The Human Female Reproductive System and Menstrual Cycle

The internal and external sex organs that are used in human reproduction make up the female reproductive system. The female genital system develops to maturity during puberty in order to produce gametes and be able to carry a pregnancy to full term. At birth, it is undeveloped. The uterus, fallopian tubes, ovaries, and vagina are among the female reproductive system's internal organs.

The cervix is the uterus' lower, narrower portion. It joins the uterus and the vagina. The cervix forms a barrier between the uterus and the vagina which ensures that the baby is held in place during pregnancy (Rudmann & Foley, 2013). The cervix is made up of a strong ligament which allows it to expand and let the baby pass through it during birth.

Vagina

The vagina is an elastic, muscular canal that connects the cervix to the outside of a woman’s body (Waters, 2008). During sexual intercourse, the make excretes semen containing spermatozoa at orgasm which gets into the female body via the vagina potentially enabling fertilization to occur. The vagina also allows blood to flow out of the female body during menstruation. The vagina is made up of fibrous and muscular tissue which makes it adapted to perform its functions.

Uterus

The uterus/womb is the primary female reproductive organ. It is a bag that appears like an inverted pear. The principal function of this part is to accept a fertilized ovum which then becomes implanted into the endometrium and derives nourishment from blood vessels that develop exclusively to ensure the growth of the zygote (Netter, 2013). The fertilized ovum develops from a zygote into an embryo then into a fetus which gestates until childbirth. The process takes nine months. If an egg does not become embedded in the wall of the uterus, them menstruation begins.

The uterus has a soft lining which allows the implantation of the placenta during pregnancy (Quilin, Black, & Podgorski, 2013). The placenta supplies the baby with adequate nutrition as blood from the mother goes through it into the umbilical cord attached to the baby. The blood usually contains oxygen, glucose and other nutritional substances for the development of the baby. The uterus holds the fertilized egg and nurtures it until it becomes an entirely developed baby ready for delivery. During pregnancy, the womb also provides mechanical protection to the baby and allows for waste removal for the developing embryo (Waters, 2008). The womb has a muscular wall which makes it adapted for pushing the fetus out during delivery.

The uterus has three suspensory ligaments that help in stabilizing the position of the fetus and thus limiting its range of movement. The ligaments include the uterosacral which prevents inferior and anterior changes, the round ligaments which restrict posterior displacement of the uterus and the cardinal ones that inhibit the inferior movements (Waters, 2008).

Fallopian Tubes

The fallopian tube is also known as the oviduct or the egg tube. It is a vessel through which the egg cells travel to the uterus. A human female has two ovaries which release a mature egg monthly. Therefore, the egg tube connects the womb to the ovaries. The fallopian tubes have very tiny hairs called cilia which aid the smooth passage of mature eggs into the uterus. The travel takes hours or days, and if the ovum is fertilized while in the oviduct, it implants in the endometrium once it reaches the uterus. The implantation signals the beginning of pregnancy (Rudmann & Foley, 2013).

Ovaries

The ovaries are small, paired organs that are located near the lateral walls of the pelvic cavity. They produce egg cells and secrete hormones. The process by which the egg cell is released is called ovulation, takes place periodically and impacts the length of a menstrual cycle (Krohmer, 2010). Females are born with hundreds of underdeveloped ova. Once an individual reaches puberty, the eggs stored in the ovaries are released monthly. Unused eggs dissolve and pass out during menstruation.

External Parts of the Human Female Reproductive System

The external parts of the female reproductive system consist of the vulva and all tissues and parts therein. It includes the mons Veneris which is a rounded mass of fatty tissue found over the pubic symphysis of the pubic bones (Klosterman, 2010). The mons veneris forms the anterior portion of the vulva which divides into the labia majora and the pudendal cleft. The size of the mons veneris is dependent on the level of hormone and body fat in any specific women. After puberty, the mons veneris becomes enlarged and is covered with pubic hair. The fatty tissue in the mons veneris is sensitive to estrogen which makes it very distinct at the onset of puberty and this pushed the forward portion of the labia majora away from the pubic bone (Rudmann & Foley, 2013). A decrease in the natural estrogen makes the mons veneris less prominent, and this is experienced mainly during menopause.

