Presentation on theme: "Reproduction in Humans Male Reproductive System Objectives: *Identify on diagrams the male reproductive system and state their function **Compare male."— Presentation transcript:
Reproduction in Humans Male Reproductive System Objectives: *Identify on diagrams the male reproductive system and state their function **Compare male and female gametes
Functions OrganFunction Testes Scrotum Sperm duct urethra Prostate and other glands Penis Produce spermatozoa and make male hormone testosterone which stimulates changes during puberty Sac covering testes which hangs outside the body to keep it cool as sperm can’t develop or be stored at 37 0 C or above Small tubules outside the testes store sperms for maturation. Sperm duct connect these tubules to urethra Urethra carries urine and sperm but not at the same time. A ring of muscle around the urethra contracts to prevent urine loss during sexual intercourse Secrete fluid for sperm cell to swim. Prostate secrete mucus and other secrete sugar for respiration of sperm cells. Sperm cell + fluid = semen Urethra runs down the centre of penis. Its main function is to deliver sperm to the vagina for fertilization
Gametes (sex cells) Cell membrane cytoplasm nucleus Egg cell Jelly coat Middle piece (Has mitochondria to power swimming by the tail) Head Acrosome (contain enzymes to break the jelly coat Drives sperm forward
Sperms and eggs are specialised. Which statements belong to a sperm and which to eggs?
Compare FeatureSperm cellEgg cell size movement food store no. of chromosomes number produced small Much larger Swim using tail that lashes from side to side Does not move itself. Moved along oviduct by cilia and peristalsis Has very little – uses sugar in seminal fluid for respiration Protein and fat in cytoplasm- enough to last till implantation in uterus 23 (haploid) Millions produced constantly after puberty often throughout life One a month after puberty until menopause except when pregnant or taking contraceptive pills
Female Reproductive System Objectives: * Identify on diagrams the female reproductive system and state their function **Describe sexual intercourse in humans
Functions OrganFunction Ovaries(attached to inside of abdomen just below the kidneys releasing 1 ova /28days alternately oviduct Uterus cervix Vagina urethra clitoris vulva Produce ova and make female hormones progesterone and oestrogen which stimulates changes during puberty. Oestrogen- development of sex organs and sec. sexual characteristics progesterone prepares uterus for receiving the embryo in case of pregnancy The egg passes out to the funnel shaped opening of the oviduct in a process called ovulation which then either gets fertilised by a sperm or die after passing into the uterus Foetus develops here. It develops a spongy wall for implantation of the embryo in case of pregnancy A separate opening above the vaginal opening for urination A ring of muscles at the lower end of the uterus leading to vagina A muscular tube opening outside the body Above urethra a very sensitive area (lot of nerves) Outer opening of vagina
Describe sexual intercourse in bullet points (remember do not have to mention movement of sperms through cervix as this happens after ) Male, female stimulate each other Blood pumped to spongy tissues of penis Causes erection of penis Penis enters vagina Fluid made by vagina lubricates movement of penis in the vagina This leads to contraction o f sperm duct to move sperms from the tubules to the penis Secretions from glands are added for easy movement of sperm Urethra contracts to move seminal fluid through penis to vagina. This is ejaculation which causes men to feel orgasm( a sense of pleasure) Repeated movement of penis against clitoris or vaginal walls may produce orgasm in women Each ejaculation contains 2-5cm 3 of semen with up to 500million sperm cells
Fertilisation and Implantation Objectives: *Describe fertilisation in humans **Describe early development of the zygote to form a ball of cells for implantation into the uterus wall
Why so many sperm cells? What is the role of the acrosome? What fuse first ? What is the number of chromosomes after fertilisation? Why do the other sperms not enter?
Fertilisation & Implantation Villi or finger like projection of the embryo to penetrate endometrium. They are surrounded by blood vessels which supply nutrients and oxygen
Division and Growth Once the egg has been fertilised, we call it a ZYGOTE. Zygote - 1 cell2 cells 4 cells 32 cells 64 cells Add timeline
Ante-natal care and Birth Objectives: *Describe the ante-natal care of pregnant women **Describe the processes involved in labour and birth ***Describe the advantages and disadvantages of breast milk and formula milk
Why is it important that the mother has a balanced diet? Which food groups are particularly important? Calcium : Iron: Carbohydrate: Protein: Bones of foetus can grow To make extra red blood cells to carry oxygen to the foetus and so that both mother and baby can make extra haemoglobin So the mother has enough energy to move her heavy body around To provide amino acids for both to make tissues. The mother makes muscle tissues in the uterus to prepare for birth and the fetus for growing and developing its organs The things a mother should not take Alcohol: can cause birth defects and mental retardation Drugs: like heroin can give baby an addiction Cigarettes: nicotine and CO result in premature and underweight babies
Causes of premature birth: Smoking Early breaking of the amnion (most common) Birth: A few weeks before birth a fetus turns over inside the uterus with the head towards the cervix. Hormones released by the fetus and the increase in pressure in the uterus stimulate hormonal changes in the mother. A hormone oxytocin is released from her pituitary gland which stimulates uterine muscle to contract. The mother feels the contraction and this is the beginning of labour. When contractions become stronger and more frequent the opening of the cervix stretches and the amnion breaks to release the amniotic fluid. The contraction is even stronger now pushing the baby towards the cervix. The cervix widens pushing the baby’s head through the vagina. The baby starts breathing for the first time when born. The airways need clearing of mucus to help the baby breath. The umbilical cord is cut and tied just above the point where it attaches to the baby. The rest heals to form the naval. After a few minutes the placenta comes away from the uterus wall. It is pushed out of the vagina as afterbirth It is a painful experience but gentle exercise, special breathing technique, painkillers in form of epidural (catheter between spine and spinal cord) to stop transmission of impulses from pain receptors to the brain.
