Disease and Immunity
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- Created by: Steph
- Created on: 08-01-13 19:31
Name 6 defences again pathogens entering the body
1) Sebum in skin lowers pH, inhibits growth of pathogens 2) Lysozymes in saliva, sweat and tears (antibacterial enzymes) 3) HCl in stomach 4) Mucus traps pathogens 5) Cilia moves mucus away to protect gas exchange system 6) Immune system targets them
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What is a pathogen?
An organism that causes disease
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Name 3 examples of pathogens
some bacteria, some fungi and all viruses
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How do pathogens cause disease?
1) By producing toxins into the body 2) Rupturing host cells to release nutrients 3) Breaking down nutrients in cell for its own use (starves and eventually kills cell) 4) Replicating inside cell and burst them when released
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What are the 4 main things to think about when interpreting risk factor data?
1) Correlation 2) Exact link 3) Relationship on graph 4) Explain graph further
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If a study is reliable, what two things make this the case?
1) Large sample size 2) Takes into account other lifestyle factors
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What triggers an immune response?
Foreign antigens in the body
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What is an antigen?
It is a molecule -usually a protein- found on the surface of cells
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What does the Cellular Response refer to and what does the Humoral response refer to?
Cellular- T-cells. Humoral- B-cells
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How do phagocytes engulf pathogens?
By phagocytosis. Found in blood and tissues. Recognises antigens. Cytoplasm moves round the pathogen to engulf it. Pathogen now in phagosome. Lysosome fuses with phaogosome. Lysozymes in phagolysosome break down pathogen, release digested contents.
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What does the phagocyte do with the pathogen's antigens?
It displays the antigens on its own surface to active other immune system cells
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What do phagocytes activate and how?
Activate T-cells. The proteins on the surface of the T-cell binds to the antigens presented by the phagocyte.
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Which 2 ways do T-cells respond?
1) Some release substances that activate B-cells 2) Some attach to antigens on a pathogen and kill the cell
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What are B-cells covered with?
They are covered with antibodies. Antibodies bind to antigens to form an antigen-antibody complex
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What makes antibodies specific?
They have a variable region (determined by amino acid sequences) which only binds to one particular shaped antigen
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What activates B-cells?
The formation of an antigen-antibody complex, along with the substances released by T-cells
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What happens once a B-cell is activated?
It divides by mitosis into plasma cells (genetically identical clones of the B-cell)
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What do plasma cells do?
They secrete lots of the antibody specific to the particular antigen
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Name 3 functions of antibodies
1) Coating the pathogen to make it easier for phagocyte to engulf 2) Coating the pathogen to prevent it from entering host cells 3) Binding to and neutralising toxins produced by pathogen
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How can you tell that an antibody has a quaternary structure?
It has several polypeptide chains
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What is the primary response?
Antigen enters body for first time (Activates immune response- slow as not many B-cells to make required antibody) 2) Body produces enough antibody to overcome infection 3) After infection, T & B-cells produce memory cells.
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What is the role of T-cell memory cells?
They remember specific antigen of a pathogen and recognise it a second time round
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What is the role of B-cell memory cells?
They will remember which antibody needs to be produced to bind to the antigen
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What is the secondary response?
If same pathogen enters body again, a quicker, stronger immune response will occur. Memory B-cells divide into plasma cells and produce correct antibody. Memory T-cells divide into correct type of T-cells to kill pathogen.
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How can vaccines protect individuals against disease?
Vaccines contain antigens (dead or weakened) to make body produce memory cells against particular pathogen. You become immune.
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How can vaccines protect populations against disease?
Those not vaccinated are less likely to catch the disease (fewer people to catch it from)
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Why are booster vaccines often given?
To ensure enough memory cells are produced
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How does antigenic variation help some pathogens evade immune system?
Pathogens can change their antigens if genes change. Memory cells don't recognise antigens. Primary response occurs. Get ill. Makes it difficult to make vaccines.
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How can monoclonal antibodies be used to target specific substances or cells?
They're antibodies produced from a single group of B-plasma cells. Identical. Only bind to one particular antigen, so they'll only target one particular substance or cell.
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Where are phagocytes found?
Blood, lymph systems, tissues
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Other cards in this set
Card 2
Front
What is a pathogen?
Back
An organism that causes disease
Card 3
Front
Name 3 examples of pathogens
Back
Card 4
Front
How do pathogens cause disease?
Back
Card 5
Front
What are the 4 main things to think about when interpreting risk factor data?
Back
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