Analyse responses to the presence of pathogens

Analyse responses to the presence of pathogens by assessing the physical and chemical changes that occur in the host animals cells and tissues (ACSBL119, ACSBL120, ACSBL121, ACSBL122)

Responses to presence of pathogens:

Inflammation:

  • Inflammation is one of the first responses of the immune system to infection.
  • The inflammatory response is characterized by the following symptoms:
    • Redness of the skin, due to locally increased blood circulation
    • Heat, either increased local temperature, such as a warm feeling around a localized infection, or a systemic fever
    • Swelling of affected tissues, such as the upper throat during the common cold or joints affected by rheumatoid arthritis
    • Increased production of mucus, which can cause symptoms like a runny nose or a productive cough
    • Pain, either local pain, such as painful joints or a sore throat, or affecting the whole body, such as body aches
    • Possible dysfunction of the organs or tissues
  • Common cytokines include interleukins that are responsible for communication between white blood cells, chemokines that promote chemotaxis and interferons that have anti-viral effects, such as shutting down protein synthesis in the host cell. Growth factors and cytotoxic factors may also be released. These cytokines and other chemicals recruit immune cells to the site of infection and promote healing of any damaged tissue following the removal of pathogens.

The Complement System:

  • A series of biochemical reactions that occurs during pathogen invasion and these reactions have the capability of killing pathogens by antibodies.
  • In humans, this response is activated by complement binding to antibodies that have attached to these microbes or the binding of complement proteins to carbohydrates on the surfaces of microbes. This recognition signal triggers a rapid killing response and the speed of the response is a result of signal amplification that occurs after sequential proteolytic activation of complement molecules, which are also proteases.
  • Some important phases in the complement system includes:
    • Opsonization:
      • Opsonization is a process in which foreign particles are marked for phagocytosis.
      • All of the pathways require an antigen to signal that there is a threat present.
      • Opsonization tags infected cells and identifies circulating pathogens expressing the same antigens.
    • Chemotaxis:
      • Chemotaxis is the attraction and movement of macrophages to a chemical signal.
      • This process is mediated by cytokines and chemokines to attract macrophages and neutrophils to the site of infection, ensuring that pathogens in the area will be destroyed.
      • By bringing immune cells to an area with identified pathogens, it improves the likelihood that the threats will be destroyed and the infection will be treated.
    • Cell Lysis:
      • Lysis is the breaking down or destruction of the membrane of a cell.
      • The proteins of the complement system puncture the membranes of foreign cells, destroying the integrity of the pathogen and weakening their ability to proliferate, putting a stop in spreading infection.
    • Agglutination:
      • Agglutination uses antibodies to cluster and bind pathogens together.
      • By bringing as many pathogens together in the same area, the cells of the immune system can mount an attack and weaken the infection.

Extract from HSC Biology Stage 6 Syllabus. © 2017 Board of Studies NSW.

EasyBio > Infectious Disease > Responses to Pathogens > Analyse responses to the presence of pathogens

Analyse responses to the presence of pathogens by assessing the physical and chemical changes that occur in the host animals cells and tissues (ACSBL119, ACSBL120, ACSBL121, ACSBL122)

Responses to presence of pathogens:

Inflammation:

  • Inflammation is one of the first responses of the immune system to infection.
  • The inflammatory response is characterized by the following symptoms:
    • Redness of the skin, due to locally increased blood circulation
    • Heat, either increased local temperature, such as a warm feeling around a localized infection, or a systemic fever
    • Swelling of affected tissues, such as the upper throat during the common cold or joints affected by rheumatoid arthritis
    • Increased production of mucus, which can cause symptoms like a runny nose or a productive cough
    • Pain, either local pain, such as painful joints or a sore throat, or affecting the whole body, such as body aches
    • Possible dysfunction of the organs or tissues
  • Common cytokines include interleukins that are responsible for communication between white blood cells, chemokines that promote chemotaxis and interferons that have anti-viral effects, such as shutting down protein synthesis in the host cell. Growth factors and cytotoxic factors may also be released. These cytokines and other chemicals recruit immune cells to the site of infection and promote healing of any damaged tissue following the removal of pathogens.

The Complement System:

  • A series of biochemical reactions that occurs during pathogen invasion and these reactions have the capability of killing pathogens by antibodies.
  • In humans, this response is activated by complement binding to antibodies that have attached to these microbes or the binding of complement proteins to carbohydrates on the surfaces of microbes. This recognition signal triggers a rapid killing response and the speed of the response is a result of signal amplification that occurs after sequential proteolytic activation of complement molecules, which are also proteases.
  • Some important phases in the complement system includes:
    • Opsonization:
      • Opsonization is a process in which foreign particles are marked for phagocytosis.
      • All of the pathways require an antigen to signal that there is a threat present.
      • Opsonization tags infected cells and identifies circulating pathogens expressing the same antigens.
    • Chemotaxis:
      • Chemotaxis is the attraction and movement of macrophages to a chemical signal.
      • This process is mediated by cytokines and chemokines to attract macrophages and neutrophils to the site of infection, ensuring that pathogens in the area will be destroyed.
      • By bringing immune cells to an area with identified pathogens, it improves the likelihood that the threats will be destroyed and the infection will be treated.
    • Cell Lysis:
      • Lysis is the breaking down or destruction of the membrane of a cell.
      • The proteins of the complement system puncture the membranes of foreign cells, destroying the integrity of the pathogen and weakening their ability to proliferate, putting a stop in spreading infection.
    • Agglutination:
      • Agglutination uses antibodies to cluster and bind pathogens together.
      • By bringing as many pathogens together in the same area, the cells of the immune system can mount an attack and weaken the infection.

Extract from HSC Biology Stage 6 Syllabus. © 2017 Board of Studies NSW.