Breast feedingFormula Milk Contains antibodies which gives baby passive immunity. The antibodies remain there after a while after breast feeding is stopped. Creates bonding Research shows less likely to develop childhood cancer, and diabetes. Mothers less likely to develop breast uterine and ovarian cancer More convenient Chance of getting infection Expensive
The Menstrual Cycle Objectives: *Describe the menstrual cycle in terms of changes in the uterus and the ovaries **Explain the roles of hormones in controlling the menstrual cycle
Girls are born with potential egg cells. Each potential egg is surrounded by small group of cells and together they form a follicle. At puberty some follicle develop and egg divide by meiosis Cytoplasm fills with stored food Each month one or a few follicle will develop At the beginning of the cycle at the end of menstruation one follicle will develop. Follicle enlarges and fills with fluid move towards the edge of the ovary After 2 weeks follicle bursts releasing egg and some fluid into the oviduct This is The follicle cells left behind make the yellow body which remains for next 2 weeks in case of pregnancy they are active otherwise they decrease in size The uterus lining thickens during egg development If not fertlised the egg passes to the vagina and the yellow body breakdown in the ovary Yellow body is stimulated in pregnancy by a hormone released by the embryo which in turn stimulates the lining of the uterus to continue to thicken
The menstrual cycle lasts about 28 days. During this time the lining of the uterus thickens and an egg is released. If, once the egg has reached the uterus it still hasn’t been fertilised by any sperm it will die and the lining of the uterus will start to break up. Within about 2 weeks, the woman has her period – blood and dead cells pass out through the vagina. This is called menstruation. A woman’s period can last between 3 and 8 days. Girls normally start their periods between the ages of 11 and 14 (but it may be a little earlier or later for some people).
The 4 stages of the menstrual cycle: These are controlled by hormones Day 1: Bleeding starts when the lining of the uterus breaks down and passes out the vagina – “Having a period” Day 6: The lining starts to build up again and thickens into a spongy layer of blood cells Day 14 (approx): An egg is released and lasts for around 3 days Day 16-21: The lining stays thick awaiting the arrival of a fertilised egg. If one doesn’t come then the lining breaks down again in next 6 days
Hormones Many processes within the body are coordinated by chemical substances called hormones. Hormones are secreted by glands and are transported to their target organs by the bloodstream. Hormones regulate the functions of many organs and cells. Hormones in the menstrual cycle FSH – follicle stimulating hormone Secreted from: pituitary gland Effects: egg matures in ovary(stimulates follicle to develop) Release of oestrogen from ovary Oestrogen Secreted from: ovaries( cells in the ovary stimulate it) Effects: inhibits release of FSH(stimulates thickening of the lining) Causes release of LH LH – luteinising hormone Secreted from: pituitary gland travels to ovary Effects: stimulates release of egg from ovary
Progesterone Secreted from: made by yellow body( corpus luteum) Effects: Thickens and maintains uterus lining for implantation If pregnancy occurs both ovarian hormones continue to be produced to prevent menstrual cycle starting again
Sex Hormones Objectives: *Describe the role of testosterone and oestrogen in developing secondary sexual characteristics at puberty **Describe artificial insemination and the use of fertility drugs and discuss their social implications Starter: What is secondary sexual characteristics? Do both sexes develop at the same time? What causes development? Do all young people grow at a definite age ? What is this time called? What does the word adolescent mean? When adolescence stops? h/w complete worksheet and hand in on 20/9
Puberty The statements below describe changes which happen to girls, boys or both during puberty. Copy the table below into your book and list the statements under the correct headings. Changes to females during puberty Changes which happen in both males and females Changes to males during puberty
Production of oestrogen and progesterone by the ovaries Production of testosterone by the testes Growth hormones released causing growth of body (height and weight increase) and reproductive organs Muscles develop and shoulders widen Ovaries begin to release ova (singular: Ovum) Voice becomes deeper Hips widen (often but not always) and breasts develop Menstrual cycle starts Growth of pubic hair Testes begin to produce sperm cells Increased body odour from sweat glands (many found in armpits) and genitals Increase in erections Increased interest in the opposite sex Growth of facial hair Growth of hair under arms and in pubic region
Fertility Drugs and Treatment What is infertility? Causes of infertilitytreatment In woman In man Ovaries do not release egg Due to lack of FSH production Regular injections of a fertility drug containing FSH or using tablets which make pituitary gland insensitive to oestrogen. It may cause multiple fertilisation. Do not produce enough sperm or problems with ejaculation Semen collected from men and placed in the uterus via a plastic tube. This is called artificial insemination (AI) in the later case or use sperms from a donor who remains unknown. It is also possible to take the nucleus from a defective sperm and inject it into an egg. The zygote is cultured for several days to grow into embryo which is then inserted in the uterus so that implantation can take place.
