BI505 - Infection And Immunity Flashcards
What is an Antibody?
What is their main function?
Antibodies are protein molecules produced by immune system cells. Their function is to protect against infection by killing oathogens.
What is an antigen?
Every substance that antagonises the immune system to produce antibodies.
At forms and subforms of immunity are there possible?
Its artificial and natural immunity. These can be either passive or active.
What is the first barrier against pathogens and what mechanisms are present?
The first barrier is the skin and with the use of mucus layers, secretion of tears and digestive fluid most of the pathogens are killed.
What are the two phases if a pathogen passes the first barrier of the immune system?
The non-specific and the specific phase.
Explain how phagocytosis occurs in the body? (Non-specific)
Neutrophils, monocytes and macrophages engulf such organisms and digest them. They are attracted by components on the membranes of these organisms. Monocytes develop into macrophages when such organisms are detected. Also, liver spleen and lymph node cells clear the tissue fluid of invaders.
Why does fever occur and how does it help as a non-specific immune responce?
Activated macrophages release cytokines (interleukin 1 and 6) that act as pyrogens to reset the hypothalamic thermostat. The iron levels fall, antigens are inhibited and neutrophils are stimulated.
How do B cells work as a specific immune phase system?
B cells carry an antibody attached on their membrane. This antibody is specific for a certain antigen which when they come in contact with they get activated. B cells turn into big cells called plasma cells. This means they will produce proteins that will help eliminate the antigen and result in the recovery of the organism from that pathogen.
How do memory cells work as part of the specific immune phase?
Memory cells result from plasma cells that have not died. These cells are as reactive as b cells. They have great mobility which helps eliminate the pathogen that has infected the organism again faster. Memory cells remain in the bloodstream for years once produced.
How are T and B cells activated when a foreign antigen is presented to an organism?
Macrophages will engulf such antigen digest it and produce cytokines (interleukin 1) that will activate helper T cells. T cells will produce other cytokines that will activate B cells and other T cells. Additionally, macrophages keep art of the digested proteins in their plasma membrane. These are antigen presenting cells such as dendrite cells…
What is the structure of an antibody.
Antibodies are proteins consisted of one or more Y peptides. Each Y unit consists of 4 peptides 2 long chain and 2 short chain held together by disulfide bonds. Each chain contains of a constant region where the bases are the same for all antibodies and a variable region which is specific for each type of antibody. This region is where the antigen would bind.
Which are the five types of antibodies?
IgG (most common) IgM IgA IgD IgE
What is the structure and function of IgM type antibodies?
IgM antibodies are pentamers. That means they have five Y units. These antibodies remain in the membrane of b cells and are good when many antigens aggregate in a part of the body. Also, they are useful because they are a pretty fast response in the first steps of the immune response.
What is the structure and function of IgA antibodies?
IgA antibodies are dimers of IgG. They are present where mucus is present (e.g. Intestinal, urinal and respiratory cavities) and are responsible for protecting mucus layers from pathogens.
What is the first way a human could get IgA antibodies?
Babies could get IgA antibodies through the colostrum which is milk produced by their mother during the first 6 months.
