Female Reproductive Cycle | Menstrual Cycle
Summary
TLDRThis video explains the female reproductive cycle, focusing on the menstrual phases. It details the roles of estrogen and progesterone in the cycle, including menstruation (shedding of the endometrial lining), the proliferative phase (regeneration of the endometrium and arteries), and the secretory phase (preparing the uterus for a potential pregnancy). The video covers the hormonal changes, uterine anatomy, and how these hormones affect the uterine lining, cervical mucus, and blood flow. It also discusses what happens if fertilization occurs, as well as the effects if it doesn’t, including the formation of the corpus albicans.
Takeaways
- 🔄 The menstrual cycle has three phases: menstruation, proliferative, and secretory.
- 🩸 Menstruation involves shedding the stratum functionalis, a layer of the endometrium, along with blood from the spiral arteries.
- 🌱 The proliferative phase, days 6-14, regenerates the stratum functionalis and spiral arteries, driven by estrogen.
- 🧬 Estrogen also leads to the creation of uterine glands and thin cervical mucus, aiding sperm movement toward the egg.
- 🚼 Around day 14, ovulation occurs, releasing an oocyte for potential fertilization.
- 🧪 The secretory phase (days 15-28) is driven by progesterone, which thickens the stratum functionalis and enhances blood supply via spiral arteries.
- 🥣 Progesterone stimulates uterine glands to secrete a nutrient-rich fluid to nourish a potential embryo.
- 🛑 If fertilization occurs, human chorionic gonadotropin (hCG) from the embryo maintains progesterone production.
- ⚠️ If no fertilization occurs, the corpus luteum dies, progesterone drops, spiral arteries weaken, and menstruation begins again.
- 🧫 The cycle restarts if no embryo forms, and the corpus luteum turns into scar tissue called the corpus albicans.
Q & A
What are the three phases of the menstrual cycle?
-The three phases of the menstrual cycle are menstruation, the proliferative phase, and the secretory phase.
What happens during the menstruation phase?
-During the menstruation phase, the stratum functionalis (the upper layer of the endometrium) is shed, resulting in blood loss from the spiral and coiled arteries.
What are the two layers of the endometrium and their functions?
-The two layers of the endometrium are the stratum functionalis, which is shed during menstruation, and the stratum basalis, which remains and regenerates the stratum functionalis during the next cycle.
What role does estrogen play in the proliferative phase?
-During the proliferative phase, estrogen helps regenerate the stratum functionalis, stimulates the growth of spiral and coiled arteries (angiogenesis), and starts the formation of uterine glands.
Why is thin cervical mucus important during the proliferative phase?
-Thin cervical mucus is important because it allows sperm to pass more easily through the cervix, facilitating fertilization during ovulation.
What happens during the secretory phase?
-In the secretory phase, progesterone thickens the stratum functionalis, promotes the growth of spiral and coiled arteries, stimulates uterine glands to produce nutrient-rich fluids, and forms a thick cervical mucus plug to protect the uterus.
What hormone drives the secretory phase, and where is it produced?
-Progesterone drives the secretory phase, and it is produced by the corpus luteum in the ovary.
What happens if fertilization does not occur by the end of the secretory phase?
-If fertilization does not occur, progesterone levels drop, the spiral arteries spasm and rupture, leading to the shedding of the stratum functionalis, which results in menstruation.
What is the corpus luteum, and what happens to it if fertilization does not occur?
-The corpus luteum is a hormone-producing structure formed from the Graafian follicle after ovulation. If fertilization does not occur, it degenerates into the corpus albicans, a scar-like tissue, and stops producing progesterone.
What is the function of human chorionic gonadotropin (hCG) if fertilization occurs?
-If fertilization occurs, the embryo releases hCG, which signals the corpus luteum to continue producing progesterone until the placenta is developed around the 12th week of pregnancy.
Outlines
🧠 Introduction to Female Reproductive Cycle Phases
The speaker introduces the video as a continuation of the female reproductive cycle, referencing the ovulatory cycle. Progesterone and estrogen production by the corpus luteum are discussed, setting the stage for explaining the three phases of the menstrual cycle: menstruation, proliferative phase, and secretory phase. The endometrium's two layers—stratum functionalis and stratum basalis—are introduced, focusing on how the stratum functionalis sheds during menstruation, along with blood from spiral and coiled arteries.
🌱 Proliferative Phase and Endometrial Regeneration
The proliferative phase is described, highlighting how the stratum functionalis and spiral arteries regenerate after menstruation (days 6–14). Estrogen plays a crucial role in this process by promoting endometrial regrowth and angiogenesis (formation of new blood vessels). Additionally, uterine glands begin forming, though they are not yet secreting fluids. Estrogen also causes the cervical glands to produce thin mucus to facilitate sperm movement during ovulation, helping in sperm capacitation.
