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1 Menstruation or Pregnancy Human Reproduction II.

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1 1 Menstruation or Pregnancy Human Reproduction II

2 S1-1-09 Describe the structure and function of the male and female reproductive systems. S1-1-10 Outline human development from conception through birth. Vocabulary & People OvulationMenstruationFertilization ZygoteEmbryoFetus

3 Ovulation: Release of ovum from a follicle in the ovary as a response to a hormonal signal (brain - LH). Follicle – cells surrounding the egg inside (becomes corpus luteum) Menstruation: Monthly cycle of changes that occur in the ovaries and uterus - including ovulation. Ovulation occurs around the 13-15 day of cycle The “egg(s)” is also know as an oocyte(s) or an ovum (ova)

4 Endometrium: the inside of the uterus – the part that prepares for the baby – also called endometrial lining Menstruation Ovulation

5 Menstrual Cycle consists for four steps: approximately 28 days before repeating STEP Key HormoneDAY Brain triggers development of a follicle Building up endometrium FSH Estrogen 1 - 13 Follicle releases ova (egg) – ovulation LH 13 - 15 Corpus Luteum forms Endometrium is maintained Progesterone 15 - 21 No fertilization – menstruation Endometrial lining and ova are expelled All hormones at low levels 21 - 28 Notice: two hormones made by the “shell ”– estrogen and progesterone – work to prepare the uterus for a fertilized egg

6 1421 142128 days 071421 Regression Pituitary gland Progesterone Estrogen 28 days FSH LH 07 07 Female Menstrual Cycle Brain Hormone Levels Ovarian Cycle Sex Hormone Levels Endometrial changes Notice: the shedding of the endometrium ends and begins the diagram - it’s a continuous CYCLE

7 Fetal Development

8 Egg and sperm meet in the oviduct - Fertilization. Remember: the sex is determined by the male - X or Y sex chromosome in the sperm Nuclei join to produce a single diploid cell called a zygote Zygote implants into the endometrium and releases hormones to maintain the lining

9 MEIOSIS– MALES 46 Chromosomes DIPLOID 2n HAPLOID 1n xy xxyyxxyy Female spermMale sperm

10 MEIOSIS– FEMALES 46 Chromosomes DIPLOID 2n HAPLOID 1n xx xxxxxxxx Female egg

11 xx x y Female zygoteMale zygote xx x y

12 There are 2 stages of “baby” development:

13 1.Embryo Stage (the first 8 weeks) Zygote implants in endometrial lining and begins to grow (divide) by mitosis. Once implanted – called an embryo Cleavage: the process of mitotic divisions that change zygote into a multicellular embryo. Congrats! You are now officially pregnant

14 2. Fetus Stage (after 8 weeks till birth) Developing embryo forms bone cells around the ninth week of pregnancy. Once bone forms - called a fetus (until born) Placenta - exchanges waste and nutrients through umbilical cord. Amnion – protective sac filled with fluid.

15 Pregnancy can also be divided in 3 trimesters: 1 st trimester – conception to 3 rd month development of all body systems and organs fetus is particularly sensitive to alcohol/drugs sex can be determined 1 st trimester

16 2 nd trimester – 4 th to 6 th months period of rapid and continuous growth Only brain and lungs still developing embryo movements can be felt 2 nd trimester

17 3 rd trimester – 7 th to 9 th (birth) month fetus kicks, stretches and moves freely Eyes sense light, fingerprints have formed At end – fetus weighs 3300 grams, 35 cm long 3 rd trimester

18 And then, before you know it...

19 CAN YOU ANSWER THESE QUESTIONS? S1-1-09: What parts make up the male and female sex systems and what is the function of each part? S1-1-10: How does a fertilized egg turn into a baby and what determines the gender? Vocabulary & People OvulationMenstruationFertilization ZygoteEmbryoFetus

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