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Chapter 19. The Reproductive System. Introduction . Reproduction: process by which genetic material is passed from one generation to the next Meiosis produces sex cells Sperm from male and egg from female join to form zygote Zygote develops into embryo Embryo develops into fetus.
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Chapter 19 The Reproductive System
Introduction • Reproduction: process by which genetic material is passed from one generation to the next • Meiosis produces sex cells • Sperm from male and egg from female join to form zygote • Zygote develops into embryo • Embryo develops into fetus
Introduction • Testes: produce sperm and male sex hormones • Accessory glands: produce secretions • Accessory organs: scrotum • Penis: transporting and supporting structure
The Scrotum • Outpouching of abdominal wall • Supports the testes • Divided internally by a septum • Scrotal sac elevates and descends
The Testes • Tunica albuginea: capsule covering with lobules • Convoluted seminiferous tubules • Spermatogenesis
The Testes (cont’d.) • Spermatogenesis • Spermatogonia > primary spermatocytes > secondary spermatocytes > spermatids > spermatozoa • Sertoli cells: supply sperm cells with nutrients • Interstitial cells of Leydig: produce testosterone
The Anatomy of the Spermatozoa • Three hundred million produced daily • Anatomy • Head: contains genetic material and acrosome • Acrosome has enzymes that aid sperm in penetrating covering of ovum • Middle piece: contains mitochondria • Tail: propels sperm
The Anatomy of the Spermatozoa (cont’d.) • Anatomy of a sperm cell
The Functions of Testosterone • Controls development, growth, and maintenance of male sex organs • Stimulates muscle buildup and bone development • Causes sperm maturation • Causes thyroid cartilage enlargement • Produces body hair patterns
The Ducts of the System • Seminiferous tubules: transport sperm cells • Rete testis: network of ducts • Ductus epididymis: site of sperm cell maturation • Epididymis located on posterior border of testis
The Ducts of the System (cont’d.) • Vas deferens: straightened portion of epididymis • Enclosed in spermatic duct • Ejaculatory duct: ejects spermatozoa into urethra • Urethra: terminal duct • Prostatic urethra, cavernous urethra, urethral orifice
The Accessory Glands • Seminal vesicles: produce viscous part of semen • Prostate gland: produces fluid part of semen • Bulbourethral glands: produce mucus
Semen • Mixture of sperm cells and secretions • Provides energy to the sperm via fructose • Neutralizes acidity of vagina • Acts as a transport medium • Contains enzymes that activate sperm • Average volume is 2.5 to 6 mL • Seminalplasmin: destroys certain bacteria
The Penis • Delivers spermatozoa to female reproductive tract • Glans penis: end of the shaft • Prepuce: loose skin covering glans penis • Circumcision: removal of prepuce
The Penis (cont’d.) • Contains masses of spongy tissue with sinuses • Sinuses fill with blood resulting in erection • Compress veins so blood is retained • Help penis penetrate vagina • During ejaculation, sphincter at base of urinary bladder is closed
Animation – Male Reproductive System [Insert male repro.swf]
Animation – Sperm Formation [Insert sperm formation.swf]
Introduction • Primary sex organs • Ovaries • Accessory organs • Uterine tubes, uterus, vagina, external genitalia • Accessory glands: produce mucus
The Ovaries • Held in position by ligaments • Covered by germinal epithelium • Tunica albuginea: cortex contains ovarian follicles • Ovarian follicles: eggs in various developmental stages • Primary follicle: contains oocyte
The Ovaries (cont’d.) • Oogenesis • Begins in developing female fetus (700,000 produced) • Puberty: ovarian cycle begins • Primary oocyte: first meiotic division • Mature egg: second meiotic division
The Uterine or Fallopian Tubes • Transport ova to the uterus • Infundibulum: funnel-shaped end with fimbriae • Cilia sweep an ovum into uterine tube • Egg moved by peristalsis toward uterus • Fertilization occurs in upper third of tube
The Uterus • Site of menstruation, egg implantation and labor • Pear shaped • Uterine cavity: interior of the body • Cervical canal: interior of the cervix • Uterine wall: endometrium, myometrium, perimetrium
The Menstrual Cycle • Menstrual phase • Endometrial lining shed along with blood and mucus • Ovarian follicles begin development • Preovulatory or proliferative phase • Secondary follicle matures into graafian follicle • Ovulation is rupturing of graafian follicle
The Menstrual Cycle (cont’d.) • Postovulatory or secretory phase • Corpus luteum develops • Secretes estrogen and progesterone • If fertilization and implantation do not occur • Corpus luteum degenerates and new cycle starts • If fertilization and implantation occur • Corpus luteum maintained for four months
Animation - Ovulation • [Insert Ovulation.swf]
The Functions of Estrogen • Development of female secondary sex characteristics • Breast development, pubic hair, fat deposits, widening of the pelvic bone • Enlargement of: • Uterine tubes, uterus, vagina, external genitalia
The Vagina • Passageway for menstrual flow • Receptacle for the penis • Lower portion of birth canal • Fornix: surrounds vaginal attachment to cervix
The External Genitalia of the Female • Vulva: external genitalia • Labia: majora and minora • Clitoris: erectile tissue • Vestibule: vaginal and urethral orifices • Glands: Skene’s and Bartholin’s
The Perineum (cont’d.) • Diamond-shaped region at inferior end of trunk between buttocks and thighs • Divided into: • Anterior urogenital triangle containing external genitalia • Posterior anal triangle containing anus
The Anatomy and Function of the Mammary Glands (cont’d.) • Produce milk in females • Contain 15 to 20 lobes with lobules • Lobules contain milk-secreting cells • Milk is conveyed through series of tubules • Areola: circular pigmented area around nipple
Pregnancy and Embryonic Development (cont’d.) • Egg fertilization 12-24 hours after ovulation • Zygote: fertilized egg • Moves down uterine tube into uterus • Blastula • Zygote embeds in endometrium, placenta develops
Pregnancy and Embryonic Development (cont’d.) • Primary germ layers • Ectoderm: skin and nervous system • Mesoderm: muscles and bones • Endoderm: linings of organs and glands • Amnion: fluid-filled sac • Attached to embryo by umbilical cord • Parturition: childbirth
Animation – Female Reproductive System [Insert female repro system.swf]
Summary • Discussed the organs of the male reproductive system • Discussed the role of testosterone • Described the process of spermatogenesis • Discussed the organs of the female reproductive system • Discussed the role of estrogen • Described the process of oogenesis
Summary (cont’d.) • Described the phases of the menstrual cycle • Discussed pregnancy and embryonic development