Diseases and immunity
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What is a pathogen?
Disease causing organism
Two types of diseases? How they spread
Transmissible and non-transmissible
What is a transmissible disease?
Disease where the pathogen can be passed from one host to another
Examples of non-transmissible diseases? 3
Coronary heart disease, cancer, diabetes
Types of pathogens 4
Bacteria, fungi, protoctista, viruses
Structure of a virus 2
Protein coat and inside genetic material
Viruses are obligate particles Define obligate
Viruses only exist in live cells of other living organisms
Ways are pathogens transmitted 2 ways + Give examples for each.
Direct contact, Bodily fluids - Sneezing and coughing, STI (HIV) and blood to blood contact (Blood transfusions or sharing hypodermic needles) Indirect contact, Water droplets in the air from sneezing/coughing; Infected water (Cholera); food(Salmonella); animals(Flys or insect bites) and contaminated surfaces(Athletes foot).
Why can’t a human virus affect other animals?
Viruses are highly specific to the cell and organism.
Measures to controlling disease spread? List 5
• Good personal hygiene - Washing hands after bathroom use + covering mouth when sneezing • Hygieneic food preparation - Store food properly before eating eg: fridge. Separate raw foods from cooked foods. • Waste disposal - Taking waste away from human civilisation. • Sewage treatment - seperating sewage from drinking water. • Clean water supply
Mechanical barriers against pathogens 2
Nose hairs, ciliated cells (traps pathogens), skin
Chemical barriers against pathogens 2
Mucus in respiratory system goblet cells (traps pathogens), HCL acid in the stomach (kills pathogens)
How do white blood cells kill pathogens? Name the term
Phagocytosis - Phagocytes engulf pathogens and break them down.
Purpose of lymphocytes?
Produce antibodies
How are lymphocyte activated?
By phagocytes which can present the pathogens antigen to them.
What are antibodies?
Proteins with a specific complementary shape to bind to pathogens. Either marking them for phagocytes or breaking them open.
How do lymphocytes form immunity?
After an infection, some lymphocytes turn into memory cells which remain in the blood If infected by the same pathogen again, memory cells respond faster, increasing antibody production. Often destroying the pathogen without any symptoms.
What type of immunity do memory cells form?
Active immunity
What is active immunity?
The body is being defended by antibody production. The infection has activley produced the immunity
Explain the types of active immunity? 2 types
Natural active immunity - Infection by the pathogen Artificial active immunity - Vaccination: Version of the pathogens antigen injected into the body to stimulate antibody production
Why is the initial production of antibodies slow?
Time is taken for lymphocytes to be found, cloned and to start produce antibodies.