chapter 5 - cell recognition and the immune system Flashcards
What is an antigen
An antigen is a spike protein on the cell surface membrane of a cell it causes phagocytosis (immune response)
What cells are involved in the humoral response
B cells/B lymphocytes are involved in the humoral response B cells make antibodies present in the bodily fluids
Which cells are involved in the cell mediated response
T cells are involved in the cell mediated response. This happens in the body cell/own cell/self cell/ host cell
What do B lymphocytes/B cells do
B cells produce antibodies
What do T cells do
T cells have receptors on the cell membrane which are specific to an antigen. When the T-cell binds to an antigen it will neutralise the pathogen
What do B cells differentiate to
B cells differentiate to plasma B cells and memory B cells
memory B cells stay in the body for decades, however they can’t divide by mitosis
plasma B cells produce more antibodies
What do T cells differentiate to
helper T cells - help B cells in antibody production
memory T cells - stay in the body for decades
surpressor T cells - acts as an ‘off switch’ and stops expansion when specific antigens have been set with
Killer T cells - combine with an antigen and perforate it, Meaning the cell can’t grow and therefore the pathogen is killed
Define clonal selection and clonal expansion
clonal selection-B/T cell binds to the antigen. In direct contact it would bind directly to the pathogen. In indirect contact the B/T cell would bind to the phagocyte/antigen Presenting cell
Clonal expansion- after clonal selection, A macrophage or neutrophil will produce interleukins, these will bind to a specific lymphocytes and this will cause the lymphocyte to divide by mitosis this produces clones (clonal expansion)
What is the definition of cancer
When control mechanisms (tumour suppressor genes/Proto Oncegens) breakdown cells undergo repeated Uncontrollable cell division
What is a benign tumour
A benign tumour is where the cells remain at the position they are formed up, as the Cheema grows it will compress tissues that are surrounding it. As they are localised tumours can be removed by surgery or radiation
what is a malignant tumour
A malignant tumour does not remain in the position that they were formed at. They travel in the blood and to other parts of the body where they can cause a new tumours. The migration of cancer cells to form new tumours in the body is called METASTASIS. Malignant tumours are more difficult to treat then benign tumours because cancer cells spread in the blood or to the lymph to other areas of the body
How can you detect cancer cells
You can detect cancer cells under a microscope this is called a biopsy
what are oncogenes
oncogenes are a type of gene that can cause cells to divide into tumour cells. They are a mutated type of Porto-oncogenes (Which stimulate cells to divide normally)
What are tumour suppressor genes
tumour suppressor genes slow down cell division, they repair mistakes in DNA and program cells to die. If a tumour suppressor gene has become mutated or damaged this will cause cell division to spiral out of control.
What is Tamoxifen
Tamoxifen is a drug used to treat breast cancer. Tamoxifen fits onto oestrogen receptors and stops oestrogen from reaching cancer cells so cancerous cells don’t divide.
what is the definition of a pathogen
A pathogen is an organism that causes disease
Describe the process of phagocytosis
1-detection of antigens, foreign antigen is bind to receptors on the cell surface membrane of phagocytes.
2-phagocyte moves towards the pathogen and the cytoplasm of the phagocytes surrounds the pathogen and engulfs it. When the pathogen is engulfed it is sealed into a phagosome. (vacuole inside the cytoplasm)
3-Digestion of the pathogen, phagocytes have many lysosomes that contain protelytic digestive enzymes(lysozymes). enzymes break down the pathogen.
4-The pathogen is antigens are transported to the phagocyte cell membrane and are presented on the soul surface. This is an antigen presenting cell (APC). The antigens can activate other cells in the immune response