BIOL 261: CH. 26 - INNATE IMMUNITY: BROADLY SPECIFIC HOST DEFENSES

Adaptive immunity

the acquired ability to recognize and destroy a particular pathogen or its products, dependent on previous exposure to the pathogen or its products

Antibody

a soluble protein produced by B cells and plasma cells that interacts with antigen; also called immunoglobulin

Antibody-dependent cell-mediated cytotoxicity (ADCC)

the process by which NK cells bind IgG-coated target cells and kill them by secreting cytolytic toxins

Antigen

a molecule capable of interacting with specific components of the immune system and that often functions as an immunogen to elicit an adaptive immune response

Antigen-presenting cell (APC)

a macrophage, dendritic cell, or B cell that takes up and processes antigen and presents it to T-helper cells

Basophil

a circulating granulocyte that contains granules of inflammatory mediators that, in some cases, contribute to allergic reactions

B cell

a lymphocyte that has immunoglobulin surface receptors, produces immunoglobulin, and may present antigens to T cells

B cell receptor (BCR)

a cell surface immunoglobulin that acts as an antigen receptor on a B cell

Chemokine

a soluble protein that recruits immune cells to an injury site; a type of cytokine

Complement system

a series of proteins that react sequentially with antibody–antigen complexes, mannose-binding lectin, or alternative activation pathway proteins to amplify or potentiate target cell destruction

Cytokine

a soluble protein produced by a leukocyte or damaged host cell; modulates an immune response

Dendritic cell

a phagocytic antigen-presenting cell found in various body tissues; transports antigen to secondary lymphoid organs

Epitope

the portion of an antigen that reacts with a specific antibody or T cell receptor

Eosinophil

a phagocytic granulocyte especially active against extracellular parasites, such as helminths

Fever

an increase in body temperature resulting from infection or the presence of toxins in the body

Granulocyte

a leukocyte derived from a myeloid precursor that contains cytoplasmic granules consisting of toxins or enzymes that are released to destroy target cells

Hematopoiesis

the process by which precursor stem cells in the bone marrow or gut differentiate into any type of blood cell

Hematopoietic stem cell

a progenitor cell found primarily in the bone marrow but also in the gut that can differentiate into any of a variety of blood cells

Immune memory (memory)

the ability to rapidly produce large quantities of specific immune cells or antibodies after subsequent exposure to a previously encountered antigen

Immunity

the ability of an organism to resist infection

Immunoglobulin

a soluble protein produced by B cells and plasma cells that interacts with antigen; also called antibody

Inflammation

a cytosolic signaling complex that contains NOD-like receptor pyrin 3 (NLRP3) and mediates the activation of potent proinflammatory cytokines

Innate immunity

the inherent ability to recognize and destroy an individual pathogen or its products that does not rely on previous exposure to a pathogen or its products

Interferons

cytokine proteins produced by virus-infected cells that induce signal transduction in nearby cells, resulting in transcription of antiviral genes and expression of antiviral proteins

Invasion

the ability of a pathogen to enter into host cells or tissues, spread, and cause disease

Leukocyte

a nucleated cell in blood; also called a white blood cell

Lymph nodes

organs that contain lymphocytes and phagocytes arranged to encounter microorganisms and antigens as they travel through the lymphatic circulation

Lymphocytes

a subset of nucleated cells in blood involved in the adaptive immune response; B cells and T cells

Macrophage

a large leukocyte found in tissues that has phagocytic and antigen-presenting capabilities

Major histocompatibility complex

a genetic region that encodes several proteins important for antigen processing and presentation; MHC I proteins are expressed on all nucleated cells, whereas MHC II proteins are expressed only on antigen-presenting cells

Mast cell

tissue granulocyte similar in function to basophils that contains intracytoplasmic granules with inflammatory mediators

Monocyte

Circulating phagocyte that contains many lysosomes and can differentiate into a macrophage or dendritic cell

Mucosa-associated lymphoid tissue (MALT)

a part of the lymphatic system that interacts with antigens and microorganisms that enter the body through mucous membranes, including those of the gut, the genitourinary tract, and the respiratory tract

Natural killer (NK cells)

a specialized lymphocyte that recognizes and destroys infected host cells or cancer cells in a nonspecific manner

Neutrophil

a leukocyte exhibiting phagocytic properties, a granular cytoplasm (granulocyte), and a multilobed nucleus; also called polymorphonuclear leukocyte or PMN

Opsonization

the deposition of antibody or complement protein on the surface of a pathogen or other antigen that results in enhanced phagocytosis

Phagocyte

a cell that engulfs foreign particles, and can ingest, kill, and digest most pathogens

Phagocytosis

a mechanism for ingesting particulate material in which a portion of the cytoplasmic membrane surrounds the particle and brings it into the cell; for phagocytes of the immune system, the process of engulfing and killing foreign particles and cells

Phagosome

an intracytoplasmic vacuole containing engulfed materials, especially pathogens or foreign particles

Plasma

the liquid portion of the blood containing proteins and other solutes

Plasma cell

a differentiated B cell that produces soluble antibodies

Serum

the liquid (noncellular) portion of the blood with clotting proteins removed

Specificity

the ability of cells of the adaptive immune response to interact with particular antigens

Stem cell

a progenitor cell found primarily in the bone marrow but also in the gut that can differentiate into any of a variety of blood cells

T-cell

a lymphocyte that interacts with antigens through a T cell receptor for antigen; T cells are divided into functional subsets including Tc (T-cytotoxic) cells and Th (T-helper) cells. Th cells are further subdivided into Th1 (inflammatory) cells and Th2 cells, which aid B cells in antibody formation

T cell receptor (TCR)

an antigen-specific receptor protein on the surface of T cells

What is immunity?

