Reproduction
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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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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…

  • 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!


Female reproductive tract


Male reproductive tract


Asexual reproduction: Binary Fission

  • animation of binary fission


Asexual Reproduction: Budding

Seen in Hydra and other species…


Asexual reproduction: fungal spores…


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


Fertilisation and embryonic growth


Male sperm production: produced in the testes under influence of testosterone


Testosterone effects


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!


Hormones of the menstrual cycle


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 for women: contraceptive patch


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…


Other methods of contraception: Barrier methods


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.


Natural methods of contraception


Natural methods of contraception: Basal body temperature


Pregnancy!


Hormones: What happens during pregnancy?


Development of the baby


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.


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