The pudendal cleft is also a part of the external female genitalia, and it’s also referred to as cleft of venus, vulval slit or rima vulvae (Klosterman, 2010). It protects the labia minora and the labia majora. The labia minora is also known as the inner lips which are two flaps of skin on the vaginal opening in the vulva. The inner lips vary regarding size, color, and shape from one individual to another. The Bartholin’s glands are pea-sized and they are located slightly posterior and to the left and right of the opening of the vagina. Their role is to secrete mucus that lubricates the vagina (Netter, 2013).

The clitoris is located above the opening of the urethra. It is the most sensitive erogenous zone in females and is used as a source of sexual pleasure. The clitoris has more than 8000 sensory nerve endings which make it adapted to its function (Krohmer, 2010). The vaginal opening is located at the outer end of the vulva, posterior to the opening of the urethra. The labia minora closes it in female virgins and those individuals who have never given birth. Its role is to protect the inner parts of the reproductive system.

The Menstrual Cycle

Hormones involved in the Menstrual Cycle

The menstrual cycle takes approximately twenty-eight days which results in the release of a mature egg from the ovary. The sequence results from a complicated interplay of several hormones. The follicle-stimulating hormone (FSH) is one of the most vital hormones. Just like the name implies, the hormone stimulates the development of new follicles and the producing of estrogen (Quilin, Black, & Podgorski, 2013). The FSH increases during the follicular phase and it stimulates the growth and development of new follicles, and one of them develops into an ovulated egg.

Estrogen is also another hormone that is responsible for the continuous development of follicles within the ovaries. The estrogen also works in the uterus where it thickens the endometrium in preparation for the implantation of the fertilized egg (Netter, 2013). Estrogen also causes the mucus within the cervix to become thicker. Estrogen also suppresses its release when a pregnancy fails to occur in a process known as a negative feedback loop. A decrease in the levels of estrogen loosens the support for the built up lining and helps to separate its which prepares for menses. Estrogen also stimulates the release of large amounts of Luteinizing Hormone in the mid-cycle stage. It also suppresses its production just before ovulation (Gordon, 2008).

Luteinizing Hormone (LH) peaks in the middle of the menstrual cycle, and this is called the LH surge. The surge serves as a signal that either of the two ovaries is about to release a mature egg (Trickery, 2011). The process of ovulation occurs approximately within nine hours of the LH surge. The egg that is released is ready for fertilization for about two days after which it begins to disintegrate and is released as part of the menses.

Progesterone is released by the ruptured follicle that releases an egg. After the egg is released, the follicle closes to become the corpus luteum which secretes progesterone (Gruhn, 2014). The hormone makes the mucus around the entrance of the uterus thicken and becomes sticky, and this prepares it for a potential pregnancy. It also leads to a rise in the body temperature. If pregnancy does not take place, the levels of progesterone fall alongside the decrease of estrogen (Quilin, Black, & Podgorski, 2013). The reduction in the levels of this hormones help the built up lining of the uterus to separate, and menstruation begins.

Events of the Menstrual Cycle

The menstrual phase takes place between the first day of menstruation and lasts up to the fifth day of the cycle. During this period, the uterus sheds its inner lining of soft tissue and blood vessels which exit the body through the vagina. The substances meant to allow for the nourishment of the growing fetus comprise the menstrual fluid. The blood loss that takes place during this phase is about 10-80 ml, and this is considered normal (Rees, Hope, & Ravnikar, 2015). During this period, individuals may experience abdominal cramps which are caused by the contraction of the uterine and muscular muscles as they expel the menstrual fluid.

