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CfE Higher Human Biology. Unit 2: Physiology and Health. Chapter 11 – Controlling Fertility. Learning Intentions. By the end of this lesson, I will be able to: State that infertility treatments and contraception are based on the biology of fertility
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CfE Higher Human Biology Unit 2: Physiology and Health Chapter 11 – Controlling Fertility
Learning Intentions By the end of this lesson, I will be able to: • State that infertility treatments and contraception are based on the biology of fertility • Give some risks and ethics associated with fertility treatments • Explain that fertile periods are continuous in the male and cyclical in the female • Calculate the fertile period and describe its use • Give examples of treatments used for infertility • State that fertility treatments such as the use of drugs, stimulate ovulation in the female • State that drugs may prevent the negative feedback effect of oestrogen on FSH secretion or mimic the action of FSH and LH • Explain that drugs may lead to super ovulation resulting in multiple births or for use in IVF treatments
Learning Intentions (continued) • Describe artificial insemination as a treatment for infertility and explain that it involves collecting several samples from a male with low sperm count over a long period of time • State that a donor may be used for this treatment if the partner is sterile • Explain that ICSI can be used if mature sperm are defective or of a very low number • Describe the procedure used in ICSI • Explain the process of IVF and the use in conjunction with PGD to determine abnormalities in the embryo
Infertility Treatments and Contraception • The biology of fertilisation is used when designing treatments for infertility and devising methods of contraception
Ethical Issues and Risks associated with infertility treatments • What? • Why / Why not? • Who? • Gamete donation – donor anonymity? - dead partner? - psychological effect on the child? - legal situation? - embryo storage –how long / how many? - embryo transfer - how many? - risks of multiple births - prematurity - Who pays? - what happens to unused embryos? - risks of taking drugs - risks of multiple births
Fertile Periods • The negative feedback effect of testosterone maintains a relatively constant level of FSH and ICSH in the bloodstream of men • This means a steady stream of testosterone is secreted and sperm is produced • Men are, therefore, constantly fertile (although production does decrease in later life) and may father children at an old age World’s oldest dad, aged 97 years Rod Stewart, 66 years Bruce Willis, 58 years
Fertile Periods (continued) • In the female, fertile periods are cyclical, due to the pituitary and ovarian hormone activity. • This means there are times when fertilisation is more likely, i.e. from a few days before release of the ovum until 1-2 days after ovulation. • Fertilisation is less likely just before, during and just after the menstrual period. • The fertile period occurs just before, during and after the surge in LH levels which trigger release of the ovum from the follicle and lasts for a few days. • This period can be detected by an increase in blood or urine LH levels, taking intra-vaginal temperatures or simply by counting the days after the last menstrual period
Knowing when she is at her most fertile period can assist the woman to become pregnant and to avoid pregnancy by either having or avoiding intercourse at these times. • Even though knowledge of the fertile period can aid conception, many woman have irregular menstrual cycles and therefore more effective methods of contraception can be used. • As before with fertility treatment however, this raises moral and ethical issues for some individuals
Calculation of the Fertile Period Temperature • The alternating processes of menstruation and ovulation are separated by around 2 weeks. • Roughly one day after the surge in LH triggering ovulation, the body temperature of the female rises by 0.2-0.5 ⁰C due to the action of progesterone. • The body temperature then remains higher for the rest of the luteal phase of the menstrual cycle. • The period of fertility lasts for 1-2 days before the infertile period returns, on average, after the third daily recording of the higher body temperature. • The unfertilised egg has then disintegrated
Mucus • The cervical mucus secreted into the vagina during the fertile period is thin and watery • This allows sperm to access the female reproductive system. • Following ovulation, the mucus increases in viscosity due to the action of progesterone. • This demonstrates a return to the infertile period. • The knowledge of changes in female body temperature and cervical mucus can be used to calculate the fertile period and help a couple to conceive a child.
