Male reproductive system


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Male reproductive system

  1. 1. The Male Reproductive System o Seminiferous Tubules  Sertolli CellsExternal Genital Organs Stimulated by Follicle-o Penis: the anatomically male copulatory organ. Stimulating Hormoneo Scrotum:It holds and protects the testes. It (FSH) also contains numerous nerves and blood o For vessels. SpermatogenesisInternal Genital Organs Testosterone Secretiono Epidydimis: a whitish mass of tightly coiled -Testosterone: produced mostly in the tubes cupped against the testicles testes  acts as a maturation and storage place -small amounts of testosterone: produced for sperm before they pass into the vas from steroids secreted by the outer layer of the deferens adrenal glands (adrenal cortex)o Vas Deferens:long, muscular tube that travels from the epididymis into the pelvic cavity Chemical signals for testosterone Secretion:  transports mature sperm to the urethra in preparation for ejaculation. -from the Pituitary Glando Testes:“male gonads”; the organs that produce -Hypothalamus (tells the testes how much sperm cells testosterone to produce)  produces hormones, including testosterone, which stimulates the controls hormone production in production of sperm cells and facilitates the pituitary gland by means of gonadotropin- male maturation releasing hormone (GnRH) tells the pituitary gland to make FSH and LHAccessory Glands Luteinizing hormone (LH): signals theo Seminal Vesicle: provides sperm cells energy testes to produce testosterone and aids in their motility. 70% of the semen is its secretion. ↑ testosterone = ↓ LHo Prostate Gland: responsible for the production of semen ↓ testosterone = ↑ LHo BulbourethralGland: produces substances related to nourishment of spermatozoa Hermaphroditism: A condition in which both*Testes has 2 compartments: ovarian and testicular tissue is present in the body o Interstitial Tissues Pseudohermaphroditism: Involve individuals  Leydig Cells with either testes or ovaries, who have accessory Stimulated by organs and external genitalia that are incompletely Luteinizing hormone developed or that are inappropriate for their (LH) chromosomal sex Secretes Testosterone o Maintain structure GONADAL AXIS and function of the male accessory sex -interactions between the hypothalamus, pituitary organs gland, and the gonads that works together to o Promote regulate development, reproduction, aging, and development of other body processes male secondary Anterior pituitary gland: release FSH and LH sex characteristics (stimulated by hypothalamus: GnRH)
  2. 2. -stimulation of spermatogenesis }Causes release of LH & FSH -stimulation of gonadal hormone secretion 4.LH & FSH travels to testicles -maintenance of the structure of the gonads 5.LH stimulates Leydig cells – testosteroneCastration: will lead to an ↑ in secretion of the 6.FSH stimulates Sertolli cells – produce androgengonadotropic hormone (FSH & LH) binding globulin and inhibin -gonads will then secrete products that exert a 7.↑levels of testosterone and inhibinnegative feedback effect of gonadotropin secretion *results in ↓production of LH & FSH; production ofNegative Feedback Mechanism: testosterone &inhibin ↓ 1.Inhibition of GnRH secretion from thehypothalamus PUBERTY 2.Inhibition of the pituitary’s response to agiven amount of GnRH -gonadotropin hormones = low until the beginning of puberty*testes and ovaries secrete inhibin, which is secretedby the Steroli cells (polypeptide hormone). -rise in gonadotropin secretion= maturational changes in the brain: result in ↑ GnRH secretion*Inhibin: inhibits the secretion of FSH w/o affectingLH secretion -Late puberty: pulsatile secretion of gonadotropins -FSH and LH secretion ↑during periods of sleep and ↓during periods of wakefulness -increased gonadotropin secretion during puberty stimulates a rise in sex steroid secretion from gonads1.Hypothalamus secretes GnRH2.GnRH goes to anterior pituitary gland3.GnRH binds with the receptors of pituitary gland
  3. 3. Secondary Sex Characteristics: physical Spermatogonia lose contact with the basementmanifestations of the hormonal changes during membrane, squeeze through the tight junctions ofpuberty the blood-testis barrier and differentiate into PRIMARY SPERMATOCYTES (diploid -46 chromosomes) Each primary spermatocyte replicate its DNA- MEIOSIS I begins. Meiotic spindle pulls one chromosome of each pair to an opposite pole of dividing cell forming SECONDARY SPERMATOCYTES (23 chromosomes:haploid) -each chromosome within a secondary spermatocyte is made up of two chromatids still attached by a centromere MEIOSIS II:The chromosomes line up in single file along the metaphase plate, two chromatids of each chromosome separate resulting to four haploid cells, Spermatids As spermatogenic cell proliferate, they fail to complete cytoplasmic separation creating CYTOPLASMIC BRIDGES (communication among cells) SPERMIOGENESIS Final stage of spermatogenesis Each spermatid becomes a single SPERM CELL HORMONAL factors (spermatogenesis) Testosterone -Secreted by Leydig Cells (interstitium of testis) -Essential for growth and division of the testicular germinal cells (first stage in forming sperm) Luteinizing hormone -secreted by anterior pituitary gland -stimulate Leydig cells to secrete testosterone FSH -secreted by anterior pituitary glandSpermatogenesis is a process creates functionalsperm from an initially undifferentiated germ cell. -stimulate sertoli cells for the conversion of spermatids to spermPrimordial germ cells migrate into the testes and Estrogenbecome immature germ cell, SPERMATOGONIA -formed from testosterone by sertoli cells
