Lymphoid Organs

It is where maturation of lymphocytes occur

Bone Marrow and Thymus are included

Primary Lymphoid Organs

It is where the contact with foreign antigens take place and lymphocyte recirculation occur

Secondary lymphoid Organ

Examples of Secondary Lymphoid Organs

Spleen

Lymph Nodes

MALT

It is the main source of hematopoietic stem cells. Place where B cell maturation occur

Bone Marrow

Small organ found in the thorax that allows a significant number of lymphocytes to pass through it to become fully immunocompetent thymus derived T cells

Thymus

Two main zones of the Thymus

Cortex and Medulla

Lymphoid Organs where contact with foreign antigens take place

Secondary Lymphoid organs

This organ acts as a large discriminating filter that removes senescent cells and foreign antigens from the blood

Spleen

Spleen is divided into two main types

_______________ - destroys senescent RBCs, more than one half of the volume

________________ - contains lymphoid tissue; found around periarteriolar lymphoid sheath

Red Pulp - senescent RBCs

White Pulp - lymphoid tissue

Central collecting point for lymph fluid that provides an ideal environment for contact with foreign antigens that have penetrated into the tissues

Provides the ideal environment for contact with foreign antigens that have penetrated into the tissues

Lymph Nodes

Filtrate of blood and arises from passage of water and low molecular weight solutes out of blood vessel walls and into the interstitial spaces

Lymph Fluid

This is the space where the lymph fluid flows slowly. It is lined with macrophages, creating an ideal location where phagocytosis can take place

Sinuses

Part of the Lymph Node that contains macrophages and aggregations of B cells in primary follicles

Cortex

Part of the Cortex that contains antigen-stimulated proliferating B cells

Secondary Follicles

Part of the Lymph Nodes that contains T cells

Paracortex

Other secondary lymph organ that is found in the gastrointestinal, respiratory, and urogenital tracts. It serves as main ports of entry for foreign antigens

Mucosal Associated Lymphoid Tissue

Other secondary Lymph Organ that contains intraepidermal lymphocytes

Cutaneous Associated Lymphoid Tissue

Cell that consists 60-80% of the circulating lymphocytes.

T-Cells

T cells differentiates and matures in the

Thymus

Precursor cells that are committed to becoming T cells

Thymocytes

Maturation of T cell is a complex process that occurs over a ____________ period

Three-week period

Maturation of T-cells starts at the _____________ and ends at the ________ region of the thymus

Starts at outer cortex

ends at medullary

Stage where the rearrangement genes that code for T-cell receptor begins.

It lacks CD4 and CD8 Markers, and thymocytes

Double Negative Stage

Double Negative Thymocytes proliferate in the outer cortex under the influence of this cytokine

IL-7

T cell receptor is composed of two specific chains ______ and ____________

and Six non specific chains (DE, GE, TT)

Alpha and Beta

Delta and Epsilon, Gamma and Epsilon, Tau-Tau

Beta chain rearrangement occurs at chromosome ______ and Alpha chain rearrangement occurs at chromosome _____

Beta = 7

Alpha = 14

Selection that occurs in the Double-Positive Stage where it checks for reaction with self-peptides other than MHC

Negative Selection

Self peptide that binds with an antigen will result in

Apoptosis

It is the elimination of clones of T-cells that are capable of eliciting an immune repsonse

Clonal Detection

Mature T cells only exhibit ____ or __

CD4 and CD 8