biology-immunology

• how are infectious diseases caused

  -by pathogens that spread from organism to organism
• what is a pathogen

  bacteria, viruses,parasites and fungi
• how are diseases transmitted

  through air droplets,diect contact,via food or water or via a vector
• what is a vector

  the transmission from a person to person via another organism such as a mosquito or typhoid mary
• what is an antigen

  foregin proteins that enter the body. they trigger an immune response. they bind to antibodies ia the epitopes
• what are some of the bodies defences

  skin

  white blood cells

  mucous membranes

  antibodies and lymphocytes
• describe active immunity

  where resistance is built up as a result of the body's contact with micro-organisms and their toxins.

  this can be acquired by getting a vaccination
• describe passive immunity

  the direct transfer of antibodies betweenmother and foetus

  tempoary protection
• what is anivenom 


  an exampel of passive immunity

  antibodies that are transferred from animals to humans

  provides protection from venom in snake bites
• how are immune cell developed

  they all develop in the bone marrow and some travel to other areas of the body to mature
• name some white blood cells

  macrophages: phagocytosis

  neutrophills: phagocytosis

  basophils: allergic reactions

  eosionophils:attack invaders

  NK cells: killing of viral infected cells

  lymphocytes:formation of T-cells from B-cells
• describe neutrophills

  they patrol tissues as they squeeze out of capillaries

  trap bacteria and engluf bacteria found inside tissues

  die after digestion of bacteria

  make up a large proportion of puss
• what are macrophages

  made in the bone marrow

  engulf pathogens foun outside of tissues

  called monocytes until they reach organs

  they can initiate an immune response as they deisplay antigens from engulfed pathogens on their surface to attract lymphocytes
• describe the lymphatic system

  Lymphoid organs include the spleen, thymus (where T-cells mature) and the lymph nodes

  They are connected to a network of vessels

  B and T lymphocytes circulate in the blood and lymph, they are ready to react with antigens

  If there is an infection the lymph nodes appear swollen.
• what is the non-specific immune response

  Physical, cellular, and chemical defences that prevent microbes from entering the body

  They are present from birth

  They are a quick response effective against a wide range of pathogens and foreign substances

  Does not distinguish between different pathogens

  Always gives the same immune response
• what are some of our bodies defense systems

  gastric juice destroys bacteria and toxins in the stomach

  acidic ph of the skin dicourages the growth of microbes
• what are some of the bodies non specific responses

  phagocytosis

  inflammation

  fever
• describe the humoral response

  -B-lymphocytes remain i and mature in the bone marrow then spread through the body

  -once matured they can make one type of antibody

  -this antibody presents itself on the surface of the B-lymphocyte

  -if an antigen enters the body it will bind to the specific antibody on the B-lymphocyte

  -the B-lymphocytes then divide into plasma(secrete specific antibodies to bind with the antigen) and memory cells
• what are vaccinations

  -they are used to trigger an immune response

  -involves a dead or inactive version of pathogens
• what is the structure of an antibody

  -produced by B cells

  -made from 4 polypeptides to form a Y shape

  -heavy chain decides what antibody is present
• what is agglutination

  make the pathogens clump together
• what is neutralisation

  neutralises the toxins produced by bacteria
• what is oposonisation

  it coats the pathogen in a protein that identifies it as a foreign cell
• what is the cell-meditated response

  • immature T-cells mature in the thymus
  • cytoxic T cells bind to an infected cell and perforin makes holes in the plasma membrane so other proteins can enter the infectious cells
  • helper t cells bind to the proteins on the surface of macrophages and divides to produce cytotoxic t cells and b cells

  -suppressor t cells shut down response when no longer needed. They reduce the activity of other t cells when they are not needed

  -memory t cells respond to antigens previously experienced a faster immune response
• how does the immune system resond to allergies

  • When the immune system responds to harmless substances such as house dust, animal skin, pollen, and faeces
  • Histamine cause blood vessels to widen and become leaky
  • Fluid and white blood cells leave capillaries
  • The area of leakage becomes hot red and inflamed
• what are autoimmune diseases

  • Immune system fails to distinguish between self and non self-cells
  • Causes of these diseases are mostly unknown but can involve genetics or the environment.
  • They can also be triggered by viruses
  • examples include diabetes type 1, MS and rheumatoid arthritis