Lymphatic System and Lymphoid Organs

These flashcards cover the vocabulary and key structural components of the lymphatic system, including lymphoid cells, primary and secondary organs, and specific tissue regions like the spleen's white and red pulp.

Lymphatic vessels

Vessels that drain lymph from tissues and transport it toward the heart in a one-way direction.

Lymph

Fluid that flows in a one-way direction toward the heart, originating from interstitial fluid.

Minivalves

Flaplike structures in lymphatic capillaries anchored by filaments that prevent the backflow of fluid.

Intestinal trunk

The lymphatic trunk that is unpaired in the human body.

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 of a lymphoid organ.

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, can directly attack and destroy infected cells.

B lymphocytes (B cells)

Cells that produce effector cells carrying out an antibody-mediated immune response; most abundant in germinal centers.

Primary lymphoid organs

Locations where B and T cells mature, specifically the thymus and red bone marrow.

Secondary lymphoid organs

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

Afferent lymphatic vessels

Vessels that carry lymph into the convex side of a lymph node.

Efferent lymphatic vessels

Vessels that carry lymph out of the concave side (hilum) of a lymph node.

Hilum

The concave region of a lymph node where efferent lymphatic vessels exit.

White pulp

The splenic region composed mostly of lymphocytes clustered around central arteries where immune functions take place.

Red pulp

The splenic region 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

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

Tonsillar crypts

Structures in the tonsils that function to trap and filter out bacteria and particulate matter.

Thymus

A primary lymphoid organ in the mediastinum where T lymphocytes mature; its stroma consists of epithelial tissue rather than reticular fibers.

Blood-thymus barrier

A barrier that prevents immature T-cells in the thymus from being activated prematurely.