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Human reproductive system

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Human reproductive system
Internalgenitaliaof a human female (left) and male (right).
External genitalia of an adult female (left) and male (right).
Details
Identifiers
Latinsystemata genitalia
TA98A09.0.00.000
TA23467
FMA7160 75572, 7160
Anatomical terminology

Thehuman reproductive systemincludes themale reproductive system,which functions to produce and depositsperm,and thefemale reproductive system,which functions to produceegg cellsand to protect and nourish thefetusuntilbirth.Humans have a high level ofsexual differentiation.In addition to differences in nearly every reproductive organ, there are numerous differences in typicalsecondary sex characteristics.

Human reproductionusually involvesinternal fertilizationbysexual intercourse.In this process, themaleinserts hispenisinto thefemale'svaginaandejaculatessemen,which containssperm.A small proportion of the sperm pass through the cervix into the uterus and then into thefallopian tubesfor fertilization of theovum.Only one sperm is required to fertilize the ovum. Upon successfulfertilization,the fertilized ovum, orzygote,travels out of the fallopian tube and into theuterus,where it implants in the uterine wall. This marks the beginning of gestation, better known aspregnancy,which continues for around nine months as the fetus develops. When the fetus has developed to a certain point, pregnancy is concluded withchildbirth,involving labor. During labor, the uterine muscles contract, and thecervix dilatestypically over a period of hours, allowing the infant to pass from the uterus through the vagina.[1]Human infants are entirely dependent on their caregivers and requireparental care.Infants rely on their caregivers for comfort, cleanliness, and food. Food may be provided bybreastfeedingorformula feeding.[2]

Structure

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Female

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Main article:Human female reproductive system
Female reproductive system

The human female reproductive system is a series of organs primarily located inside the body and around thepelvicregion of afemalethat contribute towards thereproductiveprocess. The human female reproductive system contains three main parts: the vagina, which leads from thevulva,the vaginal opening, to the uterus; theuterus,which holds the developing fetus; and theovaries,which produce the female's ova. Thebreastsare involved during the parenting stage of reproduction, but in most classifications they are not considered to be part of the female reproductive system.[3]

The vulva

The vagina meets the outside at thevulva,which is made up of thelabia,clitorisandurethra;[4]during intercourse this area is lubricated by mucus secreted by theBartholin's glands.Thevaginais attached to the uterus through thecervix,while the uterus is attached to the ovaries via thefallopian tubes.Each ovary contains hundreds of egg cells or ova (singularovum).

Approximatelyevery 28 days,thepituitary glandreleases ahormonethat stimulates some of the ova to develop and grow. One ovum is released and it passes through the fallopian tube into the uterus. Hormones produced by the ovaries prepare the uterus to receive the ovum. The lining of the uterus, called theendometrium,and unfertilized ova are shed each cycle through the process ofmenstruation.If the ova is fertilized by sperm, it attaches to the endometrium and the fetus develops.[3]

Male

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Main article:Human male reproductive system
Male reproductive system

The male reproductive system is a series of organs located outside the body and around thepelvisregion of amalethat contribute towards the reproduction process. The primary direct function of the male reproductive system is to provide the malespermfor fertilization of the ovum.[3]

Penile shrinkage due to low temperatures. The scrotum is in a tense state to regulate testicular temperatures.

The major reproductive organs of the male can be grouped into three categories. The first category produces and stores sperm (spermatozoa). These are produced in thetesticles,which are housed in the temperature-regulatingscrotum;immature sperm then travel to theepididymidesfor development and storage. The second category are the ejaculatory fluid producing glands which include theCowper's gland(also called bulbourethral gland),seminal vesicles,prostate,andvas deferens.The final category are those used forcopulationand deposition of the sperm within the female; these include thepenis,urethra,andvas deferens.[3]

Major secondary sexual characteristics include a larger, more muscular stature, deepened voice,facialandbody hair,broad shoulders, and the development of anAdam's apple.[5]An important sexual hormone of males isandrogen,particularlytestosterone.[6]

The testes release a hormone that controls the development of sperm. This hormone is also responsible for the development of physical characteristics in men, such as facial hair and a deep voice.

Development

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Thedevelopment of the reproductive systemand thedevelopment of the urinary systemare closely tied to thedevelopmentof the human fetus. Despite the differences between them, theadultmaleandfemalearedeterminedin early development in the 6th week. The gonads and external genitals are derived from theintermediate mesoderm.[7]The three main fetal precursors of the reproductive organs are theWolffian duct,theMüllerian ducts,and thegonads.Endocrinehormones are a well-known and critical controlling factor in the normal differentiation of the reproductive system.[8]

The Wolffian duct forms theepididymis,vas deferens,ejaculatory duct,andseminal vesiclein the male reproductive system, but essentially disappears in the female reproductive system.[9]The reverse is true for the Müllerian duct, as it essentially disappears in the male reproductive system and forms the fallopian tubes, uterus, and vagina in the female system. In both sexes, the gonads go on to form the testes and ovaries; because they are derived from the same undeveloped structure, they are consideredhomologousorgans. There are a number of other homologous structures shared between male and female reproductive systems. However, despite the similarity in function of the female fallopian tubes and the male epididymis and vas deferens, they are not homologous but ratheranalogousstructures as they arise from different fetal structures.

