reproduction - sexual/asexual 

• sexual reproduction - used by most animals
  • union of gametes (sperm/ova) >> zygote
• asexual reproduction - used by protests, cnidarians, tunicates, and others
  • produces genetically identical cells through mitosis
  • fission - organism divides into 2 identical organisms
  • budding - part of body separates, becomes new organism
• parthenogenesis - form of asexual reproduction in arthropods
  • females produce offspring from unfertilized eggs
• hermaphroditism - organism has both testes/ovaries
  • able to fertilize itself
  • sequential hermaphroditism - ability to change sex
• sex determination - environment or DNA determines sex
  • all mammals will develop into females w/o the SRY gene

fertilization - evolved in the water 

• external fertilization - sperm/ova unite outside of the organisms
  • must be synchronized or else gametes disperse
• internal fertilization - evolved due to drying on land
  • male gametes introduced into female reproductive tract
  • oviparity - fertilized eggs placed outside mother to develop
  • ovoviviparity - fertilized eggs stay within mother, but get nutrition from egg yolk
  • viviparity - young develop inside mother, receive nutrition from mother’s blood
• estrus - period of sexual receptivity in females
  • occurs around time of ovulation

birth control - aka contraception 

• abstinence - not having sex
• condoms - most common form of birth control
• douche - washing out vagina immediately after sex to kill the sperm
• oral contraceptives - birth control pills
  • blocks ovulation through negative feedback
• inserting irregularly shaped object >> embryo can’t implant onto the wall
  • major discomfort for women using it
• “morning after pill” - contains extreme dose of estrogen
  • used as emergency contraception
• sterilization - vasectomy in males, removing part of fallopian tubes in females

sexual response cycle - excitement, plateau, orgasm, resolution  

• excitement - sexual arousal
• plateau - blood goes to reproductive organs
• orgasm - peak of sexual response
• resolution - return to pre-sexual stimulation level
• Viagra - preserves cGMP levels >> maintains erection
  • still requires sexual thoughts to stimulate erection >> not an aphrodisiac