Micro E1 Chap 14-16

What is the first line of defense?

What is the first line of defense?

Any barrier that blocks invasion at the portal of entry: innate/nonspecific -physical, chemical, genetic barriers

What are some examples of physical barriers?

skin, tears, coughing, sneezing

What are some examples of chemical barriers?

low pH, lysosomes, digestive enzymes

What are some examples of genetic barriers?

resistance inherent in genetic makeup of host

What is the second line of defense?

Internalized system of protective cells and fluids which includes inflammation and phagocytosis: innate/nonspecific

What are some examples of second line defense mechanisms?

inflammatory response, fever, phagocytosis, interferons, complement cascade

What is the third line of defense?

Acquired on an individual basis with exposure to foreign substances; produces protective antibodies and creates memory cells that come into play if the microbe is encountered again: specific

What are some examples of the third line of defense?

T lymphocytes, B lymphocytes, antibodies

What is the role of pathogen-associated molecular patterns (PAMPs)?

serve as a red flag to signal WBCs

What is the role of pattern recognition receptors (PRRs)?

sense pathogens and recognize foreign cells

What are the 4 major subdivision of the immune system?

Mononuclear phagocyte system (MPS), extracellular fluid (ECF), bloodstream, lymphatic system

What is the mononuclear phagocyte system?

Network of connective tissue fibers that interconnects other cells and meshes with the connective tissue network surrounding organs

Why is the mononuclear phagocyte system critical to the immune system?

allows phagocytic WBCs to move within tissues

What is serum?

liquid portion of blood after clot has formed

What is plasma?

liquid portion of blood with clotting factors

What do lymphoid stem cells turn into?

NK cells or lymphoblast → T cells or B cells

What do Myeloid stem cells turn into?

mono blasts, myeloblast, megakaryoblast, erythroblast

What do myeloblast differentiate into?

mast cells, neutrophils, basophils, eosinophils

Which are the first immune cells to defend against infection? What is their primary function?

Neutrophils: phagocytosis

What do the cytoplasmic granules do?

Carry digestive enzymes that degrade the phagocytosed material

What do eosinophil granules primarily target? What other conditions will cause the eosinophils to react?

Eukaryotic pathogens, especially larval forms of worm parasites and fungi; also inflammation and allergies

What abnormality would you expect on a WBC in an individual with a helminth infection?

elevated eosinophil count

What chemical mediators do basophils release?

histamine and heparin

What conditions do basophils respond to?

inflammation, allergic reactions, asthma

How do basophils affect blood vessels?

cause blood vessels to dilate in response to injury and helps prevent blood from clotting

What is the difference between basophils and mast cells?

Mast cells are larger and contain more granules than basophiles, have a round nucleus, not bilobar; are nonmotile

Which WBC is the key to the third line or specific immune response?

lymphocytes

What do lymphocytes differentiate into and where do they mature?

B cells -bone marrow and T cells -thymus

Which type of lymphocyte provides humoral immunity?

B-lymphocytes

How do B lymphocytes fight bacterial infections?

secrete antibodies into the bloodstream and lymphatic fluid

What is another name for humoral immunity?

antibody-mediated immunity

Which type of lymphocyte provides cell-mediated immunity?

T-lymphocytes

How do T lymphocytes fight bacterial infections?

attack infected host, cancer, and foreign cells that are marked by the antibodies

What do T lymphocytes become when activated?

helper cells, suppressor cells, cytotoxic cells

What do monocytes differentiate into?

Macrophages and dendritic cells

What is the role of a macrophage?

-              process foreign molecules and presents them to lymphocytes

-              secret biologically active compounds that assist, mediate and attract, and inhibit immune cells and reactions

What is the role of the dendritic cell?

-              Trap pathogens

-              Highly effective processors and presenters of foreign proteins

What is lymph?

Plasma like-liquid carrier by lymphatic circulation

What type of immunity are natural killer (NK) cells involved with?

innate/nonspecific immunity

Why are natural killer (NK) cells not typically considered part of the third line of defense?

they do not display specificity or involve immunologic memory

Does natural killer (NK) cells activation involve immunologic memory?

No

What is the function of the lymphatic system?

-              Provides an auxiliary route for return of ECF to the circulatory system

-              Acts as a drain-off system for the inflammatory response

-              Rends surveillance, recognition, and protection against foreign material through the use of lymphocytes, phagocytes, and antibodies

Which direction is the movement of lymphatic flow?

One direction: toward the heart; eventually returns to the bloodstream

What are the primary lymphoid organs?

thymus and bone marrow

What are the secondary lymphoid organs?

spleen and lymph nodes

When does the thymus start to shrink?

gradually after puberty

What are the actions of the second line of defense?

recognition, inflammation, phagocytosis, interferon, complement

What term describes WBCs migrating out of blood vessels and entering the tissue?

diapedesis

What circulating substances cause fever?

pyrogens

How is an elevated temperature beneficial for fighting infection?

