Formation And Development Of The Fetus

Question 1

Sexual intercourse

Answer 1

Insertig an erected penis into the vagina

Question 2

Penis when stimulated

Answer 2

Spongy tissue in the penis fills with blood and becomes erect
Semen is ejaculated from the penis into the neck of the vagina
Muscles in the wall of the perm ducts help to propel the semen forwards

Question 3

Sperm enters

Answer 3

Using their tails the sperm swim from the vagina through the cervix and uterus into an oviduct

Question 4

Fertilisation

Answer 4

May occur if there is an ovum passing down the oviduct
- a single speed penetrates the membrane of the ovum by secreting a protease enzyme
The speed nucleus fuses with the egg nucleus to form a zygote

Question 5

Zygote

Answer 5

A single cell formed as the result of the fusion of two gametes

Question 6

After fertilisation

Answer 6

Zygote starts to divide by mitosis to form a ball of cells (blastula)
It continues to move down the oviduct until it reaches the uterus

Question 7

Implantation

Answer 7

Occurs when the blastula embeds in the lining of the uterus

Question 8

Development of the foetus

Answer 8

The blastula develops into an embryo and some of the cells for a placenta, linking the embryo with the uterus lining

Question 9

Growth of the fetus

Answer 9

Organs such as the heart develop and after 8 weeks the embryo is a foetus

• good supply of nutrients and oxygen
• this is achieved through the link between the placenta and the mother’s blood supply in the uterus lining

Question 10

The placenta

Answer 10

Brings the blood supply of the foetus close to that of the mother, but prevents it from mixing

• this is important as baby and mother may have different blood groups
• any mixing could be result in blood clotting = which could be fatal