Natural Sciences Grade 7 Term 1: Live and Living Sexual Reproduction in Humans (Part 3) (PPT 7)

Topic 3 Sexual Reproduction Fertilisation, pregnancy and menstruation Natural Sciences – Grade 7

Fertilisation Fertilisation happens when a sperm joins with an egg. During sexual intercourse, millions of tiny sperms are released in the semen from the penis into the vagina. The sperms swim up the uterus towards the egg cell. When the ovum (egg cell) and one sperm join, it is called fertilisation. Refer to illustrations on the next 2 slides. Sexual intercourse is also known as “sex” for short. The male’s penis becomes stiff and erect to enter the female’s vagina. Only one sperm is required to fertilise the ovum. Natural Sciences - Grade 7 Natural Sciences - Grade 7 Natural Sciences - Grade 7

Fertilisation in humans 1: Semen (containing sperm) enters the uterus. Natural Sciences - Grade 7 Natural Sciences - Grade 7 Natural Sciences - Grade 7

Fertilisation Natural Sciences - Grade 7 Natural Sciences - Grade 7

How the uterus prepares for a fertilized egg The female’s body produces an egg and prepares to reproduce once per month. If fertilisation does not take place, the thick blood-rich layer in the uterus breaks down and the female bleeds through her vagina. This is called menstruation. This is how the woman’s body clears all the preparations and starts the cycle with a new egg. This is called the menstrual cycle. Natural Sciences - Grade 7 Natural Sciences - Grade 7 Natural Sciences - Grade 7

Menstruation This is when the blood and tissue of the lining of the uterus is lost from the woman’s body and comes out through her vagina. The bleeding may last for 4 to 5 days. Females have a menstrual cycle from puberty until about age 50. The average menstrual cycle is 28 days, that means, the woman will start bleeding every 28 days. All women are different, so their cycles are different too. Menstruation is also known as a period. Explain the cycle by means of the illustration on the next slide. Natural Sciences - Grade 7 Natural Sciences - Grade 7 Natural Sciences - Grade 7

The stages of the menstrual cycle Just before and during a woman’s period, she might feel a bit moody. She sometimes also experiences pain in her stomach and breasts. Natural Sciences - Grade 7 Natural Sciences - Grade 7 Natural Sciences - Grade 7

Pregnancy If fertilisation takes place, the fertilised egg is implanted into the blood-rich lining of the uterus. The female is now pregnant. The woman’s period stops during pregnancy. It takes 39 weeks for the fertilised egg to develop into the baby. For the first 9 weeks in the uterus, the baby is known as an embryo. After 9 weeks in the uterus, the baby is called a foetus. Just before and during a woman’s period, she might feel a bit moody. She sometimes also experiences pain in her stomach and breasts. Natural Sciences - Grade 7 Natural Sciences - Grade 7 Natural Sciences - Grade 7

Development of baby during pregnancy Natural Sciences - Grade 7 Natural Sciences - Grade 7 Natural Sciences - Grade 7