Reproduction

IS2

Sexual Reproduction

• Egg = female sex cell• Sperm = male sex cell• Sperm joins the egg = fertilization• Fertilized egg = zygote• Zygote divides many times to form the embryo and then the fetus• Cells contain nucleus where DNA is• DNA makes up chromosomes = contain all information the cell

needs to work / determine your characteristics• Humans should have 46 chromosomes• Some people have more or less than this. Example: Down Syndrome = 47 chromosomes

Male Reproductive System• Produces sperm• Produces testosterone = controls the

development of secondary sexual characteristics and the production of sperm

• Testes = many tubes where sperm cells are produced

• Located in scrotum = lower temperature allow sperm to develop

• Sperm production starts in teenage years• Sperm travel with semen (fluid

containing nutrients)• Path: testes → vas deferens → urethra

(penis) • Remember: urethra = common pathway

for urine AND semen

Female Reproductive System• Produces eggs• Nourishes a baby until birth• Ovaries = produce eggs (only 1

matures every month)• Also produce estrogen = controls the

development of secondary sexual characteristics and helps prepare the uterus for the baby

• Path: ovary → fallopian tube → uterus

• Uterus = muscular organ where embryo develops into a baby

• If the egg is not fertilized = it gets destroyed and leaves the body (along with the lining of the uterus) through the cervix and then the vagina

Menstrual Cycle• Every girl is born with about 400,000

undeveloped eggs in the ovaries• Only about 500 will become mature

and leave (normally one per month)• Monthly cycle = egg develops + uterus

prepares for the embryo• Normally takes about 28 days (could

be more or less)• Ovulation = when the egg is released

from ovary• Menstruation = lining of uterus +

undeveloped egg leave the body through vagina

• Hormones control this process

Human embryo at 5-6 weeks