5.1.2 Flashcards
what r the 5 main structures in the vagina for fertilisation
-fallopian tube
-ovary
-endometrium
-uterus
-vagina
how long does the menstrual cycle go?
28 days on average
what occurs on day 14 of the menstrual cycle
ovulation cycle begins, if there has been mating, fertilisation occurs 1-2 days later
illustrate when a baby is a zygote, embryo, foetus, newborn
zygote : 1-5 days
embryo : day 5- week12
foetus : week 12+
born : newborn
when does implantation occur
day 7 of pregnancy
how does fertilisation occur ?
1.the ovary releases an egg in ovulation and it is taken to the middle of the fallopian tube
2. when sexual intercourse takes place, a male release semen which is comprised of sperm
3. the sperm swims into the vagina then through the cervix and uterus to the fallopian tube where the egg lays
4. sperm fuses with egg to create zygote
5. zygote then travels down the oviduct to the uterus where it is implanted
where does fertilisation occur specifically in the vagina
outer 1/3 of the fallopian tube
when the sperm reaches the egg cell, it must cross 3 layers, what r they?
- first membrane, the sperm physically pushes thro
- zygote creates a strong membrane which prevents any other sperm fertilising the egg
- surface protrins allows only one sperm 2 penetraste pass the plasma membrane
what is implantation?
its around day 8 of pregnancy, and the embryo attaches to uterus lining, the endometrium section
- the myometrium muscle underneath endometrium
- The blastocyst/zygote is implanted on the walls of the reproductive tract (uterine wall).
- Successfully implantation means pregnancy.
- This implantation process onto the walls establishes blastocyst’s access to nutrients (glucose, proteins, oxygen) to develop into a grown fetus (blood vessels surrounding the blastocyst carries blood which has dissolved nutrients)
Implantation is the process of adhering the fertilised egg to stick to the walls of the reproductive tract, providing the most suitable environment for zygote development.
what r hormones?
- chemical messengers that travel in the bloodstream
- hormones r released by glands (endocrine system)
what are the two most important hormones in the body generally, located in the brain
- hypothalamus ; releases hormones
- pituitary gland ; hormones r transported from here to the other glands
where r hormones released for pregnancy
hormones r released from the ovarian follicle outer cells
e.g, estrogen
how r hormones controlled in pregnancy
- hypothalamus releases hormones
- the gonadtropin GNRH releases the hormones to the pituitary
- this this leads to LH and FSH acting upon the estrogen and progesterone
what is a negative feedback loop
it ensures homeostasis stability so not too many hormones (FSH, LH, GnRH) are produced, so once estrogen levels rise, they exert negative feedback, causing less levels of GnRH being produced.
Fluctuations should always be curved as shown in the graph due to negative feedback.
what does FSH and LH do n link it together
FSH = allow the release of follicle by the ovaries
* initiates the ripening of follicle and egg in the ovary. this stimulates secretion of estrogen
by day 14, a surge in luteinising hormone takes place, causing ovulation
Causes follicle to release egg also known as ovulation, allows empty follicle to grow into corpus luteum and inhibits secretion of estrogen.
what is the corpus luteum
The hormones are then all produced by this structure called corpus luteum until the placenta can take over around week 8 of pregnancy
pool of hormone
what is estrogen’s role in the early stage of pregnancy?
It will travel through the blood stream and cause the development, repair and thickening of the endometrium, and it increases the nutrients and glucose with it
- It comes from the outer lining cells of the follicle
- It thickens the endometrium to prepare it for implantation for the clump of cells in the embryo
what is progestrone role in the beginning of pregnancy?
Maintains the wall of the uterus to ensure its not contracting against the embryo
- Maintains pregnancy by ensuring the muscle walls of the uterus don’t crush the embryo
That’s why when women give birth, they’re given anti progesterone drugs sometimes to contract the uterus, pushing the baby out
whats Beta HCG ?? what is it released in ?
Hormone that determines ones pregnancy as it is released through urine
- It is released through the outer cells of the implanted embryo – implantation
- Chorionic = placenta
- It acts on the gonads
- It allows the ovary to continuously release the hormones of progesterone and estrogen
what is the link between corupus luteum and placenta
The corpus luteum continuously produces estrogen and progesterone until the placenta can take over. About week 8 of pregnancy, the placenta begins to produce the nutrients and hormones necessary for the embryo
what r the two things that can occur after day 14 of the menstrual cycle?
fertilisation or no fertilisation
what happens if ovulation occurs and no sperm makes its way to the egg in the fallopian tube
no implantation occurs after the hypothetical 7th day of pregnancy . this will lead to the decreased level of estrogen and progestrone as theyre not needed.
- Decrease in estrogen breaks down the thickening of the endometrium
- The uterine muscles contract due to no progesterone control
There are blood vessel within the uterus as uterine walls contract upon them, the blood vessel are squished to the point where they’re thin and stop blood flow
- Stopped Blood flow would cause a stroke to the brain the uterine lining will die as if it has had a heart attack
-The shedding of the dead cells are what is referred to as the first day of menstruation (menses) for a female as it leaves the body
why does LH stimulate the beginning of ovulation?
By day 13, like there is a negative feedback loop, there is also a positive one which tends to occur at around day 13 of the reproductive cycle for a female which causes instead of a decrease an increase in LH. This increase causes in LH is primarily what begins implantation and release of hormones. The decrease however in the graph shows how fertilisation doesn’t occur because LH and the hormones drops
whatll happen after week 12 with the corpus luteum
The corpus luteum produces high levels of hCG in the first ten weeks of pregnancy as seen below, but then it drops. this is because the placenta has taken over, a new organism, getting rid of b-hcg
what r the four main roles of the placenta
- nutrient exchange, glucose mainly (takes blood sugar from mommy bloodstream thro the umbilical vein)
- interface - ensures mama and embryo blood never mix
- protects the baby as it is 50% foreign so mamas immune system will naturally want to destory it.
- it ensures the baby can breathe. umbilical cord provides oxygen fo rbaby to breathe while it is swimming in amniotic fluid.
- releases the hormones estrogen and progesterone
what are the hormonal changes when giving birth at 37 weeks? whats the main hormone utilised
- The muscles in the uterus must contract to expel the baby.
- The tissue of the cervix must soften so that the cervix can dilate (widen) to allow the passage of the baby.
oxytocin - *
Causes contractions of the uterine muscle caused by the nerves surrounding the cervix
* A positive feedback loop is occurring where everything continues to increase until the fetus has been deliver
o The nerves surrounding the cervix is increasing
o The baby’s head is getting pushed harder against the cervix
o Oxytocin levels are increasing
o The contractions increasing
Until finally resulting in the fetus delivery
