Chapter 11- Immunity Flashcards
Immune system
The body’s internal defense
system
What is a phagocyte? and how are they spread through the body?
Phagocytes are white blood cells that are produced continuously in the bone marrow. They are stored in the bone marrow before being distributed around the body in the blood
What are phagocytes responsible for?
They are responsible for removing dead cells and invasive microorganisms. They carry out what is known as a non-specific immune response
What are the two main types of phagocytes?
Neutrophils
Monocytes (mature to Macrophages)
What is the main action/ process of removing a pathogen by a phagocyte
The process of recognizing and engulfing them.
What are neutrophils?
Neutrophils short-lived phagocyte cells that travel throughout the body and often leave the blood by squeezing through capillary walls to ‘patrol’ the body tissues.
Mode of action of neutrophils
1-neutrophils are attracted to the location of pathogens because of the chemicals the produce.
2-There could also be the attraction made from antibodies as well.
3-Once they move closer, the neutrophils cell surface membrane extends out to the pathogen and engulfs it trapping it within a phagocytic vacuole. (endocytosis)
4- Digestive enzymes are released by lysosomes to destroy the pathogen.
5-After destroying the pathogen, neutrophils die.
What are monocytes?
Monocytes are larger than neutrophils and are long-lived cells. Rather than remaining in the blood, they move into several organs.
How do Monocytes mature to Macrophages?
After being produced in the bone marrow, monocytes travel in the blood and then develop into macrophages once they leave the blood to settle in the various organs.
List down the various organs that macrophages travel to once they leave the blood
-lungs
-spleen
-lymph nodes
-kidney
Mode of action of macrophages
1-Macrophages carry out the same processes as neutrophils however do not break down the pathogen completely
2-They simply cut up the pathogens so that they can display the antigens
3-This makes them to be displayed antigens aka antigen- presenting cell which are then recognised by lymphocytes.
What is an antigen
A foreign substance introduced to the body that stimulates an immune response
What is an antibody
An antibody is a glycoprotein made by plasma cells derived from B-cells and are secreted in response to antigens. Antibodies have complementary shapes to their antigen
What is immune response
A complex series of responses of the body toward foreign antigen with the use of white blood cells
What does Non-self and Self refer to
Non-self: Substances/cells that are recognised as foreign and stimulates an immune response
Self: Substances/ cells that are not recognised as foreign and don’t stimulate an immune response.
Give examples of Non-self substances/cells
-Bacteria
-Viruses
-A different blood type from a blood transfusion
Where are antigens found
-cell Surfaces of pathogens:
-surfaces of viruses
-bacteria cell walls
State the features of a lymphocyte
- smaller than phagocytes
- large nucleus that fills the cell
- produced in the bone marrow before birth
Describe B-lymphocytes
Mention;
- they remain in the bone marrow until they are mature and can travel to the spleen and lymph nodes and other parts
- Each type of B-cell makes one type of antibody however aren’t immediately released.
-Their combinations are specific to the antigen based on the glycoprotein receptor
B-cells that have complementary receptors to the antigen present are stimulated to divide by mitosis. This is known as____________ ________________
CLONAL SELECTION
Describe the mode of action for B-cells
1- One B-cell will contain an antibody receptor that is specific to the antigen that was introduced
2- This B-cell will divide by mitosis to form plasma and memory cells
3- Plasma cells will be able to secrete antibodies that are specific to the antigen in step 1
4- The antigen may re-enter again and due to our memory cells produced in stage 2, they divide once again by mitosis and plasma cells are produced to secrete antibodies.
Describe T-lymphocytes
Mention;
- Immature T-cells leave the bone marrow to mature in the thymus
-They have specific cell surface receptors similar to antibodies that bind to antigens
- there are 2 types of T-cells; killer and helper
What is the function of the T-helper cells
~T-helper cells can secrete a hormone like gland called cytokines. They stimulate B-cells to divide into antibody secreting plasma cells.
~They can also help increase the rate of phagocytosis in macrophages
What is the function of the T-killer cells
-These guys produce toxins that kill body cells and the pathogen by attaching to the antigen .
