Cells and Tissues of Immune System

Flashcards covering lymphoid organ classification, spleen and lymph node structure, innate vs adaptive immunity, and naturally vs artificially acquired immunity.

What are the primary lymphoid organs?

Bone marrow and thymus (sites of lymphocyte development).

Name some secondary lymphoid organs where antigens are encountered.

Spleen, lymph nodes, adenoids/tonsils, Peyer's patches, appendix; also MALT (Mucosa-associated Lymphoid Tissue), GALT, and BALT.

What do lymph nodes do?

• Collecting points for lymph fluid

• Lymphocytes come into contact with antigen from TISSUES

What are the two major sections of the spleen and their functions?

Red pulp removes old/damaged red blood cells and foreign antigens; white pulp is where lymphocytes and macrophages encounter antigens.

What is a germinal center?

A site within lymphoid tissue where mature B cells proliferate and differentiate after encountering antigen; class switching and somatic hypermutation occur there.

What is the fate of most lymphocytes if they are not activated by antigen?

They die within a few days.

How do innate and adaptive immunity differ in speed and specificity?

Innate is rapid (minutes to hours) and non-specific; adaptive is slower (days) but antigen-specific and capable of memory.

Name common components of innate immunity.

Physical barriers (skin, mucous membranes); phagocytic cells; antimicrobial proteins; inflammatory response; natural killer (NK) cells; pattern recognition receptors for PAMPS.

Name common components of adaptive immunity.

Lymphocytes (T and B), memory, humoral immunity (antibodies), and cell-mediated immunity (cytotoxic T cells).

What are the two main arms of the adaptive immune response and what do they do?

Humoral response uses antibodies in body fluids; cell-mediated response uses cytotoxic T cells to kill infected cells.

What does MALT stand for and what tissues does it include?

Mucosa-associated lymphoid tissue; includes GALT (gut), BALT (bronchus), and other mucosal lymphoid tissues such as tonsils/adenoids, Peyer's patches, and appendix.

What are naturally acquired and artificially acquired immunity?

Naturally acquired immunity arises through infection or maternal transfer; artificially acquired immunity arises through vaccines or immune sera.

What is naturally acquired active immunity?

Infection leads to an active immune response with memory.

What is naturally acquired passive immunity?

Antibodies transferred from mother to fetus through placenta or to infant via breast milk.

What is artificially acquired active immunity?

Vaccines (dead or attenuated pathogens) stimulate an active immune response.

What is artificially acquired passive immunity?

Injection of immune serum (gamma globulin).

Which cell types are typically involved in innate immunity?

Dendritic cells, mast cells, macrophages, natural killer cells, basophils, neutrophils, eosinophils; plus complement proteins and interferons.

Which receptors are used by innate vs. adaptive immunity?

Innate uses pattern recognition receptors for PAMPs; adaptive uses antigen recognition receptors on T and B cells.