The immune response Flashcards
Antigen
A FOREIGN molecule (that can be a protein/glycoprotein) that can stimulate an immune response
What type of foreign antigens cause an immune response?
Antigens on pathogens
Antigens on abnormal body cells (cancer)
Antigens as toxins
Antigens on transplanted cells from same organism
2 types of immune response
Cellular response
Humoral response
Cellular response
Clonal selection of Th cells
Humoral response
The targeted removal of antigens by producing antibodies by B-cells
Phagocytosis
When a phagocyte engulfs a pathogen
Stages of phagocytosis
PHAGOCYTE RECOGNISES FOREIGN ANTIGEN ON PATHOGEN
Phagocyte engulfs pathogen by its cytoplasm surrounding it
Pathogen taken into cell in a vesicle (phagosome)
Fuses with lysosome = phagolysosome
Lysosomes hydrologic enzymes hydrolyse pathogen
What happens after phagocytosis?
The cell can process pathogen fragments and present the antigen on its surface
Antigen presenting cell
When a phagocyte presents a processed antigen after hydrolysing the pathogen to alert T-cells
What binds to antigen presenting cells and why?
T helper cell that has a specific receptor complementary to the antigen
So it can be stimulated to undergo mitosis
When are Th cells stimulated to undergo mitosis and
divide?
After complementary receptors on Th cells bind to the specific presented antigen and stimulates the Th cell to undergo clonal selection
What does mitosis/clonal selection of Th cells produce?
Cloned Th cells with the same specific receptor which is complementary to the specific antigen of the pathogen detected
And memory T cells
What are the 4 uses of cloned Th cells in an immune response?
Stimulating humoral response (B cells)
Produce memory Th
Stimulate increased phagocytosis
Activate cytotoxic T cells
How does the humoral response start?
A Th cell with a complementary receptor to antigen is activated by binding to antigen on phagocyte
How does clonal selection of B cells occur?
B cells with complementary receptor to antigen have bound to antigen at its receptor
B cell is stimulated to undergo clonal selection by activated Th cell
What does clonal selection of B cell produce?
Clones of plasma cells which release the specific antibodies complementary to specific antigen
And memory B cells
How do plasma cells releasing antibodies remove infection?
Antibody bonds to 2 antigens (has 2 binding sites)
Agglutination of antigens
Which stimulates phagocytes to engulf these, antibodies mark presence of bacteria to phagocyte
Memory B cells use
Has same specific antibodies complementary to specific antigen which will divide into antibody producing B cells in case of secondary infection
Adaptation or plasma cells
Lots of rough endoplasmic reticulum for protein synthesis or many protein antibodies
Use of memory T helper cells
Will divide to correct type of T-helper cell which is complementary to specific antigen to stimulate B cell production if reinfected (by same antigen) for a faster secondary response
How do cloned T helper cells kill virally infected cells or cancer cells?
By stimulating cytotoxic T cells
Which kill these cells
Active immunity
When the immune system will produce its own antibodies after being stimulated to by an antigen
Pathogen
Pathogens are microorganisms (e.g. bacteria, fungi, protists) or viruses that cause infectious disease
How allows cells to identify themselves?
By their specific protein on its cell surface membrane
