Female Reproductive System – Menstrual Cycle, Hormones and Regulation

Female Reproductive System – Menstrual Cycle, Hormones and Regulation


Armando Hasudungan biology and medicine videos Please make sure to [subscribe] join the forum in group for the latest videos please visit Facebook Armando Hasudungan In this video we will look at the hormonal regulation of the female reproductive cycle so we will be looking at the menstrual cycle basically and Yes, so the menstrual cycle the Hormones of the female is So much more complicated the Male’s but hopefully we’ll be able to understand it by the end of this video, so [we] begin with the hypothalamus and the pituitary glands which are made up of the anterior and posterior pituitary glands We’ll be focusing on the anterior pituitary gland the hypothalamus regulates hormones released by the anterior pituitary through the portal blood here in The female reproductive system the hypothalamus produces a hormone called gonadotropin-releasing hormone which will travel here to the anterior pituitary via the portal blood and It will cause the cells in the anterior pituitary gland to produce two important hormones known as FSH, follicle stimulating Hormone and LH luteinizing hormone Please note that in males this same process also occurs Males also produce Gonadotropin releasing hormone which will Cause the anterior pituitary to release Luteinizing hormone and follicle stimulating hormone, so what will these hormones do in the female body? Well these hormones will travel to the female ovaries where the female eggs are produced So let’s just recap quickly. What the ovary is and where it is. So here. We have the uterus and the Ovaries Which connects to the Uterus via the Fallopian Tube essentially But it’s now known as a uterine tube so we [will] focus on this over here, so let’s zoom in so here is the ovary and it has blood vessels and This and it’s through these capillaries these blood vessels that the hormones can enter Now in each ovary there are follicles Women have many many follicles in the ovaries and each month only some will begin to mature But only one will ovulate and become essentially will ovulate and produce an egg Now let’s just say it’s the beginning of the menstrual cycle. So just after female has shed her uterine wall just had the period now within the ovaries females have many many many primordial follicles and Each month only some of these primordial follicles will mature Into primary Follicles, and they will keep maturing but only one will ovulate So here. I’m drawing one primary follicle, and it’s the beginning of the menstrual cycle Before we continue on let’s look at the let’s look at the changes [of] the hormone concentrations That come from the brain by looking at a graph so here we have a y-Axis which shows the concentration of the hormones in blood and On the [x-axis] is a duration of the female menstrual cycle which normally goes for about 28 days So the dotted line in the middle is 14 days. Which is halfway Now just to simplify things even more the menstrual cycle can be divided into two phases the first 14 days is known as the follicular Phase and the Last 14 days Is known as the luteal phase and this is important to keep in mind, so the first is the follicular Phase II is the luteal Phase Now initially in the beginning of the menstrual cycle there is an increase in Gonadotropin releasing hormone secreted by the hypothalamus because it’s the start of the menstrual cycle and this should cause a steady increase in Follicles stimulating hormone and luteinizing hormone but instead we see a Increase and then a slow Dropping level of follicle stimulating hormone, and we have a steady level of luteinizing hormone Why is this? Well the reason is actually quite complicated, but just hold on to that thought and hopefully it’ll make sense So let’s go back to the ovary So follicle stimulating hormone Will initially rises remember? Because the follicular phase is the first phase of the menstrual cycle Follicle stimulating hormone will enter the ovaries and what they will essentially do is stimulate it will stimulate follicle Maturation of these primary Follicles and so some of these primary follicles will mature into A secondary follicle, I’m only drawing one secondary follicle for simplicity While these follicles are maturing they produce another hormone called Estrogen Now Estrogen has many effects in the first ten days of the menstrual cycle So in the beginning estrogen has a negative feedback on the pituitary gland inhibiting the release of luteinizing hormone To put it simply at low concentrations estrogen inhibits luteinizing hormone secretion from the anterior pituitary And that is why we only see a steady level of luteinizing hormone in the blood Because even though gonadotropin-releasing hormone from the hypothalamus is stimulating the release of luteinizing hormone at low concentrations estrogen will inhibit luteinizing hormone release Another fact is that follicle stimulating hormone is secreted primarily in response to Low Estrogen concentrations, so when Estrogen levels rise Follicle stimulating hormone levels will fall and that is why we see in the graph a steady drop in Follicle stimulating hormone because there’s a increase in Estrogen levels from the follicles So let’s draw another graph and see the concentrations of the hormones produced by the ovaries during the menstrual cycle Which goes on for 28 days So as the follicle matures they will produce more estrogen which as I mentioned at low concentrations estrogen will inhibit the secretion