immunity

• type of white blood cell
• travel in blood
• non-specific                                          

1. phagocyte is attracted to the pathogen by chemoattractants - moves down a concentration gradient

2. the phagocyte binds to the pathogen

3. phagocyte engulfs pathogen = phagosome - lysosome moves towards it

4. lysosome releases lytic enzymes into phagosome - break down the pathogen by hydrolysis

5. break down products are absorbed by the phagocyte  

Type of white blood cell
Specific immune response

T Lymphocytes: (T-Cells)
1. Produced in Bone Marrow
2. Cell-mediated Immunity
3. Matured in Thymus Gland
4. Responds to foreign material inside body cells
5. Responds to own cells altered by viruses, cancer and transplanted tissue

B Lymphocytes: (B-Cells)
1. Produced & Matured in Bone Marrow
2. Humoral Immunity
3. Produces Antobodies
4. Responds to foreign material outside body cells (in body fluids/humour)
5. Responds to bacteria and viruses

1. Pathogen invades body cell/ is taken in by phagocytosis

2. Phagocyte/cell places anitgens from the pathogen on its surface (as a sign of distress)

3. Receptors on T helper Cells fit onto these antigens

4. This activates other T cells to divide by mitosis to form clones

5. The cloned T cells:

• Develop into memory cells
• Stimulate phagocytes
• Stimulate B cells (T killer cells produce protein to make holes in cell membrane)

1. The surface antigens of invading pathogens are taken up by B cells

2. B cells process and present the pathogens antigens

3. T helper cells attach to the anitgens on the B cells and therefore activate them to divide by mitosis - produces plasma cells and memory cells

4. Cloned plasma cells produce anitbodies that fit the antigens on the pathogens surface

5. Antibodies attach to antigens and destroy them = primary immune response

6.  Memory Cells respond to future infections by dividing rapidly and producing plasma cells and more memory cells = secondary immune response

Antibodies = proteins synthesised by B cells

Structure:

• 4 Polypeptide Chains - 2 are long = 2 heavy chains - 2 are short = 2 light chains
• Constant Region = inbetween heavy chains, same on every antibody, where receptors bind
• Variable Region = inbetween light chains, different on each antibody, where the antigen binds (to form antigen-antibody complex), made of a sequence of amino acids specific to that antibody

Monoclonal Antibodies:

when a specific antibody is isolated and cloned outside of the body
used: pregnancy tests, drugs tests, cancer treatment, transplant surgery