Unit5 reproductionandsexuality


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Unit5 reproductionandsexuality

  1. 1. INDEX 1. The Reproductive Process in Human Beings 2. The Male Reproductive System 3. The Female Reproductive System 4. The Ovarian and Menstrual Cycle 5. Fertilisation, gestation and birth 6. Assisted reproduction 7. Contraception 8. Sexually transmitted diseases
  2. 2. Type of reproduction Gonads (sexual organs) Gametes (sexual cells) Male sexual Testicles Spermatozoon/ sperm cell Female Ovaries Ovum / egg 1. The Reproductive Process in Human Beings
  3. 3. Formation of gametes Embryonic development (pregnancy)  embryo and foetus Birth
  4. 4. Sexual characteristics: • Primary sexual characteristics  characteristics present at birth (female/male genitalia) • Secondary sexual characteristics  characteristics which appear with maturity. These changes occur at a very specific age, called puberty.
  5. 5. Reproductive life in humans In humans, reproductive and sexual life start during puberty. A. Puberty Puberty starts when boys start to produce sperm and become capable of ejaculation, and when girls have their first period. Both of them take place as a result of increased levels of pituitary hormones (FSH and LH) which stimulate gamete production. http://www.cyh.com/HealthTopics/HealthTopicDetailsKids.aspx?p=335&np=289&id=1774  more information
  6. 6. Changes during puberty in girls • the genitals get bigger • breasts develop and the hips get wider • hair grows on the pubis and under the arms • the sebaceous glands start to secrete more sebum • menarche (first period) • the amount of body fat increases
  7. 7. Changes during puberty in boys • the genitals get bigger • the shoulders widen and the pelvis narrows • body hear starts to grow • the larynx and vocal cords grow, resulting in a lower voice • the sebaceous glands start to secrete more sebum • muscle mass increases
  8. 8. Some Mental Changes During Puberty • Boys and girls start to want more freedom and independence • They feel more self-sufficient • They feel that most people around them do not understand them •They want to belong to a group of people of their own age • Their behaviour changes quickly from passiveness and a lack of interest to non- conformism, rebellion and even violence. It can result in communication problems both at home and at school.
  9. 9. B. The end of reproductive life Men produce sperm throughout almost their whole life, although the quantity and quality of these gametes decrease gradually after 50 years of age. It is caused by a decrease in testosterone levels and it is called andropause. Women are born with all of the immature eggs that they will ever have. However, they stop ovulating, and therefore menstruating at a certain point in life (between 45-50 years of age). It is caused by a decrease in estrogens and progesterone levels. It is called menopause.
  10. 10. 2. The Male Reproductive System Cowper’s glands
  11. 11.  Parts of the male reproductive system  Testicles  Located outside the abdominal cavity, inside a skin sac called scrotum. Testicles contain many seminiferous tubules (containing the cells which produce sperm) and cells producing male sex hormones.  Cowper’s glands: secrete a lubricant that facilitates sexual intercourse.  Other glands  they produce susbstances that mix with sperm to produce a fluid called semen: • Seminal vesicles: they produce nutrients for the sperm cells • Prostate: secretes substances that protect sperm Cowper’s glands
  12. 12.  Reproductive ducts: • Epididymis  tubules where sperm matures • Vas deferens  it conects epididymis with urethra • Urethra  it carries the semen outside of the body. Common duct to the excretor system  Penis: Organ that men use to deposit semen inside a woman’s body during sexual intercourse. It contains two spongy masses of erectile tissue. The penis ends at the glans (glande), surrounded by some skin called prepuce (prepucio)
  13. 13. 3. Female reproductive system
  14. 14.  Parts of the female reproductive system The ovaries  They are found in the abdominal cavity. Inside them, each month an ovum matures and is then released. They also produce female sex hormones.
