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The Reproductive System

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The Reproductive System. Chapter 26. The Male Reproductive System. Scrotum Testes Epididymus Vas deferens Urethra. The Scrotum. Pouch supporting testes Consists of skin and superficial fascia Divided into 2 sacs Cremaster muscle, tunica dartos Regulate temperature of testes.

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The Reproductive System

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  1. The Reproductive System Chapter 26

  2. The Male Reproductive System • Scrotum • Testes • Epididymus • Vas deferens • Urethra

  3. The Scrotum • Pouch supporting testes • Consists of skin and superficial fascia • Divided into 2 sacs • Cremaster muscle, tunica dartos • Regulate temperature of testes

  4. The Testes • Paired oval glands • Development • High on embryo’s abdominal wall • Begin descent into scrotum during latter ½ of 7th month • Cryptorchism

  5. The Testes • Tunica vaginalis forms a capsule over testis • Derived from peritoneum • Tunica albuginea • Immediately covers testis • Divides testis into lobules • Lobules contain tightly coiled seminiferous tubules • Function • Spermatogenesis

  6. A Few Concepts with Regard to the Formation of Gametes • In sexual reproduction, a new organism is produced by the union and fusion of sex cells called gametes • A zygote results from the union and fusion of gametes • Zygote repeatedly divides (mitosis), develops into a new organism • Gametes differ from all other body cells in that they contain ½ the number of chromosomes • Human cells have 23 chromosomes (haploid, or n) = 1 set • Or 46 chromosomes (diploid, or 2n) = 23 pairs, or 2 sets • Meiosis = a process of cell division by which gametes are produced in the testes and ovaries; receive the haploid chromosome number (n)

  7. Spermatozoa • Produced at the rate of about 300 million/day • Life expectancy – about 48 hours in the female reproductive tract • Structure • Head with acrosome • Midpiece • Tail (flagellum)

  8. Accessory Glands • Seminal fluids (semen) are added to the sperm • Seminal vesicles • Prostate gland • Bulbourethral gland

  9. The Penis • Contains distal portion of urethra • Regions • Root • Body (shaft) • Contains erectile tissue • Corpora cavernosa • Corpora spongiosum • Glans • Surrounded by prepuce

  10. Semen • Mixture of sperm and secretions from accessory glands • Average volume for each ejaculation • 2.5 – 5 ml • Average # sperm/ejaculation • 50 – 100 million/ ml. • = 125 – 500 million/ejaculation • Only a small % reach ovum • Many sperm cells act on ovum to dissolve the barrier • Only 1 enters the ovum

  11. Overview of the Male Reproductive System • Sperm are produced in the seminiferous tubules of the testes • Spermatogenesis • Sperm are stored in the epidymus • Sperm are transported through the vas deferens • Accessory glands add seminal fluid • Sperm leave the body through the urethra

  12. The Female Reproductive System • Ovaries • Fallopian tubes • Uterus • Vagina

  13. The Ovaries • Location – upper pelvic cavity • Function • Oogenesis • Within a follicle • Production of hormones

  14. Oogenesis Before Birth • Formation of haploid ovum by meiosis • Division of cytoplasm is uneven • Before birth, many primordial follicles formed • Begin meiosis • Meiosis stops at chromosome duplication

  15. Oogenesis Continues at Puberty Once a month: • FSH causes ovaries to enlarge • Primordial follicles mature • Oocyte becomes larger • Follicle cells divide • Follicle fills with fluid, oocyte pressed to 1 side http://www.healthsquare.com/fgwh/wh1ch17.htm

  16. Ovulation • Ovum undergoes 1st meiotic division • Ovum is released into peritoneal cavity • Ovum is propelled to the fallopian tube • If not fertilized, it degenerates • If fertilized, 2nd meiotic division occurs • Empty follicle becomes corpus luteum • Progesterone secretion

  17. The Fallopian Tubes • Extend laterally from uterus • Not attached to ovary • Function • Transport ova • Fertilization occurs • Ectopic pregnancy

  18. The Uterus • Functions • Site of menstruation • Implantation of fertilized ovum • Development of fetus during pregnancy • Labor • Location • Between the bladder and rectum • Structure • Body • Cervix

  19. The Uterine Wall • 3 layers • Endometrium • Myometrium • Perimetrium

  20. The Vagina • Function • Passageway for menstrual flow • Receptacle for penis during intercourse • Lower portion of birth canal • Structure • Muscular • Lined with mucous membrane • pH is low

  21. The Female External Genitalia • Vulva (pudendum) • Labia majora • Labia minora • Vestibule • Urethral opening • Vaginal opening • Clitoris • Contains erectile tissue • Surrounded by prepuce

  22. Overview of the Female Reproductive System • Ova (oocytes) are produced in the ovaries (oogenesis) • Approximately every 28 days one ovum is expelled from the ovary (ovulation) • An ovum transported through the fallopian tube to the uterus where it becomes embedded in the uterine lining • Fertilization occurs in the fallopian tube • If the egg is not fertilized, the uterine lining detaches and is shed in menstruation • If the egg is fertilized, the uterine lining is held in place and supported by progesterone

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