🌸 Secretory Phase and the Role of Progesterone
In the secretory phase (days 15–28), progesterone takes over as the dominant hormone, thickening the stratum functionalis and increasing the number of spiral arteries. Progesterone also stimulates the uterine glands to produce a nutrient-rich fluid for potential embryo nourishment. It thickens cervical mucus, forming a plug to protect a potential embryo by preventing substances or organisms from entering the uterus. This phase is essential for preparing the body for implantation if fertilization occurs.
⏳ Menstrual Cycle Recap and Potential Outcomes
The video outlines the end of the menstrual cycle, explaining that if fertilization does not occur, progesterone levels drop, causing the spiral arteries to spasm and rupture, leading to the shedding of the stratum functionalis. This results in menstruation, beginning a new cycle. If fertilization does occur, human chorionic gonadotropin (hCG) from the embryo signals the corpus luteum to continue producing progesterone until the placenta forms.
💔 Corpus Luteum Degeneration and Conclusion
If fertilization does not occur, the corpus luteum degenerates and transforms into a fibrous tissue called the corpus albicans, marking the end of its role in hormone production. The video concludes with a promise to review the entire female reproductive cycle in a subsequent video, ensuring viewers understand the complex hormonal interactions throughout the menstrual cycle.
Mindmap
Keywords
💡Menstruation
💡Endometrium
💡Stratum functionalis
💡Proliferative phase
💡Spiral and coiled arteries
💡Estrogen
💡Secretory phase
💡Progesterone
💡Corpus luteum
💡Corpus albicans
Highlights
Introduction to the female reproductive cycle and its dependence on understanding the ovulatory cycle.
Explanation of progesterone and estrogen production from the corpus luteum and their role in the menstrual cycle.
Introduction of the three phases of the menstrual cycle: menstruation, proliferative phase, and secretory phase.
Detailed description of menstruation as the shedding of the stratum functionalis layer from the endometrium.
Distinction between the stratum functionalis and the stratum basalis in the uterus, with the former being shed during menstruation.
Explanation of the role of spiral and coiled arteries in the stratum functionalis, contributing to blood loss during menstruation.
Proliferative phase overview: regeneration of the stratum functionalis and spiral arteries, influenced by estrogen.
Explanation of angiogenesis and the creation of new arteries during the proliferative phase.
Role of estrogen in forming thin cervical mucus, aiding sperm movement and capacitation during ovulation.
Secretory phase discussion, focusing on the role of progesterone in thickening the endometrium and stimulating uterine glands.
Formation of a thick cervical mucus plug during the secretory phase to protect the uterus if fertilization occurs.
Impact of progesterone on maintaining stable blood vessel activity in the endometrium, preventing necrosis.
Menstruation as a result of ischemia and necrosis when progesterone levels drop, leading to the shedding of the stratum functionalis.
Role of human chorionic gonadotropin (hCG) in sustaining the corpus luteum and progesterone production during pregnancy.
Corpus luteum degeneration into corpus albicans if fertilization does not occur, marking the end of the menstrual cycle.
Transcripts
iron engineer it's in this video we're
gonna continue our discussion about the
female reproductive cycle if you guys
haven't already seen it go and watch the
ovulatory cycle first because it's
completely dependent upon being able to
do this video okay alright so now if you
guys remember we left off with
progesterone production right from the
corpus luteum and then we had estrogen
production also right so let's bring
estrogen over here so we can have them
together so over here you're gonna have
a stroke gin and progesterone now before
we actually go into what these hormones
are gonna do to the uterus let's map out
the three phases of the menstrual cycle
okay so the three phases in order first
one is going to be menstruation now the
menstruation face is the shedding face
that's how what they can actually go you
know will actually put like a little
like a thing here to kind of describe it
so this is a shedding face what do I
mean by shedding okay in here in the
uterus you have an inner lining so
there's an inner lining of the uterus
just called the endometrium okay so
again what are the two layers here
there's actually the specific layer is
called the endo metrium now the
endometrium is actually composed of two
like sub layers or strata if you will
you see this like lime green one right
there that lime green one is actually
called the stratum function Alice okay
so this green one right here is actually
called the stratum function Alice okay
it's that green layer right there this
blue layer below it is actually called
the stratum base Alex okay so one more
time endometrium is the inner lining of
the uterus which is made up of simple
columnar epithelial tissue and it
consists of two different sub layers one
is the stratum function Alice which is
this green lime layer right there and
then the
other one is the Shraddha massage which
is this actual blue layer here during
menstruation the stratum function Alice
is the one that gets shed out of the
uterus so what is actually being shed
out of the uterine lining it's actually
going to be the stratum function Alice
that's being shed okay now about how
long is the menstruation period now
again assuming that it's an average that
average is about days one to five
