Human reproductive system The structure and function of the male and female reproductive systems The role of the placenta in the nutrition of the developing embryo The role of the amniotic fluid in protecting the developing embryo
Human Reproductive Systems embryo Foetus The human reproductive system has evolved to achieve the following: The production of gametes To maximise the probability of fertilisation taking place To allow the development of a foetus until childbirth
Male Reproductive System
StructureFunction TestesWhere sperm are made Vas deferens (sperm duct) Muscular tube, carries sperm towards the urethra Glands Produce liquid that is added to sperm to make semen Urethra A tube that carries sperm through the penis during ejaculation. Also passes urine. Erectile tissue Swells when filled with blood, making the penis erect ScrotumHangs behind the penis and contains the testis Male Reproductive System
Female Reproductive System
StructureFunction Ovary An organ that produces and matures ova (eggs) and also produces sex hormones. Fallopian tube (oviduct) A muscular tube that carries the ovum from the ovary to the uterus. Uterus (womb) The organ where an embryo develops into a foetus (unborn baby) Endometrium (uterus lining) Has a good blood supply for the implantation of an embryo Muscular uterus wallContracts during child birth CervixThe neck of the uterus Vagina Where sperm are deposited during sexual intercourse Female Reproductive System
Sex Hormones During puberty, the body starts releasing sex hormones. Males produce testosterone and females produce oestrogen. Over the course of puberty, it is these hormones that bring about the development of secondary sexual characteristics. Oestrogen is produced in the ovaries Testosterone is produced in the testes
What effects do the sex hormones have? Oestrogen Extra hair on the underarms & pubic area Hips widen Breast development Ovum release and periods start Testosterone Extra hair on face and body Muscles develop more Penis & testicles enlarge Sperm production Deepening of voice
Pregnancy After fertilisation and the creation of an embryo, what happens next? How does a developing foetus receive nutrition and get rid of waste products? How is a developing foetus protected during pregnancy
Pregnancy After fertilisation and the creation of an embryo, what happens next? Implantation – the embryo implants in the wall of the uterus (endometrium) The placenta develops, allowing the foetus to exchange digested food, oxygen & waste The amnion membrane forms. This surrounds the embryo and is full of amniotic fluid, which protects the embryo from jolts and bumps
The Placenta The placenta forms once the embryo implants in the wall of the uterus. It is the ‘interface’ between the mother’s blood and the blood of the foetus. The blood of the foetus circulates to and from the placenta via the umbilical cord, collecting nutrients & oxygen, and getting rid of wastes (e.g. CO 2 ) Warning: the next slide shows a real human placenta after birth Can you think how this works?
The placenta has a very rich blood supply
The Placenta The blood from the foetus flows very close to the mother’s blood as it passes through the chorionic villi, though they never mix. There is a short distance for diffusion so exchange of substances is very efficient.
Amniotic Fluid This is produced by the amnion membrane which encloses the developing foetus. It’s function is to cushion the foetus from knocks and bumps.