  15. 15.  Reproductive ducts: • Fallopian tubes: They collect the mature eggs released by the ovaries. Fertilisation normally takes place here. • Uterus or womb: Gestation occurs here. The wall of the uterus has a thick muscular layer (the myometrium) lined with a mucous membrane (endometrium). • Vagina: Elastic tract which conects the uterum with the outside. Semen is deposited in the vagina during sexual intercourse. To both side of the vagina are the Bartholin glands, which produce lubricants. • Vulva: External female sex organ, made of labia minora, labia majora and the clitoris (a small, especially sensitive protuberance).
  16. 16. 4. The ovarian and menstrual cycle  The ovarian cycle After puberty, oogenesis takes place regularly in women, approximately every 28 days. One egg cell matures and is then released. Phases: 1. Follicular phase  FSH (follicle stimulating hormone) stimulates the development of one follicle in the ovary. It lasts around 14 days. 2. Ovulation  LH (luteinising hormone) stimulates the release of an egg by the ovary. The body temperature increases. 3. Luteal phase  Once the egg has been released, the corresponding area in the ovary transforms into the corpus luteum, which secretes progesterone. After 10-12 days, the corpus luteum decays, initiation the start of a new cycle.
  17. 17.  The menstrual cycle It is a series of periodical changes that occur in women’s sex organs. It prepares the uterus for the implantaion of an embryo. However, the cycle happens even if an egg has not been fertilised. Phases: 1. Proliferative phase  the endometrium is built up. It lasts around 11 days. 2. Luteal phase  the endometrium reaches its maximum thickness and prepares to receive and give nutrients to an embryo. It last around 12 days. If there is an embryo, the luteal phase continues. 3. Menstruation (or period) Only happens when there is no embryo. The endometrium comes off, and is then expelled from the body along with some blood. A period usually lasts 4-5 days.
  18. 18. The menstrual cycle and the ovarian cycle are controlled by hormones, which are produced by the adenohypophysys (FSH and LH) and by the ovaries (estrogen and progesterone)
  19. 19. Menstrual cycle and ovary cycle
  20. 20. Most fertile days Menstruation
  21. 21. The body basal temperature also changes slightly during these cycles Activities 1, 2, 3 and 4 page 119
  22. 22. 5. Fertilisation, gestation and birth
  23. 23. 5.1 Fertilisation It takes places inside the female reproductive system, usually in the Fallopian tubes. The spermatozoids are introduced into the vagina during coitus, when ejaculation occurs. Spermatozoa only live for 5 days and an ovum only lives for 48 hours. If a spermatozoid finds an ovum: 1. The spermatozoid secretes a substance that breaks down the ovum’s outer membrane. 2. The two gametes recognise each other. 3. The sperm enters the ovum. 4. The nuclei of the two gametes join together. This is the fertilisation. The new cell formed is called zygote. 5. A barrier around the zygote is formed, preventing the access of any other sperm.
  24. 24. The genetic information in the 23 paternal chromosomes transported by the spermatozoid is mixed with the maternal genetic information contained in the 23 chromosomes transported by the ovum. This new cell is the zygote, which contains 46 cromosomes. After 24 hours this cell starts dividing, and it is called embryo. zygote embryo
  25. 25. 5.2 Pregnancy (human gestation) It is the period of time between fertilisation and birth. It lasts around 9 months.
  26. 26. The zygote divides many times during its way to the uterus. The structure is known as the embryo, which becomes implanted in the uterus in 7 days after fertilisation.
  27. 27. About 2 - 3 months after fertilisation, the embryo becomes a foetus. A foetus looks like a baby. It continues growing and developing in the uterus until birth. The embryo and the foetus develop inside a membrane called amnion, which is submerged in a liquid called amniotic fluid. foetus
  28. 28. The foetus receives the nutrition it needs via the placenta, an organ that develops around the 60th day of gestation. It is connected to the foetus through the umbilical cord. Placenta
  30. 30. 5.3 Labour and birth In the eighth month of pregnancy, the foetus turns around in the uterus so that the head is pointing downwards. The baby is ready to be born in the nineth month of gestation. The labour takes place in three phases:  Dilation of the uterine neck: 3-12 hours. The cervix dilates and and there are contractions, which cause the rupture of the bag of amniotic fluid. The uterine neck or cervix is the part of the female reproductive system that lies between the body uterus and vagina
  31. 31.  Expulsion of the foetus: The contractions of the walls of the uterus push The foetus along the vagina to the exterior. The foetus comes out head first.  Expulsion of the placenta: After the baby is born and the umbilical cord is cut, the uterus undergoes further contractions to expel the placenta.