obviously it could change from person to
person right depending upon whether they
have that actual menstruation period or
whether they have heavy menstruation you
know men arrayed you okay now days one
through five is the period in time in
which this actual stratum function house
is being shed so now let's show that
then so what also is being broken down
oh before I do that let's actually
discuss something really quick you see
the stratum bus house right there you
see that red artery that's going through
it that's a straight artery then the one
in the stratum function Alice is
actually going to be spirally and coyly
artist let's write that down right now
so that you guys have that in your mind
so the stratum function Alice is really
really important it has these things
called the spiral and coiled arteries
okay I know it might seem insignificant
but it is extremely important that we
understand this and differentiate that
in the stratum bus Alice it consists of
straight arteries now specifically these
are branches of the yeren artery which
comes off the internal iliac artery so
these spiralling coyly arteries in these
straight arteries are going to be
arteries that are coming off of the
uterine artery which is a branch of the
internal iliac artery now whenever the
stratum functionals being shed what are
you actually losing with it the spirally
and coiled arteries that's why there's
blood being lost so not only is there
tissue loss there's also going to be
blood loss and that blood that you're
losing is the vessels those spiralling
coyly arteries but what are you keeping
those straight arteries which are
than the stratum ViSalus okay that's the
first step so that's our menstruation
phase and what was the ministrations
consisting of specifically the shedding
of the stratum function Alice with the
blood that's carried by the spiral and
coyly arteries cool now what did you see
that actually remains here - raddimus
Alice remains so this next phase is
actually called the pro literate 'iv
phase now the proliferative phase is
actually going to be whenever you're
regenerating your actual stratum
function out of the endometrium so the
proliferative phase you actually
regenerate your stratum function Alice
layer so you shat it off in the
menstruation phase and then you
regenerate it within the proliferative
phase another thing that you're going to
regenerate is you're gonna regenerate
these spirally and coyly arteries so
you're gonna regenerate this spiraled
and coiled arteries and I'm gonna
explain how this happens okay so first
off what days is the proliferative phase
actually occurring from it's occurring
approximately from about days 6 to 14
now if we come back over here for a
second - the actual follicular phase you
guys remember what days with a
follicular phase days 1 through 14 and
what was the primary hormone working in
that area FSH right what was the primary
hormone being produced estrogen so now
let's go ahead and see what this
estrogen that we produced over here what
it's actually doing in the uterus we
heard he told you what it's doing it's
regenerating the stratum function house
so let's show that what is it going to
regenerate here it's gonna regenerate
the stratum function Alice that's why
they call it the proliferative phase
because it's gonna cause proliferation
right of the endometrium
all right specifically the stratum
function what else did I say it was
gonna do it was gonna regenerate those
spirally and coyly arteries what does
that call whenever you actually make new
arteries you know that's called
angiogenesis
it's kind of a long-term autoregulation
but this is where you're making these
new spirally and coyly arteries and
again who's doing this this is actually
going to be the job of Astra j'en now
you know what else a surgeon is doing
not only is this regenerating the
straddle functionality not only is it
regenerating the spiralling coyly
arteries but you know there's also
uterine glands that we have to have
these little uterine glands that are
secreting specific fluids he's starting
the process of making these uterine
plants and these uterine glands are
gonna be really important in the next
phase that we talk about but again what
is it doing it's leading to the starting
the production of these uterine glands
they're not secreting anything they're
just making these uterine glands so
what's the next thing that they also do
up here so not only was it regenerating
the stratum function Alice and the
spiraling core the arteries but it was
also making uterine glands look what
else it does it's also really smart too
you know here this is the cervix of your
uterus there's specific glands within
the cervix of yours
you know these glands these actually
like like mucous glands look what
estrogen does to these glands it tells
these glands to start producing a mucus
but this mucus that it produces is very
thin so there's brown stuff that I'm
drawing here this is a mucus but this
mucus is very very thin mucus why is it
important to have a thin mucus because
what happens around day 14 to about do
you know day 14 or 15 the female
actually undergoes what's called
ovulation right and injects that Oh a
site out into the ampulla the fallopian
tubes
if sperms if someone's a little swimmer
decides to run up through this actual
female reproductive tract do you want it
to be blocked by a thick mucus plug no
you do not you want it to be nice and
thin and if it's thin it's gonna be
easier for it to actually move towards
the actual egg so not only do you want
it to be skin but you also wanted to
consists of very specific chemicals that
