotension, syncope and diaphoresis (sweating)

73
Q

how do you establish that a patient is haemodynamically stable?

A

when vital signs are good and theres no evidence of hypotension or tachycardia

74
Q

what factors does treatment of ectopic pregnancies depend on?

A

haemodynamic stability of the woman, the site of implantation of the ectopic pregnancy, the risk of tubal rupture, serum hCG level, the level of pain the woman has, and the acceptability of the method of treatment to the woman.

75
Q

how often should hCG levels be double in the first 4 weeks of a viable pregnancy?

A

every 2-3 days

76
Q

how is an ectopic pregnancy diagnosed?

A

with a transvaginal ultrasound to see inside the uterus and look for an intrauterine pregnancy which should be visible by week 5-6- so unlikely to have an ectopic pregnancy if this is seen

77
Q

how can we treat ectopic pregnancies with medication?

A

methotrexate is used

78
Q

how does methotrexate work as treatment for an ectopic pregnancy?

A

competitive inhibition of folate-dependent steps in nucleic acid synthesis, effectively kills the rapidly dividing ectopic trophoblast.

79
Q

what is a salpingostomy/fimbrioplasty?

A

when the Fallopian tube is opened to remove the pregnancy and then re-closed

80
Q

what is a salpingectomy?

A

the complete removal of a Fallopian tube

81
Q

what are some complications of ectopic pregnancies?

A

rupture of Fallopian tube= profound bleeding
pregnancy loss
infertility
pregnancy-related maternal mortality in first trimester

82
Q

what is sub fertility?

A

the failure to establish a clinical pregnancy after 12 months of regular, unprotected sexual intercourse or an impairment in a person’s capacity to reproduce

83
Q

what’s the difference between sub fertility and infertility?

A

infertility means you cannot conceive whereas sub fertile means its possible to conceive naturally but you are less fertile so it takes longer than average

84
Q

what are some causes of sub fertility in women?

A

blocked Fallopian tubes caused by endometriosis, PID, scar tissue, gonorrhoea/chlamidyia history
uterine abnormalities e.g. fibroids or septet uterus
thyroid disease
ovulatory disorders e.g. POD, diminished ovarian reserve, premature ovarian insufficiency hypothalamus/pituitary gland conditions
tubal disease
advancing female age

85
Q

how can hypothyroidism impact fertility?

A

Low levels of thyroid hormone can interfere with ovulation, which impairs fertility.

86
Q

what are some causes of sub fertility in men?

A

low sperm count or poor function caused by chlamidyia, HIV, diabetes, mumps, cancer, varicocele, Klinefelter syndrome
low testosterone
problems with sperm delivery caused by CF, prem ejaculaton, injury or damage to testes

87
Q

when can sub fertile patients be referred sooner than the usual 1 year?

A

if they have had cancer, treatment of cancer, genital surgery or previous sub fertility

88
Q

what are some religious arguments against IVF?

A

it goes against natural conception, encourages unmarried couples to have kids, same sex couples can have kids

89
Q

what are some ethical arguments for not allowing IVF?

A

thousands of embryos are destroyed in the process
survival of frozen eggs is fairly low
it encourages the mentality that people are objects that can be bought/sold
these babies are more at risk of birth defects
poses physical and psychological health risks on parents
permissibility of sex selection or choosing embryos for traits

90
Q

what are some pros for IVF?

A

increases the odds of pregnancy
helps get around fertility problems
more successful than other assisted reproductive technology
unused embryos can be donated to other couples or research
can help single/same-sex couples

91
Q

what are cons for IVF?

A

costs loads
pro-life outrage
IVF cycles can be unsuccessful
side effects e.g. ovarian hyper stimulation
increased risk of ectopic pregnancy
risk of premature birth and low birth weight
can take an emotional/psyhcological toll

92
Q

who is eligible for IVF?

A

women under the age of 43 who have been trying to get pregnant through regular unprotected sex for 2 years. Or who have had 12 cycles of artificial insemination, with at least 6 of these cycles using a method called intrauterine insemination

93
Q

what will women aged 40 or under be offered in terms of IVF?

A

3 cycles of iVF

94
Q

what will women of age 40-42 be offered in terms of IVF on the NHS?

A

1 cycle but you cant have had IVF before and have no evidence of a low ovarian reserver

95
Q

how can you increase chance of IVF success if having limited success?

A

donor eggs

96
Q

how is funding for IVF given out?

A

NHS gives it out based on local CCG policies e.g. some places may require you to not have children already or be a healthy weight

97
Q

how much does a cycle of IVF cost privately?

A

between 6-10,000 pounds

98
Q

what’s the most valid pregnancy test?

A

blood tests are slightly higher but both blood and urine pregnancy tests are 99% accurate when done correctly

99
Q

what’s the advanatage of a blood pregnancy test over a urine test?

A

can detect a pregnancy before you have even missed a period as it can find smaller amounts of hCG

100
Q

what’s the benefit of a urine pregnancy test over a blood pregnancy test

A

it can be done at home so is private and convenient

101
Q

what are the 2 types of blood pregnancy tests?

A

qualitative hCG test

quantitative hCG test - can also track problems during pregnancy

102
Q

how do pregnancy tests work?

A

the pad absorbs urine and if pregnant hCG will bind to mobile antibodies which are attached to blue dye. If regnant the immubolized antibodies in the test zone attach to hCG which is attached to dye and so will form a positive line
in the control window, the excess dye antibodies that are not attached to hCG will flow into the control area where there are antibodies which recognise the dye-antibody complex and bind to it, forming a control line

103
Q

What is given during IVF to cause down regulation of the menstrual cycle?

A

GnRH agonist as a daily injection for 2 weeks

104
Q

why is it important to downregulate the menstrual cycle at the start of IVF?

A

it helps bring about a baseline and prevents you from ovulating on your own

105
Q

What is given in IVF to cause ovarian hyperstimulation?

A

FSH drugs

106
Q

what is intracytoplasmic sperm injections?

A

when the sperm is directly placed into the egg using a needle

107
Q

what is the woman given in IVF just before the embryo is placed back into her?

A

progesterone or hCG to help the lining of the womb receive the embryo

108
Q

what are fibroids?

A

non-cancerous growths of the womb made up of muscle and fibrous tissue

109
Q

what can be symptoms of fibroids?

A

heavy periods, abdominal swelling and urinary problems

110
Q

how can large fibroids impact fertility?

A

they can sometimes prevent a fertilised egg from attaching itself to the lining of the womb or prevent the sperm itself from meeting the egg- very rare!

111
Q

what is the difference between testicular sperm extraction (TESE) and testicular sperm aspiration (TESA)?

A

TESE is when a fine syringe is inserted into the epididymis/testicyle to extract the sperm whilst TESA is taking a biopsy of the testicula from which hopefully sperm can be recovered

112
Q

why are single embryo transfers now more commonly used in the UK over multiple embryo transfers?

A

it avoids risks to the mothers health associated with carrying multiple children and it prevents risks like preterm babies, low birth weights etc

113
Q

what is a varicocele?

A

an enlargement of a vein within the scrotum

114
Q

why can varicoceles cause infertility?

A

they can cause low sperm production and decreased sperm quality

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