The Immune System Flashcards
what 4 things do specific molecules on the CSM allow for identification of?
Pathogens
Cells from other organism of the same species (eg from organ donation)
Toxins (produced by pathogens)
Abnormal body cells (cancer)
antigen
protein on cell surface which may be recognised by the immune system and induce an immune response.
process of phagocytosis
- Phagocyte is attracted to the pathogen by chemicals (toxins) the pathogen releases and its foreign antigen.
- The phagocyte ingests the pathogen, which is enclosed in the phagosome.
- Lysosomes, which contain lysozymes (enzymes) fuse with the phagosome and release the enzymes into it.
- The enzymes hydrolyse the pathogen’s molecules
- The phagocyte absorbs the products of hydrolysis
how are ingested pathogens destroyed after phagocytosis?
lysozymes, hydrolytic enzymes, are released into the phagosome containing the pathogen. Lysozymes hydrolyse and destroy the pathogen.
what do helper T cells respond to?
specific foreign antigens presented on the CSM of body cells which have engulfed the pathogen
what is a pathogen?
microorganism that causes disease/ an immune response
which type of immune response involves helper T cells?
cellular response
what are body cells that present foreign antigens from pathogens on their CSM called?
antigen-presenting cells.
Process of the cellular immune response
1- Pathogens invade body cells or are engulfed by phagocytes (phagocytosis)
2- The body cell places the pathogen antigens on its cell surface membrane
3- Specific TH (helper T) cells have receptors that can fit exactly onto the antigens.
4- This attachment activates the TH cell to divide by mitosis to form a clone of genetically identical cells.
5- The cloned T cells:
- Develop into memory cells ⇒ rapid response on reinfection
- Stimulate phagocytosis of pathogens
- Stimulate division of B cells ⇒ secrete antibodies
- Activate cytotoxic T cells (TC cells)
which type of immune response are B cells involved in?
the humoral response - response to foreign antigens present in body fluids.
what 4 things do cloned helper T cells stimulate?
- Develop into memory cells ⇒ rapid response on reinfection
- Stimulate phagocytosis of pathogens
- Stimulate division of B cells ⇒ secrete antibodies
- Activate cytotoxic T cells (TC cells)
Humoral immune response (B cells) stages:
antibodies on the surface of a specific B cell bind to a complementary foreign antigen.
helper T cells activate the B cell to divide by mitosis and form a clone. This is clonal selection.
Plasma cells are formed.
Role of plasma cells in the humoral immune response
plasma cells produce and secrete the antibody specific to the foreign antigen. This is part of the primary immune response.
Role of memory cells from the secondary immune response
remain in the blood and can respond to future infections by the same pathogen. Upon reinfection they divide rapidly to form plasma cells which secrete the antibodies. This is the secondary immune response.
primary immune response
why slow?
primary:
occurs when an antigen enters the body for the first time. this is slow because there aren’t many of the correct B cells initially, it takes time for clonal selection and antibody production to occur.
symptoms of disease are shown. memory cells are produced.
antibody
These are proteins with specific binding sites complementary to a specific antigen which are synthesised by B cells.