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In this lecture we’re gonna cover the menstrual cycle as well as the pharmacology of hormonal the menstrual cycle is defined by the regular, throughout a female’s reproductive life. the normal menstrual cycle results from a complex feedback system involving the hypothalamus, pituitary, ovary, and uterus. the average
Length of the cycle is 28 days, but this can vary between according to convention, the cycle is divided into two phases of approximately 14 days each. the first half of the cycle is called the follicular hypothalamus sets the beat for the menstrual cycle by the pulsatile release of gonadotropin-releasing hormone
(Gnrh). gnrh then acts on the anterior pituitary gonadotropic cells and causes them to release two hormones, follicle stimulating hormone we’re gonnna use a graph to illustrate the day-to-day changes of these and other hormones in plasma that play a role in the menstrual cycle. travels to the ovary where it binds
To immature maturation. as the ovarian follicles grow, they become surrounded by layers of so called theca and granulosa cells. at this point lh joins the party and stimulates lh receptors expressed on theca cells causing them to produce androgens, in response to fsh binding to the fsh receptors graph,
As a result of these events, in the first week of the cycle we will see slightly elevated levels of fsh and lh, and then around day 7 we now, estrogen serves two primary purposes. known as endometrium, to grow thicker in these endometrial changes are proliferative, secondly, the initial rise in estrogen
Levels sends a negative feedback signal suppress further production of fsh and lh. growing follicles produce another hormone called inhibin, which selectively suppresses fsh secretion. as the follicular phase progresses, remain sensitive to decreasing levels of fsh, grow and produce increasing amounts of
Estrogen. once again, the lining of the uterus continues to become thicker and spongier with blood-rich matures within the ovary, estrogen begins to exert positive feedback on lh production, when lh reaches its peak, it triggers the mature follicle to rupture and release the egg into fallopian tube in a process
Called ovulation. this marks the end of the follicular phase and the beginning of the second half of the menstrual cycle called luteal phase. so, after ovulation, develop into a structure called the corpus luteum. this structure becomes a center for the production of the final key hormone that is progesterone.
Just like estrogen, progesterone helps the uterine lining to become thicker and more vascular. in addition to this, progesterone stimulates glands in the uterine wall to produce fluids necessary for the nutrition of the potential embryo, and it stimulates glands in the cervix to secrete thick and becomes a barrier to
Sperm and bacteria. cycle is also called the secretory phase. now, going back to our graph. during the first few days following ovulation, the corpus luteum secretes high levels of progesterone, as well as lower levels of estrogen. this is why the graph shows a steep rise in progesterone and a slight bump
In estrogen levels, which peak around day 21. levels of circulating estrogen, progesterone, effect on the hypothalamus and anterior pituitary thereby inhibiting secretion of gnrh, fsh and lh, which prevents new follicles from developing. occur during this short period of time, the corpus luteum will start
To break down causing levels of both estrogen and progesterone to fall progesterone and estrogen levels that causes the uterine lining to break down and ultimately come out in the form of menstrual bleeding, now that we covered the menstrual cycle, let’s move on to the second part of this lecture that
Is the pharmacology of hormonal contraceptives. so, hormonal contraception refers to birth system of the female to prevent ovulation or fertilization. there are two main types of hormonal contraceptives. first is the so-called forms of both estrogen and progesterone. and the second is progestin-only method,
Which contains only progestin that is synthetic version of progesterone. alright, so before we discuss how each of these methods prevent pregnancy, of endogenous hormones throughout the now, although hormonal contraceptives come in different forms such as patches, injections, and vaginal rings, the most widely
Used form is the oral tablet also known as the birth control pill. combination birth control pills come in different formulations commonly referred to as monophasic and multiphasic. in monophasic formulations, the pills deliver the same amount of estrogen and progestin each day for the first 21 days followed by 7
Days suspension or 7 days of placebo pills. progestin leads to continuous suppression of lh and fsh output from the pituitary which results in inhibition of ovulation. the last 7 days of suspension or placebo, in turn allow estrogen and progestin levels to fall dramatically bleeding that mimics the normal menstrual
Cycle. formulations. in this type of combination birth control, the pills deliver varying levels of estrogen and progestin that intend to mimic reduce the total exogenous hormone dose per cycle. women can end their menstrual periods altogether by continuously taking combined estrogen-progestin we have
Progestin-only birth control pills, long-term hormonal contraception and for whom exogenous estrogen is contraindicated because of breastfeeding or cardiovascular disease. now, progestin-only pills are taken continuously, cycles leading to consistent suppression of fsh and endogenous progesterone production.
Intramuscular depot-medroxyprogesterone, systemic dose of progestin delivered by all as a result, there is less suppression of occasional lh surge that can trigger ovulation. instead, progestin-only contraceptives are thought to function primarily by thickening cervical mucus changes inhibit egg implantation
And make it more difficult for sperm to enter the uterus. now, to end with some examples of actual drugs used in birth control products, commonly found synthetic derivatives of estrogen are ethinyl estradiol progesterone are; desogestrel, drospirenone, and norethindrone. and with that i wanted to thank
You for watching i hope you found this video useful and as always stay tuned for more.
Transcribed from video
Pharmacology – MENSTRUAL CYCLE AND HORMONAL CONTRACEPTIVES (MADE EASY) By Speed Pharmacology
