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Chapter 19 Reproductive System

Chapter 19 Reproductive System. Anatomy Male Reproductive System. Introduction. Primary Sex Organs Gonads Testes – male Produce sperm – male gamete (sex cell) – exocrine function Produce testosterone – male hormone – endocrine function Ovaries – female

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Chapter 19 Reproductive System

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  1. Chapter 19Reproductive System Anatomy Male Reproductive System

  2. Introduction • Primary Sex Organs • Gonads • Testes – male • Produce sperm – male gamete (sex cell) – exocrine function • Produce testosterone – male hormone – endocrine function • Ovaries – female • Produce Ova/egg – female gamete (sex cell) • Produce estrogen – female hormone • Accessory Sex Organs • Remaining sex organs

  3. Sex Hormones • Testosterone/Estrogen • For the development and functioning of the reproductive organs • For growth and development of other organs and tissues of the body

  4. Male Reproductive OrgansFigure 19.1 Scrotum Fleshy pouch divided into two chambers each housing a testis (male gonads) Extends outside of the body posterior to base of penis Superficial dartos smooth muscle which wrinkles the scrotal surface Deeper skeletal muscle – cremaster Contracts to pull testes closer to the body Sperm need to be cooler than body temperature

  5. Testis Appearance • Olive-size • Covered by capsule – tunica albuginea • Capsule extends in dividing testis into lobules • Lobules contain tightly coiled seminiferous tubules • Sperm producing factories • Empty sperm into rete testis which empty into the epididymis

  6. Interstitial Cells • Surrounding the seminiferous tubules • Produce testosterone – male reproductive hormone • Duct System • Accessory male organs • Transports sperm from the testes through the penis • Epididymis, ductus (vas) deferens, ejaculatory duct, urethra

  7. Male Reproductive Tract • Epididymis • Appearance • Tightly coiled threadlike tube; 20 feet long • Location • On top of the testis, descends along the posterior surface • Epididymis becomes the ductus/vas deferens as it turns up towards the body

  8. Function • Passageway for sperm to the ductus/vas deferens • 2 week journey • Immature sperm and non-motile • Allows time for sperm to mature • Contains cells to reabsorb cellular debris from abnormal or damaged sperm • Contains cells to absorb nutrients from blood • Secretes a substance which prevents premature capicitation • Becoming motile and fully functional • Requires secretion from seminal glands and acidic conditions inside female tract

  9. Ductus (Vas) Deferens • Appearance • Long, winding tube • Location • Continuation of the epididymis • Passes thru the inguinal canal into the abdominal cavity • Arches over the urinary bladder • Enclosed with nerves and blood vessels in connective tissue forming the spermatic cord • Peristaltic contractions empties sperm into the ejaculatory duct which passes through the prostate gland

  10. Function • Store sperm for several months • Transport sperm from to ejaculatory duct • Vasectomy • Small incision into the scrotum cutting through the part of the vas deferens in the scrotum • Sperm are still produced but can no long be expelled out of the body

  11. Ejaculatory DuctFigure 19-5 • Junction of ductus deferens with duct from seminal vesicle • Extends about 1 inch into the prostate gland • Empties sperm into the prostatic urethra

  12. Urethra • Location • Extends from the base of the urinary bladder to the tip of the penis • Last part of the duct system • Regions • Prostatic urethra • Passes through the prostrate gland • Contains the internal urethral sphincter • Membranous urethra • Passes through the muscles of the pelvic floor • Contains external urethral sphincter • Penile urethra • Passes through the length of the penis

  13. Urethral Function • Carries both urine and semen • Semen • Sperm and fluids from the accessory glands • Semen and urine never pass at the same time • During ejaculation, the internal urinary sphincter contracts preventing passage of sperm to bladder and passage of urine to urethra

  14. Accessory Glands • Produce seminal fluid • Seminal vesicles • Prostate gland • Bulbourethral glands • Functions • Contribute fluids of semen – seminal fluids • Nutrients for motility • Activate the sperm • Peristalsis of sperm and fluids • Produce buffers against acidity of urethra and vagina

  15. Seminal Vesicle • Paired tubular glands which attach to the vas deferens at the base of the urinary bladder • Secretes the major portion of the seminal fluid (60%) • Thick, yellowish secretion • Fructose - sugar - energy for the sperm motility • Prostaglandins for peristalsis in male and female tract • Fibrinogen – forming a temporary clot of semen in vagina after ejaculation • Alkaline secretion to neutralize acids • Secretion causes sperm to become motile