Inhibits multiplication of temperature-sensitive microorganism, impedes nutrition of bacteria, increases metabolisms and stimulates immune reaction and protective physiological processes

What are the phases of phagocytosis?

chemotaxis, ingestion, phagolysosome formation, destruction, elimination

What is the end product of the complement system, and how does it affect the cell membrane?

Membrane-attack complex (MAC): produce hundreds of tiny holes in the cell membrane → cell lyses and death

What are the molecules that stimulate the third line of defense?

antigens

What two features characterize acquired immunity?

specificity and memory

Does cell-mediated immunity involve antibodies?

no

Which T-cells have CD4 receptors?

helper T cells

Which T-cells have CD-8 receptors?

cytotoxic T cells

Where are Class 1 MHC genes located? What cells do they present antigens to?

all nucleated human cell; killer T-cells

Where are Class 2 MHC genes located? What cells do they present antigens to?

some types of WBCs; helper T-cells

What are antigens?

molecules that bind components of the immune response and has the POTENTIAL of invoking an immune response

What is an epitope?

molecular fragment of an antigen that serves as the primary signal to lymphocytes that the molecule is foreign

What are immunogens?

molecules that ALWAYS provoke a specific immune response when introduced to the body

What are haptens?

small foreign molecues that are too small by themselves to elicit an immune response

What are alloantigens?

cell surface markers and molecules that occur in some members of the same species but not in others

What are super antigens?

provoke an overwhelming response and massive release of cytokines

What are allergens?

antigen that evokes allergic reactions

What are auto antigens?

molecules on self tissues for which tolerance is in inadequate

What are the classes of immunoglobulins?

IgG, IgA, IgM, IgD,IgE

What is opsonization?

process of coating microorganisms or other particles with specific antibodies so they are more readily recognized by phagoctyes

What is neutralization?

abs fill the surface receptors on a virus or the active site on a microbial enzyme to prevent it from attaching to their target cells

What is agglutination?

Ab aggregation; cross-linking cells or particles into large clumps renders microbes immobile and increases the speed with which they are phagocytized

What is complement fixation?

activation of the classical complement pathway can result in the specific rupturing of cells and some viruses

What is precipitation?

aggregation of free antigen molecules increases the speed they are phagocytized

Which immunoglobulins can cross the placenta?

IgG

Which immunoglobulin is involved in allergic and parasitic infections?

IgE

Which immunoglobulin is the first to be synthesized following an antigen encounter?

IgM

What is an anamnestic response, and is it primary or secondary?

Secondary: after second contact with same Ag, immune system produces a more rapid, stronger response due to memory cells

What happens when T cells are exposed to super antigens?

provokes an overwhelming immune response by large numbers of T cells (Drastic consequences: cytokines, vessel damage, toxic shock, multiorgan damage)

What is natural immunity?

acquired as part of normal life experiences

What is artificial immunity?

acquired through a medical procedure

What is active immunity?

results when a person is challenged with antigen that stimulates production of antibodies; creates memory, is lasting

What is passive immunity?

antibodies produced by the immune system of another human are donated to an individual; does not create memory, is short term

What is an example of natural immunity?

breast milk, developing immunity from measles post infection

What is an example of artificial immunity?

vaccine, immune serum

What is an example of active immunity?

develops immune response to chickenpox

What is an example of passive immunity?

antibodies from mother

What is a live attenuated vaccine?

contains live virus particles or bacterial cells

Should live attenuated vaccines be used in immunocompromised individuals?

no

What vaccines are considered live-attenuated?

MMR, chickenpox, yellow fever, TB, typhoid (oral)

What is an inactivated vaccine?

contain whole bacterial cells or virus particles that have been killed or inactivated

Why do inactivated vaccines require boosters?

microbe does not multiply

What vaccines are inactivated?

Hep A, Flu, Polio, rabies, typhoid (shot)

What is a viral vector vaccine?

uses a modified version of a different virus to deliver protection

What vaccines are viral vectors?

Ebola, COVID

What is a subunit vaccine?

made from viruses (Hep B, HPV, Shingles)

What is an acellular vaccine?

made from bacterial cell parts (pneumonia, meningitis)

What is a toxoid vaccine?

Consists of a purified fragment of bacterial exotoxin that has been inactivated (diptheria, tetanus)

What is herd immunity?

resistance to the spread of an infectious disease within a population that is based on pre-existing immunity

What is a hypersensitivity?

exaggerated, misdirected expression of immune responses

What is an autoimmune disease?

abnormal responses to self Ag due to inability to distinguish between self and nonself