Reproduction

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Further information:Human reproduction

Production of gametes

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Main articles:SpermatogenesisandOogenesis

Gametes are produced within the gonads through a process known asgametogenesis.This occurs when certain types ofgerm cellsundergomeiosisto split the normaldiploidnumber ofchromosomes(n=46) intohaploidcells containing only 23 chromosomes.[10]

Anatomy of the testis

In males, this process is known asspermatogenesisand occurs only afterpubertyin theseminiferous tubulesof the testes. The immaturespermatozoaor sperm are then sent to theepididymis,where they gain a tail, enablingmotility.Each of the original diploid germ cells or primaryspermatocytesforms four functional gametes, each forever young.[clarification needed]The production and survival of sperms require a temperature below the normal core body temperature. Since the scrotum, where the testes is present, is situated outside the body cavity, it provides a temperature about 3 °C below normal body temperature.

In females, gametogenesis is known asoogenesis;this occurs in theovarian folliclesof the ovaries. This process does not produce mature ovum until puberty. In contrast with males, each of the original diploid germ cells or primaryoocyteswill form only one mature ovum, and threepolar bodieswhich are not capable of fertilization. It has long been understood that in females, unlike males, all the primary oocytes ever found in a female will be created prior to birth, and that the final stages of ova production will then not resume until puberty.[10]However, recent scientific research has challenged that hypothesis.[11]This new research indicates that in at least some species of mammal, oocytes continue to be replenished in females well after birth.[12]

Disease

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Main article:Reproductive system disease

Like all complex organ systems, the human reproductive system is affected by many diseases. There are four main categories of reproductive diseases in humans. They are:

Rate ofsexually transmitted diseases in the U.S

Specific reproductive diseases are oftensymptomsof other diseases anddisorders,or have multiple, or unknown causes making them difficult to classify. Examples of unclassifiable disorders arePeyronie's diseasein males andendometriosisin females. Many congenital conditions cause reproductive abnormalities, but are better known for their other symptoms. These include:Turner syndrome,Klinefelter's syndrome,cystic fibrosis,andBloom syndrome.[14]

References

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Wikimedia Commons has media related toHuman reproductive system.
  1. ^Hanley, Gillian E.; Munro, Sarah; Greyson, Devon; Gross, Mechthild M.; Hundley, Vanora; Spiby, Helen; Janssen, Patricia A. (2016)."Diagnosing onset of labor: a systematic review of definitions in the research literature".BMC Pregnancy and Childbirth.16(1): 1.RetrievedJune 17,2024– via Springer Nature: BMC.
  2. ^Sexual Reproduction in Humans.Archived2018-02-17 at theWayback Machine2006. John W. Kimball. Kimball's Biology Pages, and online textbook.
  3. ^abcd"BIO304-14.1-Brief overview of Male and Female Reproductive System"(PDF).Saylor.org.RetrievedJune 17,2024.
  4. ^Nguyen, John D.; Duong, Hieu (2024),"Anatomy, Abdomen and Pelvis: Female External Genitalia",StatPearls,Treasure Island (FL): StatPearls Publishing,PMID31613483,retrieved2024-06-21
  5. ^"Puberty guide: Signs and stages for boys and girls".www.medicalnewstoday.com.2020-10-07.Retrieved2024-06-17.
  6. ^"Testosterone — What It Does And Doesn't Do".Harvard Health.2015-07-16.Retrieved2024-06-17.
  7. ^Rey, Rodolfo; Josso, Nathalie; Racine, Chrystèle (2000), Feingold, Kenneth R.; Anawalt, Bradley; Blackman, Marc R.; Boyce, Alison (eds.),"Sexual Differentiation",Endotext,South Dartmouth (MA): MDText.com, Inc.,PMID25905232,retrieved2023-12-19
  8. ^EDRI Federal Project Inventory: Cellular and Molecular Mechanisms of Abnormal Reproductive DevelopmentArchived2008-12-06 at theWayback MachineUS EPA. Dr. William R. Kelce. 2006.
  9. ^Imperato-McGinley, Julianne; Zhu, Yuan-Shan (2002). "Gender and Behavior in subjects with Genetic Defects in Male Sexual Differentiation".Hormones, Brain, and Behavior.Elsevier Science. p. 304.ISBN978-0128035924.
  10. ^abDevelopment of sex cellsArchived2008-07-05 at theWayback Machinein Reproductive system, Body Guide. Adam.
  11. ^Tilly JL, Niikura Y, Rueda BR (August 2008)."The Current Status of Evidence for and Against Postnatal Oogenesis in Mammals: A Case of Ovarian Optimism Versus Pessimism?".Biol. Reprod.80(1): 2–12.doi:10.1095/biolreprod.108.069088.PMC2804806.PMID18753611.
  12. ^Johnson J, Canning J, Kaneko T, Pru JK, Tilly JL (March 2004). "Germline stem cells and follicular renewal in the postnatal mammalian ovary".Nature.428(6979): 145–50.Bibcode:2004Natur.428..145J.doi:10.1038/nature02316.PMID15014492.S2CID1124530.
  13. ^Jensen, Christian Fuglesang S.; Østergren, Peter; Dupree, James M.; Ohl, Dana A.; Sønksen, Jens; Fode, Mikkel (September 2017)."Varicocele and male infertility".Nature Reviews Urology.14(9): 523–533.doi:10.1038/nrurol.2017.98.ISSN1759-4820.PMID28675168.S2CID19357838.Archivedfrom the original on 2022-08-27.Retrieved2022-08-27.
  14. ^Genetic Conditions > Reproductive system.Archived2008-12-04 at theWayback Machine2007. Genetics Home Reference. U.S. National Library of Medicine.
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