reproductive system

• Reproduction is the process by which an organism produces its own kind to continue its existence
• There are two types of reproduction: asexual and sexual
• Asexual reproduction: new organism develops from single parent, offspring are genetically identical to parent
• Sexual reproduction: new organism develops from fusion of male and female sex cells, forming a zygote
• Fusion of male and female gametes is called fertilization
• Zygote develops into an embryo, which develops into a baby, and eventually into an adult
• Organs involved in reproduction constitute the reproductive system
• Testis produce gametes or sperm in males, ovaries produce gametes or sex cells in females
• Testes and ovaries are primary sex organs
• Various organs, ducts, and glands essential for reproduction but do not produce gametes are called secondary sex organs or accessory reproductive structures
• Secondary sexual characters distinguish male and female sexes in external appearance but do not have a direct role in reproduction
• Male secondary characteristics: beard, moustaches, body hair, pubic hair, voice
• Female secondary characteristics: breast, body contour, broadening of pelvic bone
• Female Reproductive Organs
• Ovaries produce ova and female sex hormones estrogen and progesterone
• Ovulation is the release of ovum from the ovary
• Oogenesis is the process of ovum-producing cells giving rise to mature ovum
• Corpus luteum secretes hormones progesterone and estrogen, controlling reproductive cycle and maintaining pregnancy
• Oviducts or Fallopian tubes extend from ovaries to the uterus
• Uterus is a hollow pear-shaped muscular structure between the bladder and rectum
• Vagina is a narrow muscular canal opening to the outside through the vaginal opening
• Menstrual cycle is a monthly cycle associated with ovulation and menstruation
• Male Reproductive Organs
• Testes produce male gametes known as sperm and male sex hormone testosterone
• Testes are located in the scrotum to maintain a temperature a few degrees below normal body temperature
• Sperm production occurs in seminiferous tubules lined by germinal epithelial cells
• Mature sperm moves through seminiferous tubules and are stored in the epididymis
• Interstitial cells or Leydig’s cells produce male hormone testosterone
• Vasa deferentia is the passage through which the testis descend down before birth
• Urethra runs from the bladder through the penis to the outside of the body
• Accessory glands secrete fluids essential for reproduction but do not produce gametes
• Seminal vesicles secrete fluid constituting the major part of semen
• Prostate gland secretes thin, slightly alkaline fluid accounting for sperm mobility and viability
• Cowper’s glands secrete mucus lubricating the urethra
• Fertilization is the union of sperm nucleus and ovum nucleus to form a zygote
• Fertilization normally occurs in the Fallopian tube within 24 hours after ovulation
• Implantation is the attachment of the fertilized egg or embryo to the uterine wall
• Pregnancy is the period in which a female carries a baby before giving birth
• Gestation period lasts for 280 days in human pregnancy
• Placenta allows exchange of substances between maternal and foetal blood by diffusion