  32. 32. BIRTH STAG ES Activities 4 and 5 page 121
  33. 33. 6. Assisted reproduction Infertility refers to the inability to have children using natural methods. It can occur in both men and women, and there are many different causes. Examples:  Low sperm count  Sperm incompatible with cervical mucus  Problems with ovulation  Uterine abnormalities which avoid implantation Methods Artificial insemination: artificial introduction of the semen in the uterus In vitro fertilisation: to get egg from the woman and fertilise them outside her body. Then, the embryos are implanted in the uterus.
  36. 36. 7. Contraception Contraceptive methods can be used by couples who want to have sexual intercourse without the woman becoming pregnant.  Natural methods: • Rhythm method or Ogino-Knaus method: It consists of observing the woman’s menstrual cycle for several months and calculating the days when ovulation is likely to take place. Intercourse can then be avoided during that time. It is not a safe method because it is difficult to calculate the exact moment of the ovulation and it does not protect against STDs.
  37. 37. • Coitus interruptus: During sexual intercourse, the man take his penis out of the woman’s vagina just before he ejaculates. Not reliable method because previouse secretions can contain sperm.  Barrier methods: • Condoms, diaphragm and intrauterine device: they prevent sperm from reaching the egg. - Condom: Thin covering made of latex, that is rolled over an erect penis . Very effective (90-98%). It protects against STDs.
  38. 38. -Diaphragm: latex dome which forms a barrier to stop sperm from reaching the cervix. It is always used with spermicidal cream. It does not avoid STDs. -Intrauterine device (DIU): small, plastic, T-shaped device that is inserted into the uterus by a doctor. It can stay there for years. It does not protect against STDs.
  39. 39.  Chemical methods: they contain hormones. • Emergency contraceptive pills or morning-after pill: It can avoid the pregnancy after a sexual intercourse without protection, avoiding the implantation of a possible embryo. It is only an emergency method because it contains high levels of hormones and it does not protect against STDs. • Contraceptive pill: It avoids ovulation, but allowing menstruation. High effectiveness. Doctor prescription necessary. It does not protect against STDs.
  40. 40.  Surgical methods: Surgeries that are used to permanently prevent fertilisation. • Tubal ligation (for women): Fallopian tubes are cut, in order to avoid eggs go through. • Vasectomy (for men): Vas deferens are cut, so that the semen does not contain sperm.
  41. 41. 8. Sexually transmitted diseases (STDs) They are diseases that can be transmitted by sexual contact. They can be caused by viruses, bacteria, funghi or protozoa. Some of them can be transmitted to the baby of a pregnant woman through the placenta or during the labour. - Syphilis (bacteria) - Gonorrhoea (bacteria) - Candidiasis - Genital herpes (virus) - Hepatitis B (virus) - HIV (Human Immunodeficiency Virus) - HPV (Human Papilloma Virus)
  42. 42. STD Microorganism Main Symptoms Syphilis Bacteria Ulcers on the genitalia, called chancres. It affects to the nervous system. Gonorrhoea Bacteria Painful urination and inflammation of the genitalia. Candidiasis Fungus Irritation of the vagina an inflammation of the glans. Genital herpes Virus Sores on the genitals and anus. Hepatitis B Virus Inflammation of the liver. AIDS HIV virus Serious weakening of the immune system. Human Papilloma Virus Virus It could cause cervix cancer. chancres Neisseria gonorrheae