Lesson 3 medterm

• Cell damage (cell injury)


  Variety of changes of stress that cells suffer due to external as well as internal environment changes, can be due to physical, chemical, infectious, biological, nutritional, or immunological factors, can be reversible or irreversible
• Inflammation


  Standard initial response of the body to injury, limits the extent of injury, partially or fully eliminates the cause of injury
• Four signs of inflammation

  • Redness
  • Swelling
  • Pain
  • Local heat
• Cellular swelling


  First manifestation of almost all forms of injury to cells, causes pallor, increased rigour, and an increase in the weight of the organ
• Fatty change


  Second manifestation, the cell has been damaged and is unable to adequately metabolize fat
• Necrosis


  Irreversible damage to the plasma membrane, organelle breakdown leading to cell death
• Stages of cellular necrosis

  • Pyknosis (dumping of chromosomes and shrinking of the nucleus)
  • Karyorrhexis (fragmentation of the nucleus and break up of the chromatin)
  • Karyolysis (the dissolution of the cell nucleus, cytosolic components that leak through the damaged plasma membrane can incite an inflammatory response)
• Apoptosis


  The programmed cell death of superfluous or potentially harmful cells in the body, an energy dependent process mediated by proteolytic enzymes called caspases
• Infection


  The invasion of tissues by pathogens, also known as a transmissible disease or communicable disease
• Types of bacteria

  • Spheres or ball shaped (cocci)
  • Rod shaped (bacilli)
  • Spiral shaped (spirochetes)
• Viruses


  Pieces of genetic information (DNA or RNA) inside of a protective capsid
• Steps to infecting cells and reproducing

  1. Attachment

  2. Entry

  3. Replication

  4. Assembly

  5. Release
• Virus entry


  Receptor binding, direct fusion, bacteriophages inject genetic material
• Virus replication cycles

  • Lytic cycle (uses host cell machinery to make more copies)
  • Lysogenic cycle (dormant or silent phase, triggered by stress, chemical signals, or temperature changes)
• Virus shapes

  • Icosahedral or polyhedral
  • Helical
  • Spherical
  • Complex (polyhedral "head", helical "body")
• Virus size


  Too small to see without a strong microscope, between 20 nm (nanometers) to 400 nm
• Genomic properties of viruses

  • DNA or RNA (linear or circular, positive sense or negative sense)
  • Single stranded or double stranded
• Major groups of parasites

  • Fungi (microscopic yeasts, macroscopic filamentous mold)
  • Protozoa (free living or parasitic, can multiply in humans)
  • Helminths (large, multicellular organisms visible to the naked eye, cannot multiply in humans)
• Protozoa infectious to humans

  • Sarcodina (the amoebas, Entamoeba)
  • Mastigophora (the flagellates, Giardia, Leishmania)
  • Ciliophora (the ciliates, Balantidium)
  • Sporozoa (Plasmodium, Cryptosporidium)
• Main groups of helminths

  • Flatworms (trematodes, cestodes)
  • Thorny headed worms (acanthocephalins)
  • Roundworms (nematodes)
• Ectoparasites


  Blood sucking arthropods such as mosquitoes
• Prion disease


  Rare progressive neurodegenerative disorders that affect both humans and animals, caused by abnormal pathogenic agents that are transmissible and able to induce abnormal folding of specific normal cellular prion