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HUMAN REPRODUCTIVE SYSTEM.
Term Paper ID:22944
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Essay Subject:
Describes male & female systems in fertile & infertile conditions, causes of dysfunction.... More...
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7 Pages / 1575 Words
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Paper Abstract:
Describes male & female systems in fertile & infertile conditions, causes of dysfunction.
Paper Introduction:
The Endocrinology of Infertility
The female and male reproductive systems share many similarities. Both are modulated by the effects of various hormones. Some of these include gonadotropin-releasing hormone, follicle-stimulating hormone, and luteinizing hormone. Likewise, endocrine abnormalities in both females and males can result in reproductive system dysfunction. Among females, progesterone deficiency may cause infertility. In males, sterility can result from insufficient gonadotropins.
Human reproduction requires the complex interplay of multiple anatomic and physiologic systems. Various interactions between the central nervous system and the gonads determine the levels of various hormones. These endocrine signals provide a mechanism by which different reproductive system processes are
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Upon filling, hydrostatic pressure within the spaces causeserection (1:6 8-611). Eventually, the corpusluteum will involute and rapidly declining levels of both estrogen andprogesterone will cause menstruation to occur. Researchers have thus far identifiedpopulations of women with "otherwise unexplained infertility who haveeither peaked or integrated luteal phase progesterones that are more thantwo standard deviations lower than those of women with infertility ofobvious cause (4:14 )." Moreover, some studies have suggested thatincreasing the progesterone levels of these women can enhance their chancesof having successful pregnancies. In males,these same hormones are ultimately responsible for spermatogenesis. During each monthlysexual cycle, the follicular cells surrounding several oocytes begin toproliferate. Theoretically, abrupt cessation of the therapyimproves spermatogenesis by stimulating reactivation of the normalendocrine response. Ifa fertilized ovum does not implant, progesterone levels will begin to waneapproximately halfway through the luteal phase. Among men, infertility may also be caused by previous infection,congenital defects, or hormonal abnormalities. Literature Cited 1. The ovum isthen transported to the uterus and implantation occurs. A congenital form of thedisease, Kallmann's syndrome, results from a deficiency of gonadotropin-releasing hormone (6:1473-1478). Under the influence of both estrogenand progesterone, the endometrium continues to thicken in preparation forimplantation of a fertilized ovum. P. Lancet. 6. Sixth edition. This gland secretes a thin milky, alkaline fluidknown as prostatic fluid. Moreover, the cycle is subdivided into thefollicular phase (prior to ovulation) and the luteal phase (afterovulation). The principal male reproductive organs include the testis, theepididymis, the vas deferens, the seminal vesicles, the prostate gland, andthe penis. Some of theseinclude gonadotropin-releasing hormone, follicle-stimulating hormone, andluteinizing hormone. BothFSH and testosterone are required for normal spermatogenesis (1:615-616). These two phases are of approximately equal length (5:1971-198 ). In: Shearman, R. In: Shearman, R. Thiscondition may be either congenital or acquired. By stimulating cellular proliferation and growth,the hormone initiates a severalfold thickening of the uterine lining, orendometrium. Itinhibits the secretion of both FSH and LH such that their levels declinearound the tenth day of the cycle (1:622-623). Two secretory male reproductiveorgans include a pair of seminal vesicles and the prostate gland. After ovulation, however, this hormone is secreted by theruptured follicle, or corpus luteum. The Endocrinology of Infertility The female and male reproductive systems share many similarities.Both are modulated by the effects of various hormones. In the female, thiscauses vasocongestion of the genital organs, including the externalgenitalia, the vaginal canal, and the uterus (1:62 -621). Volume 2. Within each ovary, these cells eventually