Treatments for Infertility • A female may fail to ovulate for a number of reasons. • This may include failure of the pituitary gland to secrete enough FSH or LH. • To overcome this problem, ovulation may be stimulated using • drugs that mimic the normal action of FSH and LH • drugs that prevent the negative feedback effect of oestrogen on the FSH secretion during the luteal period of the menstrual cycle. • There are, however, problems associated with taking infertility drugs. • These can include super-ovulation i.e. the release of many ova which may result in multiple births e.g. quadruplets. • Drugs that promote super-ovulation are used to promote the release of ova to be collected for use in IVF (in vitro fertilisation) treatments
Artificial Insemination • Artificial insemination is the introduction of semen into the female uterus by means other than sexual intercourse • Artificial insemination is particularly useful if the male has a low sperm count • This involves collecting several samples of semen over a period of time, each sample is then preserved by freezing until required • The sperm are then defrosted and released together into the partner’s cervical region when she is likely to be at her most fertile • Artificial insemination may also be used to insert sperm from a donor into the female if her partner is sterile
Intra-cytoplasmic Sperm Injection (ICSI) • There is only a good chance of fertilisation occurring if a large number of active sperm are present around the ova • If the mature sperm are defective or very low in number, ICSI can be used. • This involves drawing the head of a healthy sperm into a syringe needle and injecting it directly into the ova to achieve fertilisation. • The egg is held in place by a holding tool while this takes place.
In vitro fertilisation (IVF) • In vitro fertilisation is commonly used to solve the problem of infertility caused by a blockage of the oviducts (uterine tubes) • This enables fertilisation to occur in a culture dish outside the body of the female
IVF procedure • Hormonal treatment is given to the woman to stimulate multiple ovulation • A surgical procedure is used to remove several eggs from the ovaries • The eggs are then mixed with sperm in a culture dish containing nutrients to allow fertilisation to occur or one sperm may be injected directly into an egg as in ICSI • Following fertilisation, the zygotes are incubated in the nutrient medium for 2-3 days to allow cell division to occur and form embryos each made of eight or more cells • Two or three of the embryos are then chosen for insertion through the vagina into the mother’s uterus • The remaining embryos are frozen and stored in case a second attempt is required.
Pre-implantation Genetic Diagnosis(PGD) • Pre-Implantation genetic diagnosis (PGD)is used to check for a known chromosomal or gene defect • Embryos are screened after fertilisation by IVF treatment to identify single gene disorders and chromosomal abnormalities that may be present in the developing embryo to avoid implanting affected embryos into the mother’s womb Day 3 8 cell embryo Surgical opening Test for genetic mutation Transfer to uterus
Contraception • Contraception is the intentional prevention of conception or pregnancy by natural or artificial means
Physical methods of contraception Barrier methods of contraception A barrier method is something that physically stops or blocks sperm from reaching an ovum. • The condom is a rubber sheath that fits over the man’s penis • The diaphragm is a dome –shaped rubber cap inserted into the vagina to block the cervix before each act of sexual intercourse • The cervical cap is a rubber structure that fits tightly around the cervix and can be left in position for a few days • These methods are very effective but not as successful as chemical methods
Intra-uterine devices • An intra-uterine device (IUD)is a T-shaped structure fitted into the uterus for many months or years to prevent the implantation of an embryo into the endometrium
Sterilisation Procedures Male • A vasectomy is a surgical procedure whereby the sperm ducts are cut and tied, preventing sperm being released during intercourse • Any sperm produced after the procedure has been checked normally undergo phagocytosis and are destroyed
Sterilisation Procedures Female • Tubal ligation involves cutting and tying the two oviducts • This prevents eggs from meeting sperm and reaching the uterus • Sterilisation in this way is normally irreversible
Chemical Methods of Contraception Pills containing Hormones • Oral contraceptive pills normally contain synthetic progesterone and oestrogen • The woman normally takes one pill per day for three weeks from the final day of the menstrual period • This system works by alternating the concentration of hormones in the bloodstream creating a negative feedback control where FSH and LH are inhibited from entering the bloodstream and follicle maturation remains inhibited and ovulation fails to occur • Placebo pills are taken in the fourth week to allow levels of oestrogen and progesterone to drop and menstruation to occur
Morning after Pills • These are known as emergency hormonal contraception pills • They contain high levels of the hormones progesterone and oestrogen • They are taken by the woman after having unprotected sexual intercourse to prevent the egg from implanting in the womb if fertilisation has occurred • These pills should be taken as soon as possible after unprotected intercourse
Mini Pills • These are Progesterone only pills as they contain synthetic progesterone • They thicken the cervical mucus reducing the viability of sperm and their entrance to the uterus
Case Studies • Risks and ethics associated with fertility treatments. • Case studies on infertility, its causes and treatment to include overcoming problems in sperm production and ovulation, predicting fertile periods, and surgical interventions.
