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18 Cards in this Set
- Front
- Back
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Functions of the reproductive system? |
1. production and transport of gametes(sex cells) by gonads(sex organs: sperm by testes, oocytes-eggs by ovaries) 2. Production of reproductive hormones-control development and function 3. fertilization: off egg by the sperm 4. Development and nourishment of fetus(in womb) and baby after birth(milk) |
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Introduction to Meiosis: |
1. meiosis produces gametes (sperm and oocytes) through 2 consecutive cell divisions 2. meiosis occurs only in testes(sperm) and ovaries(oocytes) 3. Somatic(body) cells have 46 chromosomes= diploid cells= a pair of 23 chromosomes a. 22 autosomal (body) pairs and 1 pair of sex chromosomes: XX-females; XY -males 4. Gametes(sperm and eggs) are haploid= 1 set of 23 chromosomes a. Sperm(23chrom)(half X, half Y) + egg(23 chrom) (all X) = zygote(46chrom) |
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Explain the process of Meiosis? |
1. start= 1 cell begins meiosis as diploid cell(2n):46 chromosomes 2. right before meiosis DNA is duplicated a. 46 chromosomes to 92 chromosomes b. 2 identical sister chromatids connected by a centromere 3. Meiosis I: a. called reduction division. Stages -prophase I, metaphase I, anaphase I, telophase I b. random assortment and crossing allows genetic material from both parents c. 2 daughter cells produced-each has 23 chromosomes( each chromosome consists of 2 chromatids) 4. Meiosis II: a. similar o mitosis. Stages: prophase II, metaphase II, anaphase II, telophase II. b. seperation of the 2 sister chromatids and pulled to opposite poles of cell c. the cell divides(cytokinesis) producing 2 daughter cells(each 23 chromosomes) d. final result= 4 daughter cells( each 23 chromosomes) haploid (n) |
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What are the functions of the male reproductive system? |
1. produce gametes by meiosis-spermatogenesis 2. production and secretion of male hormones(testosterone) 3. transfers sperm to female reproductive tract |
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Describe the male testes?
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A.testes-testicles (2of them) singular=testis 1. found within the scrotum : a loose pouch of skin and subcutaneous(under skin) tissue 2. Inguinal Canal contains the Spermatic Cord: the inguinal canal is a passageway from pelvic cavity to scrotum; spermatic cord contains vas deferens(ductus deferens), blood vessels, and nerves and suspends each testis superiorly 3. Scrotum/Testis Temperature: is lower than body temp (94-95F) this is necessary for sperm production 4. Cremaster Muscle: skeletal muscle in spermatic cord- when testes exposed to cold, elevates the testes closer to pelvic cavity where can absorb heat 5. Dartos Muscle: smooth muscle surrounds testis- when cold muscle contracts and skin of scrotum becomes wrinkled- decreased overall size of scrotum to keep warmer 6. Tunica Albuginea: fibrous C.T. capsule surronds testis; extends inward as Septa to divide the testis into Lobules (200-300/testis) 7. Seminiferous Tubules: - 1-3 tubulues inside each lobule - about 31 inches long, highly coiled - avascular epithelium make up tubule wall - location of the production of sperm(spermatogenesis):300 million sperm/day - seminiferous tubules to straight tubule(tubulus rectus) to rete testis to vas efferentia(efferent ducts that exit the testis) to the epididymis |
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Explain the Sperm Development inside the testes? |
A. Interstitial cells (Leydig Cells) - found in the connective tissue between the seminiferous tubules: produce and secrete the hormone TESTOSTERONE and other androgens B. Sustentacular cells (Sertoli cells) - make up the epithelium of the seminiferous tubules- extend from basement membrane to lumen - developing sperm cells are partially embedded in them - make up blood-testis barrier: sustentacular cells form tight juctions; protects sperm from immune attack - secrete INHIBIN hormone that inhibits sperm production when #'s are sufficient - secrete androgen binding protein (ABP) binds to and concentrates testosterone in seminiferous tubules for sperm production and binds to testosterone in blood |
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Explain Spermatogenesis? |
A. Spermatogonia (immature sperm) near basement membrane(BM) -46 chromosomes B. After puberty, when stimulated by testosterone to become active, spermatogoonia undergo mitosis: - one daughter cell becomes a new spermatogonia and remains near BM - the other daughter cell differentiates to form a primary (1^) spermatocyte - (immature-46 chrom) C. the 1^ spermatocyte undergoes meiosis I to form two secondary (2^) spermatocytes (immature-26 chromosomes) D. Each of the two 2^ spermatocytes undergoes meiosis II to produce 2 spermatids for total of 4 spermatids (immature 23-chrom) E. Spermiogenesis(last stage of spermatogenesis): conversion of spermatid into sperm cell(spermatozoon) cells in the more advances stages of development are pushed towards lumen of seminiferous tubule by sertoli cells |
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Describe the sperm structure?
