1. Human Reproduction

2. Humans, like many living things, reproduce by Sexual Reproduction.
This is when 2 organisms combine their genetic information to make a new organism
This method involves meiosis
This is different from Asexual Reproduction
When a single organism uses its genetic information to make an offspring
This does not involve meiosis
Human Reproduction

3. In order to sexually reproduce, we need meiosis as it makes gametes.
Male gametes are sperm
Female gametes are ovum or eggs
In humans, gametes are made in the gonads.
Male gonads are the testes
Female gonads are the ovaries
Human Reproduction

4. Gametogenesis So how do these gametes form?
It all happens through meiosis within the gonads.
This process is called gametogenesis
Spermatogenesis in men
Oogenesis in women
Gametogenesis

5. In order to understand how sperm are made, we need to understand a little about male anatomy.
I apologize for the awkwardness of the next slide…
Spermatogenesis

6. Male Anatomy

7. The Male Reproductive System
Penis – the male reproductive organ.
Urethra – The tube that carries urine and semen out of the penis
Testicle – where sperm are produced.
Epididymis – where sperm mature and are stored
Vas Deferens – tube that carries mature sperm to the urethra
Prostate Gland – creates a fluid that is added to sperm to make semen. Acts as a valve that allows semen to pass through.
Seminal Vesicle – add a fluid to sperm to make semen. Fluid is a nutrient and aids in motility.

8. Testes The testes are the site of spermatogenesis
They are housed within the scrotum, a sack made of skin that keeps the testes cool.
This is because spermatogenesis works best at a temperature slightly lower than body temperature
Testes

9. Semen Sperm mature in the epididymis
At the time of ejaculation, the sperm exit the body
Ejaculation – when the prostate gland allows sperm to exit through the urethra
During ejaculation, the sperm mix with liquids from the prostate gland and the seminal vesicle
This liquid is called semen
Semen – a liquid with nutrients that helps lubricate the sperm and provide them with energy as they travel
Semen

10. Female Reproductive System
Now that we understand the male reproductive system, let’s take a look at the female reproductive system.
Female Reproductive System

11. The Female Reproductive System

12. Fallopian Tubes – Transport the egg from the ovary to the uterus
Fallopian Tubes – Transport the egg from the ovary to the uterus. Where egg is fertilized
Ovaries – Female organ that produces eggs
Uterus – Accepts the fertilized egg. Where the embryo develops. Strong muscular walls help push child out during childbirth
Cervix – directs sperm during sexual intercourse. Allows flow of endometrium during menstruation by opening slightly
Vagina –The vagina is a muscular, hollow tube that extends from the vaginal opening to the cervix

13. Oogenesis Oogenesis is meiosis in the female body
It creates 1 egg cell and 3 polar bodies (non-useful cells)
This takes place in the ovaries
Oogenesis begins a cycle in the female body to prepare it for fertilization
This process is called the Menstrual Cycle
Oogenesis

14. Meiosis in the Gonads

15. Before reproduction happens, the female body prepares in case of fertilization
This process of the body preparing itself is called the Menstrual Cycle
It is a regular cycle that typically lasts 28 days in most human women.
The Menstrual Cycle

16. Menstrual Cycle Stage 1 – Menstruation –
During this time, the ovaries are undergoing the first stages of oogenesis.
The inner lining of the uterus called the endometrium starts to break down
This causes some bleeding to occur as the endometrium is shed
This lining and blood is removed from the body via the vagina.
Menstruation typically lasts about 4 days
Menstrual Cycle

17. Menstrual Cycle Stage 2 – Follicular Phase
The next step in the menstrual cycle is the endometrium starts to rebuild and thicken
The egg now begins to grow and develop slightly larger
The egg could be fertilized at this stage
This stage usually lasts another 8-9 days
Menstrual Cycle

18. Menstrual Cycle Stage 3 – Ovulation The egg is released from the ovary
At this time, the egg will travel through the fallopian tube heading toward the uterus
This is the time that the egg is most likely to be fertilized
This stage only lasts about 2-3 days as the egg will disintegrate after that
Menstrual Cycle

19. Menstrual Cycle Stage 4 – Luteal Stage
The endometrium has reached its full size
The spot in the ovary where the egg was released begins to release hormones
This causes the body to be prepared in case of fertilization
If there was no fertilization, the body goes through the menstrual phase again and the cycle repeats
This process lasts about days
Menstrual Cycle

20. All of these processes lead to the process of sexual reproduction
Every organism that participates in sexual reproduction on Earth strives to pass on its genes. Some go to extended lengths such as fights to the death, ornamental displays, special calls, pheromones, and much much more.
It is the process striving to reproduce that can push evolution in a variety of directions.
Reproduction

21. Reproduction in humans is carried out by the male and female sex organs – the penis and the vagina
The male inserts the penis into the vagina. This process is called sexual intercourse
At the end of intercourse, the male ejaculates
This causes the semen to be released into the vagina
Human Reproduction

22. The semen provides lubrication and nutrients to the sperm as they make a long trek
Sperm pass:
Through the vagina
Past the cervix
Through the uterus
Into the fallopian tubes
Sperm travel at about 50μm/s
Human Reproduction

23. About 300 million sperm make the journey to the fallopian tube where only 1 is allowed to penetrate the egg
The sperm and egg fuse into one cell called a zygote
This causes the cell to change the ‘polarization’ of the membrane which pushes other sperm away from the egg.
The zygote then gets a hard membrane that does not allow any more sperm to penetrate
Human Reproduction

24. The zygote finishes traveling down the fallopian tube and implants in the uterus
The zygote now begins to grow through
mitosis
Where the zygote implants, the uterus creates a connection called the placenta
This is where the mother’s blood will exchange oxygen and nutrients with the embryo
Zygote

25. The first stage of development in the uterus is the Embryonic stage
This lasts about 9 weeks
During this time:
The cells specialize and differentiate into different types of cells
The organs begin to develop
This is the time that the new individual is most vulnerable to deformities
Embryonic Stage

26. Fetal Stage The fetal stage lasts about 30-31 weeks
Most of structures of the body have formed already
The internal structures such as organs and systems finish developing
At the time of birth, the fetus is ready to survive on its own.
Fetal Stage

27. After 9 months in the uterus, the fetus is ready to survive outside the mother’s body
The cervix with open (dilate) and through muscle action in the uterus, the baby will be pushed out
The baby typically comes out head first
Birth