Immune response Flashcards
(39 cards)
Pathogens are
disease-causing microorganisms
Pathogens can infect both
plants and animals
Bacteria
They reproduce rapidly and can affect the host by releasing toxins, these damage tissues and make us feel unwell.
Viruses
They need a host to survive and reproduce
Fungi
They grow on living tissue, some are single-celled and others have a body made of hyphae.
Protists
Eukaryotic organisms. Some of them are parisitic, that live on or inside the host organism. They are often transferred by vectors.
Direct transmission
- Direct contact such as shaking hands
- sexual contact
- Placental transfer from mother to foetus over the placenta.
Indirect transmission
- vector- organisms that can transfer the pathogen from one host to another
- Droplet infection- droplets of mucus can contain the pathogen are coughed and sneezed out.
- Waterborne and food- the pathogen infects the water or uncooked food and is ingested by the organism.
Prevention methods
- destroying vectors- killing vectors can prevent the spread of certain diseases such as malaria.
- simple hygiene methods- washing hands and using a tissue to sneeze or cough can prevent the spread of disease.
- Isolation and vaccines- Isolation of infected individuals and vaccinations to prevent infections can reduce spread.
Antibiotics are only effective against
bacterial pathogens
How can the spread of malaria be reduced?
1, stop mosquitoes breeding
2, use mosquito nets
3, wear/use insect repellent
Phagocytosis
- Phagocytes engulf and digest pathogens, this can be non-specific or helped by antibodies which cause agglutination (clumping) of pathogens
- The phagocyte surrounds the pathogen and releases enzymes to digest and break it down to destroy it
- tracking pathogen
- binding
- engulfing
Toxins
Tiny poisons that can damage our cells
anti-toxins
small molecules that can bind and counteract the toxins- no damage
Antigen is detected as
foreign
Antibodies
small proteins that are made by our own white blood cells
- can act as signals
- lock on
Each antibody is specific
to an antigen
memory cells
Our body will start to produce so many antibodies so quickly- kill pathogens- immune
What is the role of the immune system once the pathogen has entered the body?
To prevent the infectious organism from reproducing and to destroy it.
How do white blood cells help to defend against pathogens?
- phagocytosis
- production of antibodies
- production of antitoxins (special types of antibody)
Phagocytosis
- Phagocytes engulf and digest pathogens, this can be non-specific or helped by antibodies which cause agglutination (clumping) of pathogens
- The phagocyte surrounds the pathogen and releases enzymes to digest and break it down to destroy it
- antibodies enhance the activity of phagocytes
- antibodies cause agglutination (clumping of pathogens)
- specific antibodies to pathogen produced
Production of antibodies
- Lymphocytes produce antibodies
- Antibodies are Y-shaped proteins – each individual has the potential to make millions of different types of antibodies, each with a slightly different shape
- The aim of antibody production is to produce the antibody that is specific (complementary) to the antigens on the surface of the pathogen
- This is a specific type of immune response as the antibodies produced are specific to each pathogen’s antibodies
- anibodies which have a complementary shape to antigens on a pathogen are produced to enhance an immune response
- each lymphocyte only produces one type of antibody
Why may you feel unwell?
It can take a few days to make the antibodies that are specific to a pathogen and this may give the pathogen causing the infection enough time to make you feel unwell (as its numbers in the body, and consequently the damage caused by them, increases).
Memory cells
-Memory cells are lymphocytes that remain in the body after an initial infection with a particular pathogen; they produce the specific antibodies against its antigens so that if you get infected by the same pathogen again in the future (and the antigens are the same) you can produce antibodies much quicker against it before its numbers increase and it can cause damage to the tissues of the body