of luteinizing, hormone and Also the increase in estrogen concentrations will cause a decrease in Follicle stimulating hormone secretion Estrogen is an important hormone Especially for females because Estrogen is basically males equivalent of testosterone, Estrogen Peripheral effects include stimulating bone and muscle Growth it stimulates endometrial growth Maintains female Secondary characteristics and maintains a female the glands the breasts amongst many other things So just to draw this graph up to Ten days of the Menstrual cycle. We see a steady a steady low concentration of luteinizing Hormone due to the inhibitory effects of estrogen remember in the first ten days and We also see a steady drop of follicle stimulating hormone due to the increase in estrogen levels as well. Which has a negative feedback So what happens after 10 days? well after 10 days estrogen levels will continue to rise as the follicles mature in the ovaries and After 10 days as estrogen levels rise. It will have a positive Feedback and It will stimulate the release of luteinizing hormone so at low concentrations estrogen will inhibit luteinizing hormone secretion however at High concentrations, Estrogen will stimulate luteinizing hormone secretion Now things are changing the increase in gonadotropin releasing hormone and estrogen will stimulate then luteinizing Hormone secretion And you see this massive spike in luteinizing hormone concentration It’s this massive luteinizing Hormone concentration that will trigger ovulation of the Most Mature Follicle in the ovary The ovulation of the follicle will release what we know as the female egg the oocyte or Oocyte After ovulation the luteinizing hormone levels will drop back down gonadotropin releasing Hormone will slowly drop as well follicle stimulating hormone also had a small spike as a side effect of the surge of luteinizing hormone release so luteinizing Hormone triggers ovulation and oocyte is released after The Follicle ovulates the follicle will turn into a corpus luteum which is a dead follicle, basically Now that is why the first 14 days of the menstrual [cycle] is called the follicular Phase Because it all has [to] do with the follicles and its maturation and the last 14 days is known as the luteal phase Because we have the formation of the corpus luteum The corpus luteum will essentially slowly degrade However it also has a purpose it in that it secretes hormones. It secretes three hormones estrogen again inhibin and Progesterone So what we see in the concentration levels of these Ovarian hormones Estrogen will increase until ovulation and then drop slightly Inhibin was not present until after ovulation then it begins to increase thanks to the corpus luteum Progesterone levels will were low until after ovulation during the luteal phase so at 21 days of the female reproductive cycle progesterone is increasing inhibin is increasing and Estrogen is still detectable and all these hormones are all produced. Thanks to the corpus luteum So what do these hormones do? Well inhibin has a negative feedback And it will essentially inhibit the secretion of follicle stimulating hormone because we are at the luteal Phase We don’t need any more follicles to mature just yet So that is why inhibin is preventing follicle stimulating hormone release to prevent follicle maturation So here. I wrote as the secondary corpus luteum develops inhibiting secretion will suppress follicle stimulating hormone release Progesterone is the most important Hormone in The Luteal phase and has many functions [one] of which is having a negative effect on the hypothalamus inhibiting the secretion of gonadotropin releasing hormone Now after ovulation during the luteal phase The progesterone levels will increase slowly and the estrogen levels will decrease Slowly kind of and this will suppress gonadotropin releasing hormone release and So progesterone will inhibit gonadotropin releasing hormone release Which will also [effect] the release of luteinizing hormone and follicle follicular stimulating hormone? So during the luteal phase as progesterone and inhibin increase This will essentially cause a decrease in gonadotropin releasing Hormone, luteinizing Hormone and follicular stimulating hormone But the main effect of progesterone is that it will stimulate endometrial growth the endometrial lining is the lining of the uterus which will shed each month or Or the endometrium is where the egg? Will implant if it’s fertilized by sperm okay, let’s just say there was no fertilization because this is just a normal menstrual cycle and Of course all good things have to come to an end the corpus luteum in the ovary will degenerate allowing a new set of Follicles to mature So as the corpus luteum degenerates all these hormones that are that were produced by the corpus luteum the estrogen, inhibin and progesterone, they will decrease like so so when the corpus luteum degenerates Progesterone will Decrease and this will mean that progesterone cannot inhibit gonadotropin releasing hormone release and So gonadotropin releasing hormone levels will increase and this will allow a new menstrual cycle to occur also because of the decrease in Progesterone and estrogen in part means that these hormones cannot maintain the endometrium the endometrial lining in the uterus and so the endometrium will shed and this is known as the period and After the endometrial lining sheds this allows a new cycle to occur and though And then you see a increase in gonadotropin releasing hormone again and the cycle continues Hope you enjoy this video. Thank you

