SEXUAL REPRODUCTION IN ANIMALS
Reproductive cells / gametes produced in organs- gonads (male- sperm = testes, female- eggs or ova = ovaries)
Humans have 46 chromosomes, 23 pairs, sperm or egg = 23 chromosomes each due to meiosis

Meiosis/ reduction division
cell division in reproductive organs at time of formation of sex cells/ gametes, 2 stages, produces 4 daughter cells = gametes, reduced (½) chromosome # (diploid > haploid), gametes (sperm, ova)= haploid, n =23, when gametes fuse: ensures zygote w/ diploid chromosome # > maintain genetic stability (genetically dissimilar offspring)

Chromosomes in man
Chromosomes; body cells: 46, gametes: 23
Homologous pair: a pair of chromosomes, identical shape, length, genes
1st 22 pairs of chromosomes in body cells = body chromosomes > give characteristics
23rd pair = sex chromosome; XX- female, XY-male

Male reproductive system
testes- positioned outside body in scrotum, at cooler temp for spermatogenesis (sperm production), sperm producing cells undergo meiosis > haploid sperms (heterogametic: 2 types of sperms, 22+ X: > female & 22+ Y: > male), sperms produced > epididymis- coiled tube: stores sperm in inactive form > sperm duct (vas deferens) > urethra > penis (glans penis- head of penis, sensitive & swollen, protected by fore skin, propuce)
seminal vesicle, prostate gland and Cowper's gland secrete alkaline seminal fluid containing nutrients, seminal fluid + sperms = semen, no ejaculation > sperms die, (semen & urine don't pass through urethra at same time)

Female reproductive system
Consists of 2 ovaries on either side of abdomen, once every 28 days one ovary of the other produces an egg (homogametic: 1 type of egg, 22+ X), egg > oviduct (Fallopian tube) > uterus, lower end of womb = cervix which opens into the vagina, opening of vagina = vulva (semen deposited in vagina during intercourse)

(Fe)male gametes Similarities; uni-cellular, haploid, formed by meiosis Differences

Male- spermatozoon	Female- ovum
Produced in testes	Produced in ovaries
Produced in large #'s (300 million's a day)	Produced 1 at a time ~every 28 days in one of the ovaries
~0.01mm long	~0.1mm long
Structure: head, middle piece, tail	Simple oval structure
Motile	Immobile
Heterogametic: 2 types of sperms, 22+ (X/Y)	Homogametic- similar types of ova, 22+ X
Don't contain yolk material as seminal fluid contains nutrients to provide energy through oxidation	Contain small amt of yolk material for initial stages of embryo until implantation

Puberty: time of some changes in the body of a child to make an adult (sex organs- active< secondary sexual characteristics develop), ~ age of 11-girls, 14-boys (affected by hormones), results in formation of secondary sexual characteristics by sex hormones (oestrogen- females, testosterone- males)
Secondary sexual characteristics (primary sexual characteristics: formed before birth)
Males: growth of beard, size of penis & testes ^, production of sperms, deeper voice, hairs appear in pelvic region and under armpits, growth of more skeletal muscles
Females: breast and uterus enlarge, hip broadens, menstruation an ovulation starts, hairs appear in pelvic region and under armpits

The menstrual cycle / female sexual cycle / oestrous cycle
Menstruation- monthly discharge of blood from uterus via vagina if egg not fertilised (sign that person is not pregnant)
1menstrual period ~5 days, during menstruation lining of uterus breaks down and a small amt of blood passes out though vagina, av. menstrual cycle for an adult woman is 28 days
2anterior lobe of pituitary gland secretes FSH- follicle simulating hormone > stimulates epithelium of ovary to divide & make follicles, 1 follicle > Graafian follicle-GF: mature ovum surrounded by follicle cells (oestrogen repair uterus wall)
3~14-16th day, LH- luteinising hormone secreted by pituitary gland > mature GF ruptures: egg > oviduct = ovulation, after ovulation GF > corpus luteum (yellow mass of body) which secretes hormone- progesterone (causes uterus wall > large, thick, fleshy, soft w/ large amt of blood vessels), uterus wall ready for implantation (embryo sinks into uterus wall)
4no fertilisation > egg & corpus luteum breaks down > progesterone level decrease > uterus wall break down > menstruation begins, if fertilisation occurs, zygote > embryo > implantation > placenta surrounds embryo

female cycle controlled by diff hormones, secreted by pituitary gland (FSH & LH) & by ovary wall (oestrogen & progesterone)
Menopause: menstruation stops at age 45: ovaries cease to release ova or produce hormones, can no longer have babies, sexual desire gradually reduces

