Sex Reproduction and development
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There are two main types of reproduction: sexual reproduction which requires the union of male and female gametes to produce offspring with a mix of genetic material from each parent, and asexual reproduction which does not require fertilization and allows for cloning but less genetic variability. Asexual reproduction occurs through several processes like binary fission, budding, fragmentation, and parthenogenesis. Sexual reproduction in humans involves internal fertilization in the female reproductive system with male sperm fertilizing eggs in the uterus.
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Sex Reproduction and development
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- 3. Types of Reproduction Sexual reproduction Union of male & female gametes (sex cells) Each parent supplies half genetic material Asexual reproduction No union of gametes Cloning, unless there is mutation
- 4. Asexual Reproduction Occurs in all 3 domains of life Disadvantage Genetic sameness means less survival with changing environments Variability only due to mutation Advantage Individuals can reproduce
- 6. Binary Fission Dividing of individual into two Common in: Archaea Bacteria Many protists
- 7. Asexual Reproduction by Spores Common in fungi Life cycle with sexual & asexual stage
- 8. Asexual Reproduction by Budding Occurs in sponges, jellyfish & anemones
- 9. Asexual Reproduction by Fragmentation Occurs in flatworms & sea stars Fragments regenerate new parts
- 10. Parthenogenesis Eggs develop without fertilization Some species engage in behaviors simulating mating
- 11. Sexual Reproduction Prevalent among most vertebrates Common in many invertebrates Zygote Fusion of haploid egg & sperm cells Produces diploid cell
- 12. Hermaphrodite Both male & female in same body Some can reproduce by self-fertilization Forms of hermaphrodite Simultaneous Sequential
- 13. Modes of Fertilization External Fertilization Female sheds eggs Male fertilizes eggs after they leave her body
- 14. Modes of Fertilization Internal Fertilization Male deposits sperm in or near the female reproductive tract Eggs are fertilized in female’s body
- 15. Human Reproduction Sexual with internal fertilization Gonads = reproductive organs Male – testes Female –ovaries Other organs transport & receive sex cells Accessory glands facilitate reproduction
- 16. Production of Sperm Testes Housed in scrotum Placement allows for development Temperature must be lower than body
- 17. Testes Structure Composed of seminiferous tubules Site of sperm production (spermatogenesis) Sperm production triggered by follicle stimulating hormone Spermatogonia give rise to sperm cells
- 18. Spermatogenesis Spermatogonia undergo mitosis Some daughter cells undergo meiosis
- 19. Epididymis Site of sperm cell storage 18 hours to 10 days Unused sperm cells are reabsorbed
- 20. Vas Defrens Long tube from epididymis thru pelvic cavity Loops over urinary bladder Delivers sperm to urethra
- 21. Accessory Glands Seminal vesicle Adds fructose to nourish sperm cells Bicarbonate buffers acidity of urethra & vagina Prostate Alkaline fluid Bulbourethral glands Mucus-like alkaline substance Lubricant for sexual intercourse
- 22. Penis Cylinders of erectile tissue
- 23. Female Reproductive System Vagina Accepts penis & receives sperm External genitals Vulva Mons pubis Labia majora Labia minora Clitoris Erectile tissue
- 24. Ovaries Female gonad Contain primary oocytes Can develop into eggs
- 25. Oogenesis One primary oocyte yields in one ovum & three polar bodies
- 26. Oviducts Ovulation – mature oocyte is released Oocyte enters oviduct Oviducts lead to uterus Oviduct is site of fertilization
- 27. Uterus Cervix – lower portion opens to vagina Uterus is site of prenatal development Endometrium – inner lining Nourishing layer for embryo Shed monthly if no pregnancy occurs
- 37. Stages of Human Development Zygote – fusion of egg & sperm Embryo Morula Blastocyst Implantation Gastrulation Neurulation Fetus
- 38. Morula 1 cell zygote begins to divide rapidly Mitosis without growth
- 39. Blastocyst Ball of cells Portion of interior destined to differentiate Cells begin to migrate (morphogenesis)
- 40. Implantation Approximately 1 week after fertilization Blastocyst secretes enzymes Digests portion of endometrial wall Nourished by digested uterine cells
- 41. Implantation Embryo completes implantation Germ layers begin development (first 2) Ectoderm Endoderm
- 42. From Ovulation to Implantation
- 43. Gastrulation Primary germ layers fully formed Organs & tissues begin development
- 44. Neurulation Development of hollow nerve cord Neural groove forms
- 45. Embryo at Four Weeks
- 46. Fetus All organ systems are formed Growth & development continues
- 47. Fetus at Five Months
- 48. Human Fetus Near Full Term
- 49. Birth is Initiated by Hormones
- 50. Newborn Physiological Changes Obtains oxygen from environment Placenta no longer the source of nutrients Blood circulation is increased to lungs