reproductive system

• If fertilization occurs, the embryo implants itself into the wall of the uterus and develops into a fetus.
• Reproduction is one of the ubiquitous properties of life
• The ability of organisms to reproduce to form their own kind is the one characteristic that best distinguishes living things from nonliving matter
• Asexual reproduction


  The process resulting in the production of genetically identical offspring from one parent, occurring without gametes or fertilization
• Basic forms of asexual reproduction

  • Fission (binary and multiple)
  • Budding
  • Fragmentation
• Asexual reproduction in flowering plants

  • Vegetative propagation
  • Stolon of strawberry plant - horizontal stem that grows above ground, takes root at nodes and produces new plants
  • Rhizomes, corms, bulbs and tap root may store food, used to accelerate early growth
• Sexual reproduction


  The process involving the fusion of the nuclei of two gametes to form a zygote and the production of offspring that are different from each other
• Male gamete


  • Small and mobile
• Female gamete


  • Larger and not often mobile
• Female gamete of an animal

  Egg
• Fertilization


  The fusion of gamete nuclei
• Fertilization


  1. Sperm enters an ovum

  2. Sperm and egg nuclei join up (fuse)
• Zygote development


  1. Fertilized egg (zygote) divides into many cells

  2. Becomes embedded in the lining of the uterus

  3. Grows into an embryo
• Primary sexual characteristics in males

  • Penis
  • Scrotum
  • Testicle
• Primary sexual characteristics in females

  • Vagina
  • Uterus
  • Ovaries
• Secondary sexual characteristics in males

  • Growth and maintenance of the male sex organs
  • Increase in body hair
  • Increase in muscle mass
  • Increased growth of the long bones of the arms and legs
  • Deepening of the voice
• Secondary sexual characteristics in females

  • Increase in growth rates of the long bones of the arms and legs
  • Develop more hair, especially under the arms and in the pubic area
  • The hips broaden
  • More fat is deposited in the breasts, buttocks, and thighs
  • The menstrual cycle begins
• Young people must adjust to remarkable physiological, anatomical, and psychological transformations during the process of puberty
• Young people should realize that there is considerable variation in the timing of the stages of puberty among different individuals, and that most people develop into "normal" adults in the course of their sexual and physical maturation
• Adolescence


  The period between puberty and adulthood, when a good deal of social learning takes place
• Biologically, teenagers are adult after they have reached puberty, when they are capable of having children.  Economically, they are adult when they can support themselves and possibly a family.  Morally, they are adult when they are responsible for their actions, can express love in a mature manner, and can have productive and meaningful relationship
• Pituitary


  Releases follicle stimulating hormone (FSH) and luteinizing hormone (LH)
• FSH causes


  Ovarian follicle to begin maturing
• Follicle cells


  • Around an egg, which formed before birth, proliferate and secrete estrogens and progesterone
• LH triggers


  Ovulation of the egg
• Corpus luteum


  Secretes progesterone that primes the uterus for pregnancy
• When the corpus luteum breaks down

  Menstruation occurs
• Ovarian cycle


  Coordinated with cyclic changes in the uterus
• Menstrual cycle


  Approximately monthly changes in the uterus
• Sperm enters the cytoplasm of the egg

  Male nucleus of the sperm fuses with the female nucleus
• Fertilization


  The moment when the male and female nuclei fuse
• Biologically, teenagers are adult after they have reached puberty, when they are capable of having children.  Economically, they are adult when they can support themselves and possibly a family.  Morally, they are adult when they are responsible for their actions, can express love in a mature manner, and can have productive and meaningful relationship
• Identical (monozygotic) twins


  Twins that come from one zygote
• Non-identical (dizygotic, fraternal) twins


  Twins that come from two zygotes
• Fraternal twins do not resemble each other any more than other children born separately in the same family
• Identical twins are strikingly alike and always of the same sex
• Development of the placenta

  1. Ball of cells reaches the uterus

  2. Some cells form the placenta instead of the embryo organs

  3. Placenta becomes closely attached to the lining of the uterus

  4. Placenta is attached to the embryo by the umbilical cord
• Sexual intercourse can pass protozoan, bacterial and viral pathogens between partners
• Consequences of STIs

  Range from mild discomfort to sterility and systemic disease
• Protozoan and bacterial STIs

  Can be cured with antibiotics