  16. Prostate Gland • Appearance • Single gland; chestnut shape • Ejaculatory duct passes through • Location • Surrounds the prostatic urethra • Function • Secretes prostatic fluid – 30% of seminal fluid • Thin, milky, alkaline fluid • Contains an antibiotic that may help prevent urinary tract infections in males • Secretion is released into the urethra

  17. Bulbourethral Glands • Location • Inferior to the prostate gland • Appearance • Very small pea-sized gland • Function • Secretes a clear, thick, sticky, alkaline mucous fluid • Lubricates the penis for sexual intercourse • Cleanse the urethra of traces of acidic urine

  18. Penis Figure 19-6 • Tubular organ, contains penile urethra • Three regions • Root • Attaches penis to body wall • Body/shaft • Contains erectile tissue to deliver the sperm to the female vagina • Spongy tissue that fills with blood causing the penis to enlarge and become rigid – Erection

  19. Glans • Expanded distal end surrounding opening • External urethral meatus • Covered by loose skin • Prepuce (foreskin) • Removed by circumcision

  20. Chapter 19The Reproductive System Anatomy Female Reproductive System

  21. Female Reproductive System • Functions • Produce the female gametes (ova) • Nurture and protect the developing fetus • Produce female sex hormones • Primary reproductive organ – Gonad • Ovaries • Exocrine function – produce eggs/ova • Endocrine function – produce hormones • Estrogens, progesterone

  22. Ovary Figure 19-8 • Appearance • Paired, almond shaped organs • Pale white or yellowish color • Nodular consistency resembling lumpy oatmeal • Location • Suspended by ligaments in the pelvic cavity • Broad ligament; Ovarian ligament • Nourishment/removal of waste • Ovarian artery and vein • Function • Development of egg cells to maturation • About 3 months

  23. Uterine Tubes/Fallopian TubesFigure 19-11 • Location • Extend from the ovaries to the uterus • Appearance • Muscular tube lined with cilia • Expands near ovaries to form funnel shaped structure – infundibulum containing finger-like projections called fimbriae • Does not make physical contact with the ovaries • Fimbriae contain cilia that beat toward the tube forming currents with move the ovum into the tube

  24. Function • Receive the ovulated egg • Depends on movements of the cilia of fimbriae • Some eggs are lost in the peritoneal cavity and might even be fertilized there • If fertilization is to occur, the secondary oocyte must meet the sperm in 12 – 24 hours • Unfertilized oocytes will degenerate • Carry egg (zygote if fertilization occurred) to the uterus • Muscular walls for peristalsis • Rhythmic beating of cilia in uterine tubes

  25. Uterus • Appearance • Hollow, muscular organ • Shape of an inverted pear • Fundus, body, cervix • Cervix - Lower 1/3 of the uterus projecting into the vagina • Location • Between urinary bladder and rectum • Superior to the vagina usually bent forward over the urinary bladder • Held in place in the pelvic cavity by ligaments • Broad ligament

  26. Function • Implantation • Attachment of embryo • Site of embryo development • Prepares each month for zygote • If no fertilization, menstruation occurs

  27. Tissue Layers of Uterus • Endometrium • Inner mucus lining • Two layers • Superficial functional layer • Undergoes changes due to sex hormone levels • Deeper basilar layer • Reponsible for reforming the functional layer monthly • Embryo burrows into this lining – implantation • Sloughs off about every 28 days if fertilization does not occur

  28. Myometrium • Thick muscular layer • Contracts during childbirth • Perimetrium • Outer layer • Visceral peritoneum

  29. Vagina • Appearance • Elastic, muscular tube; 3-4 inches long • Opening is the vaginal orifice covered by the hymen • Contains resident bacterial supported by nutrients in mucus of vagina • pH is 3.5 – 4.5 restricts growth of pathogens • Location • Extends from the uterus to the outside • Posterior to the bladder/Anterior to the rectum

  30. Functions • Transports uterine secretions • Transports the fetus during childbirth – birth canal • Receives the penis during intercourse

  31. External Genitalia Figure 19-12 • Female reproductive structures external to the vagina • Also called the Vulva • Mon pubis, labia, clitoris, vestibular glands • Mons pubis • Fatty rounded area over the pubic symphysis • Covered with pubic hair after puberty

  32. Labia • Labia majora • Hair covered skin folds • Labia minora • Located between the labia majora • Hairless • Clitoris • Small projection at anterior end of vulva • Corresponding to penis of the male • Hooded by the prepuce • Contains erectile tissue which becomes swollen with blood during sexual excitement