Fertilisation
Sperms enter vaginal canal > ovum > only one sperm fuses w/ an ovum (fertilisation) in an oviduct, sometimes 2 eggs released > both fertilised by 2 sperms > 2 zygotes not containing same genetic materials > non-identical twins, fraternal twins (fertility drugs, diet & genetic factors cause >1 egg to be produce at one time)
identical twins: single egg fertilised by single sperm > splits longitudinally > 2 embryos w/ exactly the same genes, sometimes 2 cells don't separate completely > embryos joined > Siamese twins

Growth of foetus
Foetus: when embryo looks like miniature human being by 3rd month of development
Foetus surrounded by membrane, amnion, which encloses amniotic cavity- filled w/ watery amniotic fluid, as embryo grows amniotic cavity expands > fills entire uterus, amniotic fluid 1cushions foetus, 2protecting it by acting as a 3shock absorber, amnion enclosed by outer membrane = chorion, chorion + amnion = embryonic membranes, chorionic villi: villi from chorion which absorbs food subs from mothers blood

Functions of placenta
Placenta- sheet of tissue formed from embryo tissue & maternal tissue
-allows diffusion of glucose, amino acids, mineral salts & O2 from mother's blood to embryo
-waste products- urea, CO2 to be passed into mother's blood
-allows antibodies to enter embryo (from mother's blood) protecting in against certain diseases
-takes over hormone prod as pregnancy progresses-endocrine gland (3rd month- secretes progesterone- support embryo, decrease > miscarriage)
-acts as shield around foetus, protects from high blood pressure of mother > crush foetus
-prevents some maternal hormones & chemicals > affect foetal development (nicotine, alcohol, heroin still can enter)
-prevents some pathogens from entering foetus (toxins of Rubella virus (German measles), can enter foetus > physical & mental damage)
foetus attached to placenta by umbilical cord containing umbilical arteries (carrying deoxygenated blood from foetus to mother) and veins (carrying oxygenated blood and food subs from mother to foetus)
at end of 9th month of pregnancy foetus fully developed ready to by born

Birth / Parturition
Gestation period- time bet fertilisation / conception and birth is ~ 9 months
End of gestation period: Stage 1: pituitary gland secrete oxytocin > vigourous contractions of uterus walls- labour pains > mucus plug dislodged > embryonic fluids flow out (about to give birth)
Stage 2: fully grown foetus pushed outwards, head 1st, after delivery umbilical cord cut & tied
Stage 3: "after-birth"- placenta & other embryonic membranes expelled through vagina

Lactation
-during pregnancy, oestrogen & progesterone > milk glands, larger
-following birth, anterior lobe of pituitary gland secretes prolactin > mammary glands start milk prod
-suckling of offspring > reflex expulsion of milk from nipple of mammary gland
-1st form of milk: colostrum, contains antibodies > immunity for baby, also a laxative > helps baby expel bile accumulated in intestines of baby during fetal stage

Advantages of breast feeding to bottle feeding
-BM easier for baby to digests (enough proteins and other mineral salts-Na, P)
-BM supplies baby w/ antibodies from mother: protection from diseases (WBC produce antibodies & ingest bact)
-BM free from harmful bact, provided breast washed prior to feeding
-BM less likely to cause allergy
-breast feeding allows sense of closeness bet baby & mother- helps emotional & psychological development

conception-fertilisation, contraception- prevention of pregnancy despite sexual intercourse

Natural method
Rhythm method (safe-period method) based on fact that in every cycle there is a fertile period when ovulation is most likely to occur, avoid pregnancy: intercourse avoided during fertile period, egg survive ~2 days in female reproductive tract, fertile period my be from 12th - 16th day from beginning of menstruation, women have to keep regular records of menstrual cycle & also daily temp for whole cycle, body temp higher at time of ovulation, unreliable- factors (emotional stress, illness, diet, anxiety, tension) alter length of menstrual cycle, unsuitable for women w/ irregular menstruation

