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Menstruation or PregnancyHuman Reproduction II

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 Ovulation Menstruation FertilizationZygote Embryo Fetus

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)

Endometrium: the inside of the uterus

– the part that prepares for the

baby – also called endometrial lining

Menstruation

Ovulation

Menstrual Cycle consists for four steps:approximately 28 days before repeating

STEP Key Hormone DAY

• 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

14 21

14 21 28 days

0 7 14 21

Regression

Pituitarygland

Progesterone

Estrogen

28 days

28 days

FSH FSH

LH

0 7

0 7

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

Fetal Development

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

MEIOSIS– MALES

46 ChromosomesDIPLOID 2n

HAPLOID 1n

x y

xx yyxx yy

Female sperm Male sperm

MEIOSIS– FEMALES

46 ChromosomesDIPLOID 2n

HAPLOID 1n

x x

xx xxxx xx

Female egg

x xx

y

Female zygote Male zygote

x xx

y

There are 2 stages of “baby” development:

1. Embryo Stage (the first 8 weeks)Zygote implants in endometrial lining and begins togrow (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

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.

Pregnancy can also be divided in 3 trimesters:

1st trimester – conception to 3rd month• development of all body systems and organs• fetus is particularly sensitive to alcohol/drugs• sex can be determined

1st trimester

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

2nd trimester

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

3rd trimester

And then, before you know it...

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 Ovulation Menstruation FertilizationZygote Embryo Fetus