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Human Reproduction

Human Reproduction

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Human Reproduction

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  1. Human Reproduction Regents Biology Chapter 23

  2. Human Reproduction 23-1 Human Reproductive Systems Section Objectives: • List the major structures of the male and female reproductive systems and explain the functions of each structure. • Describe the male and female secondary sex characteristics and name the hormones involved in their development. • List the stages of the menstrual cycle and explain the role of hormones in the cycle. Biology Chapter 23 Human Reproduction

  3. Male Reproductive System A. The Male Reproductive System 1. Testes: produce sperm and testosterone. • contain seminiferous tubules which produce sperm. 2. Vas deferens: tube that leads sperm towards body. 3. Scrotum: located outside body to allow health production of sperm. 4. Seminal vesicle & Cowper’s glands, secretes lubricating, nourishing fluid for sperm (semen). Biology Chapter 23 Human Reproduction

  4. Male Reproductive System 5. Prostate gland: where vas deferens and urethra connect. • Also adds secretions to sperm. 6. Urethra: Passage way for urine and sperm to outside of the body. • Ejaculation: Involuntary muscular contractions that force the semen through the urethra and out of the body. Biology Chapter 23 Human Reproduction

  5. Female Reproductive System B. The Female Reproductive System 1. Ovary: produces egg and estrogen. • follicle nourishes egg. • 200 000 follicles or eggs. • 500 eggs will mature in woman’s life. 2. Oviduct: (fallopian tube) allows egg to travel to uterus. • primary place where fertilization occurs. • fertilized egg travels to uterus. 3. Uterus: thick muscular walled structure. • egg attaches, embryo develops. Biology Chapter 23 Human Reproduction

  6. Female Reproductive Ssystem 4.Cervix: donut shaped, smooth muscle. • holds baby in until birth. 5. Vagina: where sperm deposited, birth canal. Biology Chapter 23 Human Reproduction

  7. Menstrual Cycle C. Menstrual cycle 1. Follicle stage: (10 - 14 days) a. hypothalamus stimulates the pituitary to release FSH (follicle stimulating hormone). b. causes immature egg to develop in follicle of ovary. c. follicle acts as an endocrine gland - produces estrogen 1. causes uterine wall to thicken. 2. causes pituitary to increase LH (luteinizing hormone). 2. Ovulation: day 14 a. LH & estrogen cause the mature egg to burst out of the follicle. b. it travels down the oviduct. Biology Chapter 23 Human Reproduction

  8. Menstrual Cycle (cont.) 3. Corpus luteum stage: 10 - 15 days long. a. LH stimulates empty follicle to produce progesterone. 1. causes uterine walls thicken. 2. pituitary keeps from producing FSH. Biology Chapter 23 Human Reproduction

  9. Menstrual Cycle (cont.) 4. Menstruation: 4 - 5 days, beginning of cycle a. unfertilized egg travels down the oviduct & passes out of body. b. corpus luteum disintegrates, stops producing progesterone c. lining of uterus breaks down & passes out of body (menses). d. LH production increases, causes pituitary to increase FSH. e. if egg is fertilized, embryo attaches to uterine wall. f. the corpus luteum remains and placenta will produce progesterone • Estrous Cycle: Occurs in most other mammals. Biology Chapter 23 Human Reproduction

  10. Fertilization 23-2 Fertilization, Implantation & Develop. Section Objectives: • Summarize the process of fertilization and implantation in humans. • Explain the roles of the placenta and umbilical cord in pregnancy. • Define the following terms: amniotic fluid, gestation period, labor, fraternal twins, and identical twins. Biology Chapter 23 Human Reproduction

  11. Fertilziation A. Fertilization • Occurs in oviduct. • Sperm penetrates ovum and genetic material combines with genetic material of egg. • Invitro fertilization: Process of fertilizing egg outside of body and then inserting the egg. Biology Chapter 23 Human Reproduction

  12. Implantation & Development B. Implantation and Development • After fertilization, the zygote undergoes cleavage and develops into blastula. • 5-10 days after fertilization, the embryo enters the uterus. • Outer layers of embryo secrete enzymes that digest part of the thick lining of the uterus. • Embryo attaches to this spot. • Implantation: The fastening of the embryo to the wall of the uterus. • Implantation marks the beginning of pregnancy. • Pregnancy is the period during which baby develops in the uterus. Biology Chapter 23 Human Reproduction

  13. Implantation & Development • After implantation the embryo undergoes gastrulation. • Three germ layers formed. • Growth and differentiation occurs. • After 8 week period the embryo is called a fetus. Biology Chapter 23 Human Reproduction

  14. Extraembryonic Membranes C. Exraembryonic Membranes 1. Chorion: outer membrane. • develops placenta: organ in uterus where exchange of foods, gases, and wastes between embryo and mother take place. • blood vessels of mother & embryo very close but not connected - food and oxygen received by diffusion. • embryo attached to placenta by umbilical cord. 2. Amnion: filled with amniotic fluid. • provides watery environment, and cushions embryo to prevent injury. Biology Chapter 23 Human Reproduction

  15. Extraembryonic Membranes 3. Yolk sac: provides food for developing embryo • in most vertebrates, sac large & is main food source for developing embryo. • in humans (mammals) yolk sac small and disappears when placenta develops. Biology Chapter 23 Human Reproduction

  16. Birth D. Birth • Gestation: period of time between fertilization and birth. • 9 months in humans. 1. First trimester: • all major body parts have begun to form. • after 8th week embryo called fetus. • heart is beating, nails grow, movement of limbs. Biology Chapter 23 Human Reproduction

  17. Birth (cont.) 2. Second trimester: • fetus grows tremendously. • skeleton begins to form. • heartbeat is stronger. • skin appears red and wrinkled. 3. Third trimester: • fetus increases greatly in size and weight. • final growth and development of all body parts. • important development of nervous system including cerebral cortex. Biology Chapter 23 Human Reproduction

  18. Birth (cont.) 4. Process of childbirth, called labor, 2-20 hours. 5. Onset of labor controlled by hormones. • increased estrogen - decreased progesterone. • smooth muscle of uterus pushes down on fetus. • cervix dilates. • contractions mild at first, 20 minutes apart. • then every minute. • cervix dilates 1- 2 cm to 10 - 11 cm. • amniotic sac breaks. • uterus pushes baby out of vagina. • followed by afterbirth (placenta, blood, amniotic sac). • oxytocin stimulates breasts to produce milk. Biology Chapter 23 Human Reproduction

  19. Multiple Births E. Multiple Births: 1.Twins: • identical - 1 egg, 1 sperm (morula splits) 1 placenta • fraternal - 2 eggs, 2 sperm, 2 placentas Biology Chapter 23 Human Reproduction