Sexual Reproduction in Human testis sperms ovary eggs (ova) zygote embryo foetus baby meiosis fertilization

Male Reproductive System testis epididymis vas deferens (sperm duct) Click here

Testes For production of male gametes (sperms) For production of male sex hormones Click here

Epididymis For temporarily storage of sperms During copulation, muscles of epididymis contract to release sperms Click here

Testis and epididymis sperm tubules epididymis vas deferens (sperm duct)

Male Reproductive System seminal vesicle prostate gland Cowper’s gland secrete seminal fluid

Functions of Seminal Fluid To provide a medium for the sperms to swim To activate and nourish the sperms To neutralize the acidity in the female reproductive tract

Male Reproductive System urethra penis

Penis Erected during copulation for insertion into vagina –Dilation of arterioles causes the erectile tissue of penis become turgid –Muscles of epididymis contract –Semen is squeezed from the penis to the top of vagina Ejaculation

Female Reproductive System Video of fertilization vagina cervix uterus oviduct ovary Click here

Functions of Ovary For production of female gametes (ova/eggs) For production of female sex hormones Click here

Oviduct Carries the ovum forward by –the beating action of the cilia on its inner surface –the contraction of muscles of oviduct Click here

Ovulation The release of an ovum from an ovary Video of ovulation Video of ovulation

Menstrual Cycle Once in about 28 days The uterine lining becomes thickened 14 days after ovulation to prepare for the fertilized ovum to implant in it

Menstrual Cycle Day –Menstruation starts –Uterine lining decreases in thickness to a minimum Day –Lining becomes thicker with increased blood supply –Day 14 : ovulation Day –Lining remains thick to ready for implantation of fertilized ovum Day 28 –No implantation of fertilization ovum –Uterine lining breaks down; menstruation starts Video on change in uterine lining

Events Happened after Fertilization Ovum is fertilized at the oviduct Fertilized ovum is carried to the uterus by –the beating cilia on the inner wall of oviduct –the contraction of muscles of oviduct After reaching the uterus, the fertilized ovum fixed firmly onto the thick uterine wall  Implantation

Development of Human Foetus uterus foetus placenta umbilical cord amnion amniotic fluid Click here Video on foetus development

Functions of the Uterus During embryo development –Protect the embryo –Provide a constant environment for the embryo to develop –Allow placenta to attach on During birth of baby – Push the baby out by muscular contraction Click here

Functions of the Amniotic Fluid To keep the foetus moist to prevent dessication As a water cushion to –support the foetus –allow it to move freely –absorb shock –protect the foetus from mechanical injuries To reduce temperature fluctuation To lubricate the vagina during birth Click here

The Placenta oxygenated blood from mother’s artery villus umbilical vein umbilical artery deoxygenated blood to mother’s vein

Functions of the Placenta As a place of exchange of materials between mother and the foetus For secreting hormones

Adaptations of the Placenta Finger-like villi – to increase the surface area for efficient diffusion Maternal blood and foetal blood flows in opposite direction –to speed up diffusion of materials between them Maternal blood capillaries and foetal blood capillaries are separated by thin membrane –to shorten the distance of diffusion of materials

Adaptations of the Placenta Maternal blood is separated from foetal blood by capillary wall –to prevent high pressure of maternal blood to break the delicate foetal blood vessels –to prevent harmful substances to enter the foetus –to prevent clotting of maternal and foetal blood if their blood groups are incompatible Click here

The Birth Process Onset of labour –Uterine muscles begin to make rhythmic contractions –Contractions gradually become stronger and closer

The Birth Process Dilation of cervix allow the head of the foetus to pass through Uterine contractions causes amnion to break and amniotic fluid to escape out of the vagina Muscular contractions push the foetus head first through the vagina, and the umbilical cord is cut and tied Further contractions push the placenta out of the body –“After birth”

Parental Care To increase the chance of survival of the young Mother feeds milk to the baby –Milk provides the babies with a balanced diet –It also contains antibodies which defend the babies against infection

Birth Control Human population increases exponentially –leads to storage of resources –problem of pollution becomes more serious –overcrowding

Rhythm Method Prevent copulation during 7 days before and after ovulation (fertile period)

Condom Male and female condom As a barrier to prevent sperms from entering the vagina

Diaphragm Fitted over the cervix To be used together with spermicides

Contraceptive Pills Contains hormones which inhibit ovulation Must be taken regularly May have side effect

Surgical Methods Vasectomy Cutting and tying of sperm ducts Tubal ligation Cutting and tying of oviducts