Sexual Reproduction The means by which we increase in number and fill the earth.

Introduction Puberty Reproductive systems Fertilisation Menstrual cycle Contraception / IVF Sexually Transmitted Diseases Premarital sex and abortion Human Reproduction

One characteristic of living organisms is that they can reproduce. What does ‘reproduce’ mean? to produce young ones or new individuals Why is there a need to reproduce? to replace those that die to ensure that the species does not become extinct What would happen if living thing didn’t reproduce? Introduction

(involves the fusion of 2 different reproductive cells) Asexual Sexual (does not involve the fusion of 2 different reproductive cells) Reproduction

Asexual Reproduction In asexual reproduction there is only one parent. All offspring are identical to the parent. They have exactly the same genes. They are called clones.

Sexual Reproduction Involve two parents Have different sex organs Producing gametes

Sexual reproduction involves the fusion of 2 different reproductive cells. What are reproductive cells and where do they come from?

(organs producing reproductive cells or gametes) TestesOvaries produce Sperm produce Ova Gonads

In higher animals, the testes and ovaries are borne by different individuals. Hence a mating process is required to allow the meeting of the gametes. Mating occurs only between physically mature individuals.

During sexual reproduction the sperm and the egg join together. This is called fertilisation. A fertilised egg, or zygote, is produced. Fertilisation

External Fertilisation – fertilisation take place outside the body – in water Internal Fertilisation – fertilisation take place inside the body of the female

When does an individual become physically mature? An individual becomes physically mature when he reaches puberty

the time of active growth in humans and other mammals during which the -reproductive organs become functional, i.e. they start producing sex hormones and gametes -physical changes develop as a result of the secretion of sex hormones When do girls and boys enter puberty? Puberty around the age of 11 to 13 around the age of 12 to 14

Changes in boys: 1. physical changes, e.g. (a) growth of hair (i) on certain parts of face (ii) on chest (iii) in armpits (iv) at pubic region (b) “Adam’s apple” appears as the larynx or voice box increases in size, causing the voice to break and deepen (c)testes and penis grow bigger 2. Testes start to produce (i) sperm and (ii) male sex hormones (testosterone) Changes in girls: 1. physical changes, e.g. (a) growth of hair (i) in armpits (ii) at pubic region (b) breasts grow bigger (c)hips become wider and rounder 2. Ovaries start to (i) produce female sex hormones (oestrogen and progesterone) and (ii) release mature eggs (ova, singular: ovum) 3.Menstruation starts

Human reproductive organs

testis scrotum epididymis sperm duct urethra penis seminal vesicle prostate gland prostate gland Cowper’s gland Cowper’s gland spermatic cord The male reproductive system

Sperm

ovary oviduct uterine lining uterus uterine lining cervix vagina vulva urethra The Female Reproductive System

egg membrane Egg /Ovum

Sperm (male gamete )Ovum (female gamete) 1. Production produced by the testes produced from puberty onwards released by the ovaries released from puberty till menopause 2. Size about 0.01 to 0.05 mm long about 0.10 mm in diameter about 500 million sperm are released at each ejaculation during mating 3. Quantity only one ovum is released at each ovulation (once in about 28 days) 4. Mobility capable of movement by itself, can swim vigorously towards the ovum to fertilise it not capable of movement Comparison of a Sperm and an Ovum

Sperm (male gamete ) Ovum (female gamete) 5. Structure divided into 3 parts: a) Head - contains large nucleus with little cytoplasm and a sac which contains enzymes that break down part of the egg membrane for penetration during fertilisation b) Middle piece - contains mitochondria that provides energy for the activity of the sperm c) Tail (flagellum) - enables the sperm to swim towards the egg spherical, surrounded by a thin membrane and a layer of jelly has a nucleus and abundant cytoplasm containing stored food

Comparison of Size

Internal Fertilisation  Before fertilisation, mating or sexual intercourse must take place

What is ovulation? release of a mature egg from an ovary occurs about once every 28 days the egg enters the funnel-shaped opening of the oviduct which carries it to the uterus fertilisation can occur if the egg meets a sperm in the oviduct Ovulation

 Have many tiny hairs (cilia) on inner walls that help to push the ovum along the oviduct as the muscles contract Oviducts (fallopian tubes)

What is fertilisation? Fertilisation is the fusion of the nuclei of the sperm and the egg. It occurs in the oviduct.  to penetrate the egg, the acrosome of the sperm releases an enzyme to break down part of the egg membrane only the head goes in, and the its nucleus fuses with the nucleus of the egg Fertilisation

 when nucleus of egg fuses with nucleus of sperm, the fertilised egg is called a zygote  zygote continues journey through the oviduct and divides to form a ball of cells called the embryo  embryo enters the uterus and attaches itself to the thick uterus lining from which it gets nourishment and oxygen  embryo grows and develops into a fetus What happens after fertilisation?

