Cell recognition and immunity Flashcards
What are the key features of your innate immune system
- non-specific
- immediate
- same for all pathogens
What are the key features of the adaptive immune system
-specific
- spefic to each pathogen
- slower
Skin and skin flora (commensal bacteria) as a natural barrier to infection- innate immune system
barrier to opportunistic infection. Vit C maintains strong connective tissue. Flora outcompete pathogenic bacteria.
Blood clotting and inflammation as a natural barrier to infection- innate immune system
Blood clotting seals wounds, inflammation isolates region.
Phagocytosis as a natural barrier to infection- innate immune system
cellular digestion of microbes / infected cells / cellular debris.
Ciliated mucous membranes as a natural barrier to infection- innate immune system
Cilliated mucous membrane trap microbes in inhaled air.
Lysozyme as a natural barrier to infection- innate immune system
Lysosomes are in tears, saliva and stomach.
Hydrochloric acid as a natural barrier to infection- innate immune system
Hydrochloric acid is present in stomach.
Detail the process of phagocytosis.
- Phagocyte e.g. macrophage
- Pathogen e.g. bacteria release toxins
- Phagocyte engages chemotaxis using protein receptors in its cell surface membrane
- Engulfs through Endocytosis on binding with pathogen
- Phagosome (vesicle) containing pathogen
- Lysosomes contain hydrolytic lysozymes (e.g. proteases)
- Fusion forming phagolysosome / phagocytic vacuole
- Digestion by hydrolysis
- Release of contents by exocytosis
Define an Antigen
molecules, which when recognised as non-self (foreign) by the immune system and can stimulate an ‘immune response’ thus producing antibodies
often proteins on the surface of cells / viruses
N.B. proteins have a specific ‘tertiary structure’ / shape which can cause them to be antigens
Antigens are specific so allow the immune system to identify
pathogens (disease causing organisms) e.g. viruses, bacteria, fungi
cells from other organisms of the same species e.g. organ transplant, blood transfusion
pathogens contained in vacuoles / vesicle / phagosomes within phagocytes
toxins released from bacteria
abnormal / cancerous cells
describe the strcuture of an antibody
Proteins produce by B lymphocytes / plasma cells.
2 longer, heavy polypeptide chains bonded to 2 lighter polypeptide chains via disulphide bonds from two cysteine molecules
Constant region
Hinge region- Gives flexibility which allows the antigen- biding site to be placed at different angles when binding to antigens
Highly variable region acting as ‘antigen binding site’
Antigen binding site- Matches the epitodes (The part of the antigen which binds to the the antibody) of antigens Vary between antibodies and they have spefic amino acid sequences unique to the antigen
N.B.
each B cell produces a different antibody
each antibody can bind to one specific antigen shape
Antibody-antigen complex
The variable region of an antibody is complementary to a specific antigen molecule.
Binding creates an antibody-antigen complex.
Opsonisation
marks pathogen / cells for phagocytes
Agglutination
makes phagocytosis easier