6.2 - Anatomy of the Immune System & Haematopoiesis Flashcards
Why are immune system organs called lymphoid organs?
because lymphocytes are found there
What is lymph? What is the structure of lymph?
mechanism for lymphocytes to travel in
clear fluid, basically ECF that has left capillaries and filter through tissues
What is the shape of lymph nodes?
bean shaped
Where are lymph nodes situated?
knee, groin, elbow, shoulder, neck
What are regions of the body outside the lymphoid organs called?
periphery
What are the types of lymphoid organs?
primary
secondary
Lymphoid organs where lymphocytes develop are called ______
primary lymphoid organs
List the primary lymphoid organs.
What do they produce?
Bone Marrow
- all blood cells develop here
- B lymphocytes mature here
Thymus
- T lymphocytes mature here
What happens at the secondary lymphoid organs?
lymphocytes interact and initiate responses
List the secondary lymphoid organs
- spleen
- lymph nodes
- tonsils
- Gut Associated Lymphoid Tissue (GALT)
What is the function of secondary lymph nodes?
to filter blood and lymph for pathogens and pathogen containing lymphocytes
What is the structure of secondary lymphoid organs? What do they do individually?
afferent lymph vessel
- brings in lymphocytes from periphery
efferent lymph vessel
- allows lymphocytes to keep circulating
pulp inside lymph node
- allows mixing of lymphocytes and other leukocytes
The spleen and lymph nodes are surrounded by a ________
fibrous wall, encapsulated
The tonsils and GALT are _______ tissues
unencapsulated, diffuse
List the 6 main types of leukocytes
- eosinophils
- basophils (mature into mast cells)
- neutrophils
- monocytes (mature into macrophages)
- lymphocytes
- dendritic cell
TRUE OR FALSE:
RBC are larger and more numerous than leukocytes
FALSE
RBC are SMALLER than leukocytes but MORE numerous
List the leukocytes by their function and morphology
Granulocytes
- have prominent cytoplasmic granules
- eosinophils, basophils, neutrophils
Phagocytes
- engulf and ingest pathogens
- eosinophils, neutrophils, macrophages
Cytotoxic cells
- kill other cells, even self cells
- eosinophils and some lymphocytes
Antigen Presenting Cells (APCs)
- display fragments of pathogens on cell surface
- some lymphocytes, dendritic cells, macrophages
What are antigens (Ag)?
Antibody generator
substances that are recognized by an antibody and induces an immune response
What are antibodies (Ab)?
proteins that bind specifically to Ags’ and target pathogens for destruction
Eosinophils have ____ staining granules and basophils have large _____ staining granules
eosinophils = bright pink
basophils = dark blue
Where are eosinophils found?
digestive tract, lungs, genital tract, skin
TRUE OR FALSE
Eosinophils live for more than 12 hours and are found a lot in peripheral circulation
FALSE
eosinophils
- few in peripheral circulation
- live only 6-12 hours
During allergic responses, eosinophils _____
degranulate
Eosinophils defend against ____ and ______
parasites and allergies
How do eosinophils respond to parasites?
- bind to antibody coated parasites and degranulate
- granule contents (toxic enzymes and oxidative chemicals) damage and kill parasites
Basophils are granulocytes involved in ____
allergic reactions
Where are basophils found?
in digestive tract, lungs, skin
Basophils are rarely found in _____ , while mast cells are found in ______
blood
tissues
What do the granules inside the basophils contain?
histamine, heparin, cytokines
TRUE OR FALSE
Like eosinophils, basophils also degranulate during allergic responses
TRUE
Neutrophils are _____ granulocytes
phagocytic
Name the most abundant leukocyte
Neutrophils (50-70%)
What is the lifespan and eating capacity of neutrophils?
1-2 days
can ingest 5-20 bacteria
TRUE OR FALSE
Neutrophils can leave the circulatory system to attack pathogens in tissues
TRUE
Neutrophils contain granules that contain ______ that cause fever and start other inflammatory responses
cytokines
What are neutrophils characterized by?
3-5 lobed nucleus, polymorphoneuclear (PMN)
Monocytes are precursor cells of _____ and are uncommon in blood (1-6% of leukocytes)
tissue macrophage
How long are monocytes in the blood for? Where do they move after?
8 hours
move into tissues to macrophage
What are macrophages? What do they do?
large ameoboid cells
phagocytoze old RBCs and dead neutrophils
TRUE OR FALSE
Macrophages can phagocyte up to 10 bacteria
FALSE
up to 100 bacteria
How can macrophages have a role in acquired immune response?
they act as APCs by presenting pathogens on the cell surface
_____ are the key players in acquired immune response
Lymphocytes
At any given time, lymphocytes make up ____ of all leukocytes. Where are most of them found?
20-30%
most of them are found in lymphoid tissues, only 5% in circulation
TRUE OR FALSE
Lymphocytes look differently under microscopes and perform different duties
FALSE
they all look alike
TRUE OR FALSE
Dendritic cells are phagocytic APCs
TRUE
What is a major feature of the dendritic cells?
have long processes like dendrites on a neuron
Where are dendritic cells found?
in skin and other organs
What is the function of dendritic cells?
recognize and engulf pathogens, placed on cell surface, travel to secondary lymphoid organs to present antigens to lymphocytes
TRUE OR FALSE:
All blood cells are produced in the thymus
FALSE
Bone marrow
Pluripotent haematopoeitic stem cells give rise to ?
commited progenitor cells and uncommited stem cells
What guides the path taken by stem cells?
cytokines
Why are B lymphocytes called B cells?
because of research in chicken
B cells leave the bone marrow and mature in the Bursa of Fabricius
TRUE OR FALSE
B cells produce antibodies on the cell surface as receptors or as free Abs in the plasma
TRUE
TRUE OR FALSE
T lymphocytes are called T cells because they mature in the thymus
TRUE
How do T cells communicate?
use contact dependent signalling via the T-cell receptor expressed on the T cell membrane
T cells can only bind to ___
T cell receptor ___ bind to free Ag
MHC antigen complexes
cannot
What does MHC stand for?
Major Histocompatibility Complex
What are MHCs?
proteins expressed on the surface of cells that display “self antigens” and “non self antigens” to T cells
TRUE OR FALSE
the name MHC is derived from the role of MHCs in transplant rejection
TRUE
What are the 2 classes of MHCs that interact with T cells?
CLASS 1
- found on all nucleited cells
CLASS 2
- only on APCs
TRUE OR FALSE
cytotoxic T cells (killer T cells), helper T cells (Th) and regulatory T cells (Treg) all recognize Ag presented on class 2 MHC
FALSE
cytotoxic T cells (Tc) only recognizes MHC on class 1 MHCs
Cytotoxic T cells kills cells that expresses _____
appropriate Ag
Helper T cells promotes differentiation between ____ and _____
They can also ______
B cells and Tc cells
they can also activate macrophages
What is the function of regulatory T cells?
suppress other immune cells to prevent excessive immune responses
