Human Reproduction

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

MALE REPRODUCTIVE ORGANS

Vas deferens bladder urethra Seminal vesicle Prostate gland penis   urethra Seminal vesicle Prostate gland penis scrotum epididymis testes

Testes For production of male gametes (sperms) For production of male sex hormones (testosterone)

Epididymis A series of tubes For temporarily storage of sperms During copulation, muscles of epididymis contract to release sperms

Vas deferens A tube that carries sperm from epididymis to urethra

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

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

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 Seminal Fluid Semen Sperms +

Penis Erection- when the penis becomes engorged with blood and hard Ejaculation- release of semen out of the penis

  uncircumcised circumcised

FEMALE REPRODUCTIVE ORGANS

Female Reproductive System   Fallopian tubes ovaries uterus vagina

  bladder vagina clitoris

  clitoris urethra vulva Vaginal opening Inner labia Outer labia anus

Female Reproductive System Oviduct/ fallopian tube ovary uterus cervix vagina

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

Fallopian tubes Carries the ovum forward by the beating action of the cilia on its inner surface the contraction of muscles of oviduct

Uterus During embryo development During birth of baby 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

Ovulation The release of an ovum from an ovary occurs at around day 14

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 1 - 5 Menstruation (bleeding )occurs Uterine lining sheds and decreases in thickness to a minimum .

Menstrual Cycle Day 6 - 14 Lining becomes thicker with increased blood supply Day 14 : ovulation

Menstrual Cycle Day 14 - 28 Lining remains thick to ready for implantation of fertilized ovum

Menstrual Cycle Day 28 No implantation of fertilization ovum Uterine lining breaks down; menstruation starts

Female Hormones Pituitary Hormones: Follicle Stimulating Hormone: stimulates maturation of egg cells Luteinizing hormone: stimulates release of egg cell form ovary during ovulation Ovary Hormones: Oestrogens- from ovaries, development of sexual organs at puberty, role in ovulation Progesterone- from ovaries, thickens endometrium (lining of uterus), role in ovulation

Oestrogen

Ovulation Primary follicle matures ( at any one time there will be a number of them that are maturing and are at different stages) The most mature follicle and ova at the time of the LH surge release the ovum into the fallopian tube The “shell” corpus luteum is absorbed by the ovary if fertilisation does not take place in 48 hours of ovulation and the egg will disintegrate.

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

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

Functions of the Amniotic Fluid To keep the foetus moist to prevent desiccation 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

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

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