form fluid-filledvesicular follicles. This midcyclegonadotropin surge ultimately results in ovulation (5:1971-198 ). During the first half of the sexualcycle, FSH initiates the growth of ovarian follicles. Thereare many causes of infertility. Howards, S. The central nervous system influences female reproductive systemfunction. Second, estrogen alsoinfluences the uterus. If, however, implantationdoes occur, the corpus luteum will continue to grow and secrete hormones.The structure's viability is maintained by chorionic gonadotropin--ahormone secreted by the developing fetal tissues (1:633). Clinical reproductive endocrinology. S. One endocrine problemassociated with male sterility is known as gonadotrophin deficiency. 4. E.; Giwercman, A.; de Kretser, D. P., ed. Guyton, A. 343:1473-1479; 1994, June 11.----------------------- 1 At the peak of sexual excitement, sympathetic nervous systemstimulation may cause both females and males to experience orgasm. Physiology of the human body. Emission involves contraction of the epididymis and the vasdeferens with subsequent movement of the sperm into the prostatic urethra.Eventually, smooth muscle contractions within the seminal vesicles and theprostate expel the organs' respective fluids, and force the sperm forward.At the onset of ejaculation, nerve signals from the sacral spinal cordstimulate rhythmic contraction of both the internal genital organs andcertain pelvic muscles to force the fluids through the urethra.Fertilization often occurs within one of the uterine tubes. D.; Ewing, L. New York, NY: Saunders College Publishing; 1984. The sperm are formed within the testis. Hudson, B.; Burger, H. Thefemale orgasmic response can include the following: (1) rhythmiccontractions of the vaginal wall; (2) rhythmic uterine contractions; (3)pelvic muscle contractions; and (4) an "intense psychic state (1:62 -621)." In contrast, the male orgasm consists of two phases, emission andejaculation. In contrast,the prostate gland is a bulbous structure that surrounds the urethra nearthe neck of the bladder. During the follicular phase of the cell cycle, progesterone levelsare low. The length of the human sexual cycle is approximately 28 days.Traditionally, the first day of menstrual bleeding is designated as thefirst day of the cycle. S.; Pfaff, D. For most men with infertility, however, no specific causal factor canbe identified. In both thefemale and the male, sexual arousal can be elicited by either psychic orphysical stimulation. Forone, it has a negative feedback effect on the anterior pituitary. In females, FSH and LH produce the sexual cycle. In males, sterility canresult from insufficient gonadotropins. C. Ovulation occurs, when this enlargedfollicle releases its ovum into the pelvic cavity (1:6 9). Human reproduction usually requires sexual activity. This organ secretes aviscid seminal fluid into the upper end of the vas deferens. At the other end, uterine tubes extend from each of the two superiorcorners. Sterility can also result fromhormonal aberrations. New York, NY: Raven Press; 1988; pp. Although there is no documented cost-effective treatmentfor idiopathic infertility, various treatments have been attempted. G.; de Kretser, D. The following two therapeutic approacheshave been employed: (1) Follicular development has been stimulated usingclomiphene and/or gonadotropins; and (2) exogenous progesterone has beenadministered subsequent to ovulation. For example, insufficient corpus luteum progesteronehas frequently been cited as a cause of otherwise unexplained infertility.If a progesterone deficiency causes the luteal phase of a person's sexualcycle to end prematurely, their endometrium might begin to bleed beforeimplantation can occur (4:14 ). The epididymis consists of a system of coiled tubesconnecting the testis and the vas deferens. Embryonic testosterone causes the formation of the male sex organs. Clinical reproductive endocrinology. Laterin life, the hormone also stimulates testicular growth and function. 2. 3. Follicle-stimulating hormone initiatesspermatogenesis, and luteinizing hormone stimulates testosterone secretion. S. Female reproductive system function is characteristically cyclical innature. 