[Music] hi there in our previous lesson we talked about the male and female reproductive systems as well as its hormones in this video we will talk about the feedback mechanism in the female reproductive system so let's get started we have previously discussed that an ovary normally releases only one egg every 28 days what controls the timing are the hormones hormones control many of the changes in the reproductive system they also coordinate the development of the ovum and the uterus remember that hormones are chemicals that can affect certain body organs this cycle among females occurs every month starting when a female is between 10 to 13 years old and it continues for about 40 years this is called the menstrual cycle the human ovaries can usually produce only one egg during a 28-day cycle of activity the mass of ovarian cells produces an ovum or an egg and it also forms a follicle the cycle is controlled by the follicle stimulating hormone this hormone is produced in the anterior lobe of the pituitary gland the follicle becomes filled with a fluid containing the hormone estrogen when the egg reaches maturity most importantly the rising level of follicle stimulating hormone stimulates follicle maturation and estrogen production if an ovum is not fertilized in the fallopian tube the corpus luteum degenerates progesterone production stops and the inside membrane of the uterus breaks down the breakdown and discharge of the soft uterine tissues and the fertilized egg is called menstruation these are the monthly changes that take place in the female reproductive system the female sex hormones control the secondary sex characteristics as well as the ovarian and uterine cycle like males females secrete follicle stimulating hormone and luteinizing hormone as directed by the pituitary gland during puberty this signals the start of puberty which includes the development of the secondary sex characteristics in females and the onset of menstruation a female experiences body changes even before the first menstruation which is also known as menarche at puberty the pituitary gland starts a series of hormonal changes that make a woman capable of pregnancy these hormonal changes and the effects they produce is called the menstrual cycle while the length of this cycle varies the typical cycle is about 28 days during this process changes in both the ovary and the uterus take place [Music] at the start of the cycle the pituitary gland secretes increased amounts of follicle stimulating hormone and this stimulates the formation of follicles in the ovaries estrogen is also secreted as the follicle cells develop when the follicle cells multiply the cells signal an increased level of estrogen in the blood and the pituitary gland secretes luteinizing hormone which stimulates ovulation ovulation is the releasing of the mature egg it usually occurs on the 14th day of the cycle during ovulation the egg is ready for fertilization within 24 hours from its release under the influence of luteinizing hormone the cells of the ruptured follicle develop into a yellow body called the corpus luteum the yellow body then produces more estrogen and progesterone both hormones prepare the uterine wall for the possible implantation of a fertilized egg the rise in the level of estrogen progesterone exerts a feedback control over the pituitary gland to inhibit the secretion of luteinizing hormone and follicle stimulating hormone the corpus luteum is deprived of the hormones that contain it with the drop in the amount of these two hormones hence the corpus luteum begins to degenerate thus the gland's influence on the progesterone level will affect the endometrial wall in a domino effect a series of changes also happens in the uterus as a consequence of the hormones while events are taking place in the female's ovary with the low levels of progesterone the surface of the endometrium begins to disintegrate and the blood vessels rupture blood and some accompanying endometrial tissues flow out of the vagina in a process called menstruation this menstrual phase lasts for about 5 days [Music] after the menstrual period the endometrium starts to build up due to the increasing amount of estrogen by the developing follicles in the ovary this is the proliferative phase of the uterine cycle which lasts for 6 to 14 days the formation of the corpus luteum and the secretion of progesterone trigger the endometrium to double in thickness and prepare itself for developing embryo the uterine glands also become mature and they produce a thick secretion hence the secretory phase of the uterine cycle begins on the 15th day until before the onset of the next menstrual phase however this cycle may be interrupted by stress health concerns and pregnancy but if pregnancy does not occur the cycle begins anew the menstrual cycle can be summarized into the following stages first the follicle stage this starts when one ovarian follicle grows to maturity second the ovulation stage this is when a ripe follicle releases a novel third the corpus luteum stage this happens when the uterus undergoes changes in preparation for the implantation of a fertilized egg and lastly the menstrual flow stage this is when the tissue lining of the uterus breaks down and is discharged from the female reproductive system [Music] in reality some females experience menstrual cramps every month did you know that menstrual cramps are the result of strong contractions of the uterine wall that occur before and during menstruation cramps can be caused by the excessive secretion of prostaglandins shedding of the endometrium of the uterus results in the inflammation of the endometrial layer as a consequence of this inflammation prostaglandins are produced so what is a feedback mechanism a feedback mechanism is the process through which the level of a certain substance influences the level of another substance a negative feedback affects the production of hormones in the menstrual cycle moreover high levels of one hormone may inhibit the production of another hormone [Music] let's take a look at this diagram follicle stimulating hormone stimulates the ovaries to release estrogen high levels of estrogen then prevent more production of follicle stimulating hormone estrogen then stimulates the release of luteinizing hormone from the pituitary gland which in turn controls the production of progesterone moreover high levels of progesterone can then inhibit the further release of luteinizing hormone this is the negative feedback mechanism what about the feedback mechanism during labor and childbirth when labor begins the baby's head is pushed downwards and results in increased pressure on the cervix this stimulates receptor cells to send a chemical signal to the brain allowing the release of accident by the posterior pituitary gland this oxytocin diffuses to the cervix via the blood where it stimulates further contractions these contractions stimulate further oxytocin release until the baby is born this is called a positive feedback [Music] now let's wrap things up the menstrual cycle is the hormonal process a woman's body goes through each month to prepare for a possible pregnancy the menstrual cycle can be summarized by the following stages follicle stage ovulation stage corpus luteum stage and menstrual flow stage a feedback mechanism is the process through which the level of a certain substance influences the level of another substance here is a table to summarize the functions of hormones in the female reproductive system estrogen is located in the follicle and ovary it is responsible for the development of female characteristics it also thickens the endometrium progesterone is located in the corpus luteum and ovary it stimulates the endometrium and inhibits uterine contractions and ovulation dilutinizing hormone and follicle stimulating hormone are both located at the pituitary gland utilizing hormone develops and maintains the corpus luteum it also stimulates ovulation on the other hand follicle stimulating hormone stimulates the formation of follicles in the ovaries that's all for now we will be discussing about how the nervous system coordinates and regulates these feedback mechanisms to maintain homeostasis in our next video so stay tuned see you on our next video and don't forget to keep your minds busy if you like this video please subscribe to our channel and hit the notification icon for more videos like this