PBL 1 Flashcards
(114 cards)
1
Q
How do sperm move?
A
a combination of their own motility and uterine contractions (oxytocin)
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
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.
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.
5
Q
where does the sperm meet the egg?
A
at the ampulla isthmus junction of fallopian tubes
6
Q
what are the layers of the egg’s membrane?
A
corona radiata, zona pellucida and vitelline membrane.
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
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
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.
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
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.
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
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
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
15
Q
what is syngamy?
A
the fusion of the 2 cell’s nuclei in reproduction.
16
Q
what are blastomeres?
A
a cell formed by the cleavage of an ovum
17
Q
at what stage does the ovum begin to make its own genes?
A
when it has cleaved into a 4 cell embryo
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
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
20
Q
what type of cells are the blastomeres within the morula?
A
totipotent
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
22
Q
where does the inner cell mass cluster within the zygote?
A
at the embryonic pole (one side)
23
Q
what will the trophoblast cells become?
A
the large part of the placenta
24
Q
what will the inner cell mass become?
A
the foetus
25
what is the blastocoel?
a cavity within the morula formed by Na+/K+ ATPase
26
when does the morula become the blastocyst?
5-6 days after fertilisation when cells begin to start differentiating
27
when does implantation begin?
8-9 days after fertilisation
28
when does the embryo hatch from the zone pellucida?
7-10 days after fertilisation
29
what is the 'implantation window'?
The reception-ready phase of the endometrium of the uterus- lasts 4 days and usually occurs 6 days after peak LH levels
30
what is the 'implantation window' characterised by?
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.
31
what is predecidualization?
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
32
what is decidualization?
the further development of uterine glands, zone compact and epithelium of decimal cells
33
what is the decider basalis?
the part of the decider located basolaterally to the embryo after implantation
34
what Is the decider capsularis
the part that grows over the embryo on the luminal side, enclosing it into the endometrium
35
what is decider parietalis?
all other decider on the uterine surface
36
what's the receptor on embryo membrane that facilitates implantation?
L selectin
37
what happens once embryo has attached to the decider basalis?
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.
38
what are the trophoblasts that proliferate into the wall known as?
synctiotrophoblast cells
39
what do trophoblast cells become?
outer layer of synctiotrophoblast cells and inner layer of cytotrophoblast cells
40
what's the function of cytotrophoblasts?
they invade the syncytiotrophoblast matrix and forms early chorionic villi.
41
how do uterine arteries react to progesterone?
they become large and coiled, engorging the endometrial layer with blood
42
what is the decidual reaction and when does it occur?
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
43
what is spiral artery remodelling?
Modification of the arteries from low-flow, high-resistance to high-flow, low-resistance vessels capable of meeting the demands of the developing foetus
44
what is the chorion?
the embryonic derived portion of the placenta
45
what are chorionic villi?
vill that sprout from the chorion after their rapid proliferation in order to give a maximum area of contact with the maternal blood.
46
what is the intervillous space?
the part of the placenta that surrounds chorionic villi and contains maternal blood
47
what does the inner cell mass differentiate into?
the bilaminar disc- hypoblast and epiblast
48
what will the hypoblast become?
the yolk sac
49
what does the yolk sac give rise to?
primordial germ cells, which develop in the embryo and eventually become ovaries or testes in the fetus.
50
what will the epiblast become?
the primary germ layers - ectoderm, mesoderm and endoderm
51
what happens as the syncitiotrophoblast expands?
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
how is the bilaminar disc connected to the trophoblast cells in the second week of development?
the connecting stalk- this is the future umbilical cord
53
what is gastrulation?
the process whereby the bilaminar embryonic dis undergoes reorganisation to form the trilamincr disc
54
outline gastrulation
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
when does neurolation occur?
in the 4th week
56
where is human chorionic gonadotropin formed from?
syncitiotrophoblast cells
57
why is hCG important?
it binds to LH receptors on the ovaries, maintaining thr corpus luteum = maintaining progesterone output and avoiding menses
58
how do hCG levels change throughout pregnancy?
they rise during the first 6-8 weeks and then the levels start to fall
59
why does the placenta produce human placental lactose?
it counters the effects of maternal insulin to ensure there is plenty of glucose available to the baby
60
what is an ectopic pregnancy?
a pregnancy that occurs somewhere other than the uterine cavity
61
what is a heterotopic pregnancy?
the presence if multiple gestations with one being present in the uterine cavity and the other outside the uterus
62
outline what happens for an ectopic pregnancy to occur?
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
what's the most common place for an egg to implant in an ectopic pregnancy?
the Fallopian tube
64
outline the pathophysiology of an ectopic pregnancy within a Fallopian tube?
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
what happens if the Fallopian tube ruptures?
