It is said that the greatest gift ofall is life. Humans or more specifically the reproductive system is able toprovide this gift. The reproductive system is an essential system for thecontinuation of the human species. The system involves many organs that worktogether to form life.
The reproductive system is on the complex side, due tothe part that males and females have different reproductive systems. However,the female reproductive system is the more complicated one. Although the femalereproductive system is more complex is does not outweigh the importance of themale reproductive system, as for both are essential in the creation of anoffspring. The female reproductive systemconsists of ovaries, fallopian tubes, the uterus and the vagina.
The mainpurpose of the reproductive system is to achieve fertilization. Which is alsoknown as pregnancy, which occurs when a sperm and egg join to create a diploidzygote. Eggs in the female body arelocated in the ovaries and in order for an egg to be fertilized it must bepresent in fallopian tube. The process by which the egg travels from the ovaryto the fallopian tube is called ovulation.
Normally around the age of 12 or 13,the female body physical develops to be able to reproduce sexual, this iscalled puberty. During puberty the female body enters a monthly cycle, calledthe menstrual cycle, in which the female body sheds thelining of the uterus. The average menstrual cycle takes about 28 days, but thatdoes not mean every female body has the same cycle.
Cyclesrange from 21 to 35 days in adults and from 21 to 45 days in young teen.However, menstruation, physical bleeding, only occurs between 3 to 5days. The menstrual cycle is broken down in three main phases: the menstrual(“destructive”) phase, also called menses; the follicular (“proliferative” or”estrogenic”) phase and the luteal (or ” secretory,” “progestational”) phase”(Jones, 54). The first day of when menstruation begins is marked as the firstday of the menstrual phase. The menstrual phase can last from 1 to 7 dayshowever, it usually last from 3 to 5 day’s. The follicular phase begins at theend of the menstrual phase, which is normally the day after menstruation stops.The follicular phase last until ovulation, which occurs around day 14 to day 16of the menstrual cycle depending on how long one’s cycle is.
The luteal phaselasts from ovulation to the beginning of the next menstruation. During the menstrual phase, thestratum functionalis of the endometrium, the scientific name for the lining ofthe uterus, starts to degenerate. The tissue starts to degenerate because theblood vessels that supply nutrients and oxygen to the tissue begin to”constrict and dilate spasmodically” (Jones, 55). The vessels then bleed whichis apart of the uterus lining degenerating. During the menstrual phase fourhormones are present which are categorized as either, pituitary hormones ,which are released from the brain and travel in the blood to the ovaries, andsteroid hormones.
Follicle stimulating hormone (FSH) and luteinizing hormone(LH) are pituitary hormones while estrogen and progesterone are steroidhormones(. All four hormones are low on day 1 of the cycle. However, by day 3 FSHcauses some follicle to increase in size because the “low levels of estrogenand progesterone signal the pituitary gland to produce FSH” (Hormone Imbalance). As follicles growthey begin to secrete estrogen so estrogen blood levels increase also by day 3.
However, progesteronelevels stay low throughout the menstrual phase. Right after the menstrual phasecomes the follicular phase, which is normally day 14 of the menstrual cycle.This cycle normally marks the halfway point of the menstrual cycle, having thenext menstrual usually starting 2 week later. During this phase the rise in estrogen level from theincrease of follicle activates a rush in the amount of luteinizing hormone thatis produced by the brain. This causes the follicle, which is a fluid-filled sac in the ovary containing eggs, torelease an egg from the ovary. The releasing of the egg is a process ovulation.During this process the egg that is released is captured by finger-likeprojections called fimbriae at the end of the fallopian tubes.
During thefollicular phase, there is an “increase in the amount and thickness of mucusproduced by the cervix (lower part of the uterus)” (The Female Reproductive System).The thick mucus captures the man’s sperm and helps it to move towards the eggfor fertilization, if sexual intercourse has taken place during this phase. Theluteal phase begins after ovulation and isconsidered the last phase of the menstrual cycle. In this phase once theegg is released from the ovary, the empty ovary changes its structure, which iscalled the corpus luteum. The corpus luteum secretes steroid hormones,estrogen and progesterone. Progesterone prepares the uterus to implant a fertilizedegg, which is if intercourse has taken place. The fertilized egg, which isalso called the embryo, will travel through the fallopian tube and implant itselfonto the uterus.
