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44 Cards in this Set

  • Front
  • Back
Circulation of lymph
blood capillaries-> tissue-> some into lymph-> lymph nodes-> thoracic duct-> venous blood circulation
List the 4 major types of lymphoid tissue
-diffuse lymphoid tissue
-lymph nodule
-lymph node and spleen (true organs)
-bone marrow and thymus
Describe diffuse lymphoid tissue
Loose collection of lymphocytes , often in connective tissue underlying epithelia that are involved in transport of materials from outside world
Describe lymph nodules
lymphocytes organized in germinal center (growth center for B cells)
germinal center
where B cell clones grow
True lymph organs
Lymph node and spleen. Have capsule, arteries and veins. Contain lymph nodules
Sites of lymphocyte production and maturation
Bone marrow and thymus
Lymphocyte precursors are generated in the ______________ from _______________ cells
bone marrow; hematopoietic
Cells of the Immune response:

3 primary

5 accessory
-B cells - cell free and plasma membrane bound antigens (humoral response)
-T cells - respond to cell-bound antigens
-Helper T cells (CD4+), cytolytic T cells (CD8+)
-Natural killer cells

-Macrophages/Dendritic Cells
-Mast cells, Eosinophils, Basophils

B cells
thymus is compartmentalized by ________ cells
Hassall's corpuscle
onion-like epithelial cells found in medulla of thymus. More and bigger in older people. histological marker for thymus
blood-thymus barrier

Where are B cells found in lymph nodules? T cells?
B cells in cortex; T cells in paracortex
Where are plasma cells and macrophages found in lymph nodes
Medullary cords (macrophages are also in lymph-filled sinuses
Where do B cell precursors differentiate?

Where do they go after they differentiate?

-To lymphoid tissue via blood
how do B cells recognize proteins (term)
Addressins: venule epithelium ligands that determine lymph destination
high endothelial venules
venules with roughly cuboidal endothelium. B cells leave from blood here
White pulp
lymphoid tissue in the spleen.
Functions of spleen
-primary filter for foreign materials
-RBC destruction
red pulp
region where RBC's are being selected for destruction
the body's 3 main lines of defense against infection
-protective surface mechanisms (eg. mucous, cilia)
-non-specific (innate) tissue defense (neutrophils, etc)
-specific immune responses (T cell/B cell)
Discuss 1st step of immune response: activation of helper cell by phagocytic cell
-Phagocytic cell phagocytizes pathogen
-Cell displays pathogen antigen (pieces of cell) on cell surface
-Helper T's (or cytolytic T's) recognize antigen and are activated
humoral immunity
B cell is activated by activated T cell (helper T cell?) and proliferates. Most cells become plasma cells and produce antibodies. Some become (resting) memory cells to respond quickly to future infections.
What happens after T cell is activated (roughly)
-activation of helper T
- "clonal expansion" of helper T cells (mitosis)
-helper T interacts with B cells
-B cell proliferates into memory cells or plasma cells
Discuss Killer T's
cell-mediated immunity
-are activated by antigen presenting cell
-proliferate, find infected cells
-kill cell
-DOES NOT trigger humoral immunity!
4 main functions of immune system
-generate immunocompetent lymphocytes
-concentrate antigens in specific tissues
-circulate lymphocytes
-deliver antibodies and effector T-cells
primary lymphatic tissue
bone marrow, thymus. Where cells originate and mature
Where are B cells produced? T cells?
Both are produced (originally) in bone marrow
Where do B cells mature? T cells?
B cells in marrow. T cells in thymus
Where is the thymus located
Upper mediastinum, but probably not visible in our cadavers
Thymus: Basic structure
-thin connective tissue capsule w/ 2 parts:
-highly lobulated
Path of T cell through thymus
-immature T cells enter cortex with no markers (CD4, CD8)
-Cells develop BOTH markers as they move toward the medulla
-Cells lose on marker
-if cells do not lose a marker or if they have "self" designating antigens, they will undergo apoptosis (macroghages ingest remains)
-Mature, specific T cells exit cortex into medulla
Secondary lymphatic tissue (3)
-Non-encapsulated Aggregates
-Lymph Nodes

Residences of mature lymphocyes (?)
Lymph follicle
collection of B cells, found in cortex of lymph nodes
Structures of a lymph node.

What does blood do when it enters a lymph node?
cortex: follicles - collections of B cells, and paracortex - lots of T-cells

Blood enters, percolates, leaves.
Whitish spot within a follicle
germinal center. Immune response has been initiated and B cells are undergoing mitosis
Chain reaction when antigen enters lymph node
Antigen is picked up by antigen presenting cell -> activates T -> T activates Bs
Do Bs and Ts always stay in a certain lymph node?
No, if they haven't been activated in a while they can wander out in the blood and enter general circulation
Medullary sinus
in lymph nodes (and others?). Space that the lymph flows through
medullary cords
cords inside sinuses which macrophages and plasma cells hang onto.
What is special about the endothelium of lymph nodes
the cells are more cuboidal than normal simple squamous. Lymphocytes see the tissue and know they are at a lymph node and leave the blood.
Basic function of lymph node
to aggregate antigens and immune defence cells (B, T, antigen presenting)
2 divisions in the spleen
white pulp - lymphocytes
red pulp - RBCs, macrophages, and everything else with the blood
PALS (slide 18)