Immune Defences And Phagocytosis Flashcards
What are the 2 types of the immune system ?
Specific
Non-specific
Define immune system.
A system of biological structures and processes that protect against disease by identifying and killing pathogens and tumour cells.
Define pathogen
Any microorganism capable of causing disease.
Define antibody
A protein produces by the lymphocytes in response to the presence of the appropriate antibody.
What is the function of lysosomes.
Contain digestive enzymes which break down worn out organelles and dead cells.
Define antigen
Found in the cell surface of pathogens and triggers an immune response by the lymphocytes.
Which biological molecule is found on the cell surface of pathogens ?
Antigens.
Which protein is produced by the lymphocytes and is is part of the immune system.
Antibody.
What is a microorganism capable of causing disease called.
Pathogen
What are the stages of defence.
- Prevent invasion - physical barrier
- Non-specific attack phagocytosis
- Specific attack- lymphocytes.
Name some physical barriers.
Skin Goblet cells Collin Stomach acid Ear wax Tears
How does the skin act as physical barrier.
It is waterproof and prevents pathogens entering the blood stream.
How are goblet cells physical barriers.
They produce mucus which contains a lot of protein. Invaiding pathogens get stuck in this mucus.
How do Cillia act as a physical barrier ?
Hair like projections which beat rhythmically to move mucus back up the trachea.
How do tears act as a physical barrier.
Contain lysozyme enzyme which breaks down the bacterial cell walls.
Outline how physical barriers prevent pathogens which enter via the airway.
Goblet cells produce mucus in the trachea. Mucus contains a lot of proteins.
Cilia best rhythmically to move mucus up the trachea.
Mucus is then swallowed down the oesophagus.
Bacteria reach the hydrochloric acid in the stomach which causes the tertiarry structure of the pathogen to denature.
What is phagocytosis.
A process which can attack any pathogen by a type of endocytosis. Phagocytes.m search the body for “non-self material”.
Explain, in detail, the process of phagocytosis.
All pathogens release chemoattractants which we attracted by phagocytes.
Phagocytes recognise this as a ‘non-self’ cells and begin to engulf the pathogen because the phagocyte and pathogen have complimentary shapes.
Cytoplasm of the phagocyte surrounds the pathogen engulfing it by endocytosis this forms a membrane bound pocket called a phagosome.
Pathogen is hydrolysis inside the phagosome and products are absorbed by the Cytoplasm.
What type of enzymes do lysosomes contain ?
Hydrolitic digestive
What is an attenuated microorganism ?
A weakened organism.
Describe how memory cells protect the body from disease.
On further exposure to the same microorganism, the antigen is recognised therefore a greater production of antibodies is produced for a faster response
Why did the number of people with whooping cough increase during the 1980s.
There was a reduction in the number of people being vaccinated yet there was an increase in birth rate.
Why may using vaccines with attenuated or dead microorganisms be a problem for patients.
The process of killing the microorganisms may not be 100% efficient and full blown diseases may be caused.
Attenuated organisms are non-virulent but may become virulent.
Side effects such as allergies could occur
Immunity may decline due to a change in the antigen so boosted injections may be needed.
What is the definition of virulent.
Extremely severe side effects.
Why does taking plant antibodies not create long term disease production ?
This is a passive process meaning the person is not creating antibodies or replacing antibodies therefore no memory cells are produced.
Explain the advantages of using plant antibodies over antibodies produced in experimental animals.
There is fewer ethical difficulties and less chance of infection.
How should a control group for a vaccine be treated ?
Injected with saline that doesn’t contain an antigen.
Why is a control group needed ?
To compare the results with your data to see any trend
Explain the advantage of giving the percentage of people with a disease as well as the total number.
Allows a comparison to be made as different numbers of people may have been treated.
Why are vaccines often most effective with young people ?
They have not yet been exposed to the disease and therefore have no natural immunity.
Explain why girls are vaccinated against Rubells when they are young.
They must be vaccinated before pregnancy so that the baby does now gain rubella or become immune.
Why are young boys vaccinated against rubella ?
Makes are vaccinated so they are not a source of infection for unprotected females.
What is a poliomyelitis antigen ?
A glycoproteins molecule on the surface of the virus which stimulates an immune response and antibody production.
Why do some vaccines not give long lasting protection ?
If passive immunity has occurred meaning that it is a secondary response and although antibodies have been produced rapidly, memory cells have not been activated.
What is an antigen (Mark scheme).
A glycoproteins molecule which stimulates an immune response.
What are lymphocytes ?
A type of white blood cell which attack non-self molecules as they recognise pathogens by a complimentary protein antigen on the surface.
How do lymphocytes recognise pathogens ?
By recognising a complimentary antigen on the cell surface of the pathogen.
Give examples of lymphocytes.
T cells and B cells
Where are T cells produced and matured ?
Produced in the bond marrow then migrate to the thymus gland where they mature.
What type of immunity do T-cells allow.
Cell-mediated immunity therefore they only respond to antigens that are attached to a body cell.
Which type of lymphocytes undergo cell mediated immunity ?
T cells
What is cell-mediated immunity.
Where T cells only respond to antigens that are attached to body cells.
What is a helper T-cell ?
Binds to antigens presented on body cells.
Activated other T cells to divide rapidly by mitosis and create clones.
The clones can then develops into memory cells, stimulate phagocytes to engulf pathogens, stimulate B cells to divide or kill infected cells by becoming cytotoxic.
What can clones T cells become
They can develop into memory cells which help long term immunity.
They can stimulate phagocytes to engulf pathogens.
They can stimulate B cells to divide by mitosis.
They can kill infected cells by becoming cytotoxic.
What do T cells need to become to kill infected cells.
Cytotoxic
What type of lymphocytes are most effective against viruses
T-cells
Where are B cells produced and matured ?
Produced in bone marrow.
Matured in bone marrow.
What type of immunity do B cells undergo and what is this ?
Humoural immunity
B cells ingest the invading pathogens which are floating in the extra cellular fluid and cytoplasm. They then become an antigen presenting elm by outing part of the antigen on their surface. The T-helper cell then attached to the antigen causing the B cell to divide into memory or plasma cells
What is humoural immunity ?
B cells ingest pathogens which are floating in the cytoplasm and extra-cellular fluid.
They then become an antigen presenting cell by putting part of the antigen on their surface. The T-helper cell then attached to the antigen causing the B cell to divide into memory or plasma cells
Draw a diagram of an antibody and label it.
In notes
What does the variable region of the antigen allow ?
The variable region allows different antibodies to be complementary to the specific antigen.
Why does an antibody have disulfide bonds ?
Holds the peptides together
Explain the polypeptide chains within an antibody.
2 long heavy chains - constant regions which are the same in all humans.
2 light chains.
What are the functions of antibodies.
Causing agglutination
Neutralisation
How do antibodies cause agglutination and why ?
Makes microbes stick together making it easier for the phagocytes to engulf them. Therefore they act as markers for the phagocytes to engulf them.
How do antibodies cause neutralisation and why ?
Antibodies attach to the toxins produced by the pathogens therefore neutralising the toxins and making them un-harmful.