Embryonic Development

Menstrual Cycle Stages of Menstrual Cycle 1.Menstruation 2.Repair and Growth of Uterine Lining 3.Ovulation 4.Further thickening of Uterine Lining

If no fertilisation occurs after ovulation, ovaries will stop producing hormones  ovum disintegrates  thick lining of uterus breaks down  broken lining, disintegrated egg and some blood flow out through the vagina – menstrual flow - marking the start of menstruation  menstruation lasts for about 5 days 1. Menstruation

(after menstruation) after menstruation, ovaries release oestrogen into bloodstream oestrogen causes growth and repair of uterine lining and blood capillaries to form within the thick lining - uterine wall becomes thick and spongy with blood vessels again 2. Repair and Growth of Uterine Lining

 occurs about the 14 th day of the menstrual cycle  if fertilisation occurs - the female becomes pregnant  if no fertilisation occurs - menstruation occurs again 14 days after ovulation  for married couples who want to have children, sexual intercourse during period of ovulation is more likely to result in pregnancy 3. Ovulation

 after ovulation, ovary secretes progesterone into bloodstream  progesterone causes uterine lining to thicken further and becomes vascularised (contain many blood capillaries) - ready for implantation of embryo  if there is no fertilisation, uterine lining breaks down and menstruation starts again 4. Further thickening of Uterine Wall

Repair and growth of uterine lining StartStart Uterine lining grows and thickens Uterine lining breaks down and is discharged Uterine lining thickens further and becomes more vascular, preparing for implantation Menstrual Cycle

Contraception refer to birth control due to over-population

Family Planning by a couple refers to  limiting the number of children to have and  spacing out the arrival of children made possible by practising  birth control or contraception which prevents ovulation or fertilisation (sperm and egg cannot meet) or a fertilised egg from being implanted in the uterine lining

an ovum released during ovulation can live for days before it dies  sperm released into the female reproductive system can live for days  time from day 11 to 17 - fertile phase because fertilisation can occur during this period  rest of the days in the menstrual cycle - infertile phase because fertilisation is usually not possible during this period The Fertile and Infertile phases

 stress  emotional disturbances  mental fatigue  illness  unbalanced diet, malnutrition Irregularities in menstrual cycle can be caused by: However, a woman’s menstrual pattern may not be a reliable indicator of her fertility.

Temporary Methods Permanent Methods (couples can have children when they stop using the methods) (couples cannot have any more children in future, very difficult to reverse) Contraceptive Methods

2. Use of contraceptive pills - contain a hormone (progesterone) - prevent ovulation - prescribed by doctor

- condoms and diaphragms (prevent sperm from meeting the egg and so prevent fertilisation) 3. use of contraceptive devices, such as

-a rubber tube worn over erect penis to collect the semen, so no sperm can enter vagina - can also prevent spread of sexually- transmitted diseases since impermeable to bacteria and viruses Condom

ligation (female sterilisation) - mid-portion of each oviduct is cut and ends tied - prevents released egg from travelling through oviduct to reach uterus Permanent Contraceptive Methods

diseases passed on from an infected person to another person through sexual intercourse dangerous - because infected person usually feels and looks healthy during early stage of infection babies born to infected mothers may be infected too Sexually Transmitted Diseases (STDs)

Gonorrhoea Syphilis AIDS (Acquired Immune Deficiency Syndrome) Sexually Transmitted Diseases (STDs)

caused by a type of bacteria can be passed on by an infected person - to his or her partner, during sexual intercourse - to a baby during birth baby can become blind if bacteria enter eyes during birth 1. Gonorrhoea

pain when passing urine for men - a discharge of pus from the penis for women - lower abdominal pain from infection of the oviducts which can lead to sterility - no symptoms in women in early stages can lead to sterility in men and women if not treated Signs and Symptoms of Gonorrhoea

can be cured by a course of antibiotics such as penicillin Treatment of Gonorrhoea

caused by a type of bacteria spread by an infected person to his or her partner, during sexual intercourse disease can be passed on from an infected woman to her fetus during pregnancy - baby born with congenital syphilis, may suffer from deafness and eye defects, have abnormal teeth, bones and joints 2. Syphilis

Earlier stage - painless sores (on lips, tongue, penis, vagina, cervix- usually heals in a week or two, even without treatment) - non-itchy skin rash Later stages - heart failure - heart failure - blindness - blindness - bone / joint deformity - bone / joint deformity - paralysis, insanity and even death - paralysis, insanity and even death Signs and Symptoms of Syphilis

can be cured by a course of antibiotics such as penicillin Treatment of Syphilis

- full course of antibiotics, such as penicillin - infected person to refrain from sexual intercourse - tracing contacts whom the patient has had intercourse and treating them Treatment for Gonorrhoea and Syphilis

- male to wear condom - discourage promiscuous sexual behaviour and keep to one sex partner Prevention and Control of Gonorrhoea and Syphilis

caused by a virus, Human Immuno- deficiency Virus (HIV) destroys body’s immune system so infections which are normally mild may prove to be fatal 3. Acquired Immune Deficiency Syndrome (AIDS)

- sexual intercourse with an infected person - sharing of HIV-contaminated needles when abusing drugs - transfusion of blood contaminate with HIV - during pregnancy or childbirth, when a HIV- positive mother passes the virus to her child Ways in which HIV can be transmitted

- no symptoms at first but - after a few months may develop symptoms such as - tiredness - loss of appetite - loss of weight - prolonged fever - night sweats- skin rash - swollen lymph glands - persistent diarrhoea - lowered resistance to infections - after several years, immune system weakens Signs and Symptoms

complete breakdown of body’s immune system against infections diseases include - pneumonia - Kaposi’s sarcoma (cancer of the blood vessels) - persistent diarrhoea - brain infection - tuberculosis AIDS (final stage of HIV infection) - within 8-10 years for half of those infected

- keep to one sex partner - male to wear condoms to reduce the risk of infection - avoid sharing items that are likely to break the skin and be contaminated with blood - go to reliable operators for acupucture, ear-piercing or tattooing, making sure instruments are sterilised or insist on using disposable instruments Prevention and control

Educating the public Never share needle Avoid sex with prostitutes / Stay with one STD-free partner Always use a condom Destroy all contaminated blood

drug AZT can slow down the course of the disease there is no cure for AIDS Treatment of AIDS Chemical Name: Azidothymidine Generic Name: Zidovudine Nick Name: AZT Brand Name: Retrovir ® (Retrovis ®) Manufacturer: Glaxo-SmithKline

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