bio chp#06

• Reproduction


  The process by which living things produce more of their own kind
• Reproduction


  • It is vital for the life of an organism itself
  • It is much more important for the continuity of its race
  • It is the process of continuation of life with a fresh start
  • It performs the function of transmission of genetic information from one generation to the next
• Main ways of reproduction

  • Asexual reproduction
  • Sexual reproduction
• Asexual reproduction


  A new organism is formed from just one parent without the participation of mate, gamete or fertilization
• Sexual reproduction


  Involves sex cells, the gametes. A male gamete, the sperm, fused with a female gamete, the ovum, to form zygote which undergoes development and a new individual is formed
• Asexual reproduction


  • The offspring produced are the exact copies and thus identical to their parents
  • No variations are seen because all the offspring are genetically identical to their parents
• Sexual reproduction


  • Leads to genetic diversity and adaptability
• Stages of reproductive process

  • Gametogenesis
  • Mating
  • Fertilization
  • Embryonic development
  • Birth or hatching of new individuals
• Hormones


  Regulate reproductive events
• Cellular differentiation


  Regulates reproductive events
• Morphological changes


  Regulate reproductive events
• Human beings are unisexual or dioecious or heterophrodite, they are either male or female having testes and ovaries respectively in body
• The male reproductive system generates and delivers sperm to the female reproductive system
• The female reproductive system produces and prepares eggs for fertilization and provides support for fetal development during pregnancy
• Testes


  Organs that produce sex cells, where sperms are produced
• Scrotum


  A pouch of skin located outside of the abdomen between the thighs that maintains the testes at around 34°C, slightly lower than the body temperature (37 °C)
• Seminiferous tubules


  Make up most of each testis, the sertoli cells in the tubules are responsible for the production of sperm, process of sperm production is called spermatogenesis
• Epididymis


  Sperm cells move towards it through the rete testis after being produced in the seminiferous tubules, sperm cells are kept in the epididymis until they are ready for ejaculation and are fully developed
• Ductus deferens


  A thick-walled tube that carries sperm from the epididymis, where the sperm are stored before being released during ejaculation
• Ampulla


  An expanded part of the ductus deferens that serves as a reservoir
• Ejaculatory duct


  One of two hollow tubes created by joining the excretory duct of a seminal vesicle and the ampulla of a ductus deferens, serves to combine the sperm deposited in the ampulla with the fluids generated by the seminal vesicles and transfer these substances to the prostate
• Urethra


  A common tube for the urinary and reproductive discharge
• Penis


  The male external genitalia and copulatory organ, consists of glans, shaft, and root
• Scrotum


  The male external genitalia, protects the testes and keeps them at a temperature several degrees below the normal body temperature
• Each ejaculation of human male averages between 2 and 5 ml and normally contains 200 to 300 million sperms
• Accessory glands of male reproductive system

  • Seminal vesicles
  • Prostate gland
  • Bulbourethral glands
• Spermatogenesis


  The process of sperm production
• Stages of spermatogenesis


  1. Spermatogonia (2n) undergo mitosis

  2. Spermatogonia transform into primary spermatocytes (2n)

  3. Meiosis I divides primary spermatocytes into secondary spermatocytes (n)

  4. Meiosis II divides secondary spermatocytes into spermatids (n)

  5. Spermatids undergo spermiogenesis to become mature spermatozoa
• Testosterone


  The primary male sex hormone produced by the testes, plays a crucial role in the development and maintenance of male reproductive tissues and secondary sexual characteristics, stimulates sperm production
• Follicle-Stimulating Hormone (FSH)


  Produced by the pituitary gland, promotes the development and maturation of sperm cells within the seminiferous tubules of the testes, stimulates the production of proteins necessary for sperm production
• Inhibin


  A peptide hormone released from sertoli cells of testes, which inhibits the secretion of follicle stimulating hormone
• Luteinizing Hormone (LH)


  Produced by the pituitary gland, stimulates the production of testosterone by the Leydig cells in the testes, triggers the release of testosterone into the bloodstream
• Gonadotropin-Releasing Hormone (GnRH)


  Produced in the hypothalamus, stimulates the release of FSH and LH from the pituitary gland, its secretion is regulated by a negative feedback loop involving testosterone levels
• The female reproductive system comprises four main parts: the ovaries, oviducts, uterus, and vagina
• Ovaries


  The female gonads, each ovary contains many follicles, a follicle consists of one egg cell surrounded by one or more layers of follicle cells, the cells of the follicle produce the female sex hormone estrogen
• Oviducts (fallopian tube or uterine tube)

  The open end of the oviduct is fringed with ciliated
• Female reproductive system


  • Ovaries
  • Oviducts
  • Uterus
  • Vagina
• Gonads (Ovaries)


  • Lie in the abdominal cavity, flanking, and attached with a mesentery to, the uterus
  • Each ovary is enclosed in a tough protective capsule and contains many follicles
  • A follicle consists of one egg cell surrounded by one or more layers of follicle cells, which nourish and protect the developing egg cell
  • Each female ovary potentially contains 200,000 follicles
  • Of these, only several hundred will release egg cells during the female reproductive years
  • Starting at puberty and continuing until menopause, usually one follicle matures and releases its egg cell during each menstrual cycle
  • The cells of the follicle produce female sex hormone called estrogen
• Oviducts (fallopian tube or uterine tube)


  • The open end of the oviduct is fringed with ciliated "fingers" called fimbriae that nearly surround the ovary
  • It has cilia on the inner epithelial linings they are where fertilization typically takes place and where the ovulated oocyte is received
  • The oviducts, which carry eggs from the ovary to the uterus, are each around 10 cm long
• Uterus


  • A muscular organ with an inverted pear form that lies between the bladder and the rectum
  • The uterus has three major regions: The fundus, the body and the cervix
  • The body, the main portion of the uterus, starts below the level of the fallopian tubes and continues downward until the uterine walls and cavity start to narrow
  • The lowest section, the cervix, extends downward from the isthmus until it opens into the vagina
  • The uterine wall is composed of three layers which are endometrium, myometrium and perimetrium
  • The endometrium is the inner epithelial layer, along with its mucous membrane it is richly supplied with blood vessels
  • The myometrium is the middle muscular layer of the uterine wall
  • The perimetrium is the outermost thin layer covers the uterus
  • The cervix is a narrow opening provides passage between the vaginal cavity and the uterine cavity