B6b Immunity Flashcards
Give four human non-specific defence systems
Skin
Nose
Trachea and bronchi
Stomach
Explain how the skin prevents the entry of pathogens
Dead barrier covering outside of body- difficult for pathogens to survive
Scab formation after skin is cut or wounded to prevent entry of pathogen
Antibacterial secretions which kill pathogens
Healthy skin microorganisms which compete with pathogens.
Explain how the nose prevents the entry of pathogens
Sticky mucus in the nose
Pathogens in air breathed in stick to mucus
Hair filters the air as it passes through the nose
Explain how the stomach prevents the entry of pathogens
Stomach secretes hydrochloric acid
Acid kills bacteria in food, drink and mucus from bronchi
How does the body defend itself against pathogens?
Immune system is used
Which type of cell defends the body against invading pathogens?
White blood cells
How do white blood cells destroy pathogens?
Phagocytosis
Antibody production
Antitoxin production
What does a vaccine contain?
Small quantity of a dead or inactive pathogen
How does a vaccine work?
Dead pathogen stimulates white blood cells to produce antibodies.
Memory cells produced
If same pathogen re-enters body the white blood cells respond quickly.
Produce large quantities of correct antibody
Antibodies kill pathogen before damage occurs
Describe what happens in phagocytosis
White blood cell engulfs pathogen
Pathogen is digested by white blood cell
How do antibodies protect us from disease?
Antibodies cause bacteria to clump together
Easier for phagocytosis to kill many bacteria
If infected a second time correct antibodies produced rapidly preventing the person becoming ill again
How do an antitoxin protect us against disease?
Antitoxins bind to toxins (poisons) released by pathogens and neutralise them
What is herd immunity?
If a sufficiently high proportion of a population are immune to a disease the spread of the disease will be limited.
What are the advantages of vaccines?
Eradicated many deadly diseases eg smallpox
Many epidemics can be prevented by vaccinations
Herd immunity protects those who cannot have a vaccination
What are the disadvantages of vaccinations?
Not guaranteed to work
May have side effects
