Immunology 2 Flashcards
What are the functions of the lymphatic system?
Drainage of tissue
Absorption and transport of fatty acids and fats
Immunity
What aspect of the lymphatic system is responsible for circulation and production of lymphocytes?
Spleen, thymus and bone marrow
How is lymph fluid formed?
Lymph is the fluid that is formed when the interstitial fluid containing dissolved components of the blood enters the conduits of the lymphatic system.
How is the lymph pumped through the body?
Contractions of skeletal muscles
Where do lymphatic vessels carry their fluid?
Away from tissues
What is the name given to the smallest lymphatic vessel?
Lymphatic capillaries
Why can’t fluid escape lymphatic vessels but it can enter?
The walls are composed of endothelium in which simple squamous cells overlap to from one-way valves
Where do both lymphatic trunks drain their fluid?
The blood circulatory system at the right and left subclavian vein
Where does Ab enter the blood from?
The lymphatic system
Where is the recognition phase of the adaptive immune system?
Secondary lymphoid organs, include lymph nodes, the spleen and mucosal associated lymphoid tissue.
Site of lymphocyte activation by antigens
Where do B cells and T cells originate and receive their training?
Primary lymphoid organs - the thymus and the bone marrow
Which part of the bone marrow can be considered lymphatic tissue?
The stem cells in the marrow from which lymphocytes develop, but not in the red bone marrow because there is no lymphatic tissue in the myeloid tissue (tissue which is able to form hematopoeisis
What is a thymocyte?
A t cell precursor
What is the epitone?
The part of the antigen that can be recognised
What is the main function of a spleen?
Acts as a filter
What is meant by white pulp in the spleen?
Small white spots consisting mainly of lymphatic nodules
What is red pulp?
Soft, red, blood rich tissue
What is the function of high endothelial venules?
They are specialised areas in blood vessels which allow lymphocytes in the blood to directly enter the lymph nodes. Although they do not allow backward passage of lymphocytes back into the blood
Where can you find lymph nodes?
Located at intervals along the route the lymph takes while being transported back to the blood
What is lymph separated into once it enters the lymph node?
B cells and T cells, the lymph node is a dating bar for antigen and lymphocyte
Where are the HEV found in lymph nodes?
On the incoming arterioles and outgoing veins
Give an example of the mucosal lymphatic associated tissue
Peyers patches - found in the small intestine - part of the secondary lymphoid tissue
How do peyers patches function?
M cells on peyers patches sample Ag from the lumen of the intestine and transport it to the peyers patch using endosomes. This sample then joins the lymph of the peyers patch and travels to the lymph node that drains the peyers patch
What type of tissue are tonsils?
Lymphoid tissue
What happens during exposure of naive lymphocytes to foreign antigens?
Some lymphocytes become memory cells - these cells are longer lived and are more responsive to their specific antigen (antibodies have a higher affinity for B cells)
What does it mean to be immune?
Individuals who have encountered the pathogen and are protected from subsequent encounters are said to be immune.
What is passive immunity?
When an individual becomes immune to a pathogen without ever having to encounter it (transfer of serum or lymphocytes from an immune individual) - transfer of maternal antibodies to the fetus
What is artificial active immunity?
Taking the antigens into the body by mouth or injection
What is artificial passive immunity?
Giving someone the antibody for that infection - short lasting - doesn’t induce the body’s natural production of that antibody
What type of immunity produces memory cells?
Active immunity, because passive immunity is not exposed to antigens
How does the memory of the adaptive immune system increase the effectiveness of its response to a pathogen?
Immunological memory occurs in part because each exposure to a particular antigen causes an expansion in the clone of lymphocytes which react to that antigen. – Exposure to antigen means the body makes more lymphocytes which respond to that antigen, also makes memory cells which are more responsive to that type of antigen than naïve lymphocytes. B cells now produce antibodies that will bind to the antigen with much higher affinity – T cells now react faster
What do B cells mature into?
Plasma cells
What are B cells responsible for?
Antibody production
What is the antigen receptor for the B cell?
Surface Immunoglobulin
Explain what happens to B cells that recognise body antigen?
- Won’t colonially expand until communication with corresponding T cell - weaken and die
- Die by activation induced apoptosis
What is the name given to any substance that is capable of making an immune response?
An antigen
What is the epitope of an antigen?
The part of an antigen molecule to which an antibody attaches itself
What is the fab region of an antibody?
The part of the antibody which is responsible for binding to the antigen. The V shaped part of a letter Y
What type of bond exists in the antigen binding region?
Disulphide bond
What is the lower region of an antibody called?
Fc region
Where is the light chain portion of the antibody?
Inner lining of the V shape
Where is the heavy chain portion of the antibody?
Surrounds the outside of the shape apart from where the light chain lies
What is the variable region of an antibody?
The upper part of the strands on the Y shape
What light chains can exist in a mammalian antibody?
One of two light chains kappa and lambda - they are however always identical
Does light chain affect the immunoglobulin (antigen receptor surface of antibody)?
No
Does changing the heavy chain affect the immunoglobulin?
Yes, they define the class of Ig
Describe the meaning of the constant region of an antibody
Defines the class of antibody - so the same in every antibody of the same class
What is the variable region of the antibody?
The part that differs between B cells, allowing antobodies collectively to bind to loads of different things
How many types of heavy chain exist
5
What are the 5 different types of antibodies and their functions?
IgM - good at fixing compliment and opsonisation
IgG- Good at opsonising
IgA - protects mucosal surfaces, resistant to stomach acid
IgE - Defends against parasites - responsible for anaphylactic shock
IgD - No known Ab function
What is T cell dependant activation of a b cell?
T cell surface protein recognises the same antigen as the B cell - Signal is given by a newly formed cluster of b cell receptors, signal also given off by T cell
When will independent activation of a B cell occur?
When a huge number or b cell receptors are clustered together by an antigen with a very large number of repeated epitopes
What is the first antibody to be produced by an antibody?
IgM
What influences the type of antibody the B cell produces as it matures?
The chemicals surrounding the area of infection
How are antibodies able to bind to epitopes far apart on the antigen.
They are flexible
Where can IgA be found?
In the gut
Why does histamine cause a runny nose and watery eyes?
Fc region of Ige binds to mast cells. On second exposure to allergen the receptors are pulled together - chemicals inside the cell are released into the tissue - causes increase in the capillary permeability - causing fluid to escape
How many antigens is each BCR specific to?
1
What must happen to the BCRs before a signal is sent?
They have to cluster together
Why is independent activation of B cells important?
T cells only recognise proteins, not all antigens are proteins
How can compliment activate B cells?
Through binding to one of the compliment proteins in the membrane, the number of antigens needed to be bound decreases.
