life cycle of humans infant (baby) sex cells gametes child adult adolescent (teenager)

Puberty The time when an individual changes from a child to a mature adult. Puberty starts when the girls are about 11 years old and the boys are about 13 years old. The puberty brings physical and emotional changes in both sexes. Physical changes that happen to both: sex hormones are released into blood, growth spurt (growing tall in short period of time). pubic hair grows, armpit hair grows Physical changes that happen to boys only: penis grows bigger, sperm production starts, shoulders broaden, muscles grow stronger, voice breaks, facial and chest hair grows, Physical changes that happen to girls only: breast develop, hips widen, menstruation starts once a month (bleeding period), mature egg is released from ovary once a month

sperm cell egg cell (ovum) jelly coat nucleus Cytoplasm contains a store of food and energy sperm cell egg cell (ovum)

1st phase: day 1-7. Menstruation-the old lining in the uterus (womb) breaks down and comes out of the vagina with blood 2nd phase: day 8-13. The new lining builds up in the uterus and one egg matures in one of the ovaries 3rd phase: day 14. Ovulation- mature egg cell goes from the ovary to the oviduct (egg tube). 4th phase: day 15-28. The lining of the uterus stays thick and waits for the fertilized egg.

male reproductive system

ejaculation – semen comes out of the penis in the top of the vagina

fertilisation – when egg and sperm join together implantation – when embryo sinks into the lining of the uterus

embryo embryo fetus fetus 5 weeks old, 5 mm long, heart pumps blood few hours after fertilization size of a pinhead fetus 10 weeks old 4 cm long, full set of organs fetus 15 weeks old mother can feel its movement

placenta amnion umbilical cord amniotic fluid baby (foetus) womb (uterus) cervix

Pregnancy – gestation period Baby develops for about 40 weeks (9 months). This is known as gestation period. The time when baby is born is called a labour. It has the following stages: The uterus starts to contract (squeeze). The contractions become stronger as the labour progresses. The cervix of the uterus widens (opens up). The amnion breaks (sack that surrounds the baby) and amniotic fluid rushes out of vagina. This is known as water breaks. Baby is born head first through vagina The umbilical cord is cut. What remains of it forms navel (belly button) Half an hour later the placenta comes out of the vagina. This is known as afterbirth.