Immune system Flashcards
What is the incubation period?
Pathogen multiplying period- days or weeks before the person feels ill
What is disease?
Any condition that impairs the normal state of an organism and usually changes the function of one or more of its organs or organ systems.
Some are caused by pathogens, which can attack and destroy cells or release toxins
What are your bodies physical defences against disease
SKIN acts as the main barrier physical barrier- if skin gets cut- SCAB forms
FINE HAIRS & MUCUS can trap pathogens before they can move deeper into the body
What are your bodies chemical defences against disease
Stomach acid is strong enough to kill any pathogens that have been caught in mucus in the airways or consumed in food or water
Body barriers (diagram)
Body barriers (words)
What are antigens?
Antigens are molecules on the outside of a pathogen that help white blood cells see that it is foreign
What happens if pathogens do make it inside your body?
2nd line of defence kicks in- the immune system kicks in to destroy them
What are the 3 lines of defence by white blood cells?
- Consume foreign cells- phagocytosis
- Release antitoxins to neutralise the poisons produced by microbes
3.Produce antibodies which lock onto invading cells so they can be found and destroyed
What’s happening in this picture?
What’s happening in this picture?
Phagocytosis
What’s happening in this picture?
Draw a diagram of phagocytosis
Draw some diagrams to describe antibodies
What are antibiotics
Bacteria can enter the body and begin to multiply. They secrete chemicals which can make us feel ill before our white blood cells have identified and destroyed them.
In 1928 Alexander Fleming observed that where mould was growing there were no bacteria. The chemicals from the mould were extracted and this formed the first antibiotic.
Antibiotics are medicines that can harm bacteria and stop them multiplying. There are now many different antibiotics and each one can harm a different type of bacteria. Bacteria that are not harmed by antibiotics are said to be resistant.
Antibiotics do not work against viruses. If you have a viral infection you can only ease the symptoms whilst your body fights the infection. To do this you can take aspirin or paracetamol while you are waiting.
What are vaccines?
A vaccine contains the microbes that normally cause disease. The difference is that the microbes have been treated so that they are no longer harmful – they are said to been inactive microbes.
Special white blood cells recognise the microbes as foreign and produce antibodies to destroy the microbes. These antibodies must be a specific shape in order to fit onto the microbe.
If we become infected by live microbes of the same disease in the future memory cells recognise the disease. These memory cells quickly produce antibodies. The antibodies in our blood will kill the microbe before we feel ill. We are said to be immune.
Antibodies can also pass from mother to child through the placenta or through breast milk, meaning that a young baby can also fight infection.
