Exam 2 Flashcards By MATI (Immune System)

most abundant phagocytes; phagocytize infectious material in tissues

1. most voracious phagocytes (most hungry/engulf large)

2. Free macrophages wander through tissue spaces; e.g., alveolar macrophages

   1. Derived from WBCs called monocytes

3. Fixed macrophages; permanent residents of particular organs; e.g., stellate macrophages of liver

   1. Formed in embryo

a membrane-bound vesicle formed in phagocytic immune cells that engulfs pathogens or debris for degradation

a cellular structure formed when a phagocyte engulfs a pathogen, and the resulting phagosome fuses with a lysosome to digest and destroy the invader

a rapid increase in oxygen consumption by phagocytic immune cells, leading to the production of reactive oxygen species (ROS) that help kill engulfed pathogens (a lot of the time if not killed in phagocytosis)

1. a cellular process in which certain cells engulf and digest large particles, such as pathogens, dead cells, or debris, playing a crucial role in immunity and tissue maintenance

   1. can also be helped by respiratory burst/defensins (in neutrophils)

Immune system counters this by coating pathogens with opsonins

1. type of molecule in the immune system that enhance the process of phagocytosis

2. complement proteins or antibodies

3. Any pathogen can be coated with opsonins, a process called opsonization

the process by which pathogens are marked for destruction by the immune system, enhancing their recognition and uptake by phagocytic cells

1. release their toxic chemicals into the extracellular fluid

   1. E.g., neutrophils undergo netosis, releasing a sticky net of their own DNA and proteins to trap and kill extracellular pathogens

2. Unlike macrophages, neutrophils rapidly destroy themselves in the process of killing their targets (sacrifice)

1. a nonspecific response to any tissue injury

   1. Causes include trauma, intense heat, irritating chemicals, or infection

   2. Suffix –itis signifies inflammation

1. Prevents spread of pathogens

2. Disposes of cell debris and pathogens

3. Alerts adaptive immune system

4. Sets stage for repair

1. redness

2. heat

3. swelling

4. pain

5. Some consider impaired function to be a fifth sign

   1. E.g., restricted movement of an inflamed joint may force person to rest it, which assists healing

a naturally occurring compound in the body that acts as a chemical messenger involved in immune responses

a type of white blood cell (WBC) important in immune defense, particularly in allergic reactions and inflammation

small peptides in the body that act as potent mediators of inflammation, vasodilation, and pain, playing a key role in regulating blood pressure and vascular permeability

hormone-like lipid compounds that play key roles in inflammation, pain, blood flow, and other physiological processes

a group of plasma proteins that work together to enhance the immune system’s ability to fight infections and clear pathogens

to clear injured area of pathogens, dead tissue cells, and any other debris so that tissue can be repaired

factors that induce leukocytosis can be classified into physiological, pharmacological, and pathological categories, each operating through distinct molecular and cellular mechanisms

the directed movement of white blood cells (WBCs) toward chemical signals, guiding them to sites of infection or inflammation

molecules that guide white blood cells (leukocytes) to sites of infection, injury, or inflammation by creating a chemical gradient that the cells can detect and follow

1. creamy yellow mixture of dead/dying neutrophils, broken-down tissue cells, and living/dead pathogens

   1. Eventually, collagen fibers wall off pus, forming an abscess, if inflammation doesn’t eliminate the debris; may need to be surgically drained to begin healing

molecules produced by the immune system that help protect the body by directly killing or inhibiting the growth of microbes such as bacteria, fungi, viruses, and parasites

a multi‑protein structure formed by complement components C5b–C9 that inserts into pathogen membranes to create pores, leading to cell lysis

1. an abnormally high body temperature, is a systemic response to invading microbes

   1. Leukocytes and macrophages exposed to foreign substances secrete pyrogens

      1. Chemicals that act on group of neurons in hypothalamus (body’s thermostat), raising temperature above normal

1. increases ability of T lymphocytes and monocytes to migrate into lymph nodes, enhancing immune response

2. Increases metabolic rate, which increases rate of repair and T lymphocyte production

3. Suppresses bacterial growth by making it more difficult for bacteria to obtain certain metal ions such as iron

1. substances that can mobilize the adaptive defenses, provoking an immune response