The follicular phase begins on the first day of menstruation and lasts up to the thirteenth day of the cycle. During this process, the pituitary gland secretes the FSH which stimulates the ovarian follicles to grow and release an egg. The follicles are usually present from birth and develop continually through a process called folliculogenesis (Gruhn, 2014). The follicles compete with one another, and only the dominant keep growing to maturity. At maturity, the follicles are referred to as Graafian, and they are the ones that contain the ovum. The egg cells take thirteen days to reach maturity. The follicle then secretes estrogen that stimulates the uterus to develop a lining of blood vessels and soft tissue called endometrium in preparation for potential pregnancy (Gruhn, 2014).

The ovulation phase takes place on the fourteenth day where the pituitary gland secretes the LH, and the ovary released the matured egg cell (Netter, 2013). The cilia of the fimbriae in the fallopian tube sweep the released egg into the oviduct which then deposits it in the uterus. The finger-like projections, fimbriae, are located at the end of the fallopian tube near the ovaries, and they contain hair-like projections which are the cilia.

The leutal phase begins on the 15th day and lasts until the end of the cycle. During this period, the egg cell that is released during the ovulation phase stays for up to twenty-four hours in the fallopian tube. The egg then disintegrates if a sperm does not fertilize it at that time. Estrogen and progesterone levels then begin to decrease at this point to allow for the menstrual cycle to start. When the menses start, the cycle begins again (Krohmer, 2010).

It is important to note that hormonal contraceptives work by disrupting the menstrual cycle. Progesterone negative feedback reduces the pulse frequency of the gonadoliberin hormone which is released by the hypothalamus and in turn decreases the FSH and LH (Rees, Hope, & Ravnikar, 2015). When the FSH levels fall, they inhibit the follicular development which prevents an increase in estradiol levels. The lack of estrogen feedback combined with the negative progesterone feedback prevents a mid-cycle surge of LH. The hormonal birth control methods work by suppressing both the estrogen and progesterone hormones which may affect the menstruation cycle (Rees, Hope, & Ravnikar, 2015).

Conclusion

It is essential to study the female reproductive system as it allows women embrace their sexuality. The women understand the reason why their genitalia appears as it does and they even learn the causes of various issues such as mood swings, changes in feeding habits and emotional responses during their reproductive years. Furthermore, the women will be empowered on how to prepare themselves adequately for their reproductive processes such as menstruation, pregnancy and even menopause (Pope & Wurlitzer, 2017). Moreover, a proper understanding of the female reproductive system helps to deal with the social stigmas that are associated with the female body. For instance, individuals understand the role of different parts such as the clitoris. Stereotypic practices such as viewing the vulva as unappealing and female genital mutilation that seeks to eliminate the clitoris will also be reduced (Pope & Wurlitzer, 2017).

References

Gordon, C. (2008). The Menstrual Cycle and Adolescent Health. Boston: Blackwell Publishing.

Gruhn, K. (2014). Hormonal Regulation of the Menstrual Cycle and the Evolution of Concepts. New York: Springer Publications.

Klosterman, L. (2010). Reproductive System. New York: Marshall Cavendish Benchmark Publications.

Krohmer, R. (2010). The Reproductive System. New York: Chelsea House Publications.

Netter, F. (2013). Female Reproductive System. Teterboro: Icon Learning Systems.

Pope, A., & Wurlitzer, S. H. (2017). Wild Power: Discover the Magic of Your Menstrual Cycle and Awaken the Feminine Path to Power. Carlsbad: Hay House Publications.

Quilin, F., Black, A., & Podgorski, T. (2013). Biological Science. Boston: Benjamin-Cummings Publishing Company.

Rees, M., Hope, S., & Ravnikar, V. (2015). The Abnormal Menstrual Cycle. London: Taylor and Francis Publications.

Rudmann, D., & Foley, G. (2013). Female Reproductive System. In Haschek and Rousseaux's Handbook of Toxicologic Pathology (pp. 2599-2663). New York: Sage Publications.

Trickery, R. (2011). Women, Hormones and the Menstrual Cycle. Fairfield: Melbourne Holistic Health Group.

Waters, S. (2008). The Female Reproductive System. New York: Rosen Central Publications.