we talked about in fertilization that
helps with called capacitation of the
sperm so what is it doing here to the
cervical mucus production it's making it
thin so what
estrogen doing here also it's also
causing thin cervical mucus production
for what so that it's easier for the
sperm to move up to the egg and it also
contains chemicals that help with help
ending capacitation of the sperm
activating the sperm helping it to clean
its head right of cholesterol and local
proteins and different types of things
like that okay that's what's happening
within this proliferative phase which is
around a six through fourteen okay
and again what is it doing just to recap
again it's causing proliferation of the
actual stratum function Alice of the
endometrium it's helping the actual
angiogenic effect to make more spirally
in coyly arteries it's leading to the
production of these actual uterine
glands they're not secreting anything
just undergoing the production of them
and on top of that it's making a thin
cervical mucus that the sperm cells it's
easier to be able to get to the egg and
helps to activate the egg right I'm
sorry activate the sperm okay for
capacitation now we go into the next
part over here what is that last phase
so this last phase here it's actually
called the secretory phase now what was
the primary hormone that was involved in
the proliferative phase just so that we
can continuously recap on that what was
the primary hormone estrogen right he
was the primary hormone that was
stimulating the proliferative phase
what's the primary hormone do you think
that's going to be stimulating the
secretory phase progesterone now who was
actually synthesizing and secreting that
pedestrian let's come back remember in
the ovary we had the luteinizing hormone
convert the graafian follicle into the
corpus luteum and then it stimulated the
corpus luteum to pick progesterone that
progesterone right there that was
produced by the corpus luteum
is gonna act on the uterus what is it
gonna do here in the actual uterus it's
gonna do some of the similar effects to
what estrogen did what did estrogen do
he caused
regeneration the stratum function house
right well guess what progesterone does
he makes the actual stratum function
Alice Eve
a little bit thicker so he makes it a
little bit thicker and then on top of
that you're gonna have to have blood
supply that part of the area right there
right so what is it going to do to this
area it's gonna help to make the
spiraling corley arteries a little bit
longer right so it's gonna make more
spirally and coyly arteries guess what
else is going to do you know how those
uterine glands were synthesized and they
were made guess what the progesterone is
gonna do progesterone is actually gonna
stimulate these uterine glands to start
producing a nice type of fluid
nutrient-rich broth I know it's a heck
of a nasty word to say but that's what
it's doing it's e creating a nice
nutrient-rich broth which is rich in
glycogen which is a polysaccharide right
a polymer of glucose a lot of lipids and
a lot of specific types of proteins so
again if we look at everything it's
doing here let's map out what
progesterone is doing again the first
thing he's doing is proliferating again
so proliferating the stratum function
Alice so making it a little bit thicker
what else is he doing angiogenesis right
making those uh spirally and corley
arteries even bigger right more of them
and it's also causing the see creation
of the uterine glands within the
endometrium but it's not done at that he
has to do something else a surgeon was
causing these cervical glands to produce
a thin cervical mucus but you know if
hypothetically if a sperm that this
little swimmer would have got up there
and fertilize that egg if it fertilizes
that around day 14 technically we should
have it at least I'm uh some type of a
blastocyst that's actually going to be
implanting into the actual uterine wall
hypothetically that's not always the
case right but let's assume that there
is an embryo and planted into the
uterine wall do you want anything to
just have free access up into this
uterus no you do not so what does this
actual progesterone do it switches
the cervical mucus production by the
cervical dance and look what happens to
it he plugs this sucker up he forms a
thick thick thick cervical mucus that
plugs up the cervix why why do you want
to do that because you want to keep this
area private you don't want to have
anything have access up into this area
so you form a thick cervical mucus plug
to prevent any type of substances or any
type of organisms up into this area to
protect the actual potential embryo so
what's the last thing that it does it
also causes a thick cervical plug to be
formed okay now we're at the last part
right and what was the secretory phase
so we said that the specifically for the
actual proliferate if it was day six
through fourteen on average the
secretory phase is approximately days 15
to 28 now everyone must realize that
this is not always the case obviously
menstrual cycles change from month to
month all the time for certain people
okay on average if I was to give you
like the average generally we say that
about 28 days is like the normal range
anything that's actually 21 or below so
anything less than 21 is pathological
okay anything that's actually greater
than 40 is also pathological so on
average we like to say that the average
menstrual cycle is 28 days with give or
take a few - 21 is the lowest anything
below that is pathological and to about
40 is the top point that you want to go
one more thing if this female is
fertilized right the embryo will implant
