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What is human reproduction
 

What is human reproduction

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    What is human reproduction What is human reproduction Document Transcript

    • What is Human Reproduction?In both animals and human beings, reproduction beginswith a single cell. Females make special cells, called ova or eggs, within their bodies. The Male produce cells in their bodies called sperms. When the sperm cell joins with an ovum inside the female’s body, fertilization takes place. The fertilized ovum develops into an embryo and continues to grow in the female’s body. The growing human embryo is later called a fetus. Pregnancy immediately occurs during this period. When the fetus is fully developed, it leaves its mother’s womb and we say that the baby is born. Every person has reproductive organs. The reproductive organs in males are the testes. The female reproductive organs are the ovaries. Fertilization is the union of the sperm and the egg cell that occurs in the Fallopian tube. The fertilized egg is developed to becomean embryo.The Male Reproductive System The male reproductive system is designed for production and transport of sperm cells. The changes in the body of a male are triggered by the hormone testosterone, which is produced in the male sex glands, the testes (testis/testicles). When a baby boy is born, his sex organs are already formed, but he cannot produce sperm. He is not able to produce sperm until he reaches the age of puberty, 12 or 13 years old. The penis is an elongated muscular organ, full of blood vessels and nerves. It is the external organ in front of the scrotum. It is where semen and urine flow out of the body. The foreskin is the fold of the skin that covers the glands of the penis. It has been a common practice to remove the foreskin soon after birth. The process is called circumcision. The scrotum is the small sac of skin at the base of the penis. This sac contains the testes (testicles). The testes are oval-shaped organs that produce testosterone. Testes produce sperm cells. Production of sperm begins at puberty.
    • The urethra is a canal through which the urine is carried outside the body and through which the semen (whitish liquid containing sperms) is discharged. It is produced chiefly by the prostate gland. Prostate gland produces a fluid called semen that helps sperm to move around.The Female Reproductive System The changes in the body of a female are caused by the hormone estrogen, which is produced in the female sex glands, the ovaries. The ovaries are the primary female sex organs. Egg cells and female hormones are produced here. The two ovaries are located to the right and left of the uterus, to which they are connected by the oviducts or Fallopian tubes. At puberty, ovaries contain hundreds of thousands of undeveloped eggs. These ovaries take turns in releasing an egg every month. The Fallopian tubes are muscular elongations as big as the size of a pencil. They have fingerlike ends. Each tube leads to the uterus. The uterus is a hollow stretchable organ with thick muscular walls lined with many blood vessels. It is about the size of a clenched fist. The uterus is the strongest muscle in the female body. It is where the fetus or unborn child develops during pregnancy. The cervix is the passageway, about one-eight of an inch wide, connecting the uterus and the vagina. Normally, the cervix is very small, but during childbirth, it opens wide enough to allow for a passage of the fetus. The vagina is a muscular tube with little internal spaces. This is the passage wher menstruation flows out. This is also where sperm cells enter. The vagina is also called the birth canal. When a baby is born, it passes from the uterus through the cervix, and out of the body through the vagina.PREPARED BY:CHERRY MAY B. CARALDEA.B. POL SCIE IV
    • The reproductive system is a group of organs whose purpose is to allow procreation (the process whichallows two living beings to produce a third, separate being). Reproduction is necessary for thecontinuation of a species, and allows genetic material to pass from one generation to another. Unlikeany other system in the human body, the male and female reproductive systems are complementary toone another.Drawing of the female reproductive system.Source: SEERs Training Web Site.Drawing of the male reproductive system.Source: SEERs Training Web Site.The reproductive system is a group of organs whose purpose is to allow procreation (theprocess which allows two living beings to produce a third, separate being). Reproduction isnecessary for the continuation of a species, and allows genetic material to pass from one
