HUMAN LIFE CYCLE
STAGES OF LIFE
WHY DO WE LOOK LIKE OUR PARENTS?
A baby is produced when sex cells from an adult male (sperm) and female (ovum) come together during sexual reproduction and develop.
All cells contain genetic information or genes that allow characteristics, like eye colour to be passed from parents to children.
We receive half of our genes from the male and the other half from the female sex cells.
FECUNDATION CAN BE NATURAL OR IN VITRO:
NATURAL FECUNDATION
IN VITRO FECUNDATION:
DIFFERENCES BETWEEN IDENTICAL AND FRATERNAL TWINS
BOYS' CHANGES IN PUBERTY
Between the age of 10 and 16, boys and girls can experience changes during puberty.
In boys the puberty starts when the brain secretes a hormone called testosterone. This causes many physical changes:
- Oily skin-Acne - Grow taller
- Pubic hair and armpit hair grow - Deeper voice
- Scrotum and penis grow larger - Semen is produced
MALE REPRODUCTIVE ORGANS
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GIRLS' CHANGES IN PUBERTY
Puberty in girls develop when the brain secretes a hormone which tells the ovaries to start producing two hormones: oestrogen and progesterone . This make that the body syffers some changes:
- Menstruation begins
-Armpit and pubic hair grow
- Oily skin - Acne
- Grow taller
- Breasts and mammary glands develop
FEMALE REPRODUCTIVE ORGANS
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MENSTRUATION
PREGNANCY
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