Infertility • Medical condition of the reproductive system that results in the inability to conceive or carry a pregnancy to term • Condition is diagnosed after a couple has had a year of unprotected, regular intercourse without conceiving, or when pregnancy occurs but does not result in a live birth. • 33% of infertility causes unknown • Other factors that can contribute to infertility include stress, smoking, alcohol use, excess weight and overall health
Infertility in Women • Impaired ovulation due to disease, birth defects, or abnormal hormone production • Blocked oviducts from infection or scar tissue • Inability of the uterus to hold the embryo (this may be due to a variety of reasons, including scar tissue on the walls of the uterus) • Endometriosis
Infertility in Men • Low sperm count • High percent of abnormally-shaped sperm • High percent of sperm that are not moving forward • Ejaculation dysfunction • Sperm production can be affected by blocked passageways, fevers, infections, or birth defects.
Treatments summary Current types include: • In vitro fertilization (IVF): Eggs and sperm are collected and fertilised in the laboratory before the resulting embryo is transferred to the womb. • Fertility drugs • Artificial insemination: Sperm are inserted into the womb at the time of ovulation using a catheter
Treating Infertility In vitro fertilisation - (outside the body in the lab) • Stage 1 Hormonal treatment to stimulate multiple ovulation • Stage 2 Several eggs removed
Stage 3 Eggs placed in a dish of nutrient medium containing sperm to allow fertilisation to occur OR injecting sperm into egg. Stage 4 Fertilised eggs incubated in nutrient medium to allow cell division to occur. Stage 5 Two or three embryos are chosen and inserted into uterus via the vagina Treating Infertility In vitro fertilisation Con’t - (outside the body in the lab)
Treating Infertility: Artificial Insemination (Inside the body) • ( Insemination is the introduction of semen into the female reproductive tract. It occurs naturally as a result of sexual intercourse. Artificial insemination - The insertion of semen by some other means other than sexual intercourse. • Used as a method of treating infertility • If a man has a low sperm count, samples of his semen can be collected and frozen until required. • They are then defrosted and released into the female’s cervix region during her most fertile period. • Can also be used to insert semen of a donor who has a normal sperm count into a women who’s partner is sterile.
Worlds first Pregnant manhttp://www.dailymail.co.uk/news/article-2019579/Worlds-pregnant-man-Thomas-Beatie-unveils-muscular-body-3-babies.html • Thomas Beatie, the transgender man who gets pregnant by artificial insemination. • “Beatie, 34, now has has 3 healthy children -which he has carried in the womb he kept intact when he became a man 10 years ago”
Continuous versus cyclical fertility con’t: Implications in calculating fertility! Male – Continuously Fertile • Negative feedback of testosterone maintains a relatively constant level of gonadotrophic hormones (FSH & ICSH) • Results in a fairly steady quantity of testosterone being produced Female - Cyclical Fertile • Egg will only survive 24 hours after being released due to hormone levels • Sperm, however, can survive for 72 hours (3 days) • Fertility is restricted to 3 – 4 days immediately following ovulation
Biological Basis of Contraception Contraception is the intentional prevention of conception by natural or artificial means. Artificial Methods: • Oral contraceptive pills • Injections • Implants Natural Methods: • Temperature • Mucus • Rhythm methods
Biological Basis of Contraception: Natural Methods:Temperature. Temperature • One day after surge of LH temperature increases by 0.5°C • Remains elevated for duration of luteal phase • Fertility lasts 3 – 4 days • By the 3rd day of the higher body temp the egg has disintegrated.
Biological Basis of Contraception: Natural Methods: Mucus. Mucus • During fertile period mucus is thin & watery to allow sperm easy access to female reproductive system • After ovulation mucus increases in viscosity – becomes thicker, returning to the infertile period.
Biological Basis of Contraception: Natural Methods: Rhythm method. Rhythm Methods • Methods of temperature and mucus viscosity are used by couples who want to have a child - they will know when the best time to have sexual intercourse to achieve successful fertilisation. • If a couple do not wish to have children, the rhythm method can also be used as a contraceptive.
Natural Contraception: Summary • Body temperature - body temperature changes through the menstrual cycle under the influence of oestrogen and progesterone. It rises slightly after ovulation. • Cervical mucus - the amount of oestrogen and progesterone alters the quantity, texture and appearance of cervical mucus, • Rhythm method - calculating how long the menstrual cycle lasts
