Unit 2 Cell Recognition and immune systems Flashcards
What is an infection?
It is an effect as well as an interaction between the pathogen and the body’s various defence mechanisms
Explain how an infection can be in 2 different ways?
1) Sometimes the pathogen can overwhelm the human defences and so the individual dies
2) Sometimes the human body defence mechanisms overwhelm the pathogen and the individual can recover so that when the pathogen infects for the second time, the body defences are better prepared and can kill the pathogen before any harm. This is immunity
Why are some vulnerable and other not due to the infection?
The young and elderly that are ill can be vulnerable as there defence mechanism is not fully fledged and a healthy individual is less likely to die from the same infection
What 2 longer-lasting defence mechanism involving a white blood cell are there?
Cell mediated responses involving T-lymphocytes
Humoral responses involving B-Lymphocytes
How does the body distinguish its own cells from foreign cells?
Each type of cell self (body’s own cells) and non-self (foreign cells) have specific molecules on its surface that creates an identity. These specific molecules are proteins that have a large variety and highly specific tertiary 3D structure that allows the cells to distinguish each other .
These 3D protein molecules allow the immune system to identify what 4 things?
1) Pathogens
2) Non-self materials from other cells or organisms of the same species
3) Toxins and pathogen produced toxins
4) Abnormal body cells such as cancer cellls
What is the relation between tissue rejection and identification of these cells?
Tissue or organ transplants allow cells from the same organism to be recognised as non-self despite being like human to human so to minimise this effect of rejection closely mathed relatives are used as donors as they are genetically close.
Also immunosuppressant drugs are used to reduce the effect of the immune system on these donor cells/ non-self cells
What is a common misconception about lymphocytes?
That they are produced when an infection is induced but actually all ten million different types of lymphocytes already exist
Why is it useful that there is a high concentration of lymphocytes during an infection?
There will be a higher probability of the protein molecule on the lymphocyte being complementary to the antigen on the pathogens surface.
What happens when there is an infection a second time in relation to the lymphocytes and pathogens?
The lymphocye with the specific protein molecule o n its surface will be stimulate to produce more of itself so that it can substantially overcome (the reson why there is a lag time between production and exposure to a pathogen)the pathogen and therefore destroy it, this is called clonal selection
How is it that from an early stage the lymphocytes in the body are recognised every single cell?
In the fetus, the lymphocyes are constantly colliding with other cells and it is rare to have an infection in the fetus because it is protected by the placenta from the outside. Therefore all the lymphocytes with the specific protein molecule will be complementary to all the cells in the fetus and those that are not will just die out. The only exception is the lymphocytes that have a specific protein molecule that is complementary to a non-self cell.
How do the lymphocytes in adults work?
In adults the lymphocytes are found in bone marrow so so initially they only encounter self-antigens, if lymphocytes encounter self-antigens and produce an immune response then these lymphocytes undergo apoptosis in which they self-destruct before differenmtiation into mature lymphocytes.
As a result there is no versions/clones of these anti-self lymphocytes (self-destruct lymphocytes) in the blood
What are the chemical defence mechanism consisting of?
Lymphocytes and Phagocytes
What are Phagocytes?
Phagocytes are a type of white blood cell that ingest pathogens and destroyting them in a process called phagocytosis before it can cause any harm
What are Lymphocytes involved in?
Lymphocytes are involved in the immune responses
What is an antigen?
Any part of an organism or substance that is recognized as non-self (foreign) by the immune system
What is the relation between antigens and microorganisms?
Antigens are proteins that are a part of the cell-surface membrane or cell-walls of invading cells such as cancer cells
What does the presence of an antigen allow the immune system to do?
To trigger an immune response via the the production of antibodies as part of the body’s defence system
What type of response is Phagocytosis?
A non-specific response
What is the difference between specific responses to non-specific responses?
Specific responses react to specific antigens and are slower in action but provide long term immunity
What do specific immune responses rely on and where are they found?
Type of white blood cell such as lymphocytes produced by the stem cells in bone marrow
What are the 2 types of Lymphocytes?
B-Lymphocytes and T-Lymphocytes
How do B-Lymphocytes work?
B-lymphocytes mature in the bone marrow and are associated with humoral immunity involving antibodies that are present in bodily fluids such as blood plasma
How do T-Lymphocytes work?
T-lymphocytes mature in the thymus gland and are associated with cell-mediated immunity which is the immunity involving body cells