Unit Three Immunology Flashcards
Define immunity
Immunity is the state of being resistant to a pathogen or infectious disease
What are antigens
Any substrate that causes the body to make an immune response against it
Describe the three lines of defence
- Non-specific physical barriers
- Non-specific immune cells
- Specific immune cells
Inborn,nonspecific and does not change over time. Give examples
Sneezing
Coughing
Describe acquired immunity
Antibodies
Briefly describe how the skin provides immunity
Closely packed epithelial cells from a physical barrier against he entry of pathogens
List your other nonspecific defences
Saliva- antibacterial enzymes
Tears- antibacterial enzymes
Mucus-lungs trap city and microbes
Skin- prevents entry
Explain the role of mast cells
Histamine is released
Describe the role of cytokines in phagocytosis
Cytokines are proteins molecules that act as a signal to specific white blood cells causing them to accumulate at the site of infection
Explain how lymphocytes are selective
Each lymphocyte has a single type of membrane receptor which is specific for one antigen
Explain how lymphocytes are selective
They have a membrane receptor which is specific for one antigen
What is the process that occurs to produce a lymphocyte clone
Antigen binding leads to repeated lymphocyte decision resulting in the formation of a clinal population of identical lymphocytes
What are 5 foreign particles
Cells infected by pathogens
Toxins released by pathogens
Antigens
Transplanted tissue
Cancer cells
What are the two main types of lymphocytes
B-lymphocytes
T-lymphocytes
Explain the role of T-lymphocytes in normal conditions
Destroy infected body cells by recognising antigens of the pathogen on the cell membrane and inducing apoptosis
Explain the role of T-lymphocytes in autoimmune disease
Failure of the regulation of the immune system leads to T-lymphocytes responding to self antigens. This causes autoimmune diseases
What is the cellular validity of an allergic reaction
B-lymphocytes can respond to antigens on substances that are harmless to the body
The hypersensitive responds is called an allergic reaction
What substance do B lymphocytes produce
Antibodies against antigens on an invading pathogen which leads to destruction of the pathogen
Describe phagocytosis
The engulfing of pathogens and their destruction by digestive enzymes contained in lysosomes
What are memory cells
Some of the cloned B and T-lymphocytes survive long term as memory cells
How do memory cells enhance immunity
When a secondary exposure to the same antigen occurs, these memory cells rapidly give rise to a new clone of specific lymphocytes.
During the secondary response antibody production is greater and more rapid than during primary tepobcr
These destroy the pathogens before symptoms occur
What is the purpose of vaccination
To prepare your immune system so it can give a better response
What is active immunity
Immunity to a pathogen that occurs following exposure to said pathogens
What can be in vaccines
Dead pathogens
Weakend pathogens
Parts of pathogen
Inactivated toxin
What is the role of the adjuvant in a vaccine
Antigens usually mixed with adjuvant when producing the vaccine
An adjuvant is a substance which makes the vaccine more effective so enhancing the immune response
As the antigens in a vaccine are identified to the known pathogen, they stimulate a primary response. How does this primary response help with long term immunity
After the initial response a memory cell is created. This decreases the time when infected for the second time
What is herd immunity
When a large percentage of a population is immunised
Who does herd immunity benefit
Everyone as it reduces the spread of diseases
What does the threshold for herd immunity depend on
Type of disease
The effectiveness of vaccine
The density of the population
Describe the difficulties that can arise obtaining widespread vaccination in the developing world
Costs a lot of money poverty
Describe the difficulties that can arise obtaining widespread vaccination in the developed world
When people don’t want to get vaccinated
What is antigenic variation
Some pathogens can change their antigens this means that memory cells are not effective against them
Some pathogens directly attack the immune system. What is the consequence of the attack
Weakened immune system
More vulnerable to opportunistic infections
Explain the difference between aids and hiv
HIV is higher number of white blood cells
Why must a vaccine be subjected to a clinical trial
To establish theirs safety and effectiveness before being licensed for use.
Statistical significance
At the end of the trial the results form two groups are compared to determine whether there are any statistically significant differences between the groups
Describe randomised clinical trial
Divided into groups randomly
Reduces bias in the distribution of characteristics such as agr and gender
describe a double-blind clinical trial
neither of the subjects nor the researchers know which group the subjects are in.
this prevents biased interpretation of the results
describe a placebo-controlled clinical trial
one group of subjects receives the vaccine or drug whilst the second group receives a placebo- control to ensure valid comparisons.
what do all clinical trials have in common
always in large groups
this is to reduce magnitude of experimental error
and to establish statistical significance .
