Reproduction in Humans (part 1): Human Reproductive System

1. Reproduction in Humans Chapter 21 Content • Sexual Reproduction in Humans • Sexually Transmitted Diseases

2. Why Biology lessons are interesting… The 10th grade teacher asks Jessica: "What part of the human body increases to 10 times it's normal size when excited?" Jessica responds: "That's disgusting! I don't have to answer that question!" So the teacher asks little Johnny, who responds: "That's easy...the pupil of the eye." "That's correct, Johnny. Very good!" And turning to Jessica, she says: "I've three things to say to you, young lady... first, you didn't do your homework; second, you have a dirty mind; and third, you're in for a big disappointment!"

3. Overview Sexual reproduction - the process where two cells (gametes) fuse to form one fertilized cell or zygote 2 types of reproduction Asexual reproduction - any type of reproduction not involving the union of gametes

4. Animal Reproduction Budding: reproduction Asexual Reproduction Fission: regeneration & reproduction Haploid eggs develop into adults without fertilization e.g. male honeybees Parthenogenesis:

5. Animal Reproduction • Sexual Reproduction • Union of egg and sperm • Fertilization 1) External • Spawning - a reproductive strategy where eggs and sperm are released into the water, where fertilization takes place 2) Internal • copulation • Dioecious versus Monoecious organisms • Separate sexes • hermaphrodites - animals or plants having both male and female reproductive organs - The act of mating for reproduction - having male and female reproductive organs in separate plants or animals

6. Gametes involved in sexual reproduction: 1. Sperm 2. Egg (Ovum)

7. Male and female gametes • Produced by gonads Male gonad Female gonad ovaries testes meiosis sperm ova (plural) ovum (singular)

8. Question: 1. How many chromosomes does a human have? 23 pairs of chromosomes (diploid, 2n) 2. So if that is the case how many chromosomes does the gametes contain? 23 chromosomes each (haploid, n) 3. Is the number of chromosomes the same for all living organisms? NO!!!

9. Sperm production 23 chromosomes haploid (n) 23 chromosomes haploid (n) 46 chromosomes diploid (2n) 23 chromosomes haploid (n) 23 chromosomes haploid (n) Definition of gamete: A reproductive cell containing the haploid number of chromosomes

10. Sperm Anatomy 2. 3. 4. 1. 5.

11. Sperm Anatomy - carries haploid number of chromosomes - provides energy for sperm activity - sac containing enzymes that break down egg membrane so that sperm can penetrate during fertilization - enables sperm to swim towards egg

13. Anatomy of ovary and follicle - eggs/ova develop within ovaries of mature female - only about 500 mature ova mature from 70 000 potential cells present at birth - released from puberty to menopause - usually one egg is released every month - the ovaries take turns to release eggs

14. Production of Eggs 23 chromosomes haploid (n) 46 chromosomes diploid (2n) Variations in the gametes, together with random fertilization produce variations in the offspring

15. Summary sperm (n) + Cells in gonads of male and female parents Fertilization egg (n) zygote (2n) (undergoes mitosis to form the embryo)

17. The Human Reproductive System

18. The Male Reproductive System 3. Urinary bladder Pubic bone Vas deferens 4. Urethra Penis 1. Seminal vesicle Large intestine 2. Prostate gland Rectum Scrotum Cowper’s gland Epididymis Testis

19. Parts of the Male Reproductive System 1. 7. 2. 3. 8. 4. 9. 5. 10. 6. 11. 12.

20. Function of structures 3. Urinary bladder Pubic bone Vas deferens (sperm duct) 4. Urethra - tube through which semen and urine pass out of the body - erectile organ Penis 1. Seminal vesicle Large intestine - contain erectile tissue with numerous blood spaces of the at the same time - the sphincter muscle prevents urine from coming out of the bladder during 2. - they do not pass out Prostate gland Rectum Scrotum - outside main body cavity → sperm development requires a temperature lower than that of the body and hard ejaculation Cowper’s gland Epididymis - temporarily stores inactive sperms before ejaculation - secretes semen - when blood spaces filled with blood, penis becomes erect Testis - produces sperms [mixture of fluid (containing nutrients and enzymes → nourish & activate sperms) + sperms] - produces testosterone

21. The Female Reproductive System Fallopian tube Fallopian tube Ovary 1. Urinary bladder Pubic bone Ovary 4. Uterus 2. Urethra Cervix 3. Vagina Rectum Vagina

22. 3. (womb) 4. (oviducts) 5. Ovary 5. 2. 1.

23. - this is where the baby develops during pregnancy - has muscular walls (womb) - inner lining (endometrium) is soft and smooth (oviducts) - part of this is sloughed off every month during menstruation - narrow, muscular tube - leads from ovary to uterus Ovary -eggs (ova) develop inside the ovaries of a mature female - the egg is fertilized here - only one egg released every month from puberty to menopause - circular ring of muscle - birth canal - it enlarges to allow passage of the fetus during birth - opening called vulva - ovaries take turns to release an egg - semen deposited here during intercourse

24. Ovum • Spherical • ~120 µm wide • Has a large nucleus containing one haploid set of chromosomes • Has abundant cytoplasm which may contain a small amt of yolk • Is surrounded by a cell surface membrane. The cell surface membrane is surrounded by an outer membrane

25. Puberty

26. Puberty • Stage of human growth and development in which a person becomes physically mature • Reproductive system begins to function properly • Onset of puberty for girls at age ~11 • Onset of puberty for boys at age ~14

27. Secondary sexual characteristics • Brought about by sex hormones • Female sex hormones → oestrogen + progesterone • Male sex hormone → testosterone