Primary response VS Secondary response
Primary- Involves the clonal selection of both T and B-cells that divide to form memory cells and plasma cells. The plasma stay for a short while however memory can stay for years.
Secondary- Occurs when the same antigen renter the body and memory cells are triggered to respond from both T and B cells. This takes a relatively faster time.
Briefly give features of antibodies
-They are globular glycoproteins
-They contain 2 heavy polypeptide chains and 2 light polypeptide chains that are bonded by disulphide bonds
-Both polypeptides contain a constant and variable region.
-Presence of the hinge region allows flexibility for the binding sites to bind at different angles.
What are the labels A, B and C
A-antigen binding site
B-heavy polypeptide chain
C-light polypeptide chain
What is the constant region responsible for
They determine the mechanism used to destroy the antigens.
Describe the function of the variable region
- This region acts as the site for attachment to the antigen to create the antibody-antigen complex.
- At the end of the region it is labeled the antigen binding site
- Each heavy and light chains contains the antigen binding site
- The binding sites vary and this creates their specificity to each antigen.
What is agglutination
When antibodies clump up several pathogens to reduce the chances of spread.
List the different ways antibodies can attack pathogens and viruses
- Punching holes on bacterial cell walls
- agglutination
- attaching to the flagella of bacteria
- They combine with viruses and produce toxins to prevent them from spreading.
Describe hybridoma method when making a hybridoma cell
- With the use of a rat, antigens are injected so as to stimulate B-cells to differentiate into plasma cells
- Plasma cells are taken from the spleen and fused with tumour cells so as to divide several times. This is done via either electric shock or through a chemical called fusogen
- The new cell formed is the hybridoma cell and they are grown in a selective growth medium and are screened to identify whether its the desired antibody for the particular pathogen
- these monoclonal antibodies are then cultured and are produced in large quantity
Monoclonal antibodies are used diagnostically for:
*Give 5 uses
-Pregnancy test
-Diagnosing HIV
-Can be used to detect the presence of pathogens
-Detecting cancer cells
-Blood typing before transfusion
What can be used to detect where antibodies have attached to fibrin molecules that end up leading to blood clotting
-a radioactive chemical is attached onto the antibody and the gamma ray camera will be able to detect where the radioactively labelled antibodies have attached to the fibrin molecule to find where blood cots come from
State 3 therapeutic uses of monoclonal antibodies
-Prevention of transplant organ rejection
-Autoimmune therapies
-Treatment for diseases
Briefly describe Active immunity
Mention;
- active immunity can be naturally acquired or artificially
- they are long term as they produce both memory and plasma cells
- if invaded again, it takes a shorter amount of time to increase the antibody production
Briefly describe Passive immunity
Mention;
- does not acquire an immunity response
- due to the persons immune response not having enough time for active immunity hence, no memory cells.
- can be done artificially passive or naturally
- considered short term
Give an example of both artificial and natural passive immunity
Artificial- injection transfusion of the antibodies
Natural- Foetus receives it from placenta OR infant receives it from breast milk( colostrum)
What is a vaccine
A suspension of antigens which are intentionally put into the body to induce artificial active immunity
What are the 2 advantages of using vaccination
+ Highly effective giving up to a life times protection
+ Generally harmless as the pathogens is killed in the primary response
What are 3 weaknesses of vaccines
- Some people could have poor response e.g being malnourished so lacking the nutrients
- At times vaccines may not trigger an immune response due to variation
- Antigenic concealment: when the pathogen hides in the body and cant be detected i.e can coat their bodies in the hosts proteins
What are the 2 types of vaccines
-Live attenuated vaccine
-Inactivated vaccines
Live attenuated vaccines VS inactivated vaccines
Live: Here pathogens have been weakened and are placed into the body for an immune response.
- unsuitable for those with weak immunity
- stronger and long lasting
Inactivated: Pathogens have been fully killed.
-More suitable for those with weak immunity
-not long lasting
-can cause several issues such as allergic reactions
What does Herd immunity mean
When a large proportion of the population has been vaccinated hence it is difficult for the pathogen to spread
What are 2 ways to increase Herd immunity
-Getting children at a young age vaccinated
-Travellers travelling to countries in epidemic should be vaccinated
