Cell Recognition and the Immune System Flashcards
AQA Biology Topic 5, Spec Ref- 3.2.4
What are the 2 types of specific defence mechanism?
Cell-mediated response, Humoral response
How does the immune system differentiate between self and non-self cells?
Specific molecules on its surface, often proteins due to their unique structure.
What are 2 examples of non-specific defence mechanisms?
Physical barrier (skin), Phagocytosis
What is a pathogen?
Any microorganism that causes disease/illness.
What is an antigen?
A molecule that triggers an immune response.
What do proteins allow the immune system to identify?
-Pathogens
-Cells from other organisms of the same species (e.g. a transplanted organ)
-Toxins
-Abnormal body cells (e.g. cancer cells)
What is a phagocyte?
A type of white blood cell that carries out phagocytosis.
What are the 2 types of phagocyte?
Macrophage, Neutrophil
What is the function of a neutrophil?
To engulf and digest pathogens.
What is the function of a macrophage?
To put holes in the cell wall of a bacterium, or add proteins to the surface.
Describe the process of phagocytosis.
-Pathogens release chemical products which attract the phagocyte.
-The phagocyte attaches to chemicals on the pathogen by receptors.
-The phagocyte engulfs the pathogen to form a phagosome.
-Lysosomes fuse with the phagosome and release lysozymes.
-The lysozymes hydrolyse bacteria cell walls.
-Soluble products from the pathogen ae absorbed into the cytoplasm.
What is a lymphocyte?
A type of white blood cell involved in immune response.
Where are lymphocytes produced?
Stem cells in bone marrow.
What are the 2 types of lymphocyte?
B and T
What are B lymphocytes?
Lymphocytes involved in humoral immunity; immunity involving antibodies.