Mechanical method
Condom/ sheath- thin rubber tube: cover erect penis before intercourse- collects semen, reliable if used properly (semen doesn't escape before put on or after taken off), helps to protect user against contracting a veneral diseases, STD's (gonorrhoea, AIDS, syphilis)
Diaphragm- dome-shaped rubber cap w/ elastic rim, inserted into top of vagina, placed over cervix, prevents sperms entering uterus (spermicidal cream can be applied to cap > more effective), effective if used & fitted correctly
Intra uterine device, IUD- coil or loop of plastic inserted into uterus- prevent implantation of egg into uterine wall

Chemical method
Spermicides- chemicals that kill sperms (jelly, cream, foam/ tablet) placed high into vagina before intercourse
Contraceptive pills- contain female sex hormones (oestrogen & progesterone-like hormones) that prevent ovulation (FSH level high - no ovulation), 1 pill must be take every 24 hours from 5th to 25th day from onset of menstruation, stop taking pill for menstruation to occur, start taking pill again on 5th day from start of menstruation, very reliable (~100%) if taken properly, side effects may develop- obesity, hypertension, nausea, cancer- take for long time (pills stop implantation, ovulation or both)

Surgical methods
done by sterilisation of (fe)male (most reliable contraceptive method but is irreversible for females only)
Male: vasectomy- sperm ducts (vasa deferentia) cut & tied back, prevents sperms > penis > no sperms in discharged
(sexual characteristics not affected as testosterone still secreted by testes)
Female: tubal ligation / laparotomy- oviducts (fallopian tubes) cut & tied back, prevents sperms from reaching egg

Sexually transmitted diseases, STD
incubation period: time bet pathogen entering body & signs (observed & measured) & symptoms (felt by patient) appearing, hours - years, longer incubation period- more harmful

Gonorrhoea (caused by bacterium, affect reproductive system)
Signs and symptoms: yellowish discharge of pus due to inflammation of urethra, burning sensation of urinating, man- narrowing of urethra > difficulty in urination , women- infection may spread from urethra & vagina to uterus & fallopian tubes > sterile

Syphillis (caused by corkscrew-shaped bact- spirocheate), occurs in 3 stages
Stage 1: ~ 3 weeks after infection, painless sore or chancre appears at site of entry of bacterium (penis or in vagina or on cervix), chancre may disappear in a few weeks even w/o treatment
Stage 2: ~2-6 months after infection, signs appear on diff parts of body, non-itchy skin rashes, sores on mouth, throat and genitals, bald patches may appear on head, lymph glands may become swollen, pain in joints, signs disappear after some time but bacteria remains dormant until 3rd stage
Stage 3: internal organs affected, liver damage, patients may suffer from heart failure and blindness, brain and spinal cord may be damage, > paralysis, insanity and even death
Syphilis can be cured at all stages if treated

Method of transmission of syphilis and gonorrhoea: through intercourse w/ infected person
Prevention & control of syphilis and gonorrhoea: antibiotics (penicillin) to treat patient, infected person should refrain from intercourse, tracing contacts w/ whom patient has had intercourse > treating involved, male wearing condom (only reduces chance of STD's), discourage promiscuous sexual behaviour and keep to one sex partner

AIDS- acquired Immuno Deficiency Syndrome
Caused by virus, HIV- human immuno-deficiency virus, HIV destroys body's immune system that protects person from infection > unable to produce sufficient antibodies to provide immunity needed to protect against other diseases
Signs and symptoms: chronic fever, severe diarrhoea lasting for months, pneumonia, Kaposi's sarcome (cancer of blood vessels), brain infection, widespread tuberculosis affecting many organs at same time, AIDS is a syndrome as it causes many signs occurring at same time, AIDS victims usually die within 2 years
Modes of transmission: sexual intercourse w/ infected person, sharing injection needles w/ infected persons, blood transfusion w/ blood from infected person, during pregnancy the virus may pass from infected mother to foetus
Prevention and control: keeps to 1 sex partner, use of condom (only reduces chances), avoid drug abuse (> sharing hypodermic needles), avoid sharing instrument that are likely to break skin and be contaminated w/ blood, go to reliable operators for acupuncture, ear-piercing, tattooing (make sure needles used are sterilised or are disposable)

Genetics
Cell Strcuture and Organisation
Enzymes
Animal and Plant Nutrition
Transport in Plants and Transpiration
Support, Movement and Locomotion
Transport in Man
Respiration
Excretion
Homeostasis
The Eye
Nervous System
Chemical Control of Plant Growth
The Use and Abuse of Drugs
Diversity of Organisms
Nutrient cycles and Ecology
Parasitism
The Human Impact on the Environment
Reproduction in plants

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