    • generation to another. Unlike any other system in the human body, the male and femalereproductive systems are complementary to one another.Other Names GenitaliaTypesThe male and female reproductive systems are separate and unique but work together to allowreproduction.Female reproductive systemThe female reproductive system includes the ovaries, Fallopian tubes, uterus, vagina, accessoryglands, external genital organs, and the mammary glands. The external genitalia are theaccessory structures of the female reproductive system that are external to the vagina. They arealso referred to as the vulva or pudendum. The external genitalia include the labia majora, monspubis, labia minora, clitoris, and glands within the vestibule. The female reproductive systemcontributes to fertilization as well as maintaining the developing fetus, birth and nursing.Male reproductive systemThe male reproductive system, like that of the female, consists of those organs whose function isto produce a new individual—to accomplish reproduction. This system consists of a pair of testesand a network of excretory ducts (epididymes, vas deferens, and ejaculatory ducts), seminalvesicles, the prostate, the bulbourethral glands, and the penis. The seminal vesicles, prostategland, and the bulbourethral glands are the accessory glands of the male reproductive system.These glands secrete fluids that enter the urethra. The male reproductive system is primarily onthe outside of the body (external), as opposed to the female system which is mostly inside thepelvis (internal).DescriptionThe reproductive system is divided into the primary and secondary, or accessory, reproductiveorgans. The primary reproductive organs, or gonads, consist of the ovaries and testes. Theseorgans are responsible for producing the egg and sperm cells (gametes), and for producinghormones. These hormones function in the maturation of the reproductive system and thedevelopment of sexual characteristics. The hormones also have important roles in regulating thenormal physiology of the reproductive system. All other organs, ducts, and glands in the
    • reproductive system are considered secondary, or accessory, reproductive organs. Thesestructures transport and sustain the gametes and nurture the developing offspring.Role of the Reproductive System in the BodyThe major function of the reproductive system is to ensure survival of the species. Other systemsin the body, such as the endocrine and urinary systems, work continuously to maintainhomeostasis (a stable internal environment) for survival of the individual. An individual may livea long, healthy, and happy life without producing offspring, but if the species is to continue, atleast some individuals must produce offspring.Within the context of producing offspring, the reproductive system has four functions: To produce egg and sperm cells To transport and sustain these cells To nurture the developing offspring To produce hormonesHow the Reproductive System WorksFemale reproductive systemThe organs of the female reproductive system do the following: Produce and sustain the female sex cells (egg cells or ova) Transport these cells to a site where they may be fertilized by sperm Provide a favorable environment for the developing fetus Move the fetus to the outside at the end of the development period Produce the female sex hormones.The female sexual response includes arousal and orgasm, but there is no ejaculation. A womanmay become pregnant without having an orgasm.Follicle-stimulating hormone, luteinizing hormone, estrogen, and progesterone have major rolesin regulating the functions of the female reproductive system. At puberty, when the ovaries anduterus are mature enough to respond to hormonal stimulation, certain stimuli cause thehypothalamus to start secreting gonadotropin-releasing hormone. This hormone enters the bloodand goes to the pituitary gland, where it stimulates the secretion of follicle-stimulating hormoneand luteinizing hormone. These hormones, in turn, affect the ovaries and uterus and the monthlycycles begin. A womans reproductive cycles last from menarche to menopause.The monthly ovarian cycle begins with the follicle development during the follicular phase,continues with ovulation during the ovulatory phase, and concludes with the development andregression of the corpus luteum during the luteal phase.
