Lymph nodes, Peyer's Patchess, & Tonsils

Lymphoid System pt. 1

Lymphoid Tissue

Specialized form of CT involved in adaptive immune defense; Lymphocyte is the primary functional cell

Humoral immunity

Antigen stimulates production of antibody

Cellular immunity

Cell directly attacks foreign host via binding to specific antigen or epitope

B-Lymphocyte

IgD & IgE surface receptors; produce antibodies

Antigen

Molecule that is foreign to the body

Antibody

Protein secreted to neutralize an antigen

T-Lymphocyte

Surface receptor binds directly to antigen; destroys foreign & altered cells

Null Cells

Small portion of lymphocytes - NK & Stem cells

NK Cells

Destroy foreign, viral altered, or cancer cells without T-lymph or thymus interactionST

Stem Cell

Cell of origin for blood cells

Reticular CT

Framework of lymphoid tissue

Reticular Cell

Fibroblast w specialized function to produce and maintain reticular CT

T-Cell Zone

Difiuse lymphoid tissue

B-Cell Zone

Dense solitary lymph nodules

MALT

Mucosa-Associated Lymphoid Tissue; non-encapsulated, found in gut and bronchus

Primary Lymphoid Organ

Sites where lymphocytes are produced & or become immunocompetent; Bone marrow & thymus

Secondary lymphoid organ

Site where immunocompetent lymohocytes contact antigens & proliferate; lymph nodes, spleen, tonsils, Peyer’s patches, Hemal nodes

Function of Lymph node

regional filtration of tissue fluid; antigen recognition, antibody production, & lymphopoeisis

Parenchyma

Cortex, Paracortex, Medulla

Cortex

Primary nodule; resting stage

Congregation of B-lymphocytes, memory b-lymphocytes, & follicular dentritic cells

Secondary Nodule

Germinal center; formed via activation of primary nodule

Paracortex

Thymus dependent zone

Localized t-lymphocytes, interdigitation of dendritic cells

Site of t-lymph proliferation

Medulla

Medullary cord & lymph sinuses

Peyer’s Patch

Secondary lymphoid

Most abundant in the Ileum

Aggregated in noduels

GALT

Peyer’s patches lack

A capsule and efferent vessel

Tonsils

Secondary lymphoid organ

Incompletely encapsulated

Found in nasal and oral openings

Tonsils unique in that

Only efferent lymphatic vessels present