Specific and Non-specific responces

• Non-specific defences:

  • physical defence -> epithelial cells create a physical barrier of closely packed cells, eg skin + linings of digestive and respiratory tracts
• Non-specific defences:

  • chemical secretions- protect against pathogens, eg tears, salive, mucus
• the inflammatory response is when mast cells release histamine in response to infection
• histamine causes vasodilation, increased blood flow, and increased blood pressure
• vasodilation caused by histamine:

  • increases clotting factors
  • allows phagocytes to release cytokines which attract more phagocytes and trigger specific responses
  • phagocytes recognise foreign antigens on a pathogen and destroy it by phagocytosis
• lymphocytes respond to specific antigens on a pathogen
• receptors bind to specific antigen, causes repeated lymphocyte division= clonal population -> some kept as memory cells
• after secondary exposure to an antigen, memory cells rapidly divide -> destroy pathogens before symptoms show
• the antibody concentration of the primary response is always less the the secondary responses
• T-lymphocytes are infected body cells displayed the antigen on their surface
• T-lymphocytes recognise and induce apoptosis (programmed cell death)
• T-lymphocytes bind to the infected cell -> release proteins which diffuse into the cell, causing release of self-destructive enzymes which cause cell death
• phagocytes remove cell remains
• autoimmune -> T-lymphocytes distinguish between self and non-self antigens
• if T-lymphocytes fail to distinguish it leads to autoimmune disease, T-lymphocytes respond to self-antigens and attack bodys own cells
• examples of autoimmune diseases:

  • type 1 diabetes
  • arthritis
• label the process of phagocytosis:

  A) phagocyte

  B) lysosome

  C) containing enzymes

  D) pathogen

  E) antigen

  F) engulf

  G) digest

  H) enzymes

  I) absorb

  J) products

  
• label the B-lymphocytes:

  A) B-lymphocytes

  B) antibody

  C) pathogen

  D) antigen

  E) antibody

  
• an antigen and and an antibody make an antigen-antibody complex
• B-lymphocytes produce specific antibodies to bind to antigens to inactivate pathogens and destroy infected cells by phagocytosisi
• antibodies possess receptor binding sites that are specific to a particular antigen on a pathogen
• B-lymphocytes give a hypersensitive response to harmless antigens eg pollen