Back to AI Flashcard MakerBiology /Biology IB HL - 6.3 Disease Defences Part 2
What is the second line of defence?
The second line of defence against infectious disease is the innate immune system, which is non-specific in its response
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Key Terms
Term
Definition
What is the second line of defence?
The second line of defence against infectious disease is the innate immune system, which is non-specific in its response
What is the PRINCIPLE component of the second line of defence?
A principle component of this line of defence are phagocytic white blood cells that engulf and digest foreign bodies
What are OTHER components of the second line of defence?
Other components of the innate immune system include inflammation, fever and antimicrobial chemicals (complement proteins)
What are the key properties fo the innate immune system?
It does not differentiate between different types of pathogens (non-specific)
It responds to an infection the same way every time (non-adaptive)
What is phagocytosis?
Phagocytosis is the process by which solid materials (such as pathogens) are ingested by a cell (i.e. cell ‘eating’ via endocytosis)
Phagocytosis - How is the process of phagocytosis initiated?
Phagocytic leukocytes circulate in the blood and move into the body tissue (extravasation) in response to infection
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| Term | Definition |
|---|---|
What is the second line of defence? | The second line of defence against infectious disease is the innate immune system, which is non-specific in its response |
What is the PRINCIPLE component of the second line of defence? | A principle component of this line of defence are phagocytic white blood cells that engulf and digest foreign bodies |
What are OTHER components of the second line of defence? | Other components of the innate immune system include inflammation, fever and antimicrobial chemicals (complement proteins) |
What are the key properties fo the innate immune system? | It does not differentiate between different types of pathogens (non-specific)
It responds to an infection the same way every time (non-adaptive) |
What is phagocytosis? | Phagocytosis is the process by which solid materials (such as pathogens) are ingested by a cell (i.e. cell ‘eating’ via endocytosis) |
Phagocytosis - How is the process of phagocytosis initiated? | Phagocytic leukocytes circulate in the blood and move into the body tissue (extravasation) in response to infection |
Phagocytosis - what does damaged tissue release and what does this trigger? | Damaged tissues release chemicals (e.g. histamine) which draw white blood cells to the site of infection (via chemotaxis) |
Phagocytosis - How is the pathogen surrounded? | Pathogens are engulfed when cellular extensions (pseudopodia) surround the pathogen and then fuse to form an internal vesicle |
Phagocytosis - What fuses with the phagosome? | The vesicle is then fused to a lysosome (forming a phagolysosome) and the pathogen is digested |
Phagocytosis - what may be done with the antigen of the digested pathogen? | Pathogen fragments (antigens) may be presented on the surface of the phagocyte in order to stimulate the third line of defence |
What is the third line of defence? | The third line of defence against infectious disease is the adaptive immune system, which is specific in its response |
Can the 3rd line of defence differentiate between particular pathogens? | YES
It can differentiate between particular pathogens and target a response that is specific to a given pathogen |
Is the 3rd line of defence involved in immunological memory? | YES; It can respond rapidly upon re-exposure to a specific pathogen, preventing symptoms from developing (immunological memory) |
What is the adaptive immune system coordinated by? | The adaptive immune system is coordinated by lymphocytes (a class of leukocyte) and results in the production of antibodies |
What are B lymphocytes? | B lymphocytes (B cells) are antibody-producing cells that recognise and target a particular pathogen fragment (antigen) |
What are helper T lymphocytes? | Helper T lymphocytes (TH cells) are regulator cells that release chemicals (cytokines) to activate specific B lymphocytes |
What may some phagocytic leukocytes present? | When phagocytic leukocytes engulf a pathogen, some will present the digested fragments (antigens) on their surface |
Antibody Production - What is the role of the antigen-presenting cells (APC)? | These antigen-presenting cells (dendritic cells) migrate to the lymph nodes and activate specific helper T lymphocytes |
Antibody Production - what do the helper T cells release? | The helper T cells then release cytokines to activate the particular B cell capable of producing antibodies specific to the antigen |
Antibody Production - what happens to the activated B cell? | The activated B cell will divide and differentiate to form short-lived plasma cells that produce high amounts of specific antibody |
Antibody Production - What will antibodies target? | Antibodies will target their specific antigen, enhancing the capacity of the immune system to recognise and destroy the pathogen |
Antibody Production - What may some activated B cells transform into? | A small proportion of activated B cell (and activated TH cell) will develop into memory cells to provide long-lasting immunity |
What is an antigen? | Antigen: An antigen is a substance that the body recognises as foreign and that will elicit an immune response |
What is an antibody? | Antibody: An antibody is a protein produced by B lymphocytes (and plasma cells) that is specific to a given antigen |
What are antibodies made of? | Antibodies are made of 4 polypeptide chains that are joined together by disulphide bonds to form Y-shaped molecules |