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REPRODUCTIVE SYSTEM

REPRODUCTIVE SYSTEM. Reproductive system: carries out the process so organisms can produce new individuals of their own kind. It stores, nourishes, and releases gametes SEXUAL DEVELOPMENT

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REPRODUCTIVE SYSTEM

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  1. REPRODUCTIVE SYSTEM • Reproductive system: carries out the process so organisms can produce new individuals of their own kind. • It stores, nourishes, and releases gametes • SEXUAL DEVELOPMENT • During 7th week, if male testes develop and produce androgens developing into male reproductive organs. • If female, the ovaries produce estrogens which develop female reproductive organs. • Puberty: Period of rapid growth and sexual maturation when sexual reproductive organs become fully functional. • Gonads: Male and female reproductive organs. • Puberty begins w/a change in the hypothalamus telling the pituitary to release the hormones FSH and LH affecting the gonads.

  2. MALE REPRODUCTIVE SYSTEM • Scrotum: Sac where the testes remain after birth regulating temp. • Seminiferous tubules: Tightly compacted forming the testes where sperm are produced. • FSH and LH stimulate production of testosterone and sperm. • Secondary sex characteristics: deep voice, beards, muscles?? • SPERM DEVELOPMENT • See fig. 43-4 • Epididymis:comma-shaped structure for storing mature sperm • From the epididymis the sperm travel into the vans deferens tube • From there the vas deferens passed into the abdominal cavity where three glands produce seminal fluid for sperm storage. • Semen: combination of sperm and seminal fluid (fig. 43-4) • 100-200 million sperm/ ml or 5,000,000/drop (2-3 ml/ejaculation) • The vas deferens merges into the urethra then to penis • Ejaculation: Contraction of smooth muscle lining vas deferens

  3. FEMALE REPRODUCTIVE SYSTEM • Fig. 43-5 • Ovary: Primary reproductive organ located in the abdominal cavity • Produce usually only one egg/month (ovum;ova) which signals the need to nourish a developing embryo. • Puberty is signaled when the hypothalamus signals the release of FSH and LH • FSH signals the production of estrogen causing reproductive system to develop • Secondary sex characteristics: enlarged breasts, wide hips, controlled hair growth • OVA DEVELOPMENT: (FSH completes the meiosis for an ova) • An ovary has about 400,000 primary follicles surrounding an ovum • Born w/400,000 immature ova but fewer than 500 actually release

  4. OVULATION • OVULATION: Follicle has completely matured and ovum is released. • Follicle ruptures, ovum moves into one of two Fallopian Tubes. (43-6) • Cilia move ovum along. Fertilization can take place during this time. • After a few days the ovum moves into the Uterus, which is designed to receive a fertilized ovum. This opens into the vagina. • Menopause: Follicle development no longer occurs, no babies possible • THE MENSTRUAL CYCLE: • The interaction of the endocrine and reproductive systems • Average occurrence every 28 days • Controlled by hormones on the negative feedback mechanism • Follicle Phase: • Level of estrogen in low causing a releasing hormone released by the hypothalamus (FSH & LH to cause a follicle to develop into maturity. • Level of estrogen goes up dramatically, uterus thickens, (10 days)

  5. MENSTRUAL CYCLE • Leteal Phase: • corpus luteum: ruptured follicle continues to release estrogen • progesterone: hormone released increasing blood supply, tissue matures, and lining is fully prepared to accept fertilized egg. • During first 2 days egg fertilization is greatest • If fertilized a zygote develops and attaches to uterus • MENSTRUATION:If egg is not fertilized, the corpus luteum begins to disintegrate, and less & less estrogen and progesterone are released. • When level of estrogen is below a certain point, lining of uterus detaches. The tissue along with blood and the unfertilized ovum are discharged through the vagina. • Lasts 3-7 days; • After a few days estrogen levels are low enough, so hypothalamus produces releasing hormones, secreting FSH and LH etc…..

  6. FERTILIZATION • FERTILIZATION • When sperm unites with the egg in the Fallopian tube. • Sperm are released during sexual intercourse. • Sperm swim actively through the uterus and up into the Fallopian tubes. • Hundreds of millions of sperm are released only a few reach the ovum, and it only takes one to fertilize the egg. • The ovum has receptor sites for sperm. Once a sperm cell reaches it, the sperm head ruptures, release an enzyme that breaks down the wall creating a pathway for the sperm nucleus. • Once this happens, cell membrane changes; no other sperm enters • Zygote: fertilized ovum after two haploid fuse into a single diploid. • After a few divisions the zygote attaches to wall of the uterus and begins to grow.

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