THIRD LINE OF DEFENCE- ADAPTIVE IMMUNITY Flashcards
What is the primary function of the third line of defense in the immune system?
Targets specific pathogens
Develops and adapts in response to specific pathogens that we encounter
Produces memory cells
Which cells produce antibodies in response to antigens?
B lymphocytes
What are lymphocytes?
- white blood cells that is found in the blood and lymphoid tissue
What is the antibody mediated response/humoral response?
The humoral response is an immune response activated by B lymphocytes, which can differentiate into plasma cells and memory B cells.
Where are B cells produced and where do they accumulate?
B cells are produced in the bone marrow and accumulate in lymphoid tissues.
What happens to B cells upon exposure to an antigen?
Upon exposure to an antigen, B cells are activated and can differentiate into plasma cells or memory B cells.
What are the functions of plasma cells?
- production of antibodies that can bind to specifc antigens on pathogens or foreign substances
What is the structure and function of antibodies?
- Antibodies are Y-shaped proteins that bind to specific antigens, forming an antigen-antibody complex. They can neutralize pathogens, enhance phagocytosis through precipitation and agglutination, and activate the complement system.
What is the role of memory B cells?
- Memory B cells have long-term memory of a specific antigen. They enable a faster and stronger defense upon reexposure to the antigen, resulting in less severe symptoms.
- provide long-term protection against re-infection.
True or False: B cells primarily reside in the thymus gland.
false- B cells are found in the lymphoid tissues
What are the main types of T lymphocytes?
Cytotoxic (killer T) cells, memory T cells, supressor cells, helper T cells
Where are T cells made and where do they mature?
- made in bone marrow and mature in thymus gland
What happens to T cells once they are matured?
Once matured, T cells are released into the blood and continuously circulate, seeking out infected cells.
What is the function of cytotoxic (killer) T cells?
T cells seek out and kill foreign infected cells by secreting toxins that prevent pathogen replication and destroy the infected cells.
What is the role of helper T cells?
- Helper T cells promote the activities of other immune responses by secreting cytokines. They enhance the activity of phagocytes, promote inflammation, stimulate the production of killer T cells, and stimulate the differentiation of B cells into plasma and memory B cells.
What is the function of suppressor T cells?
Suppressor T cells turn off the immune response after the pathogen has been removed and destroyed,
What is the role of memory T cells?
Memory T cells provide long-term defense and can quickly recognize and respond to specific antigens upon reexposure.
What is cell mediated response?
- When T lymphocytes target and destroy infected host cells along with the pathogens inside them
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What is cell mediated response effective against?
- intracellular pathogens
protozoa, bacteria, viruses - tapeworms
- cancer cells
What is the role of antigen-presenting cells (such as macrophages) in the cell-mediated response?
Antigen-presenting cells engulf foreign material and display the antigen on their surface using MHC II molecules.
What happens when an antigen-presenting macrophage encounters helper T cells in the lymph nodes?
The antigen-presenting macrophage, recognized by helper T cells through their receptors, triggers the release of cytokines by the helper T cells.
What is the outcome of the activation of helper T cells?
Activation of helper T cells leads to the production of cytokines and the activation of killer T cells and memory T cells specific to the antige
Where do killer T cells migrate to in the cell-mediated response?
Killer T cells migrate to the site of infection where their receptors bind with the antigen.
What do killer T cells release, and what is the result?
Killer T cells release toxic chemicals that cause cell death, killing the infected cell and the pathogen.
How does the release of chemicals by killer T cells contribute to inflammation and phagocytosis?
The released chemicals may increase inflammation, attracting more macrophages and enhancing phagocytosis.
What is the role of memory T cells in the cell-mediated response?
Some activated T cells differentiate into memory T cells, which remain in the body. Upon re-exposure to the same antigen, memory T cells can quickly respond and produce killer T cells, preventing the person from experiencing the same symptoms again.
Which type of immune response is more effective against intracellular pathogens?
The cell-mediated response.
Which type of immune response is primarily effective against pathogens present in body fluids or extracellular spaces?
The humoral response.