Methods of Birth Control Objectives: *Describe the methods of birth control by: natural, chemical, mechanical and surgical means Starter: What is birth control? Stop the sperm from reaching the egg Stop the eggs from being made Stop the fertilised egg from implanting and developing in the uterus
Mechanical methods: IUD – A small plastic device wrapped in copper or contains hormones(progesterone). Fitted in uterus prevents either sperm entering uterus or embryo implanting. Progesterone makes mucus in cervix sticky. Cap or diaphragm – A rubber dome used with sperm killing cream or foam placed over cervix before intercourse prevents sperm from entering uterus Condom/ femidom – Most common, rubber tube rolled over penis or inserted in vagina stops sperm entering the vagina and stops STDs Chemical methods: The pill – different types available. Contains oestrogen and progesterone in varying concentrations. Inhibits FSH thus no egg matures. Failure to take it regularly may cause pregnancy. Side effects are weight gain, sore breast, painful period depression and heart and circulation problems Spermicides – Foam, cream or jelly to kill sperms. Not very effective on its own.
Natural methods: Abstinence / rhythm method– during the most likely time of fertilisation. Determine ovulation date by keeping a record of period cycle and abstain 2 days before and after that date. It is unreliable Sometimes checking symptoms of ovulation like increase in body temperature, change in cervical mucus( less sticky).Easy for people without access to other methods. Surgical method: Vasectomy – Operate to cut and tie sperm duct. Irreversible. Ejaculation happens but no sperm released Sterilisation – Minor operation on women. Oviducts are cut and blocked. Irreversible.
Sexually transmitted diseases Objectives: *Describe the methods of transmission of HIV and the ways in which HIV/AIDS can be prevented from spreading **Describe the symptoms, signs, effects and treatment of gonorrhoea ***Describe how HIV affects the immune system
H/W Revise for test on 26/9 HIV(human immunodeficiency virus) identified in 1980s leads to AIDS ( acquired immunodeficiency virus syndrome). It is a collection of diseases due to weak immune system and that is why called a syndrome. HIV positive- HIV attacks an important type of lymphocytes (T). T- lymphocytes stimulate other lymphocytes to produce antibodies. During HIV infection the number of T lymphocytes decreases and so fewer antibodies are produced every time there is an infection. Therefore diseases as well as cancers, that form can’t be destroyed by the immune system because they fail to recognise them. Early symptoms of AIDS are very much like flu with swollen glands and high temperature. Later symptoms include weight loss, various types of cancer and decrease in brain function. Some HIV + people do not develop any symptoms.
Transmission: In blood ( not by blood sucking insects) In semen Unprotected sex ( not by touch) Hypodermic needles contaminated with infected blood ( not by sharing glasses or cups) Blood transfusion Across placenta At birth when two bloodstreams come in close contact Breast milk Prevention: Antiviral drugs ( prevent virus from multiplying) Use of condoms Free needle exchange schemes to reduce the use of shared needles among drug users Careful screening of donated blood for transfusion
Gonorrhoea only transmitted by sexual intercourse. Cause by spherical bacteria Neisseria gonoerrhoea. It can only survive in the moist lining of the male and female reproductive tract. If the bacteria is present in vagina or urethra in female and male respectively it can be transmitted by sexual intercourse.Symptoms after 2-7 days of infection. In male bacteria multiply within urethra producing an unpleasant discharge and pain when urinating. Sores develop on the penis. If not treated can cause long term damage to both urinary and reproductive system( sterility). In female bacteria multiply in cervix producing a discharge which is not noticeable and painful but will lead to same kind of damage if not treated. Prevention: Have only one partner who is disease free Use condom Treatments: Antibiotics