B10 Diseases and immunity Flashcards
(15 cards)
What is a pathogen
A pathogen is a disease-causing organism
What is a transmissible disease
A disease in which the pathogen that can be passed from one host to another
How can a pathogen be transmitted ?
+ Direct contact, including through blood and other body fluids
+ Indirectly, including from contaminated surfaces, food, animals and air
4 main methods of transmission
- Droplets in air; e.g common cold, influenza, COVID-19
- Food or water; e.g cholera, typhoid, dysentery
- Touching contaminated surfaces; e.g athletes foot, salmonella
- Insect bites: Malaria, dengue fever
Describe body defences against pathogens
- Mechanical barriers:
1. Nose hair - make it difficult for pathogens to get past them further up the nose, so they are not inhaled into the lungs
2. Skin - covers almost all parts of your body to prevent infection from pathogens, if it is cut, it immediately begins to heal itself by forming scab. - Chemical barriers:
1. Mucus - traps pathogens and the ciliated epithelial cells waft the ball of mucus to the back of your throat, where it can be swallowed into the stomach / cough up and out
2. Stomach acid is very strong, killing most bacterial as well as any swallowed balls of mucus
3. White blood cells
+ Phagocytosis: engulfing and digesting pathogenic cells
+ Producing antibodies: Clump pathogenic cells together so they can’t move as easily and releasing chemicals that signal to other cells that they must be destroyed.
The importance of controlling the spread of disease ?
- Clean water supply - ensures water is free of pathogens which will prevent waterborne diseases like Cholera
- Hygienic food preparation - Washing hand with soap and correct food cooking methods will help to prevent contamination of food with harmful bacteria and fungi
- Good personal hygiene - Washing with soap or using tissues to catch sneezes and coughs and then disposing of them will reduce transmission of diseases such as cold and flu
- Waste disposal - proper disposal of waste e.g food waste prevent will reduce the prevalence of pest
- Sewage treatment - Treatment of sewage removes harmful pathogens from waste before it is released into the environment, reduces the risk of diseases spreading in contaminated water .
What is active immunity ?
Defence against a pathogen by antibody production in the body
What does each pathogen has ?
Each pathogen has its own antigens, which have specific shapes
What are antibodies ?
Proteins than bind to antigens leading to direct destruction of pathogens or marking of pathogens for destruction by phagocytes
State the features of viruses
- Genetic material - the information stored in the virus either DNA (the instruction manual for how to build the virus) or RNA
- Protein coat - formation of the capsid that protects the virus genome against degradation
What can you say between the relationship between antibodies and antigens ?
Specific antibodies have complementary shapes which fit specific antigens.
How can active immunity be gained ?
- Gained after infection by pathogen - the lymphocytes go through the process of making antibodies specific to that pathogen, this then creates memory cells that allow faster and stronger response if the same pathogen enters the body again in the future.
- By vaccination
Outline the process of vaccination
- Weakened pathogens or their antigens are put into the body.
- The antigens stimulate an immune response by lymphocytes which produce antibodies that have complementary shape to the antigen.
- Memory cells are produced, if antigen is encountered again, antibodies are produced much faster, this give long-term immunity,
Statement about vaccinations
Vaccinations are available for some pathogens to help control the spread of diseases
Explain the role of vaccination in controlling the spread of diseases
Vaccination can be used to control the spread of disease by providing herd immunity, this is where large amount of population is vaccinated and are thus immune to the pathogen, so disease can not spread.
