Cell Recognition and the Immune System Questions and Correct Answers
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Cell recognition and the immune system
Institution
Cell Recognition And The Immune System
Cell Recognition and the Immune System
Questions and Correct Answers
Cell Recognition and the Immune System
Questions and Correct Answers
Cell Recognition and the Immune System
Questions and Correct Answers
Cell Recognition and the Immune System
Questions and Correct Answers
Cell Recognitio...
Cell Recognition and the Immune System
Questions and Correct Answers
The human body's two types of defences to protect itself from pathogens
✓ ~~~ - Non-specific
✓ > General and immediate defences
✓ - Specific
✓ > Less rapid but longer-lasting
Non-specific
✓ ~~~ - Skin forming a barrier to prevents pathogens from entering
✓ - Phagocytosis - to kill any pathogens
Specific
✓ ~~~ Involves lymphocytes (a type of white blood cell) and takes two forms:
✓ 1) Cell-mediated responses involving T-lymphocytes
✓ 2) Humoral responses involving B-lymphocytes
How are all lymphocytes able to distinguish between the body's own cells and
molecules (self) and those that are foreign (non-self)?
✓ ~~~ 1. All types of cells, self or non-self, have specific molecules on its surface that
identify it
2. There is a variety of types of these molecules, but it is the proteins (glycoproteins)
that are the most important:
- Proteins have a huge variety and a highly specific tertiary structure
- It is this variety that distinguishes once cell from another
,What do protein molecules on lymphocyte surfaces allow the immune system to
identify?
✓ ~~~ o Pathogens (e.g. HIV)
o Non-self material (e.g. cells form other organisms of the same species)
o Toxins (e.g. those produced by certain pathogens, like the bacterium that causes
cholera)
o Abnormal body cells (e.g. Cancer cells)
What is the first stage to removing the threat foreign cells pose?
✓ ~~~ Identifying them
How can the immune response be an issue for organ transplantation and what is
done to overcome this issue?
✓ ~~~ - The immune system will recognise tissue or organ transplants as non-self and
therefore tries to destroy the transplant
- To minimise tissue rejection, donor tissues for transplants are normally matched as
closely as possible to those of the recipient
- Best matches are often from relatives
- In addition, immunosuppressant drugs are often administered to reduce the level of
the immune response
We lymphocytes produced in response to an infection?
, ✓ ~~~ No - they already exist
Why is there a high probability that when a pathogen enters the body a lymphocyte
will 'recognise' the pathogen?
✓ ~~~ Given there are ten million different types of lymphocyte, one of these
lymphocytes will have a protein on its surface that is complementary to one of the
proteins of the pathogen
What explains the lag time between the body's exposure to a pathogen and the
body's defences bringing it under control?
✓ ~~~ Clonal selection
Clonal selection
✓ ~~~ 1. As there are so many different types of lymphocytes, there are very few of
each type
2. When an infection occurs, the one type already present that has the
complementary proteins to that of the pathogen is stimulated to divide to build up its
numbers to a level where it can be effectively destroyed
How do lymphocytes recognised own body cells?
✓ ~~~ 1. In the foetus, the lymphocytes are constantly colliding with other cells
2. Infections in the foetus are rare as it is protected from the outside world by the
mother and the placenta
3. So therefore, lymphocytes collide almost exclusively with the body's own material
(self)
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