Biology - Week 6 Notes

Biology - Week 6 Notes - Biology 2108 Summer 2008 Dr. Davis...

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Unformatted text preview: Biology 2108 Summer 2008 Dr. Davis Abbreviated lecture notes from the week starting 6/23/08. Corresponds with Chapter 41-45 in Campbell (7th Edition) 46 Animal Reproduction Asexual reproduction is the creation of new individuals whose genes all come from one parent Sexual reproduction is the creation of offspring by the fusion of male and female gametes to form a zygote The female gamete is the egg The male gamete is the sperm Sexual Reproduction Fertilization depends on mechanisms that help sperm meet eggs of the same species Some species have external fertilization , in which eggs shed by the female are fertilized by sperm in the external environment Other species have internal fertilization , in which sperm are deposited in or near the female reproductive tract, and fertilization occurs within the tract Internal fertilization Requires important behavioral interactions between male and female animals Requires compatible copulatory organs Reproductive anatomy of the human female (Figure 46.9) Ovaries The female gonads, the ovaries Lie in the abdominal cavity Each ovary is enclosed in a tough protective capsule and contains many follicles A follicle consists of one egg cell surrounded by one or more layers of follicle cells Ovulation, Oviducts, and Uterus The process of ovulation Expels an egg cell from the follicle The remaining follicular tissue then grows within the ovary To form a solid mass called the corpus luteum , which secretes hormones, depending on whether or not pregnancy occurs The egg cell is released into the abdominal cavity near the opening of the oviduct , or fallopian tube Cilia in the tube convey the egg to the uterus Vagina and Vulva The vagina is a thin-walled chamber That is the repository for sperm during copulation That serves as the birth canal through which a baby is born The vagina opens to the outside at the vulva Which includes the vestibule , labia minora , labia majora , and clitoris Mammary Glands The mammary glands are not part of the reproductive system But are important to mammalian reproduction Within the glands small sacs of epithelial tissue secrete milk Male Reproductive Anatomy (Figure 46.10) In most mammalian species the male s external reproductive organs are the scrotum and penis The internal organs consist of the gonads (testes) , which produce sperm and hormones (testosterone) , and accessory glands Testes The male gonads, or testes consist of many highly coiled tubes surrounded by several layers of connective tissue The tubes are seminiferous tubules where sperm form Production of normal sperm cannot occur at the body temperatures of most mammals So, the testes of humans and many mammals are held outside the abdominal cavity in the scrotum Ducts & Glands From the seminiferous tubules of a testis , the sperm pass into the coiled tubules of the epididymis...
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Biology - Week 6 Notes - Biology 2108 Summer 2008 Dr. Davis...

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