Biology

1. Pregnancy

1.1. When the egg and sperm fuse (fertilisation) the resulting zygote begins to divide by mitosis and becomes an embryo

1.2. The embryo quickly develops a placenta, which brings the mother’s blood supply very close to the foetus’ blood supply.

1.3. The placenta is adapted for diffusion in much the same way as other exchange organs

2. Reproductive Hormones

2.1. During puberty boys make testosterone in their testes and girls make oestrogen in their ovaries

2.1.1. tetosterone

2.1.1.1. - Causes testes to drop & penis to enlarge - Triggers spermatogenesis - Causes growth of pubic and body hair - Causes larynx to enlarge - Causes muscles to grow

2.1.2. Oestrogen

2.1.2.1. - Triggers menstruation to begin - Causes maturation of vagina - Causes breasts to grow - Causes growth of pubic and body hair - Causes hips to widen

3. Kidney

3.1. Function: to filter blood, removing urea and excess H2O, reabsorbing glucose, some H2O and some mineral salts.

3.2. The final liquid produced by the kidneys is a solution of urea and salts in water.

3.3. This is a link of a video of the kidney: https://www.youtube.com/watch?v=vNvZaGcLzEo

4. Excretion

4.1. the removal of waste products of metabolism from living organisms

4.1.1. Excretion in Humans: Humans have 3 main excretory organs

4.1.1.1. Lungs – excrete CO2 and H2O

4.1.1.2. Skin – excretes H2O

4.1.1.3. Kidneys – excrete H2O, urea, excess minerals and other wastes.