into the wall of the uterus and it will
start producing specific types of
chemicals one of those chemicals is
called human chorionic gonadotropin and
what human chorionic gonadotropin does
it helps to be able to continuously
stimulate the
corpus luteum to make progesterone right
so if the female is not fertilized so
she doesn't have fertilization if their
embryo isn't producing those chemicals
like human chorionic gonadotropin to let
the corpus luteum know that he can start
producing progesterone right until the
placenta develops around the 12th week
right of gestation if he it doesn't get
those signals from the embryo the canoe
corpus luteum produce progesterone no so
what happens is let's say that this egg
over here is waiting for the sperm and
it gets to about you know day 26 27 28
and there's no fertilization occurring
no fertilization occurring means no
embryos implanting no embryo implanting
means no human chorionic gonadotropin no
human chorionic gonadotropin causes the
corpus luteum to not produce
progesterone why is that significant you
know these spirally and coyly arteries
that says zoom in on one let's say here
I have my spiraling core the artery it's
activity so it's activity it's normal
vasoconstriction and vasodilation
activities is completely dependent upon
the stable levels of progesterone so
progesterone is keeping the normal
contraction and relaxation of these
blood vessels it's keeping it normal but
what happens if there's no fertilization
occurring progesterone levels start
decreasing can they regulate the
contraction and relaxation of these
vessels now no so what starts happening
as a result if you don't have this
progesterone and these vessels start
undergoing spasms where they undergo
very very basal constrictive days of
relaxation phase of constriction
vasodilation so much that over time
these vessels become very very weak and
their walls become very very fragile
that what happens is eventually after
one strong basal constriction the blood
vessels dilate so much that so much
blood rushes into this area that the
capillaries in this area rupture
if the blood ruptures in this area what
starts happening so let's say that these
vessels here rupture what starts
happening then this blood starts
accumulating
in the stratum function Alice right
because these spiraling corley arteries
have ruptured
so I say here's some blood accumulates
here also and then what else over here
to write these spiraling corley arteries
also ruptured if these guys are
rupturing can the actual oxygen and
nutrients be delivered to these actual
stratum function Alice's no if the
nutrients and oxygen aren't delivered to
the stratum function Alice's they become
what's called ischemic you know what
ischemia means ischemic means it's not
getting enough oxygen supply to that
area if they become ischemic eventually
they don't get enough oxygen to where
they become necrotic in other words they
die if these tissue cells start dying
what happens they start sloughing off
it's a heck of a word I'm sorry for the
word but it's what it is it's sloughing
these actual layers off and what is it
sloughing off its sloughing off this
actual shraddha function Alice and the
blood from the ruptured spirally in
corley arteries and whenever it's lost
out through the actual vaginal canal
because what happens is eventually the
progesterone production stops right so
what happens to the cervical plug it
goes away right that's another result of
it and look what happens here look what
you lose as a result coming out of
vaginal canal they're actually gonna
have what is this this is the stratum
function Alice and what else is going to
be a part of that stratum function house
all that blood that was lost from the
spiraling coronary arteries what is this
call whenever you're shedding the inner
lining of the actual uterus menstruation
so now guess what happened the normal
menstrual cycle ended at day 28 if
fertilization didn't occur and it starts
back over on day 1 to begin the
menstruation process all over again now
like I said if fertilization does occur
then the corpus luteum continues to act
like the hormone producing structure for
progesterone until the placenta develops
around the 12th week and then it
actually dies off if the corpus luteum
doesn't I mean if their fertilization
doesn't occur then the corpus luteum
doesn't get those signals from
embryo guess what happens to the corpus
luteum the corpus luteum starts dying
and actually starts becoming scar tissue
so he starts dying and look what happens
to it it starts turning into a nice scar
and fibrous tissue scar and fibrous
fatty tissue
what is this scarred and fatty fibrous
tissue here called this structure right
here is called the corpus albicans so
it's called the corpus albicans and the
corpus albicans is again the result of
fertilization not occurring and the
corpus luteum starts dying because it
doesn't get signals from the LH or from
the human chorionic gonadotropin and
what happens it starts undergoing death
and gets converted into fibrous tissue
what is that fibrous scar tissue called
the corpus albicans okay and can this
thing produce progesterone can it
respond to LH no so then the actual
whole ovulatory cycle has to start from
the beginning also are a ninja nerds in
this video we cover a lot of information
about the female reproductive cycle I
really hope you guys enjoyed it I hope
it made sense guys what we're gonna do
in the next video is we're gonna do a
nice little overview of everything here
just to get a quick recap and make sure
that you guys truly understand all of
this
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