SEXUAL Reproduction  TWO parents, offspring is genetically different from either parent - Adds variation to a species  MEIOSIS – produce gametes that have half the number of chromosomes so that two parents can contribute to the offspring AND still maintain the chromosome number of that species!!!  Gametes fuse during FERTILIZATION  Fertilized egg-ZYGOTE-undergoes rapid mitosis and differentiation to become-> an EMBRYO

HUMAN Reproduction and Development  Have INTERNAL FERTILZATION  Fully INTERNAL DEVELOPMENT, where the placenta and umbilical cord maintain the embryo inside the uterus After Nine Months (40 weeks) GESTATION – fert to birth  The placenta is no longer efficient enough to maintain the fetus, so it’s time for her or him to get outta there !

mitosis zygote Putting it all together… egg sperm 46 meiosis fertilization mitosis & development meiosis  fertilization  mitosis + development 46 gametes

Fertilization

Twins  Identical – ONE sperm + ONE egg Cells split apart in EARLY stages of cleavage SAME DNA – MUST be SAME Gender  Fraternal – TWO sperm + TWO eggs No more closely relate than any two siblings Can be girl/girl, boy/boy, OR boy/girl Different DNA

Types of Cells Different cells have different structures/shape and therefore different functions because they make different proteins because they have different genes turned “ON”

Placenta - Food & gases diffuse across blood vessels – with NO mixing of blood

Birth/Labor – it’s hard work  1. Dilation – opening of cervix to 10 cm Usually the longest phase  2. Expulsion – pushing the baby out  3. Placental stage – placenta is expelled from the uterus; also called the “afterbirth” Must come out AFTER the baby

HORMONES and the Ability to Reproduce  Hormones direct the changes that occur during development and growth  Begin maturing of egg and production of sperm at PUBERTY, usually in the early teens.  Wanes (lessens) as humans age  Females cease menstruation at MENOPAUSE, after age 50  Males continue to produce sperm throughout lifetime

 Sperm production  Sperm delivered to female Male reproductive system seminiferous tubules

Male reproductive system  Testes & epididymis sperm production & maturation  Glands seminal vesicles, prostate, bulbourethal produce seminal fluid nutrient-rich meiosis

Male reproductive system  Testicles - testes & epididymis produces sperm & hormones - testosterone  Scrotum degrees cooler sac that holds testicles outside of body  Epididymis where sperm mature  Vas deferens - vasectomy vs. castration (neutering) tubes for sperm to travel from testes to penis  Prostate, seminal vesicles, Cowper’s (bulbourethal) glands nutrient rich fluid to feed & protect sperm

Female reproductive system womb - muscle fertilization implantation

Female reproductive system (oviduct) womb Birth canal

Female reproductive system  Ovaries – follicle and corpus luteum produces eggs & hormones – estrogen & progesterone  Uterus – womb – implantation occurs nurtures fetus; lining (endometrium) builds up each month  Fallopian tubes - oviducts; fertilization occurs tubes for eggs to travel from ovaries to uterus  Cervix opening to uterus, dilates 10 cm for birthing baby  Vagina – sperm deposited birth canal for birthing baby