Immunology Flashcards
Describe the non-specific defence mechanisms the body may launch against pathogens (5m)
Phagocytosis
1. Pathogen is engulfed by phagocyte
2. Engulfed pathogen enters cytoplasm of the phagocyte in a vesicle
3. Lysosomes fuse with vesicle releasing hydrolytic digestive enzymes
4. Lysosomes break down pathogen
5.waste materials are ejected out of cell via exocytosis
Describe how a phagocyte destroys a pathogen in the blood.
1.engulfs pathogen
2. Forms a vesicle which fuses with lysosome
3. Pathogen destroyed as it is hydrolysed by digestive enzymes released by lysosome
Give three types of cell, other than pathogens, that can stimulate an immune response.
- Cells from other organisms for example transplants
- Cancerous cells like tumour cells
- Cells infected by a virus
When a vaccine is given to a person, it leads to the production of antibodies against a disease causing organism. Describe how.
Vaccine contains antigen from the pathogen
Macrophage presents antigen on its surface
T helper cell with complementary receptor protein binds to antigen
Stimulating a B cell with a complementary antibody
B cell divides to produce same antibodies
B cells secrete large amounts of antibodies
Explain how the humoral response leads to immunity.
B cells with complementary antibody to antigen reproduce by mitosis
B cells produce plasma and memory cells
If second infection occurs antibodies are produced in larger quantities AND quicker
Describe and explain the two ways that antibodies stimulate phagocytosis.
Antibodies bind to antigen and cause agglutination, meaning they clump together.
Antibodies are markers and attract phagocytes.
Describe the difference between active and passive immunity.
Active involves memory cells whereas passive does not
Active involves production of antibodies by plasma cells passive does not
Passive introduces antibodies to body from the outside whereas active is long term as it produces antibodies in response to antigen
Passive is short term as antigen give is broken down
Passive takes longer to work whereas active is faster acting
State why some antibodies are referred to as monoclonal.
Antibodies produced from the same b cell/ plasma cell
Tests using monoclonal antibodies are specific. Use your knowledge of protein structure to explain why
Specific primary structure
Specific tertiary structure
So only binds to complementary antigen
Describe the structure of hiv
RNA as genetic material
Reverse transcriptase
Protein capsid
Envelope made of membrane
Attachment proteins
Describe how a person infected with HIV will develop AIDS if untreated and die of secondary infections
High viral load leads to increased destruction of helper T cells
Less activation of B cells
Less production of plasma cells thus antibodies
Less able to kill virus infected cells
More able Destroy other pathogens
Describe the role of antibodies in producing a positive result in an ELISA test
Antibody binds to complementary antigen
Second antibody with enzyme attached is added
Second antibody attaches to antigen
Substrate added and colour changes
Antigens
Antigens are molecules that stimulate an immune response and results in the production of a specific antibody
Phagocytes
Group of white blood cells which can recognise if a cell is non- self and then engulf and destroy (phagocytosis)
What type of process is phagocytosis
Non specific