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A. 48 hr life expectancy in female reproductive tract B. HEAD - contains (23) chromosomes - X and Y sperm - X sperm- larger oval-headed body, short tail; stronger, survives longer, more resistant to acid vagina - Y sperm -smaller, round headed body with a long tail, move faster lighter weight - half Y sperm, half X sperm C. ACROSOME(part of head) - dense granules at tip of head -is a lysosome, like a vesicles, has enzymes(hyaluronidase, proteinases) - helps sperm penetrate ovum D. NECK -centrioles E. MIDPIECE - numerous mitochondria because need energy for locomotion (need ATP) F. TAIL -flagellum for locomotion |
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Describe the epididymus (plural=epididymides)?
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1. lies along posterior border of testis (not part of testis) 2. head, body, tail regions made of coiled tubules 3. wall has epithelium, smooth muscle for ejaculation peristalsis 4. site of sperm maturation and storage (up to a month) 5. turns into the vas deferens (ductus deferens) |
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Describe the Vas Deferens (Ductus Deferens)?
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1.2 of them 2. ascends through the inguinal canal in the spermatic cord and enters abdominopelvic cavity and passes over urinary bladder 3. ampulla-vas deferens is enlarged at end(posterior of urinary bladder) 4. wall -pseudostratified columnar epithelium -3 layers of smooth muscle-peristalsis- ejaculation - 16-18 inches long in spermatic cord 5. functions to store sperm up to several months suspended animation and ejaculation(peristalsis) 6. Vasectomy- vas deferens cut, tied. Sperm are produced but are not part of the semen because they unable to reach urethra, no change in testosterone levels |
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Explain ejaculatory ducts?
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A. 2 of them B. formed by unions of seminal vesicle duct and ampulla of vas deferens from each testis C. <1 inch long D. 2 ejaculatory ducts empty into the prostatic urethra E. Accessory glands - 2 seminal vesicles: fluid secretion to dilute sperm for motility and high fructose for energy sperm becomes mobile; 60% of volume of semen; alkaline-more basic; has clotting proteins that clot it in 5 minutes after ejaculation - Prostate Gland: size and shape of a walnut; has 20-30 ducts that empty into prostatic urethra; 30% of semen volume; secretes slightly acidic milky fluid(ph:3.5-4.0),sperm motility not optimal in acid vagina; contains seminalplasmin: an antibiotic to destroy certain bacteria, reliquifies semen in 10-20 minutes after ejaculation |
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Describe the urethra? |
A. Prostatic urethra: - 1 inch long - closest to bladder - passes through the prostate gland B. Membranous Urethra: - 1/2 inch long - passes through muscle of the floor of pelvis called urogenital diaphragm - Cowpers Gland (bulbourethral-2: size of peas on either side of the membranous urethra; thick-sticky-mucous alkaline secretion into penile(spongy) urethra; neutralizes acidic penile urethra and provides lubrication before ejaculation C. Spongy or Penile Urethra: - 6 inches long - passes through the corpus spongiosum |
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Describe the Penis?
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A. copulatory(intercourse) organ, places sperm in females B. Glans penis: expanded distal end, many nerve endings C. Prepuce: foreskin; loose circular fold of skin over the glans penis; circumcision-removed surgically D. composed of erectile tissue(vascular connective tissue) |
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Describe Semen? |
- Composition: sperm: 1-5% + secretions (seminal vesicles=60%, prostate= 30%, bulbourethral= 5-9%) -2.5-5 ml/ejaculation; 50-100 million sperm/ml |
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Explain the physiology of an Erection?
