11. Immunity Flashcards
Name and describe 3 of the external defense system
- Epithelia that cover the airways are an effective barrier to the entry of pathogens
- Hydrochloric acid in the stomach kills many bacteria that we ingest with food and drink
- Blood clotting
What are the two types of white blood cells?
Phagocytes and lymphocytes
What are antibodies?
Glycoprotein molecules that act against specific antigens
What is an immune response?
The response of lymphocytes to the presence of a foreign antigen
What are the types of phagocytes?
Neutrophils and macrophages
Explain what happens when pathogens invade the body.
Some of the cells under attack respond by releasing chemicals such as histamine
Explain the process of Phagocytosis.
-The neutrophils move towards the pathogens which are clustered together and covered in antibodies.
-The antibodies stimulate the neutrophils to attack the pathogens, this is because neutrophils have receptor proteins on their surfaces that recognize antibody molecules and attach to them.
-After the neutrophil attaches to the pathogens, the neutrophil’s cell membrane engulfs the pathogens and traps them within a phagocytic vacuole in a process called endocytosis.
-Lysosomes fuse with the phagocytic vacuoles releasing enzymes that breakdown the pathogens.
What is the lifespan of a neutrophil?
After killing and digesting some pathogens they die.
Dead neutrophils collect at a site of infection to form pus
What are the two types of lymphocytes?
B-lymphocytes (B cells)
T-lymphocytes (T cells)
Describe where you can find the B cells
They remain in the bone marrow until they are mature then they spread throughout the body.
Concentrating in lymph nodes and the spleen.
Describe where you can find the T cells
They leave the bone marrow and collect in the thymus where they mature.
Describe the immune response by the T cells.
-T cells coordinate the immune response stimulating B cells to divide and then secrete antibodies into the blood.
-The antibodies recognize the antigens on the pathogens and help destroy the pathogens.
-Other T cells find and kill any of the body’s own cells that are affected with pathogens.
Describe what is clonal selection?
When the antigen enters the body for the first time, the small numbers of B cells with their cell membrane receptors complementary to the antigen are stimulated to divide by mitosis
What is the primary immune response?
The first immune response to a specific antigen.
It is slow because there are very few B cells that are specific to the antigen.
What is the secondary immune response?
The second and subsequent immune responses to a specific antigen. It is faster because there are now many memory cells which quickly divide and differentiate into plasma cells.
Describe the structure of an antibody molecule
Each one consists of four polypeptide chains: two ‘long’/heavy chains and two ‘short’/‘light’ chains
Disulfide bonds hold the chains together
What is the variable region on an antibody molecule?
The region that forms the antigen-binding site; the amino acid sequences of the variable site form a specific shape that is complementary to a particular antigen
What are the two types of T cell
T-helper cells
T-killer cells
What is the function of T-helper cells
When they are activated, they release cytokines that stimulate appropriate B cells to divide, develop into plasma cells and secrete antibodies
What is the function of T-killer cells?
They search the body for cells that have become invaded by pathogens and are displaying foreign antigens from the pathogens on their cell surface membranes.
They recognize the antigens attach themselves to the surface of infected cells and secrete toxic substances such as hydrogen peroxide killing the body cells and the pathogens inside
What is active immunity ?
Immunity gained when an antigen enters the body, an immune response occurs and antibodies are produced by plasma cells
What is natural active immunity?
Immunity gained by being infected by a pathogen
What is artificial active immunity
Immunity gained by putting antigens into the body either by injection or by mouth
What is passive immunity
The temporary immunity gained without there being an immune response
What is artificial passive immunity
The immunity gained by injecting antibodies
What is natural passive immunity
The immunity gained by a fetus when maternal antibodies cross the placenta or from breast milk
What is herd immunity?
Vaccinating a large proportion of the population which provides protection for those not immunized as transmission of a pathogen is reduced
Where are phagocytes produced and stored ?
In the bone marrow
Where are macrophages located?
The lungs
Liver
Spleen
Kidney
Lymph Nodes
What crucial role do the macrophages play?
They initiate immune responses and do not destroy the pathogens completely but cut them up to display antigen that can be recognized by lymphocytes
Some of the activated B cells become 1._______ and others become 2._________. State the function of each of these.
- Plasma cells
Produce antibody molecules very quickly and they secrete the antibodies into the blood, lymph or linings of the lungs and gut. - Memory cells
Remain circulating in the body for a long time if the same antigen is reintroduced a few weeks or months after the first infection, memory cells divide rapidly and develop into plasma cells and more memory cells.
What is the function of the “hinge” region on an antibody?
It gives the flexibility for the antibody molecule to bind to antigens on the surface of a pathogen
How are T-cells activated ?
They are activated when they recognize this antigen on another cell of the host ( the owners cells )
What is a vaccine?
A preparation containing antigens which is used to stimulate an immune response artificially
What can be used in the vaccine?
A whole live microorganism
A dead microorganism
A harmless microorganism (attenuated organism)
What is a booster injection?
They are given after receiving less effective vaccines so that it stimulates secondary responses that give enhanced protection
It is also a good idea to receive booster shots if you are likely to be exposed to a disease
What is ring immunity?
Vaccinating all those people in contact with a person infected with a specific disease to prevent disease transmission in the immediate area
What is hybridoma?
A cell formed by the fusion of a plasma cell and a cancer cell, it can both secrete antibodies and divide to form other cells like itself
How are the antibodies used in MABS produced?
By injecting a mouse with human fibrin (main protein found in blood clots) the mouse makes many plasma cells that secrete the antibody against fibrin. Then these plasma cells are collected from its spleen. Plasma cells are fused with cancer cells to form hybridoma that secrete the antifibrin antibody
How are Mabs used to locate blood clots?
The radioactively labeled Mab is introduced to the patients blood and binds to any fibrin molecules it comes into contact with in the bloodstream. The radioactivity emitted by these labeled antibodies is used to detect where they are in the body. Then a gamma ray camera is used to detect the exact position of the antibodies in the person’s body
What are Mabs used for?
To locate the position of blood clots in the body of a person though to have deep vein thrombosis
To locate cancer cells
To identify the exact strain of a virus or bacterium that is causing an infection
How has Mabs now been developed to humanize it?
- Altering the genes that code for the heavy and light polypeptide chains of the antibodies so that they code for human sequences of amino acids rather than mouse or rabbit sequences
- Changing the type and position of the sugar groups that are attached to the heavy chains to the arrangement found in human antibodies
State the role of the constant region on an antibody molecule
Determines the mechanism used to destroy the antigens
Name 5 functions of the antibodies.
- They can combine with viruses and toxins of pathogens to block them from entering or damaging cells.
- They can act as antitoxins by binding to toxins produced by pathogens which neutralize them and make them harmless.
- They can attach to bacteria making them readily identifiable to phagocytes.
- They can attach to the flagella of bacteria making them less active which makes it easier for phagocytosis
- They can create holes in the cell walls of pathogens causing them to burst when water is absorbed by osmosis.
