module 4: communicable diseases

• pathogen

  microorganism that causes disease
• types of pathogen that cause communicable diseases

  bacteria

  viruses

  fungi

  protoctista
• bacteria

  -enter host + multiply rapidly

  -damage cells // release waste products/toxins
• viruses

  -invade living cells

  -take over genetic machinery inside cell = replicate

  -host cell bursts releasing many new viruses - infect healthy cells
• fungi

  -hyphae grow under skin

  -reproductive hyphae grow to skin surface = releases spores = redness + irritation 

  -lives in vascular tissues (nutrients)

  -hyphae release extracellular enzymes = digests surrounding tissue = decay

  e.g. celluloses released digest cellulose in plant cell walls
• protocista

  -enter host cell + feed on contents as they grow
• tuberculosis:

  -what is it?

  -what causes it?

  -method of transmission?

  -kills cells + tissues - mainly in lungs

  -bacteria

  -direct -  droplets in air