    • The uterine cycle takes place simultaneously with the ovarian cycle. The uterine cycle beginswith menstruation during the menstrual phase, continues with repair of the endometrium duringthe proliferative phase, and ends with the growth of glands and blood vessels during thesecretory phase.Menopause occurs when a womans reproductive cycles stop. This period is marked bydecreased levels of ovarian hormones and increased levels of pituitary follicle-stimulatinghormone and luteinizing hormone. The changing hormone levels are responsible for thesymptoms associated with menopause.Male reproductive systemSperm are produced in the testicles. Sperm cells pass through a series of ducts to reach theoutside of the body. After they leave the testicles, the sperm passes through the epididymis,ductus deferens, ejaculatory duct, and urethra.Seminal fluid, or semen, is a slightly alkaline mixture of sperm cells and secretions from theaccessory glands. Secretions from the seminal vesicles make up about 60% of the volume of thesemen, with most of the remainder coming from the prostate gland. The sperm and secretionsfrom the bulbourethral gland contribute only a small volume.The volume of semen in a single ejaculation may vary from 1.5 to 6.0 ml. There are usuallybetween 50 to 150 million sperm per milliliter of semen. Sperm counts below 10 to 20 millionper milliliter usually present fertility problems. Although only one sperm actually penetrates andfertilizes the ovum, it takes several million sperm in an ejaculation to ensure that fertilization willtake place.The male sexual response includes erection and orgasm accompanied by ejaculation of semen.Orgasm is followed by a variable time period during which it is not possible to achieve anothererection.Three hormones are the principle regulators of the male reproductive system. Follicle-stimulatinghormone (FSH) stimulates spermatogenesis (the creation of sperm); luteinizing hormone (LH)stimulates the production of testosterone; and testosterone stimulates the development of malesecondary sex characteristics and spermatogenesis.Diseases of the Reproductive SystemSome diseases that directly involve the reproductive system are the following: Benign prostatic hyperplasia Cancer o Cervical cancer o Prostate cancer o Uterine cancer o Vaginal cancer
    • Disorders of sexual differentiation Ectopic pregnancy Endometriosis Hypogonadism Infertility Pelvic inflammatory disease Peyronie disease Premenstrual syndrome Sexually transmitted diseasesDiseases of the body that are associated with problems in the reproductive system, along withother symptoms elsewhere in the body, include these: Cystic fibrosis Klinefelter syndrome Turner syndromeSymptomsSymptoms indicating that there may be a problem in the reproductive system include thefollowing: Infertility Impotence Menorrhagia (heavy menstrual bleeding) Pelvic pain UrethritisProceduresSome procedures that may be done to diagnose problems with the reproductive system include: Hysteroscopy Pap smearSurgerySome types of surgery that are done on the reproductive system are the following: Hysterectomy Tubal ligation VasectomyPREPARED BY: CHERRY MAY B. CARALDE A.B. POL SCIE IV
    • The Reproductive System (Low Band Width)For life to have an on-going process, there must be the process of creating new life. This processis called reproduction. Human beings reproduce in much the same way as other mammals. Thereis need for both male and female to be involved in the human reproductive process. Female Reproductive System o Ovary  Ovum(ova) egg cell  Luteinizing hormone (LH)  Corpus Luteum  Progesterone o Fallopian tube (oviduct) o Fertilization (conception)  Ovulation  Blastula  Zygote  Menstruation o Uterus (womb)  Cervix  Endometrium o Vagina Male Reproductive System
    • o Male Urethra o Glands  Prostrate Gland  Bulbourethral Glands  Seminal vesicle  Semen o Testicles (testes, testis)  Epididymis  Scrotum  Sperm (spermatozoa)  Vas deferen o PenisThe Female Reproductive SystemThe female reproductive system consists of the fallopian tube, ovum,ovary, uterus, cervix andvagina.OvaryThis is the name for the sex gland that is similar in function to the male testicle. They are two innumber and are located on either side of the uterus (womb). Each ovary is coverd by a toughprotective capsule and contains many follicles. A follicle-sound is an egg cell sourounded byone or more layers of follicle cells. It is estimated that about 400,000 eggs (ovum) are stored ineachovary at birth. However, only one egg becomes ripe each month, once puberty begins, anddeparts from the ovary and travels into the fallopian tubes (oviduct). They also manufacture thefemale hormones estrogen and progesterone which is instrumental in the onset of the menstrualcycle.Ovum(ova) egg cellA microscopic egg cell is released from one of the two ovaries at an average cycle of once every28 days. When sperm cells encounter an ovum in the fallopian tube, they swarm around it likebees around honey. Once one sperm cell breaks through the outer membrane of the ovum byusing hydrolitic enzymes, the egg immediately produces a wall that blocks a second sperm fromentering.When fertilization of an ovum occurs, menstruation stops and no other ovum can bedischarged until the fetus has left the uterus.Luteinizing hormone (LH)-soundThis hormone is responsible for triggering the release of the ripe egg from the ovary.