Immunity is the ability of an organism to resist infection.

What are the two types of immunity?

The two types of immunity are innate immunity and acquired (or adaptive) immunity.

What is innate immunity?

Innate immunity is immunity that an organism is born with and is nonspecific.

What is acquired (or adaptive) immunity?

Acquired immunity is immunity that develops after birth and involves a specific response to an antigen.

What is humoral immunity?

Humoral immunity is a type of immune response where antibodies are produced to target and neutralize antigens.

What is the role of B-cells in humoral immunity?

B-cells differentiate into plasma cells that produce antibodies in response to an antigen.

What triggers the differentiation of B-cells into plasma cells?

The presence of an antigen triggers the differentiation of B-cells into plasma cells.

What do plasma cells do?

Plasma cells produce antibodies that target specific antigens.

What is cell-mediated immunity?

Cell-mediated immunity is an immune response involving T-cells that target infected cells.

What are the types of T-cells involved in cell-mediated immunity?

The two main types of T-cells involved are T-helper cells and cytotoxic T-cells.

What is the role of T-helper cells in cell-mediated immunity?

T-helper cells assist in the immune response by triggering inflammation (Type I) and presenting antigens to B-cells (Type II).

What does Type I T-helper cell activation trigger?

Type I T-helper cell activation triggers an inflammation reaction.

What does Type II T-helper cell activation do?

Type II T-helper cell activation helps present the antigen to B-cells for antibody production.

What is the function of cytotoxic T-cells?

Cytotoxic T-cells directly destroy infected cells by lysing them.

Why don't pathogens easily infect tissues?

Pathogens do not easily infect tissues because harmless microbes limit available nutrients and sites for infection through competitive exclusion.

What is competitive exclusion?

Competitive exclusion is when normal flora bacteria block pathogens from being able to attach and grow.

What is the function of mucus in the mucous membranes?

Mucus is sticky and traps bacteria, viruses, and debris.

What is the role of ciliated epithelial cells in the respiratory tract?

Cilia move mucus away from the lungs.

What is lysozyme and what does it do?

Lysozyme breaks beta 1-4 linkages in peptidoglycan cell walls of bacteria.

What is complement?

Complement is a serum protein responsible for lysing cells.

Why is stomach acid important in defending against infection?

The pH of stomach acid is 2, which prevents bacteria from growing since they typically grow at neutral pH.

What is the role of white blood cells in immune defense?

Some white blood cells, like neutrophils and macrophages, are phagocytic and help eliminate pathogens.

What are neutrophils and what is their role?

Neutrophils are a type of white blood cell with three or more lobes in their nucleus, and they are involved in phagocytosis.

What is the function of macrophages in immunity?

Macrophages are antigen-presenting cells and also part of adaptive immunity.

How does urine flow help protect against infection?

Urine flow flushes out any bacteria in the urethra.

Why is intact skin important in defending against infection?

Intact skin serves as a physical barrier that prevents pathogens from entering the body.

What are antimicrobial peptides and where are they made?

Antimicrobial peptides are made by human cells and help combat pathogens.

What are the 3 routes of infection?

• Inhalation

• Direct & indirect contact

• Ingestion

What is the etiological agent?

The etiological agent is the pathogen or the cause of the disease.

What is an example of an etiological agent?

An example of an etiological agent is HIV, which causes AIDS.

What is the role of the host in the development of a disease?

The host is the organism that is affected by the etiological agent, such as humans being affected by HIV.

What are CD4T Helper cells and how are they related to HIV?

CD4T Helper cells are a type of white blood cell that HIV targets, leading to immune system dysfunction in individuals with AIDS.

How does skin help limit bacterial growth?

Skin is salty and acidic, which limits bacterial growth.

Which type of bacteria does this primarily affect?

It primarily affects staphylococci.

What is the primary function of the heart in the circulatory system?

The heart functions as the pump in the circulatory system, circulating blood throughout the body.

What is the difference between arteries and veins in the circulatory system?

Arteries carry oxygenated blood away from the heart, while veins carry deoxygenated blood back to the heart.

Does the lymphatic system have a pump?

No, the lymphatic system does not have a pump; it relies on the movement of lymph through veins.

What do veins in the lymphatic system have to assist with circulation?

Veins in the lymphatic system have valves to help direct the flow of lymph and prevent backflow.

How does skeletal muscle contribute to the lymphatic system?

Skeletal muscle helps move lymph through the lymphatic system by contracting and squeezing the lymphatic vessels.

What type of epithelial cells are found in capillary beds?

Simple squamous epithelial cells.

How do substances move across the capillary beds?

Through simple diffusion.

What drives the process of simple diffusion in capillary beds?

Concentration gradients.

What are RBCs?

RBCs, or erythrocytes, are the most numerous cells in the blood.

What do RBCs carry?

RBCs carry oxygen (O2) and carbon dioxide (CO2).

What is the role of RBCs in blood types?

RBCs determine blood types.

What is another name for RBCs?

Another name for RBCs is erythrocytes.

What are WBCs?

WBCs, or leukocytes, are white blood cells that have nuclei.

How are WBCs classified?

WBCs are classified into granulocytes and agranulocytes.

What are granulocytes?

Granulocytes are WBCs that have granules in their cytoplasm.

What are agranulocytes?

Agranulocytes are WBCs that do not have granules in their cytoplasm.

What are lymphocytes?

Lymphocytes are a type of agranulocyte that includes B-cells and T-cells, involved in immune responses.

What are B-cells?

B-cells are a type of lymphocyte involved in antibody production.

What are T-cells?

T-cells are a type of lymphocyte involved in cell-mediated immune responses.

What are monocytes?

Monocytes are a type of WBC found in the blood.