Chapter 20: The Lymphatic System and Lymphoid Organs and Tissues

Vocabulary-style flashcards covering the lymphatic system components, vessel distribution, lymphoid cell types, and specific organs such as the spleen, thymus, and lymph nodes.

Lymph

Fluid derived from interstitial fluid that flows in a one-way direction and does not circulate back into the blood.

Lacks of Lymphatic Capillaries

Specific body parts that do not have lymphatic capillaries, including the teeth, brain, and bone.

Lymphatic Transport Order

The pathway of fluid from tissues toward the heart: lymphatic capillaries → collecting vessels → lymphatic trunks → lymphatic ducts.

Minivalves

Flaplike structures in lymphatic capillaries that prevent backflow and facilitate the uptake of fluid.

Intestinal trunk

The specific lymphatic trunk that is unpaired.

Right lymphatic duct

The vessel that empties its lymph into the right subclavian vein.

Plasma cells

Progeny of activated B cells that produce and release antibodies.

Reticular cells

Fibroblast-like cells that produce the structural framework (stroma) of most lymphoid organs.

Dendritic cells

Spiny-looking cells that capture antigens and bring them to lymph nodes.

Macrophages

Cells that phagocytize tissue cells, bacteria, and other foreign substances and help to activate T cells.

T lymphocytes ($T$ cells)

Cells that direct the immune response and, when activated, some directly attack and destroy infected cells.

B lymphocytes ($B$ cells)

Cells that when activated produce effector cells that carry out an antibody-mediated immune response.

Diffuse lymphoid tissue

A loose arrangement of lymphoid cells and some reticular fibers.

Lymphoid follicles

Solid, spherical bodies consisting of tightly packed lymphoid cells and reticular fibers.

Primary lymphoid organs

The thymus and red bone marrow, which serve as the locations where $B$ and $T$ cells mature.

Secondary lymphoid organs

Organs such as the spleen and lymph nodes where lymphocytes first encounter antigens.

Germinal center

The area within a lymphoid follicle where $B$ lymphocytes are most abundant.

Spleen Location

The left side of the body, located right under the diaphragm.

White pulp

The region of the spleen where immune functions take place; it clusters around central arteries and is composed mostly of lymphocytes.

Red pulp

The region of the spleen consisting of splenic cords and sinusoids where worn-out red blood cells are destroyed.

MALT

Mucosa-associated lymphoid tissue, which guards the body's entryways against pathogens.

Pharyngeal tonsil

The type of tonsil located in the posterior wall of the nasopharynx, referred to as the adenoid if enlarged.

Thymus Stroma

Unlike other lymphoid organs, the stroma of this organ consists of epithelial tissue rather than reticular connective tissue.

Blood thymus barrier

A physiological barrier that prevents immature $T$-cells from activating prematurely.