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
why can an ectopic pregnancy cause referred pain to the shoulder?
the bleeding irritates the phrenic nerve
67
what are some causes of ectopic pregnancies?
-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
what are some risk factors for ectopic pregnancies?
```
history of pelvic inflammatory disease
C-section history
endometriosis
chlamidia/gonorrhoea
congenital abnormalities
smoking
IVF
IUD
previous ectopic pregnancy
```
69
how does age affect chance of ectopic pregnancy?
The incidence of ectopic pregnancy showed a steady increase with increasing maternal age
70
what are symptoms of ectopic pregnancy?
amenorrhea, pelvic pain and vaginal bleeding
| you may also get normal early pregnancy discomforts e.g. nausea and breast tenderness
71
when would symptoms for ectopic pregnancies come on?
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
what are symptoms of Fallopian tube rupture?
severe abdominal pain which may refer to the shoulder
| haemodynamic instability e.g. feeling faint, tachycardia, hypotension, syncope and diaphoresis (sweating)
73
how do you establish that a patient is haemodynamically stable?
when vital signs are good and theres no evidence of hypotension or tachycardia
74
what factors does treatment of ectopic pregnancies depend on?
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
how often should hCG levels be double in the first 4 weeks of a viable pregnancy?
every 2-3 days
76
how is an ectopic pregnancy diagnosed?
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
how can we treat ectopic pregnancies with medication?
methotrexate is used
78
how does methotrexate work as treatment for an ectopic pregnancy?
competitive inhibition of folate-dependent steps in nucleic acid synthesis, effectively kills the rapidly dividing ectopic trophoblast.
79
what is a salpingostomy/fimbrioplasty?
when the Fallopian tube is opened to remove the pregnancy and then re-closed
80
what is a salpingectomy?
the complete removal of a Fallopian tube
81
what are some complications of ectopic pregnancies?
rupture of Fallopian tube= profound bleeding
pregnancy loss
infertility
pregnancy-related maternal mortality in first trimester
82
what is sub fertility?
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
what's the difference between sub fertility and infertility?
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
what are some causes of sub fertility in women?
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
how can hypothyroidism impact fertility?
Low levels of thyroid hormone can interfere with ovulation, which impairs fertility.
86
what are some causes of sub fertility in men?
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
when can sub fertile patients be referred sooner than the usual 1 year?
if they have had cancer, treatment of cancer, genital surgery or previous sub fertility
88
what are some religious arguments against IVF?
it goes against natural conception, encourages unmarried couples to have kids, same sex couples can have kids
89
what are some ethical arguments for not allowing IVF?
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
what are some pros for IVF?
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
what are cons for IVF?
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
who is eligible for IVF?
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
what will women aged 40 or under be offered in terms of IVF?
3 cycles of iVF
94
what will women of age 40-42 be offered in terms of IVF on the NHS?
1 cycle but you cant have had IVF before and have no evidence of a low ovarian reserver
95
how can you increase chance of IVF success if having limited success?
donor eggs
96
how is funding for IVF given out?
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
how much does a cycle of IVF cost privately?
between 6-10,000 pounds
98
what's the most valid pregnancy test?
blood tests are slightly higher but both blood and urine pregnancy tests are 99% accurate when done correctly
99
what's the advanatage of a blood pregnancy test over a urine test?
can detect a pregnancy before you have even missed a period as it can find smaller amounts of hCG
100
what's the benefit of a urine pregnancy test over a blood pregnancy test
it can be done at home so is private and convenient
101
what are the 2 types of blood pregnancy tests?
qualitative hCG test
| quantitative hCG test - can also track problems during pregnancy
102
how do pregnancy tests work?
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
What is given during IVF to cause down regulation of the menstrual cycle?
GnRH agonist as a daily injection for 2 weeks
104
why is it important to downregulate the menstrual cycle at the start of IVF?
it helps bring about a baseline and prevents you from ovulating on your own
105
What is given in IVF to cause ovarian hyperstimulation?
FSH drugs
106
what is intracytoplasmic sperm injections?
when the sperm is directly placed into the egg using a needle
107
what is the woman given in IVF just before the embryo is placed back into her?
progesterone or hCG to help the lining of the womb receive the embryo
108
what are fibroids?
non-cancerous growths of the womb made up of muscle and fibrous tissue
109
what can be symptoms of fibroids?
heavy periods, abdominal swelling and urinary problems
110
how can large fibroids impact fertility?
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
what is the difference between testicular sperm extraction (TESE) and testicular sperm aspiration (TESA)?
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
why are single embryo transfers now more commonly used in the UK over multiple embryo transfers?
it avoids risks to the mothers health associated with carrying multiple children and it prevents risks like preterm babies, low birth weights etc
113
what is a varicocele?
an enlargement of a vein within the scrotum
114
why can varicoceles cause infertility?
they can cause low sperm production and decreased sperm quality