  4. 4. -essential for spermiogenesis i. Coloration of the skin develops less consistentlyGrowth hormone than in the female-metabolic functions of testes EXCITEMENT IN MALE: o Penis becomes partially erect-early division of spermatogonia (if absent, cause o Erection may be partially lost and regainedinfertility) repeatedly during an extended excitement phaseSPERM o Testicles: become drawn upward toward the perineum  300 million sperm complete the process of o Scrotum: tense and thicken during the erection spermatogenesis process  60 micrometers (to reach and penetrate the secondary oocyte) B. Plateau Phase o Period of sexual excitement prior to orgasm  PARTS: o Increase in circulation and heart rate 1. Head : 4-5 micrometers PLATEAU PHASE IN MALE *nucleus – 23 highly condensed acrosome o Male urethral sphincter contracts o To prevent urine from mixing with semen *acrosome – covers the ant. 2/3 of the o Guard against retrograde ejaculation (semen isnucleus redirected to the urinary bladder) - caplike vesicle filled with enzymes that o start to secrete seminal fluid or pre-ejaculatoryhelp a sperm to penetrate a second oocyte to bring fluidabout fertilization o Testicles rise closer to the body2. Tail C. Orgasmic Phase o Conclusion of the plateau phase *neck – constricted region behind the head o Experienced by both males and females(contains centrioles) o Accompanied by quick cycles of muscle contraction in the lower pelvic muscles *middle piece-contains mitochondria o Heart rate is increased even further(energy for locomotion of sperm to site offertilization and for sperm metabolism) ORGASMIC PHASE IN MALE *principal piece- longest portion o Usually associated with ejaculation o Each ejection – associated with a wave of*end piece-terminal,tapering portion of the tail sexual pleasure o Produce the greatest quantity of semen o Each contraction – associated with a THE HUMAN RESPONSE diminishing volume of semen and a milder wave of pleasure A. Excitation Phase: (arousal phase) o Occurs at the result of any erotic D. Resolution Phase physical or mental stimulation (kissing, o Allows the muscles to relax, blood pressure to foreplay, etc.) drop, and the body to slow down o Preparation for sexual intercourse o Refractory Period: May or may not be o ↑ Heart rate, breathing rate, and rise in experienced blood pressure o Further stimulation may cause a return to the o Myotonia: Increase in muscle tone plateau stage – allows the possibility of (voluntarily and involuntarily) multiple orgasms o Vasocongestion (“sex flush”)
  5. 5. ERECTION SEMEN —Erectiono ejaculated at the same time of orgasmo came from: sperm and seminal plasma —Erection – an increase in length and width of theo rapid decline of volume and sperm count with penis achieved as a result of blood flow into the repeated ejaculation erectile tissues  average volume= 2.5 to 3.5 ml  100 million sperms per ml of semen —Erectile Tissueso sperm count under 20 million = sterileo speed: 3mm per minute ◦Corpora Cavernosa (2)SEMEN COMPOSITION: ◦Corpus Spongiosum Seminal Vesicles (60%) –Urethra runs through it fructose: main energy Achievedby parasympathetic nerve-induced Phosphorylcholine vasodilation of arterioles that allows blood flow Ergothioneine into the corpora cavernosa. Ascorbic Acid Flavins Nitric Oxide: neurotransmitter Prostaglandin: stimulate muscle Erectile tissues become engorged with blood contractions in female and veins are restricted thus comes erection Prostate gland (20%) —Controlled by two portions of the central Spermine: counteracts the vaginal fluid Citric acid nervous system Cholesterol and Phospholipid ◦Hypothalamus Zinc Acid Phosphate ◦Sacral portion of spinal cord Bulbourethral Gland —Conscious sexual thoughts originate in the Alkaline Mucus based cerebral cortex via hypothalamus thus increasing the parasympathetic nerve activity to promote the Lubrication prior to ejaculation erection. (Vasodilation) “precum”: provide sexual activity with a natural lubricant EMISSION AND EJACULATIONBuffers: Phosphate&Bicarbonate —Emission- movement of semen into the urethra SEMEN PATHWAY —Ejaculation-forcible expulsion of semen from urethra outside the penis ◦Stimulated by sympathetic nerves, causing peristaltic contractions of the Vas Ejacula tubular system, the seminal vesicles, Epidyd Urethr Testes Defere tory imis ns Duct a prostate, and muscles at the base of the penis MALE FERTILITY
  6. 6. —Each ejaculation is 1.5 -5.0 ml.—Bulk of Semen is fluid from seminal vesicles andprostate—For people who can’t control their ownhormones a suggestion of a Vasectomy is on order—Vasectomy- to tie or block the vas deferenswhich restrict sperm from entering urethra—Sperm accumulates in crypts, phagocytosed anddestroyed by immune system.—Condoms —-only effective 97 % of the time —-Aids in preventing STDs Diseases—Gonorrhea (Tulo) -caused by bacteriumNeisseriaGonorrhoeae -Sexually transmitted (Oral, vaginal, anal) -symptoms are burning sensation andpenile discharge (hence Tulo)—Herpes (Can be Oral or Genital) -Viral infection caused by the HerpesSimplex Virus