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Reproduction. Topics in Reproduction. (Review) : Reproductive organs. What does what? Fertilisation : The science The female menstrual cycle Birth control in males and females: the pros and cons The placenta Breastfeeding . Questions….For us to discuss on Monday….
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Topics in Reproduction • (Review) : Reproductive organs. What does what? • Fertilisation: The science • The female menstrual cycle • Birth control in males and females: the pros and cons • The placenta • Breastfeeding
Questions….For us to discuss on Monday… • What is the future for male contraception – way more than condoms • What are the risks of getting pregnant if you don’t use birth control – on how many days of her cycle can a woman get pregnant? • What preciselydoes drinking alcohol and smoking during pregnancy do to a developing baby? • What are the pros and cons of breastfeeding compared with bottle feeding?
Reproductive organs. What does what? Check the links on the Blog to review anatomy and function!
Asexual reproduction: Binary Fission • animation of binary fission
Asexual Reproduction: Budding Seen in Hydra and other species…
Why go for sexual rather than asexual reproduction? Links to explain… • From the Natural history museum • A simple explanation
The basic vocabulary of sexual reproduction • Gametes (sex cells) are produced by gonads (sex organs – testes and ovaries) • Gametes are produced through meiosis (reduction division – and have the haploid (n) number of chromosomes • Female gametes are eggs (large, stationary) • Male gametes are sperm (small, motile) • Gametes join together at fertilisation to produce a zygote (diploid number of chromosomes, 2n) • After fertilisation, the zygote grows by mitosis, with the full (2n) chromosome set in every cell
Comparing the ovum and the sperm The egg is the largest cell, while the sperm is the smallest in the human body
Male sperm production: produced in the testes under influence of testosterone
Romantic relationships and testosterone… According to wikipedia… • Falling in love decreases testosterone in men but increases it in women • Testosterone ‘returns to normal’ after the honeymoon period • Fatherhood decreases testosterone levels • ‘competition’ affects testosterone levels
Sperm are delicate… • Sensitive to heat • Sensitive to environmental oestrogens (Phyto-oestrogens in plants e.g. SOY, Beer), chemicals • Link - environmental oestrogens 'wreck' sperm...
Female egg production: Produced in the ovaries… • Eggs are produced pre-birth • Eggs are arrested in prophase I of meiosis until puberty • From puberty until the menopause, one egg will be produced each menstrual cycle under hormonal control (oestrogen from the overies, FSH and LH from the pituitary gland) • The egg is the largest cell in the body
Female menstrual cycle • An animated version… • …and a detailed diagram • …and a movie!
Oral contraceptives interfere with the normal menstrual cycle • Pills exploit feedback controls over hormone secretion • They contain combinations of oestrogen and progesterone OR progesterone only • 100% effective if used properly
Combination pill • They contain combinations of oestrogenand progesterone • You take the hormone pills for 7 days, and then sugar pills for 7 days, long enough for menstruation to occur but not long enough for ova to develop • Combination pills can be monophasic, biphasic or triphasic(dose increasing in 1 or 2 stages)
‘Mini pill’ • Low-dose progesterone only – for 28 days • Ovulation occurs • Uterus is not favourable for implantation • Less reliable • Safer for older women, breastfeeding women
Side effects of the pill… • Sore boobs • Mood swings • Headaches • Can affect blood pressure • No protection aginst STI’s
Alternatives to the pill: contraceptive ring • Hormones (oestrogen, progesterone) released into the vagina • Lower doses of hormones are needed • Just as reliable as the pill • Lower hormone doses so more reliable…
Condoms Male Condom – The male condom is the only method of contraception boys can use. It's really just a rubber tube. It's closed at one end like the finger of a glove so that when a boy puts it over his penis it stops the sperm going inside a girl's body
Female Condom Female Condom The female condom is a fairly new barrier method. It is not as widely available as the male condom and it is more expensive
IUD or Coil ‘The IUD’ – which stands for ‘intra-uterine device.’ Most IUDs are T-shaped. They’re made of plastic and copper, sometimes with a little silver inside. They prevent your partner’s sperms from getting through your womb and into your tubes
Diaphragm and cap Diaphragms and caps fit inside the vagina and cover the cervix (entrance to the womb). They are barrier methods of contraception and stop sperm meeting an egg.
Spermicide Spermicides come in several different forms: cream, gel and foam. Most spermicides contain nonoxynol-9, a chemical that kills sperm. Spermicides can be used alone but are more effective when used with another method of birth control, such as a condom or diaphragm.
Implant Contraceptive Implant - The contraceptive implant is a small, flexible tube that's inserted under the skin in the upper arm. It slowly releases a hormone called progestogen and works for three years.
Injection Contraceptive Injection The contraceptive injection contains a hormone called progestogen and is a long-term method of contraception. It's injected into a muscle and the hormone is released very slowly into the body.
Placenta • Baby is called a foetusfrom 8 w, when embryo has all of its major structures • Developing baby is totally dependent on mother for nutrients, oxygen and elimination of wastes • The placentais the specialised organ that performs this role • Placenta also produces hormones to help maintain pregnancy • placenta is joined to foetus by the umbilical cord
Structure of the placenta • Note that foetal blood and maternal blood do not mix • Oxygen and nutrients from the mother diffuse into the capillaries of the chorionic villae • Carbon dioxide and other wastes leave the foetus through the umbilical arteries, pass into the capillaries of the villi and out into the maternal blood
What does the placenta deliver to the baby? • Vitamins • Oxygen • Triglycerides • Hormones • Minerals • Protein • Water • Drugs What does the placenta remove from the baby? • Carbon dioxide • Waste products of metabolism • Water • Urea
Figure 5 A microscope photograph of a cross-section of one of the smallest branches (called a villus) of a tree-like placental cotyledon at term. Mother’s red blood cells surround the villus, while the baby’s red blood cells are inside large capillaries within the villus. The blood of the mother and the blood of the baby are everywhere separated by the syncytial trophoblast, which is a seamless layer comprising a single cell.
