Communicable disease

  • Created by: 5mjduodu
  • Created on: 20-03-19 19:04
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  • Communicable disease
    • Health
      • Healthiness
        • a state of physical, mental and social well-being
      • Communicable diseases
        • infectious diseases caused by pathogens
          • pathogens allow diseases to be transmitted, which lets the disease be passed on within a species or between species
          • pathogens are microorganisms which cause disease
            • bacteria
            • viruses
            • fungi
            • protists
          • we come in contact with the pathogen which causes the disease
            • bacteria multiply rapidly and damage cells by producing toxins
              • a toxin is a poison produced by a living organism
                • a poison is a substance that has a noxious effect on living organisms
      • Mechanisms of disease being spread
        • air
          • infection caused by airborne transmission
            • coughing, sneezing, talking or spores on a breeze
        • direct contact
          • infection caused by contact and faeces
            • sexually transmitted, cuts, scratches or via vectors
        • water
          • infection caused by contaminated water
            • fungal spores in splashing matter or water contaminated with faecal matter
    • Growing micro-organisms
      • Growth of micro-organisms in the lab
        • suspension of bacterial cells in spread on a petri plate with agar gel and incubated for 1-2 days until there are visible colonies which are each a clone of the corresponding single cell
          • the cells are incubated at 37 degrees C, the  average human body temperature which provides an ideal bacterial reproduction climate
      • Precautions for safely growing bacteria
        • sterile agar or nutrient broth
          • avoid contact with other bacterias
        • sterilise inoculating loop or spreader
          • any spore can get on them if they are exposed
        • bunsen burner on and working close to it
          • air goes into the flame so less will settle on the equipment
        • lifting the lid at an angle and for minimal length of time
          • prevent bacteria settling from the air
        • keep lid in place with two pieces of tape
          • allows oxygen in while keeping lid secure and keeps bacteria in and others out
          • if plate is completely sealed oxygen cannot get in so no aerobic respiration pathogens can form
    • Semmelweis and cleanliness
      • Ignaz Semmelweis
        • doctor who worked in the maternity units of hospitals
          • 30 percent of women died giving birth as doctors helping with births would cut up dead bodies and not wash their hands after, and women would have open wounds from birthing tears and die from infection
            • when only midwives assisted with birthing less that 1 percent of women died, showing that dirty conditions contributed to the deaths
          • Pasteur proved that microbes cause decay and Lister made the connection between microbes and dirty conditions
          • he used carbonic acid to wash everything as well as heat, steam and pressure and had lots of success preventing illness
    • Pathogens
      • Pathogens are micro-organisms which cause disease
      • Viral diseases
        • measles
          • fever, red skin rash
            • transmitted by inhalation of droplets from coughs and sneezes
        • HIV
          • mild flu-like illness
            • transmitted by direct sexual contact in exchange of body fluids or a mother to a child in breast milk
        • colds
          • sore throat, runny nose, cough and sneezing, mild fever
            • transmitted by inhaling airborne virus after infected individuals cough or sneeze
        • influenza
          • fever, cough, sore throat, runny nose, fatigue, muscle and headache
            • transmitted by inhalation of droplets from coughs and sneezes
        • tobacco mosaic
          • mosaic pattern of discolouration on leaves
            • transmitted by contact between diseased and healthy plants material or insects acting as vectors
      • Bacterial diseases
        • salmonella
          • fever, abdominal cramps, vomiting, diarrhoea
            • transmitted by eating under-cooked food or food prepared in unhygenic conditions where it is contaminated
        • gonorrhoea
          • thick yellow discharge from vagina or penis, pain on urination
            • transmitted by unprotected sexual contact with an infected person
        • crown gall
          • mass of unspecialised cells growing between plant root and shoot
            • transmitted by bacteria inserting plasmids into plant cells
      • Fungal diseases
        • athlete's foot
          • itching, stinging and burning on the feet, blisters, cracking and peeling soles
            • transmitted by direct contact with the infection or skin particles left on towels, shoes and floors
        • rose black spot
          • purple or black spots on leaves
            • spores are spread by wind and drops of water splash on plants
    • Malaria and plant diseases
      • Malaria process
        • female anopheles mosquito takes a blood meal from a human and injects saliva containing the material protist into their blood
          • the plasmodium travels to the liver and reproduces
            • the plasmodium breaks out of the liver and injects the red blood cells
              • as it spreads it bursts the red blood cells causing the symptoms seen with the disease
                • another mosquito takes a blood meal from the infected person
                  • the protist reproduces in the mosquito and ends up in its saliva
                    • female anopheles mosquito takes a blood meal from a human and injects saliva containing the material protist into their blood
                      • the plasmodium travels to the liver and reproduces
                        • the plasmodium breaks out of the liver and injects the red blood cells
                          • as it spreads it bursts the red blood cells causing the symptoms seen with the disease
                            • another mosquito takes a blood meal from the infected person
                              • the protist reproduces in the mosquito and ends up in its saliva
        • Plant diseases
          • APHIDS are asexually-reproducing pests which feed on sugar-rich sap on trees in large colonies thus depriving the trees of products of photosynthesis and weaken and damage it
          • NEMATADE WORMS live in soil and feed on roots which damages them in the process
      • Plant defences
        • Physical barriers
          • leaf fall
            • deciduous trees lose leaves in autumn to take any pathogens with them
          • cellulose cell walls are strong
          • bark on trees and layer of dead cells on stems
            • pathogens lost when dead cells are shed
          • tough waxy cuticle on leaf surfaces
        • Adaptive barriers
          • poisons
            • deter herbivores
              • foxgloves, deadly nightshade yew
          • thorns
            • unpleasant or painful to eat
              • brambles, cacti, gorse
          • hairy stems and leaves
            • deter larger animals from feeding or laying eggs on plants
              • lamb's ears, pelargoniums
          • drooping or curling when touched
            • dislodging insects and frightening larger animals
              • mimosapudica
          • mimicry
            • drooping to mimic unhealthy plants so animals do not eat them

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