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1. is a vascular phenomenon
2. 5-10 sec spinal cord reflex (once initiated, will proceed) 3. penis flaccid--firm(erect) 4. normally arteries to to vascular erectile tissue are constricted and contain little blood 5. During sexual excitation: - arteries dilate:parasympathetic( also stimulates cowpers gland secretion) - spongy tissue fills with blood -- penis rigid - veins compressed(constricted) to prevent outflow of blood 6. Impotence: inability to achieve and /or maintain an erection (psychological stimuli or physical factors) |
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Explain the physiology of Ejaculation?
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A. semen is expelled from penis by a series of rapid muscle contractions
B. sensory impulses from mechanoreceptors (physical receptors) of penis sent to sacral region of spinal cord - First trigger "emission" = increase sympathetic output to smooth muscle in ducts of glands: release of sperm from testes, and secretions from accessory glands organs to mix and form semen; peristaltic contractions of walls of testicular ducts, epididymides, vas deferens, ejaculatory ducts, seminal vesicles and prostate gland C. Then trigger ejaculation "expulsion": sensory impulses from urethra in response to urethral filling of semen causes motor impulses to be transmitted from spinal cord to skeletal (pelvic floor muscles) muscles at base of penis(not tip) and smooth muscle of urethra; reflex also triggers closure of internal urethral sphincter(smooth muscle) by bladder to prevent expulsion of urine D. accompanied by orgasm: release of endorphins in cerebrum, increase in cardiac output, and blood pressure E. average volume of fluid ejaculated is 3 ml, which contains 300-400 million sperm |
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Testes: Testosterone is the main androgen |
A. male sex hormone B. testosterone is a steroid hormone- testosterone deficiency results in sterility C. stimulates spermatogenesis: testosterone secreted by interstitial cells or Leydig cells and carried into seminiferous tubules by ABP (androgen binding protein) D. development and maintenance of penis and accessory reproductive organs E. behavior- development and maintenance of normal sex drive F. secondary sex characteristics almost all are testosterone dependent - more body hair - deepening of voice ( due to larynx and vocal cord enlargement) - thicker, more coarse and rough skin texture - more erythropoetin from kidneys (EPO) - increase RBC - increases size of muscle - higher cell metabolism - rapid bone growth |
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Explain the anterior pituitary and hypothalamic control of testicular function? |
both hypothalamic and pituitary hormones are involved A. hypothalamus secretes gonadotropin-releasing hormone( GnRH) B. GnRH travels through portal vessels to anterior pituitary gland which secretes FSH and LH - FSH: Follicle(sperm) stimulating hormone - LH: Luteinizing hormone (ICSH, interstitial (leydig) cell stimulating hormone) - LH stimulates secretion of testosterone by Leydig cells or interstitial cells - FSH stimulates proliferation, growth, maturation and responsiveness to testosterone in the sertoli cells (sustentacular cells) - In presence of both FSH and testosterone in sertoli cells, spermatogenesis is stimulated C. Testosterone exerts negative feedback inhibition of LH via anterior pituitary and hypothalamus (when levels of testosterone too high) D. But If sperm count gets too high, INHIBIN a protein hormone released from the seminiferous tubule sustentacular/sertoli cells, exerts negative feedback to hypothalamus (to decrease GnRH) and anterior pituitary (to decrease FSH and decrease permatogenesis E. A drug which would inhibit FSH and not LH would be the ideal male contraceptive because it would stop spermatogenesis but not interfere with testosterone secretion F. EX: LH-- Leydig cells to make testosterone--blood development of sex organs and secondary sex characteristics -- too much testosterone produce too much sperm, too concentrated-- send message to pituitary to decrease LH or up to hypothalamus to decrease GnRH--decreases both FSH and LH G: EX: FSH--sustentacular(sertoli) cells of seminiferous tubules--take testosterone made by leydig cells-- stimulates spermatogenesis |