    • Corpus Luteum-soundAfter the ovum (egg) is released from the ovary, a small temporary gland forms in the ovary andbegins to produce the hormone progesterone.Progesterone-soundProgesterone is secreted to help prepare the endometrium to receive a fertilized ovum. Oncemenstruation occurs, progesterone levels decrease and slowly rise again to form a newendometrium.Fallopian tube (oviduct)-soundThe ovum is transported from the ovary to the uterus over a period of one to five days via thefallopian tube. They are two in number and lead directly to the uterus. As the egg travels downthe tube, hair-like cillia move the egg toward the uterus by a swaying motion. If one fallopiantube becomes blocked and an egg attempts to travel down to the uterus through it, the egg willnot be able to make contact with a sperm cell. Occasionally, an egg will implant on the fallopiantube wall. When this happens, the tube painfully ruptures as the egg matures into an embryo. Theembryo is expelled from the body and the fertilization process must begin again.Fertilization (conception)Fertilization occurs when one sperm unites with an egg. This usually happens in the fallopiantubules of the female.OvulationOvulation is a period of time when a female becomes fertile and can conceive (when a sperm celland an egg can unite). It usually occurs two weeks before the onset of the female menstrual cycleand lasts for one to five days; the amount of time it takes for an egg to travel down the fallopiantube.Blastula-soundThe name for a zygote after the process of clevage, cell division. The blastula is a hollow ball ofcells and travels down the fallopian tube to the uterus. During this stage the growing eggimplants itself into the endomertium.Zygote-sound
    • The fertilized ovum that can divide into a group of human tissue cells and becomes an embryo iscalled thezygote. A zygote usualy forms in the fallopian tubules.Menstruation-soundTwo weeks, on the average, after ovulation, if the egg is not fertilized, it dies and the blood richcells of the membrane of the uterus and the microscopic unfertilized ovum pass through theuterus out through the vagina in a process called menstruation..Uterus (womb)-soundThe uterus is an thick, muscular organ in the reproductive system shaped like an upside downpear located within the abdomen of a female. It is the place where the membrane lining of theuterus endometrium becomes thicker as it amasses blood and nutrients to accommodate theembryo which will develop and grow into a fetus. It is also the origin of the bloody dischargethat usually occurs monthly during the reproductive years of a female. The unique arrangementof hteWhen it is time for the fetus to be born, the uterus will contract to expel its contents.CervixAn opening at the top end of the vagina leading to the uterus is called the cervix. After anembryo has favorably been implanted in the uterus, the cervix is sealed off to stop infection andallow amniotic fluid (the fluid that surrounds the fetus) to fill the uterus. During the first stage oflabor, expulsion of the fetus from the uterus, the cervix dilates (increases in size) to form apassageway for the fetus into the vagina.Endometrium-soundThis is the lining of the uterus that is prepared to receive the fertilized ovum. The richendomerium is equipped with blood vessels which attach to the growing embryo and nourish it.Vagina-soundThis tubular female sex organ serves many functions. It is the place where menstrual dischargespass out of the body. It also stretches to function as a birth canal when it is time for the fetus tobe expelled from the uterus. It is the channel through which the sperm in the semen travel uptoward the fallopian tube to fertilize an egg. Although its muscular tissue is much thinner than
    • the uterus, the walls are strong enough to contract to hold a penis or allow passage of a babyshead.The Male Reproductive SystemThe male reproductive system consists of the urethra, prostrate gland, testicles, scrotum, vasdeferens, seminal vesicle, and penis.Male UrethraUnlike the female, the males urethra is concerned with reproduction. It serves as a channel forall male sexual fluid. It also is the conduit from the bladder to the urinary opening in the penis.GlandsProstrate GlandImmediately beneath the bladder (the place where urine is stored until it is emptied) is anopening that leads to the prostrate gland. The prostrate gland is a small cone shaped organ that isnormally about one-half inch long and weighs less than an ounce. It totally encircles the base ofthe urethra