Mind map
Unit One
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Unit One
Disease and Immunity
- Disease
- Causes of Disease
- Infectious
- Pathogens e.g. bacteria
- Non infectious
- Body malfunctioning e.g. cancer
- Lifestyle or environment e.g. malnutrition
- Coronary Heart Disease (CHD)
- Affects heart
- Lifestyle factors that increase risk of developing CHD
- Poor diet - high intake of saturated fats or salt
- Smoking
- Lack of exercise
- Leads to high blood pressure - damaging the heart and blood vessels
- Excessive alcohol intake
- Cancer
- The result of uncontrolled cell division
- Factors that increase the risk of many types of cancer
- Smoking - mouth, throat and lung cancer
- Excessive exposure to sunlight - skin cancer
- Excessive alcohol intake - liver cancer
- Coronary Heart Disease (CHD)
- Infectious
- Causes of Disease
- Pathogens
- "An organism that causes a disease"
- Types of pathogen
- Fungi
- Bacteria
- Virus
- Entry into the body
- Gas exchange system
- breathing in air containing pathogens (p)
- p get trapped in mucus lining the lung epithelium
- cells have cilia that beat and move the mucus up the trachea to the mouth - where removed
- HOWEVER some pathogens are still able to reach the alveoli where they can invade cells and cause damage
- cells have cilia that beat and move the mucus up the trachea to the mouth - where removed
- p get trapped in mucus lining the lung epithelium
- breathing in air containing pathogens (p)
- The skin
- Damaged skin = pathogens on surface can enter bloodstream
- Blood clots and dries, forming scab to prevent pathogens from entering
- HOWEVER some may get in before scab forms
- Blood clots and dries, forming scab to prevent pathogens from entering
- Damaged skin = pathogens on surface can enter bloodstream
- Digestive system
- Eat or drink something that contains pathogens
- Most of them will be killed by acidic conditions of stomach
- HOWEVER some may survive and pass into the intestines where they invade cells of gut wall
- Most of them will be killed by acidic conditions of stomach
- Eat or drink something that contains pathogens
- Gas exchange system
- How pathogens cause disease
- Production of toxins
- Cell damage
- Done by...
- Rupturing to release nutrients
- Breaking down nutrients inside the cell for own use
- Starves and eventually kills cell
- Breaking down nutrients inside the cell for own use
- Replicating inside the cell; bursting them when they're released
- Rupturing to release nutrients
- Done by...
- Immune Response
- If a pathogen gets past your first line of defences, the immune system kicks in
- Activating the immune response
- Pathogen invades body -> molecules on surface (antigens) are identified as foreign -> activates cells in immune system
- Antigens = a protein (or polysaccharide) that causes an immune response
- ANTIbody GENerator
- Antigens = a protein (or polysaccharide) that causes an immune response
- Pathogen invades body -> molecules on surface (antigens) are identified as foreign -> activates cells in immune system
- Four main stages of immune response
- (1) phagocytosis
- A phagocyte is a type of WBC that carries out the engulfment of pathogens
- Found in the bloody and in tissues and are the first cells to respond to a pathogen inside body
- The phagocyte recognises the antigens on a pathogen
- Cytoplasm of phagocyte moves round pathogen -- now contained in phagocytic vacuole
- Lysosome fuses with the vacuole, releasing lysosomal enzymes which break pathogen down
- phagocyte presents pathogen's antigens on its surface to activate other immune system cells
- Lysosome fuses with the vacuole, releasing lysosomal enzymes which break pathogen down
- Cytoplasm of phagocyte moves round pathogen -- now contained in phagocytic vacuole
- A phagocyte is a type of WBC that carries out the engulfment of pathogens
- (2) T-cell activation
- T-Cell = WBC
- Has proteins on its surface that bind to antigens presented by phagocytes, activating T Cell
- Different t-cells respond in different ways
- Helper T Cells
- activates B Cells
- Killer T Cells
- Destroy cell by attaching to antigens on pathogen
- Suppressor T Cells
- Stops the immune response (or it'll get out of hand)
- Memory Cells
- Helper T Cells
- Different t-cells respond in different ways
- (3) B-cell activation & plasma cell production
- B-cell = WBC
- covered with antibodies (that bind with antigens)
- antigen-antibody complex
- activates B-cell; which divides to produce more b cells called plasma cells (clones)
- antigen-antibody complex
- Memory Cells
- remember specific antigen from primary response
- bind to it second time around = immune; quicker and stronger response
- remember specific antigen from primary response
- (4) Antibody production
- plasma cells secrete loads of antibodies
- Functions
- coating pathogen making it easier for phagocyte to engulf it
- coating it - preventing it from entering host cell
- Binding & neuatrisling (inactivating) toxins produced by pathogen
- Functions
- plasma cells secrete loads of antibodies
- (1) phagocytosis
- Antibody structure
- made up of chains of amino acid monomers linked by peptide bonds
- Specificity of antibody depends on its variable region (different shape due to different amino acid sequences)
- Each antibody is complementary to one specific antigen
- Cellular response
- T-cells
- Humoral response
- B-cells
- Primary & secondary response
- Primary
- B-cells do their antibody thing and eventually overcome infection
- Secondary
- memory cells produced from primary response go go go
- production of antibodies is quicker and greater
- memory cells produced from primary response go go go
- Primary
- Vaccines
- contain antigens that cause your body to produce memory cells against a particular pathogen, without causing any disease
- Immune
- Herd immunity
- fewer people to catch it from, so those not vaccinated are less likely to catch the disease
- The antigens are either free or attached to a dead or weakened pathogen
- taken orally or injected
- disadvantage for taking orally = can be broken down by enzymes in the gut or molecules of vaccine may be too large to be absorbed into the blood
- Ethical issues
- Tested on animals
- Testing on people can be risky
- Some people don't want to take vaccine due to side effects
- but still protected due to herd immunity
- some see this as being unfair
- but still protected due to herd immunity
- outbreak of a new disease - who would receive the vaccine first?
- Antigenic Variation
- some pathogens can change their surface antigens
- (changes in the genes of a pathogen form different antigens)
- memory cells produced from primary response do not recognise the antigens
- Immune system starts from scratch
- This takes time and so you get ill again
- Immune system starts from scratch
- Hard to develop vaccines against pathogen
- Influenza virus
- some pathogens can change their surface antigens
- Monoclonal Antibodies
- they are antibodies produced from a single group of genetically identical b-cells (plasma cells) - so identical in structure
- can make monoclonal antibodies that bind to anything you want - they will only bind to this target molecule
- Pregnancy tests, AIDS & anti-cancer drugs (pg 19-20)
- Ethical issues
- animal rights issues
- Validating New Knowledge About Vaccines and Antibodies
- when a study presents evidence for a new theory it's important that other scientists come up with more evidence to validate the theory i.e. repeat the study
- MMR Vaccine (pg 21)
- Herceptin - monoclonal antibodies (pg 22)
- Using scientific knowledge to make decisions
- when a study presents evidence for a new theory it's important that other scientists come up with more evidence to validate the theory i.e. repeat the study
- Disease