100 Replies to “Female Reproductive System – Menstrual Cycle, Hormones and Regulation”

  1. Hi! I'm taking my units in Anatomy and Physiology this semester and your videos are really great! I could easily visualize the contents in my book by just watching your collection! Thank you so much ๐Ÿ˜€ . Greetings from Philippines!

  2. Well done! Great detail! Thank you! I do wish you had panned back (is that even possible?) or somehow captured the completed drawing all in one frame. It would be helpful to be able to review the entire drawing.

  3. i would like to make a correction here, the menstrual cycle has 3 phases which are menstrual, proliferative and secretory phase, the ovarian cycle has two phases which are mentioned by the video follicular phase and luteal phase

  4. I've been struggling the learn the menstrual cycle for the MCAT for months. Every review book I came past just put up a picture of that stupid graph and I didn't understand anything until I found this video. Saying this video is a lifesaver is an understatement. Armando, you not only explained this concept amazingly but your approach of explaining WHY each step happened made this topic seem so easy. Thank you, seriously.

  5. 14:56, this right here ladies and gentlemen, is a fucking masterpiece!

    Thank you for the most clear, understandable, and awesome explanation!

    P.S.
    I hope you framed it and put it on a wall or donated it to a museum or something

  6. Oh you made it so easy to understand. Very well done.. ๐Ÿ‘๐Ÿป๐Ÿ‘๐Ÿป๐Ÿ‘๐Ÿป

  7. question, should a women then struggle to ovulate or ovulate only day 29/30 will a oestrogen based birth control such as qlairs used only for a week in folical phase then not help stimulate ovulation, please note I am only a normal women not a med student asking a simple question

  8. I'm a psych major. This video is quite excellent at explaining the menstrual cycle. In particular, it explains so clearly the roles that GRH, FSH and LH play. Before watching this video, I was trying to understand the menstrual cycle by reading the textbook. Frankly, I got lost pretty easily. This video makes it easier to understand AND retain. Thanks.

  9. great video! very helpful and easy to understand! The only complaint is how you pronounce estrogen haha but I don't mind because of how helpful this is

  10. This is AMAZING!! It's so artistic but at the same time the explanation is so clear and accurate! The artistic make up of the video makes things easier to understand!

  11. I remember there was a video on same menstrual cycle topic but in that you had also explained the reason for conversion of only one follicle into grafian follicle and it was related with no. Of receptors of FSH. I did not find the same details here in this video as well. If you still have that video than please let me know where to find it. It was amazing.

  12. Thank you SIR….๐Ÿก๐ŸŒ๐ŸŒ๐ŸŒŽ๐ŸŒ๐ŸŽ๐ŸŽ€๐ŸŽ€๐ŸŽ๐ŸŒ๐ŸŒŽ๐ŸŒ๐ŸŒ๐Ÿก๐Ÿก๐ŸŒ๐ŸŒ๐ŸŒŽ๐ŸŒ๐ŸŽ๐ŸŽ€๐Ÿ’›๐Ÿ’š๐Ÿ’™โ™ฅ๏ธ๐Ÿงก๐Ÿ’œ๐ŸŽ€๐ŸŽ๐Ÿ’›๐Ÿ’š๐ŸŒ๐Ÿ’™๐ŸŒŽ๐Ÿ‘‹๐ŸŒ๐Ÿค”๐ŸŒโ™ฆ๏ธ๐Ÿกโ™ฅ๏ธ

  13. I am so grateful for these videos. As a holistic health practitioner, a good understanding of anatomy and physiology makes all the difference, and your guided/narrated illustrations map things out so well…so grateful for you but it is sad that one has to be 40 before they actually fully understand their body well! Better late than never though, thanks much!!

  14. This presentation is very thorough and his drawings are excellent. Author is very thorough…starts at hypothalmus. A++

  15. After 10 days… Hows is it possible…
    Because after 14 days estrogen level falls…
    We have only 14 days…
    Before and after 10 days….???

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