   1. They are the targets of all adaptive immune responses

   2. Most are large, complex molecules (natural or synthetic) that are foreign

      1. Not normally found in body, so viewed as nonself by our immune system

1. complete

2. incomplete

1. Immunogenicity

2. Reactivity

ability to stimulate proliferation of specific lymphocytes

ability to react with activated lymphocytes and the antibodies released by immunogenic reactions

molecules that can both induce an immune response and bind the resulting antibodies, and in the complement system they are the antigens capable of forming antibody–antigen complexes that efficiently trigger complement activation

1. Virtually all foreign proteins (strongest antigens), many large polysaccharides, and some lipids and nucleic acids

2. Pollen grains and microbes are immunogenic because their surfaces bear many foreign macromolecules

1. small molecules that aren’t immunogenic by themselves, but become so when attached to protein carrier

2. Combination viewed as foreign, triggering immune response

3. Certain drugs, and chemicals in poison ivy, animal dander, detergents, cosmetics, and many household and industrial products act as haptens

1. parts of antigen that are immunogenic (antibodies/lymphocyte receptors bind to)

   1. Most natural antigens have variety of antigenic determinants, different lymphocytes “recognize” different antigenic determinants

      1. one antigen stimulates many lymphocytes, formation of different types of antibodies vs them

1. all body cell surfaces covered with variety of proteins that are not (normally) antigenic to self, but strongly antigenic to others

   1. Basis of transfusion reactions and graft rejection

1. cell-surface molecules that display antigen fragments to T cells, enabling the immune system to distinguish self from non‑self and mount targeted immune responses

2. Coded by genes of major histocompatibility complex (MHC) and unique to each individual

1. Each MHC protein contains deep groove that holds (displays) a peptide (either a self- or foreign antigen)

2. T lymphocytes can only bind antigens that are presented on MHC proteins

a group of genes that encode cell‑surface proteins responsible for presenting antigens to the immune system, enabling the body to distinguish self from non‑self

1. B-lymphocytes

2. T-lymphocytes

3. Antigen-presenting cells (APCs)

1. Play essential auxiliary roles in immunity

2. present antigens to T cells

3. engulf antigens and display fragments for T cells to recognize (i.e., they present antigens to the cells that will deal with them)

process by which a single B lymphocyte that specifically recognizes an antigen is activated to proliferate and differentiate, producing a large population of identical cells that generate targeted antibodies

activated immune cells that directly carry out the work of eliminating pathogens, such as killing infected cells, producing antibodies, or releasing inflammatory molecules

long‑lived immune cells that “remember” past infections or vaccinations so the body can respond faster and more effectively when it encounters the same pathogen again

1. dendritic cells

2. macrophages

3. B lymphocytes

1. Act as mobile lookouts in membranes (cutaneous and mucous) that contact the external environment

2. Specialized to capture (phagocytize) antigens, then enter lymphatics to present them to T cells in lymph nodes

3. Most effective antigen presenter known (it's their only job)

1. Widely distributed throughout lymphoid organs

2. Present antigens to naive T cells to activate them (like dendritic cells do)

3. To maintain T cell activation

4. Become activated macrophages themselves, insatiable phagocytes that also:

   1. Trigger powerful inflammatory responses

   2. Recruit additional defenses

Present antigens to helper T cell to assist their own activation (they do not activate naive T cells)

the adaptive immune system’s ability to “remember” a pathogen after an initial encounter so it can mount a faster, stronger, and more efficient response upon future exposure

1. Provide antigenic determinants that are immunogenic and reactive

2. Spare us most of the symptoms and discomfort of a primary response (via infection with disease)

1. Prevent hepatitis A (antiserum)

2. Treat poisonous snake bites (antivenom) and botulism, rabies, and tetanus (antitoxin)

structures formed when antibodies bind to antigens, creating clusters that help the immune system neutralize and clear foreign substances

the clumping together of cells or particles when antibodies bind to antigens on their surfaces, forming visible aggregates

1. pure antibody preparations specific for a single antigenic determinant

   1. Commercially made for use in research, clinical testing, and cancer treatment

      1. E.g., used to diagnose pregnancy, certain sexually transmitted infections, some cancers, hepatitis, and rabies

1. CD4

2. CD8

1. most become helper T cells that help activate B cells, other T cells, and macrophages, and direct adaptive immune response

2. Some become regulatory T cells that moderate immune response

1. most become cytotoxic T cells capable of destroying infected and abnormal or foreign cells

2. Activated CD4 and CD8 cells can also become memory T cells