B1 - Pathogens Flashcards
What are the 2 main types of pathogen?
Bacteria
Viruses
What are pathogens?
Viruses, bacteria or fungi that enter the body and cause infectious diseases
What are bacteria?
Very small cells (100th of body cell size) which can reproduce rapidly inside your body
What are the 2 ways that bacteria make us feel ill?
Damaging your cells
Producing toxins (poisons)
What are viruses and how do they replicate inside the body?
They are infections that are not cells and are 100th the size of bacteria
They replicate themselves by invading your cells and using your cells’ machinery to produce many copies of themselves, the cell then bursts releasing all of the new viruses
How do viruses make us feel ill?
When the cell bursts to release the new viruses, this causes us to feel ill
What are the 3 ways that our bodies fight pathogens?
Skin, hairs and mucus in the breathing system stop a lot of pathogens from getting in your body
Platelets (cell fragments) in the blood help blood clot so that pathogens don’t get in your body via cuts
If pathogens make it through, the immune system kicks in. The white blood cells patrol the blood and attack invading pathogens
What are the 3 ways that white blood cells destroy pathogens?
Consuming them (and break them down)
Producing antibodies
Producing antitoxins that counter toxins made by bacteria
Describe fully how antibodies work
All cells have antigens (unique molecules) on their surface
When white blood cells come across a foreign antigen, they produce called antibodies that lock on and kill the invaders (the antibodies are specific to that antigen)
Those specific antibodies are produced rapidly and are carried around the blood to destroy the rest of that type of pathogen
If someone is infected with the same pathogen again, the white blood cells will very quickly produce the same antibodies again so the person is immune
How do vaccinations work?
When you are infected with a new pathogen, you become seriously ill before the antibodies are produced and you become immune
If a small amount of dead or inactive pathogen is injected, the antibodies for that pathogen are produced and destroy it
You are now immune to that pathogen so without becoming seriously ill. If the real pathogen infects you, the antibodies that destroy it are produced before it can cause damage
What are the 2 advantages of vaccinations?
Vaccines have helped control many infectious diseases that are very serious and even completely stopped some
Big outbreaks of diseases (called epidemics) can be prevented if everyone is vaccinated so that the disease can’t spread
What are the 2 disadvantages of vaccinations?
Sometimes vaccines don’t work
Some people can have serious reactions to vaccines but they are quite rare
What is the problem with painkillers?
They don’t actually tackle the cause if the disease, just relieve the pain
What are antibiotics?
Medicines that actually kill bacteria causing the problem without killing body cells (they are specific to types of bacteria)
They don’t do anything to viruses
Why is it difficult to develop drugs that destroy viruses?
They reproduce using your own body cells so it is hard to make a drug that destroys the virus and doesn’t harm your body cells
What is the problem with antibiotics?
Bacteria can quickly evolve inside the body to become resistant to the antibiotics
Describe how bacteria can become resistant to antibiotics
Bacteria can mutate and sometimes these mutations make the bacteria resistant to the antibiotics
When you are treated, only the non-resistant bacteria are killed
The resistant bacteria survive and reproduce
This means that all of the bacteria are now resistant to antibiotics
Describe fully how microorganisms are cultured (grown)
They are cultured in a culture medium which is agar jelly with carbohydrates, minerals, proteins and vitamins they need to grow
All equipment is sterilised before use to prevent contamination including agar and dish
Inoculating loops are sterilised with a flame
Hot agar jelly is poured into shallow round plastic dishes called Petri dishes
When the jelly is cooled and set, inoculating loops (wire loops) are used to transfer microorganisms to the culture medium
A lid has to be taped on the Petri dish to prevent contamination
The microorganisms then multiply
What must be done in a school lab when culturing microorganisms?
Must be done below 25 degrees C to prevent harmful pathogens growing
Describe what Semmelweis did
He was working in a hospital and saw that many women were dying after childbirth from puerperal fever
He believed that the doctors were spreading the disease from their unwashed hands so he told them all to always wash their hands with antiseptic solution which cut the death rate massively
The antiseptic solution was killing the microorganisms on the doctors’ hands
Why is antibiotic resistance becoming more common?
Antibiotics are used much more and more than they need to be
The resistant bacteria are spread easily by people
What are the 2 main dangers of bacteria?
Diseases made from resistant bacteria are much more common now
A new bacterial disease could come along and no one would be immune so it could spread rapidly
What are the 3 main dangers of viruses?
They tend to mutate often so it is hard to develop vaccines against them because their antigens keep changing
It is a possibility that a virus could evolve to be very deadly and infectious
In the case of viral epidemics, it can take a long time to develop vaccines against them