  33. Vestibular glands • Produce mucus • Lubricates distal end of vagina during intercourse

  34. Mammary Glands Figure 19-13 • Glands of the breast secreting milk in a process called lactation • Breast is divided into lobes each containing ducts which converge to a single lactiferous duct • Near the nipple, the lactiferous ducts expands into the lactiferous sinus • Open onto surface of the nipple • Nipple surrounded by reddish-brown tissue called areola containing sebaceous glands • Breast is connected to chest muscle wall by suspensory ligaments

  35. Chapter 19Reproductive System Physiology of the Reproductive System

  36. Human Life Cycle Figure 16.4 • Somatic body cells contain 46 chromosomes – diploid number or 2n • Sex cells – gametes – haploid number or n • Sperm cell – 23 chromosomes • Egg cell – 23 chromosomes • Fertilization • Union of sperm and egg produces a zygote with 46 chromosomes • Half the characteristics from male sex cell • Half the characteristics from female sex cell

  37. Meiosis • Special type of division which occurs in gonads – ovaries, testes • Production of gametes with n number of chromosomes • Reduces the diploid number of chromosomes to the haploid number • Oogenesis • Production of the female sex cells – ova • Spermatogenesis • Production of the male sex cells - spermatozoa

  38. Meiosis • Consists of two successive divisions of the nucleus • Meiosis I and Meiosis II • Each division is divided into stages • Prophase, metaphase, anaphase, telophase • Results in 4 daughter cells (gametes) instead of 2 • A way to reduce the number of chromosomes in half

  39. Spermatogenesis Figure 19-3 • Sperm production • 3 processes • Mitosis • Stem cells – spermatogonia • Beings during puberty and continues throughout life • Millions of sperm produced daily • Occurs in the seminiferous tubules • One daughter cell remains in seminiferous tubule; the other is pushed into the lumen • Primary Spermatocyte

  40. Meiosis I • Meiosis I • Chromosomes replicate • Homologous pairs – maternal and paternal come together in a process called synapsis • 4 chromosomes called a tetrad • Crossing over of genetic information may occur • At the end of meiosis I daughter cells receive both copies of either the maternal chromosome or the paternal chromosome from each tetrad • Forms the secondary spermatocytes

  41. Meiosis II • Each secondary spermatocyte contains 23 chromosomes but each consists of 2 chromatids • Duplicate chromatids will separate in meiosis II • Forms the spermatids • Each with 23 single chromosomes • n number of chromosomes

  42. Spermiogenesis Figure 16.5b • Process of the last stage of sperm development • Excess cytoplasm is sloughed off • Sperm is compacted into three regions – head, midpiece and tail • Tail – flagella develops

  43. Mature Sperm Figure 19-4 • Head • Nucleus containing DNA – 23 chromosomes • Covered with an acrosome • Similar to a large lysosome • In close contact with the oocyte the acrosomal membrane breaks down and releases enzymes that help the sperm penetrate through the follicle cells surrounding the oocyte

  44. Midpiece • Contains centrioles which contain filaments that form the flagella • Filaments are covered by mitochondria providing he energy for movements of the flagella • Tail • Flagella • Only example of a flagellum in humans • Enable sperm to move long distances in a short time

  45. Hormones • FSH stimulates the seminiferous tubules to produce sperm • LH luteinizing hormone/ISCH interstitial cell stimulating hormone • Testosterone Production • Function of the interstitial cells in seminiferous tubules • Testosterone • Stimulates reproductive organs to develop • Functions in the sex drive • Causes the secondary male sex characteristics to appear

  46. Male Secondary Sex Characteristics • Deepening of voice due to enlargement of larynx • Increased hair growth all over the body • Axillary regions • Pubic regions • Face • Enlargement of skeletal muscles • Thickening of bones

  47. Oogenesis Figure 19-9 • Process of production of female gametes – ova • Total number of eggs a female can release is determined by the time she is born • Release of eggs begins during puberty and ends in her 50’s or earlier • Menopause – gradual decline and end to a woman’s ability to reproduce

  48. Oogonia – female stem cells • Somatic cells containing the 2n number of chromosomes • These cells are located in the periphery of the ovary • These cells go through mitosis in the female FETUS • Daughter cells are called primary oocytes – in prophase I of meiosis • Primary ooctye is pushed into the ovary connective tissue and is surrounded by follicle cells

  49. At birth all the cells are primary oocytes • Oogonia no longer exist • This the females’ life supply of eggs approximately 2 million • Waiting to undergo meiosis and produce functional eggs • Remain at this point until puberty

  50. Meiosis • Production of 4 daughter cells but the cytoplasm is not evenly distributed • One functional ovum with cytoplasm • 3 nonfunctional polar bodies which disintegrate • Ovary releases a secondary oocyte not a mature ovum • Meiosis II does not occur producing a mature ovum unless fertilization occurs

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