Lymphoid Organs and Lymphocytes

thymus, salivary glands, bone marrow, spleen, lymph nodes, urogenital system, intestine, mammary glands, respiratory tract

List 3 of the 9 major lymphoid tissues

pluripotent stem cells

Lymphocytes develop from _____________________-

yolk sac/liver

where do lymphocytes origionate in the embryo/fetus?

bone marrow

where do lymphocytes origionate in the neonate and adult?

Bone marrow - bursa - B cell

Thymus - T cell

There are two divergent pathways for lymphocytes. What are they?

blood to secondary lymphoid organs

Naive lymphocytes constantly move from _______ to _______ and back again

thymus, bursa of fabricius, peyer's patch, bone marrow

What are the primary lymphoid organs?

tonsils, spleen, lymph nodes, peyer's patch, bone marrow

what are the secondary lymphoid organs?

primary lymphoid organs

____________________: sites of lymphocyte development

secondary lymphoid organs

________________: sites where lymphocytes respond to antigens

mature naive lymhocytes

What is the goal of primary lymphocytes?

To produce ______ _______ __________

dont react to self

during the initial selection in the primary lymphoid organs; immature lymphocytes are selected for those that dont what?

VDJ recombination, V, D, J

a process that generates diversity in antigen receptors, it involves the rearrangement of gene segments ____ ____ and ______ to create unique receptor genes

thymus

where do T lymphocytes mature?

t cells;

antigen presenting cells

Functionally, the cortex of the thymus produces _________ and the corticomedullary region and medulla produce _______________

cortex, medulla, antigen presenting cells

Immunocompetent naïve T cells circulate from the_______ to the _______ of the thymus. This maximizes lymphocytic exposure to the _______________ in the medulla.

does this react strongly with self antigens?

What question is asked when weeding out T cells via NEGATIVE selection

Does this react with self MHC?

What question is asked when weeding out T cells via POSITIVE selection

if it reacts to self,

if it doesnt or only weakly reacts to self MHC

What cells are weeded out during the the thymic selection process?

bone marrow, bursa, peyer's patches

where is the site of B lymphocyte maturation in adults and neonates

antigen presenting cells

Lymphocytes recirculate through secondary lymphoid organs. This maximizes encounters between _____________________ and lymphocytes

antigen, proliferate, differentiate

Lymphocytes recognize ________, interact with other cells, ________, and _________ to "effector" or memory lymphocytes

efferent lymph, venous blood

Differentiated lymphocytes leave via ________________ or ____________________

afferent lymphatics, efferent tubules, B cells, T cells

Antigens enter through _________________, and lymphatic fluid exits through the _______________________. The yellow follicles here are rich in ______ while the purple bands are rich in _____________

Spleen

________________: site of immune response to antigens specifically in the BLOOD

T cells

the spleen is rich in what kind of lymphocyte?

mucosa associated lymphoid tissue

_________________: Site of immune response to antigens along mucous membranes

M cells, peyers patch, naive T and B cells

___________ cells shuttle the bacteria to waiting dendrites that deliver it to the _____________.

The antigen is then brought to _______________.

They form receptors to this type of antigen.

false: they enter circulation, but ultimately return home to the site of exposure if not sued elsewhere

True/false: after exposure, lymphocytes form receptors and then leave this site of exposure to enter circulation for the rest of their days

cutaneous immune system

_________________: Process through which immune system responds to antigens penetrating stratified squamous epithelium

adhesion molecules and chemokines

Lymphocyte recirculation and rehoming is governed by ________ and _________

so sick

Read this super simple lymph timeline:

Mature naive Lymphocytes are circulating in lymph, they enter a lymph node and look for antigens, IF they find nothing, thye move on the next lymph node, If they find an antigen, they form receptors and continue circulating OR leave lymph via the thoracic duct into the bloodstream

true

true/false: most T cells are Helper T cells

40%, 2%

__________% of lymphocytes are found in the lymph nodes, but only about _______% of lymphocytes are seen in the blood

B lymphocytes, T lymphocytes, NK cells, Regulatory lymphocytes

What are the types of lymphocytes? (4)

B and T lymphocytes

______ and ______________ are the only cells that recognize and respond specifically to antigens

true

true/false: Only a small number of naïve lymphocytes are dedicated to any single antigen epitope

Immunophenotype

process that identifies cells based on the types of antigens or markers on the surface of the cell

true

true/false: cell receptors are the defining criteria for any specific type of cell and define the isotype of antibody that a lymphocyte is capable of producing

regulatory receptors

T cells have a very large number of what kind of receptors?

native antigens, secrete antibodies

B cells typically recognize __________; ("big ol parasites with multiple epitopes") and their main function is to ___________

surface immunoglobulin

B cells' antigen receptors are ______________-

TCR + CD4

Helper T cells antigen receptors are _______________---

processed peptide, secrete cytokines

Helper T cells main antigen that they recognize is _________--and their main function is to _______________

TCR + CD8

cytotoxic t cells antigen receptors are:

processed peptide, kill abnormal cells

Cytotoxic Tcells main antigen that they recognize is _________--and their main function is to _______________

MHC class I

CD8 T cells, also known as cytotoxic or killer T cells, complex with antigen presented in association with a ___________molecule.

MHC Class II

CD4 T cells or helper cells bind to antigens presented in association with a _________________ molecule

up regulate cell mediated immunity,

up regulate antibody production

There are two types of helper T cells

T helper 1 cells do what?

And T helper 2 cells?

true

true/false: Receptor/ligand phenotypes can vary with lymphocyte maturation and activation status

cytokine receptors, antibody receptors, complement receptors, integrins, selectins

what molecules can regulate lymphocyte function?

tyrosine kinase phosphorylation

what is the key mechanism for cell activation? (a vital bridge between antigen recognition and subsequent immune response)

right, right...

read:....

Receptors with tyrosine kinase activity are present within the cell membrane. When bound to a signal molecule such as an antigen, the intrinsic tyrosine kinase domains of the receptor become closer in proximity, allowing for phosphorylation. Other intracytoplasmic signaling proteins join the phosphorylated complex, effectively transducing the signal through the cell

clonal expansion

Once activated, the naïve lymphocyte becomes an effector cell, and there is rapid proliferation and differentiation of that specific lymphocyte to form a clone designed to eliminate that specific antigen.