Lymphatic System and Innate Immunity Practice Flashcards

A comprehensive set of vocabulary flashcards covering the lymphatic system, lymphoid organs, and innate immune responses based on the lecture material.

Lymphatic System

Consists of networks of lymphatic vessels, lymphoid tissues, and organs that function in immunity and returning interstitial fluid to the bloodstream.

Lymph

Interstitial fluid that has entered the lymphatic vessels.

Thoracic Duct

The larger of the two main lymphatic ducts that drains lymph from most of the body into the left subclavian vein.

Right Lymphatic Duct

The lymphatic duct that drains lymph from the upper right quadrant of the body into the right subclavian vein.

Primary Lymphoid Organs

The sites where lymphocytes are formed and mature, specifically the thymus and red bone marrow.

Secondary Lymphoid Organs

Sites where lymphocytes are activated and cloned, including the lymph nodes, tonsils, spleen, Peyer’s patches, and appendix.

Cisterna Chyli

An expanded, saclike chamber that receives lymph from the inferior part of the abdomen, pelvis, and lower limbs.

Lymphatic Capillaries

Vessels that originate as pockets, have larger diameters and thinner walls than blood capillaries, and are often flattened or irregular in cross section.

Lymphedema

A condition caused by the blockage of lymphatic drainage, leading to the accumulation of toxins and pathogens.

Cytotoxic T Cells

T cells involved in cell-mediated immunity that attack foreign cells or body cells infected by viruses.

Helper T Cells

T cells that stimulate the activation and function of both T cells and B cells.

Suppressor T Cells

T cells that inhibit the activation and function of both T cells and B cells.

Plasma Cells

Differentiated B cells that are responsible for the production and secretion of antibodies.

Lymphopoiesis

The process of lymphocyte production and differentiation involving red bone marrow, the thymus, and peripheral lymphoid tissues.

Blood-thymus Barrier

A barrier in the thymus that prevents premature stimulation of developing T cells by circulating antigens.

MALT (Mucosa-associated lymphoid tissue)

A collection of lymphoid tissues that protect the epithelia of the digestive, respiratory, urinary, and reproductive systems.

Lymphoid Nodules

Densely packed areas of areolar tissue containing lymphocytes, often without a distinct capsule, such as Peyer’s patches.

Peyer’s Patches

Aggregated lymphoid nodules located in the mucosal lining of the small intestine.

Lymph Nodes

Small lymphoid organs, up to $1\,in$ in diameter, that filter lymph to remove $99\%$ of pathogens before it reaches vital organs.

Thymus Involution

The process where the thymus shrinks and becomes less active after puberty, decreasing from about $40\,g$ to $12\,g$, which may increase susceptibility to disease.

Spleen

The largest lymphoid organ; its functions include removing abnormal blood cells, storing iron from recycled RBCs, and initiating immune responses.

White Pulp

Areas of the spleen that resemble lymphoid nodules and contain high concentrations of lymphocytes.

Red Pulp

Splenic tissue containing large numbers of red blood cells, as well as fixed and free macrophages.

Splenectomy

The surgical removal of the spleen, which can increase the risk of bacterial infection.

Innate Immunity

Nonspecific defenses that do not distinguish between different types of threats and are present at birth.

Adaptive Immunity

Specific defenses that protect against particular threats and depend on the activities of lymphocytes.

Phagocytes

Cells such as neutrophils, eosinophils, and macrophages that engulf and destroy pathogens and cell debris.

Emigration (Diapedesis)

The process by which phagocytes leave capillaries by squeezing between adjacent endothelial cells.

Chemotaxis

The phenomenon where phagocytes are attracted to or repelled by chemicals in the surrounding fluids.

Immune Surveillance

The constant monitoring of peripheral tissues by Natural Killer (NK) cells to identify and destroy abnormal cells like cancer cells.

Perforins

Proteins released by NK cells that create pores in the membranes of abnormal cells, leading to their lysis.

Interferons

Cytokines released by activated lymphocytes, macrophages, and virus-infected cells that trigger the production of antiviral proteins.

Complement System

A system of over $30$ specialized proteins that 'complement' the action of antibodies in destroying pathogens through cascades.

Membrane Attack Complex (MAC)

A structure formed by complement proteins (C5b–C9) that creates pores in a target cell's membrane, causing it to lyse.

Opsonization

A process where complement proteins or antibodies coat a pathogen’s surface to enhance phagocytosis.

Inflammation

A localized tissue response to injury characterized by redness, swelling, heat, and pain.

Leukocytosis

An increase in the number of white blood cells in the bloodstream, often in response to inflammatory chemicals.

Pyrogens

Fever-inducing proteins that can be endogenous (like cytokines) or exogenous (like bacterial endotoxins).

Fever

A body temperature greater than $99^{\circ}F$ that can inhibit some viruses and bacteria while increasing metabolic rate.

Thymic Corpuscles

Structures in the thymic medulla where T cells gather after maturing for approximately $3$ weeks before entering the bloodstream.