Question

Given the Assertion and Reason below, Choose one of the following responses Assertion:Lymphocytes arise in the bone marrow and differentiate in the bursal lymphoid tissues or in the thymus into B-cells and T-cells.Reason:B-cells and T-cells are prepared for providing humoral and cell-mediated immunity.

Answer 1

The organs of the immune system are positioned throughout the body. They are called lymphoid organs because they are home to lymphocytes, small white bloodcells that are the key players in the immune system.

There are two groups of immune system organs.

Primary (central)--organs where immature lymphocytes develop

Thymus

Bone marrow

Secondary (peripheral)--tissues where antigen is localized so that it can be effectively exposed to mature lymphocytes

Lymph nodes

Appendix

Peyer's Patches (of GI tract)

Tonsils

Adenoids

Spleen

MALT (Mucosal-Associated Lymphoid Tissue)

GALT (Gut-Associated Lymphoid Tissue)

BALT (Bronchial/Tracheal-Associated Lymphoid Tissue)

NALT (Nose-Associated Lymphoid Tissue)

VALT (Vulvovaginal-Associated Lymphoid Tissue)

Note: Some sources place the vermiform appendix, small intestine Peyer's Patches, tonsils, and adenoids within the GALT.