1 9-164. When sterility results from some endocrineproblem, hormone replacement therapy is sometimes effective. The vagina is a tubularanatomic structure. Ovulation normally occurs around the fourteenth day (1:6 9). In: Knobil, E.; Neill, J. The uterus is approximately triangular in shape. This testosterone suppressespituitary gland function. Among women, common causes of infertility include previousinfection and congenital abnormalities. P., ed. M. The primary female reproductive organs include the vagina, theuterus, the uterine tubes, and the ovaries. Through the secretion of gonadotropin-releasing hormones intothe pituitary portal circulation, the hypothalamus plays "a limiting rolein the control of gonadotropin secretion (5:1971-198 )." The anteriorpituitary secretes both FSH and LH. Eventually, the tubes come in contact with theovaries: One ovary is associated with the distal opening of each uterinetube (1:617). Various interactions between the centralnervous system and the gonads determine the levels of various hormones.These endocrine signals provide a mechanism by which different reproductivesystem processes are controlled and coordinated. New England Journal of Medicine. The external male sexual organ, the penis,consists of two types of tissue, the corpora cavernosa and the corpusspongiosum. At one end, itprotrudes into the posterior wall of the vagina to form the uterine cervix. The female and male reproductive systems are obviously verycomplicated. As the sexual cycle continues, one of the folliclesgrows much larger than the rest. New York, NY: Churchill Livingstone; 1985; pp. 5. The estrogen has multiple effects. Forone, testosterone-rebound therapy involves the temporary administration oflarge doses of exogenous testosterone. The testis'interstitial cells of Leydig also secrete the male sex hormone,testosterone. As sperm pass through theepididymis, they gradually mature. Human reproduction requires the complex interplay of multipleanatomic and physiologic systems. 1971-1994. Itsenlarged upper end forms the ampulla. At birth, femalespossess several hundred thousand immature ova, or primary oocytes.Following puberty, these oocytes mature sequentially. These tissues contain cavernous spaces capable of holdingblood. It leads from the external genitalia to the muscularuterus. The anteriorpituitary suddenly begins to secrete increased quantities of gonadotropins. Erotic thoughts or direct stimulation of the genitalorgans activates the parasympathetic nervous system. Virility and infertility. Once the follicles grow to about half their maximum size, estrogenceases to have a negative feedback effect on the pituitary. The combination ofa single sperm and a single ovum may then "grow into an embryo, then into afetus, and eventually into a newborn baby (1:61 )." In both women and men, there are many causes of infertility. In contrast, any disorder (e.g., a tumor)that destroys anterior pituitary function can cause acquired deficiency.Treatment generally includes the administration of both FSH and LH (3:64-65). L.; Greenwald, G. Clomiphene administration may increasehypothalamic secretion of gonadotropin-releasing hormone (2:312-316). The uterine tubes curve laterally and posteriorly around the wallof the pelvic cavity. Knobil, E.; Hotchkiss, J. Likewise, endocrine abnormalities in both females andmales can result in reproductive system dysfunction. These growing cellsthen begin to secrete estrogens. In the male, itresults in erection (1:614-615). The menstrual cycle and its neuroendocrine control. Skakkebaek, N. The vas deferens stores sperm. Pathogenesis and management of male infertility. New York, NY: Churchill Livingstone; 1985; pp. Jansen, R. Maintenance of the corpus luteum depends on gonadotropic support. About 1female in 2 is sterile; whereas about 1 male out of 2 to 25 is sterile(1:615-62 ). 332:312-317; 1995, February 2. Treatment of male infertility. Perhaps the most commonly used modality thoughconsists of antiestrogen agents. W., eds. Endocrine response in the female genital tract. In contrast,the hormone appears to switch to a positive feedback effect. Eachseminal vesicle consists of a coiled tubular gland. 46-8 . L.; Markert, C. The female sexual cycle is controlled by complex interactionsbetween a number of different hormones (1:6 9-61 ). Among females,progesterone deficiency may cause infertility. The physiology of reproduction. Most of this secretion consists of LH (1:622-623). As in the female, the male reproductive system is controlled byanterior pituitary hormones.
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