B1.1.2 How our bodies defend themselves against infectious diseases Flashcards
What are pathogens?
Microorganisms that cause infectious diseases
How do bactiera and viruses make us feel ill?
Reproduce rapidly inside body Producing poisons (toxins) that make us feel ill
Viruses damage cells in which they reproduce
3 ways white blood cells help defend against pathogens
Ingesting pathogens
Antibodies, destroy particular bacteria/viruses
Antigens, counteract toxins released by pathogens
What leads to immunity from a pathogen?
Iimmune system
specific antibodies
kill
particular pathogen
When is the spread of a pathogen reduced?
Large proportion of population
Immune to the pathogen
Describe Semmelweis and his links with handwashing and reducing diseases
Importance of hand-washing
Prevention of spreading some infectious diseases
Doctors washed hands before examining patients
Greatedly reduced number of deaths
from infectious diseases
in his hospital
What is the role of painkillers?
Help relieve symptons of infectious diseases
Do not kill pathogens
What are antibiotics?
Medicines
help to cure bacterial disease
killing infectious bacteria inside body
What are viral pathogens?
Pathogens that live and reproduce inside cells
Can antibiotics be used to kill viral pathogens?
No
How should specific bacteria be treated?
By specific antibiotics
Viruses reproduce inside body cells. How is this relevant to the development of drugs?
Difficult to develop drugs
kill viruses
without also damaging body’s tissues
Effect of using antibiotics
Greatly reduced
deaths
infectious bacterial diseases
Effect of overuse + inappropriate use of antibiotics
Increased rate of development
antibiotic resistant strains of bacteria
How have many strains of bacteria developed resistance to antibiotics?
Pathogens mutate
Natural selection
What prevents further resistance arising?
Avoid over-using antibiotics
What slowed down the rate of development of resistant strains?
Antibiotics not used to treat non-serious infections
Mild throat infections eg
Example of an antibiotic-resistant strain
MRSA
Why does the population of the resistant strain increase?
Antibiotics kills individual pathogens
non-resistant strain
Individual resistant pathogens surive + reproduce
What are new strains produced by?
Mutation
Why would a new strain spread rapidly?
Antibiotics + vacciations no onger effective against it
People are not immune to it
No effective treatment
What does the development of antibiotic-resistant strains of bacteria lead to?
The necessities of the development of new antibiotics
What is vaccination?
People immunised against a disease/ future infection by the microorganism
Introducing small quantities
Dead/inactive forms of pathogen
Into body
How does vaccines make a person immunised to future infections?
Stimulate white blood cells
produce antibodies that destroy pathogens
A person has vaccination againts a pathogen. What happens when a person is attacked by this pathogen?
Body responses rapidly
by making the correct antibody
in the same way as if the person had previously had the disease
What are MMR vaccines used for?
Protecting children against measles, mumps and rubella
Why are uncontaminated cultures of microorganisms required?
Investigating the action of disinfectants + antibiotics
How to keep the culture pure?
Petri dishes + culture media sterilised before use
Kill unwanted microorganisms
Inoculating loops used to transfer microorganisms to media
sterilised by passing through a flame
Lid of Petri dish
secured with adhesive tape
Prevent microorganisms from air contaminating culture
Conditions to grow cultures in school + college labs and why
Incubated
At max temp 25
greatly reduces the likelyhood
of growth
of pathogens might be harmful to humans
Why is higher temperatures used in industrial conditions?
For rapid growth
