ch 10: diseases and immunity

• what is a pathogen?

  A microorganism that causes disease
• four types of pathogens

  viruses, bacteria, protoctists and fungi
• how do pathogens enter the body?

  direct contact and indirect contact
• direct contact definition


  disease-causing microbe is passed from one person to another when their bodies touch in some way..
• indirect contact definition


  when microorganisms are carried to a person in some way, for example through respiratory passage/food and water/vector
• vector transmission


  transmission of an infectious agent by an insect, arthropod, or animal
• food transmission


  eating raw or undercooked food or drinking contaminated water (who does that?!) e.g. salmonella
• transmissible disease


  a disease in which the pathogen can be passed from one host to another
• mechanical barriers examples


  definition (in case you don't know) a physical barrier in order to prevent pathogens from entering our body.

  example: skin, NOSE HAIR LOL
• chemical barriers


  chemical substances in the body which help to trap or destroy pathogens

  example: mucous and stomach acid
• what are the chemical substances on the surface of all cells called?

  antigen
• what proteins do lymphocytes produce?

  antibodies
• What are antibodies?


  proteins which attacks the antigens of pathogens that invade the body by binding onto the antigens
• how does the body defend against pathogens?

  - the lymphocyte scans the pathogen and starts to divide (via mitosis), making a clone (this takes time)

  - It then secretes antibodies (not all produces antibodies, some remain in the blood) that has a complementary to the antigen on the pathogen

  - The antibodies bind with the antigen and destroys it
• what cells produces antibodies?

  white blood cells
• why is it important that newborn babies need to have antibodies?

  - provides passive immunity

  - protects against infection

  - immune system of babies have not fully developed
• difference between antigen and antibody

  antigen is a foreign substance found on pathogens while antibody is a protein molecule produced by your immune system to attack and fight antigens
• how can a person develop active immunity?

  having the disease and recovering from it.

  antibody is created in response of body defense.
• what is passive immunity?


  short-term defense against a pathogen by antibody

  example: breastfeeding
• what is active immunity?

  make their own antibodies and memory cells; long term defense against a pathogen

  example: being vaccinated with dead or weakened cells
• phagocytosis


  1. the phagocytes moves towards the pathogen

  2. membrane extends to engulf the pathogen

  3. the pathogen is enclosed into the vacuole

  4. the pathogen(s) are destroyed in the vacuole by a digestive enzyme called lysozyme. The destroyed particles enter the cytoplasm

  
• all transmissible diseases are caused by (1), which are passed from one (2) to another. (what are 1 and 2?)

  (1) - pathogens

  (2) - host
• what are memory cells

  cells that can spring into action at a moment's notice to make antibodies and stop the infection of the pathogen.
• how does cholera toxin causes diarrhea? (6 points)

  1. cholera bacteria are ingested and multiply

  2. the bacteria attaches to the wall of the alimentary canal

  3. the bacteria release toxin

  4. the toxin causes chloride ion to be released

  5. the release of chloride ions causes water to move into the small intestine by osmosis (water movement from high to low region) [as the water potential in SI is low and water potential in the blood is higher]

  6. there is now a lot of water in the canal and too little chloride ion and water in the blood