where it joins the bladder . It emits prostatic fluid, which is thin, milky, and basic.These substances are important as they enable the spermatozoa(sperm) that come from thetesticles (or testes) to remain alive and thrive. In fact, prostatic fluids basic properties helpbalance the acidic environment of the vagina-hyper link and also protect the sperm from urinarytraces. It also acts, to a certain degree, as a control mechanism to stop semen and urine frommixing together as both are discharged through the urethra. Because of the close relationship ofthe prostrate gland and the urinary tract, a problem in one system can have far reaching effectson the other system.Bulbourethral GlandsLocated under the prostate gland are a pair of small glands that are connected to the urethra. Themain function of these two glands is still in question. However, they do secrete a fluid beforeejaculation. Many believe that the fluid lubricatesSeminal vesicleAn organ in the abdomen situated on either side of the urethra in an area just above the prostrategland is called the seminal vesicle. It is the place where almost 55% of semen is produced. Theseminal vesicle fluid is thick and clear. It contains mucus, amino acids, and fructose, which givessperm cells energy. In addition, it also has hormones called prostaglandins which stimulate theuterine muscles to move the sperm cells to the egg.the penis; however, the secreted fluid which is one or two drops is insufficient to lubricate such alarge area.
    • SemenA thick white opaque fluid that is secreted by seminal vesicals, glands that open into the urethrais called semen.. The function of semen is to protect the sperm cells in the vagina, provide energyfor weakened sperm cells, and help contract the uterine muscle to move the sperm cells into theuterus faster. Millions of sperm cells join with this fluid and are spewed out of the urethra byundulating contractions. The contractions and discharging of semen is called ejaculation.Testicles (testes, testis)Two testicles dangle down beneath the penis bag of skin called the scrotum. Each testicle ismade up of tightly coiled seminiferous tubules which manufactures more than 250 million spermcells each day. The sperm cells are stored in the testis itself. If the sperm are not released, theybreak down and are absorbed into the bloodstream. In addition to producing sperm, theinterstitial cells, which are scattered in the seminiferous tubules, produce testosterone, a steroidhormone accountable for male sexual urges. Some scientists think that the testicles are in such avulnerable position outside the body because the spermatozoa(sperm) need to be maintained at atemperature that is 2°C less than interior body temperature.EpididymisA long winding tube in the scrotum attached to the testicle where mature sperm cells are storedbefore they are discharged through the vas deference is called the epididymis. (There is oneattached to each testicle.)ScrotumA small walnut shaped wrinkled bag of skin holds the testicles and is called the scrotum. Musclefibers in the scrotum contract to help hold the sperm producing testicles closer to the body whenwarmth is needed and relax to allow the testicles to move farther away when it is too warm.Sperm (spermatozoa)An egg cell cannot begin to divide and develop into a life form unless it is joined by a sperm cell,a small tad-pole shaped cell propelled by a tail called a flagelum-sound. Sperm cells areproduced in the seminiferous tubules of the testes and contain genetic material. A sperm cell iscalled a gamete and contains only half the amount of chromosome(genetic material) necessaryfor producing an embryo. The other half is supplied by the egg cell-hyper link of the female.Vas deferenTwo seminal tubes from which sperm cells produced in the testicles travel (one from eachtesticle) are called thevasdeferens . They go upward through the urethra and are located on bothsides of the scrotum.
    • PenisThe male external sex organ consisting of spongy tissue like mass is called the penis. The shaftof the penis is covered by a thick layer of skin whereas the head has only a thin layer, making itmore sensitive. When aroused sexually, the spongy areas called cavernous bodies-sound fillwith blood. As the blood begins to flow, the pressure seals the veins which drain the penis. Thisin turn enables the penis to enlarge and become firm (an erection). It is the main vehicle used totransport semen from the male into the vagina of the female for reproductive purposes.PREPARED BY:CHERRY MAY B. CARALDEA.B. POL SCIE IV