Specific Immune Response Flashcards
Where are B cells produced?
Bone marrow
Where do B cells mature?
Bone marrow
Explain the activation of B cells - 7
- B cells are covered in antibodies
- Antibodies bind to antigens to form antibody-antigen complex
- Each B cell has different shaped antibodies so each will bind to a different complementary antigen
- Activated T helper cell with complementary receptors binds to APC
- Produces cytokines that stimulate B cell
- B cell divides by mitosis to form B memory cell and plasma cells
- Plasma cells release antibodies
What are the 4 types of antibody defence?
- Phagocytosis
- Aggulating pathogens
- Neutralising toxins
- Preventing pathogen binding
Explain how antibodies are involved in phagocytosis 2
- Antibodies bind to antigens and label them
- Macrophage engulf antibodies and pathogen and phagocytosis occurs
Explain how antibodies neutralise toxins 3
- Antibodies bind to toxins from pathogens
- Prevent toxins from affecting human cells so toxins are neutralised
- Toxin-antibody complexes phagocytosised
Explain how antibodies prevent pathogen binding 3
- Antibodies bind to antigens on pathogens
- Blocks cell surface receptors
- Pathogens cannot bind to host cells to infect them
What are antibodies made up of?
- 4 polypeptide chains
- Two heavy chains
- Two light chains
- Each chain made up of variable region and constant region
- Each heavy chain has a hinge region
What are the variable regions in antibodies?
- Antigen binding sites
- Different amino acid sequence so different shape for each antibody
- Complementary to particular antigen
What are the hinge regions in antibodies?
Areas allowing flexibility for when antibodies bind to antigens
What are the constant regions in antibodies? 2
- Regions for binding to receptors on immune system cells e.g phagocytes
- They all have the same amino acid sequence so same shape
What holds the polypeptide chains in an antibody together?
Disulphide bridges
Give the 2 types of antibody
- Membrane bound
- Secreted
What are membrane bound antibodies?
Antibodies attached to the membrane of a B cell
What do membrane bound antibodies have that secreted antibodies do not?
Extra section of protein in the heavy chain anchoring them to the B cell membrane
What are secreted membrane bound antibodies?
Antibodies free from any attachment to a B cell
What is the same between membrane bound antibodies and secreted antibodies?
Both heavy chain proteins are coded for by a single gene copied into mRNA for protein synthesis
Explain how antibodies are specific to each antigen - 5
- Antibodies are proteins
- They have a specific primary structure
- Specific tertiary structure
- Antibodies are complementary to antigens
- Form antibody-antigen complex
Where are T cells produced?
Bone marrow
Where do T cells mature?
Thymus gland
Explain the activation of T cells - 5
- Pathogen engulfed by macrophage
- Macrophage presents antigens on surface - becomes APC [antigen presenting cell]
- T helper cell CD4 receptors bind to complementary antigens
- T helper cell is activated
- Divides to produce clones: T memory cells and active T helper cells
Explain the activation of T killer cells - 9
- Infected cell presents antigens of pathogen becomes APC
- T killer cell with complementary receptors bind to APC
- Cytokines from T helper cells stimulate T killer cell division
- T killer cells divide to form 2 clones: active and memory T killer cells
- Active T killer cells bind to infected cells presenting antigens
- T killer cells release an enzymes that create pores in infected cell membrane
- Ions and water flow in - cell swells and bursts in lysis and dies
- Releases pathogens in cell
- Can be labelled by antibodies from B cells as targets for destruction by macrophages
What are the 3 types of T cell?
- T helper cells
- T killer cells
- T memory cells
What are T helper cells?
On activation they:
- Stimulate B cells to divide and produce antibodies
- Release cytokines that stimulate enough active T killer cells to fight infection
What are T killer cells?
T cells destroying any cells with foreign antigens
What are T memory cells?
T cells that will recognise the specific antigens if the same pathogen returns