Since the egg is fertilized pregnancy occurs in which theembryo will turn into a fetus. However, if the egg attaches to the uterus andis not fertilized, the uterus will recognize this and the lining of the uterus willstart to degenerate. This now returns to the menstrual phase in whichmenstruation begins again. Asthere is an age for the beginning of the menstrual cycle there is also an end.The end of the menstrual cycle is called menopausal period, also just known asmenopause. Menopause normally occurs between the ages 45 and 52 years, but itcan occurs as early as 42 or as late as 55.
Menopause occurs due to aging andthe ovaries no longer being active. The reproductive organs also becomesmaller, “no more ova mature; therefore no ovarian hormones are produced. Anearly menopause may occur if the ovaries are surgically removed or aredestroyed by radiation or chemotherapy”(Hinkle). Thealternative of menstruation is fertilization, which leads to pregnancy. Human’suse one of the two types of fertilization, which internal. In order tounderstand the aftermath of fertilization, the general information of theinternal female reproductive system needs to be recognized. Aside from theovaries, the vagina and uterus are also very important.
The vagina is atubular-shaped canal in which semen is deposited during sexual intercourse, andit is also the pathway for the flow of menstruation blood. The semen travelsthrough the vaginal canal to get to the fallopian tubes to inseminate the egg.”The canal is also referred to as the birth canal because the baby moves out ofthe uterus and through the vagina during childbirth” (Freeman). Themajor reproductive organ is the uterus. The uterus is the site of fetusdevelopment and is a pear-shaped muscular organ.
Before a women’s first pregnancy, the uterus is around the size and shape of apear and is narrow. However, after childbirth, the uterus expands in size, andthen reverts back after menopause. The uterine wall has three layers.
Theendometrium, which is the most inner layer, is “highly vascular and responds to hormone stimulation to prepare toreceive the developing ovum” (Hinkle). This is the tissue that degenerates iffertilization does not occur which results in menstruation. However, the tissuealso degenerates after childbirth. The myometrium is the middle layer, which ismade up of smooth muscle layer. The myometrium itself had three layers. Theouter layer is made up of fibers that help eject the fetus.
The middle layer ofthe myometrium is made up of fibers that interlace with blood vessels to helpcontrol blood loss after childbirth. The inner layer of the myometrium is madeup of fiber that helps keep the cervix closed during pregnancy. The third layerof the uterine wall is the parietal peritoneum, which covers the uterusand holds it in place.
The uterus also has four parts: thecervix, the fundus, the corpus and the isthmus. The cervix isthe opening of the uterus and projects into the vagina. The large round areaabove the fallopian tubes is the fundus. The isthmus connects the cervix andcorpus. Corpus is the main part of the uterus and is located between the fundusand isthmus. The cervix is the major part of the uterus in which it producesmucus, which is an important factor in fertility awareness. The uterus is coated with thismucus membrane rich in the blood capillaries to form the placenta which responsible for providing nourishment to thefetus during pregnancy through the umbilical cord.
Theumbilical cord only develops during pregnancy through embryonic tissue. Thiscord is essential for the growth of the fetus as it provides a the exchange ofgases, nutrients and wastes between the mother and the fetal blood, but the”maternal and fetal blood do not commingle”(Freeman). The placenta is anotherorgan that develops during pregnancy and helps develop the fetus. The placentaproduces many hormones, including large amounts of progesterone and estrogen.The production of these steroid hormones suppresses GnRH(Gonadotropin-releasing hormone), which stimulates the pituitary gland torelease luteinizing hormone (LH) and follicle-stimulating hormone(FSH).
By suppressing GnRH prevents the ovulation ofmore follicles, hence menstruation does not occur during pregnancy. Thefemale reproduction system is not the only reproductive system involved increating human life, the male reproductive system is just as vital. Whencompared to the female reproductive system, the male reproductive system ismuch simpler and doesn’t extend during pregnancy because the male does notcarry the fetus. The reproductive organs of males include, “a pair of testes and excretory ducts (such as epididymis,vas deferens, and ejaculatory duct), seminal vesicles, the prostate, the bulbourethralglands, and the penis” (SEER). The sperm, or semen, is the malereproductive cell.
Sperm is produced in the testes and is stored in theepididymis. “When the sperm leave the testes, they are immature and incapableof fertilizing ova. They complete their maturation process and become fertileas they move through the epididymis”(SEER). The vas deferens is a musculartube that moves the sperm from the epididymis to the ejaculatory duct, wherethe sperm mixes with accessory fluids. The accessory fluids form in the seminalvesicles, prostate gland and bulbourethral gland.
The accessory fluids buildonto the sperm to create semen, which can fertilize an egg. The semen passes throughthe ejaculatory duct and enters the urethra that passes through the penis, inwhich the semen can be released from the male body through ejaculation.