communicable diseases Flashcards
What is a communicable disease?
A disease caused by a pathogen which can
be passed between animals or plants eg. flu
What is a pathogen?
A disease-causing microorganism e.g. bacteria.
How do bacteria cause disease?
Once inside the body, they divide rapidly by
binary fission. They kill cells and produce
harmful toxins.
How do viruses cause disease?
They invade and reproduce inside living
body cells, leading to cell damage.
Give three ways in which pathogens can be
spread
● By air - flu, tuberculosis and the common cold are spread by droplet infection.
● By water - fungal spores in water spread plant diseases.
● By direct contact - common in plant diseases and sexually transmitted infections.
Give four ways in which the spread of
pathogens can be reduced
● Hygiene - handwashing, disinfectants, tissues.
● Reducing contact with infected individuals - quarantine.
● Removing vectors - use of pesticides and
insecticides, removal of habitats.
● Vaccination.
Why is it especially important to prevent the
spread of viral diseases?
Scientists have not yet developed cures for
many viral diseases.
How does the skin prevent pathogens from
entering the body?
● Acts as a physical barrier.
● Scab formation after skin is cut/wounded.
● Antimicrobial secretions, sebum, which can kill pathogens.
How does the respiratory system prevent
pathogens from entering the body?
● Nose - has hairs and mucus which trap
pathogens.
● Trachea and bronchi - have mucus that traps pathogens. Ciliated cells move mucus to the mouth so it can be swallowed.
How does the stomach prevent pathogens
infecting the body?
● Secretes hydrochloric acid - kills any pathogens present.
How does phagocytosis protect us against
disease?
White blood cells (phagocytes) ingest and destroy pathogens so they cannot infect more cells.
How does antibody production protect us
against disease?
White blood cells produce antibodies which are complementary to a specific antigen on a pathogen.
- The binding of antibodies to antigens causes pathogens to clump together, making them easier to destroy.
- In the case of a second infection, the correct antibodies can be produced rapidly, preventing the person getting the same
disease again.
How does antitoxin production protect us
against disease?
Antitoxins bind to toxins released by pathogens and neutralise them.
