Quiz 6 Immune System

characteristic of antibodies

Has y-shaped proteins, each antibody is specific to a particular antigen, has five classes, helps neutralize pathogens and mark them for destruction, located in blood, lymph, and body fluids 

characteristics of passive immunity

The antibodies are given to a person (not made by their own body), provides immediate protection, short term (doesn’t last long because the body doesn’t produce memory cells 

function of neutrophils

destroy bacteria and fungi

site of action of neutrophils

blood and tissues

mode of action of neutrophils

phagocytic (engulf and digest microbes)

function of macrophages

eat pathogens and dead cells; activate other immune cells 

site of action of macrophages

tissues

mode of action of macrophages

phagocytic and recruit other cells by releasing signals 

function of lymphocytes

B cells make antibodies; T cells kill infected cells or help other immune cells 

site of action of lymphocytes

blood, lymph, tissues

mode of action of lymphocytes

B cells are antibody production; t cells directly kill or recruit 

function of natural killer cells

kill virus-infected and cancer cells 

site of action of natural killer cells

blood and tissues

mode of action of natural killer cells

direct killing (not phagocytic) 

function of dendritic cells

present antigens to T cells to start immune response 

site of action of dendritic cells

tissues and lymph nodes

mode of action of dendritic cells

recruit and activate other immune cells 

function of eosinophils and basophils

fight parasites and help with allergic responses 

site of action of eosinophils and basophils

blood and tissues

mode of action of eosinophils and basophils

release chemicals to recruit and activate other cells

helper T cells (CD4+)

coordinate the immune response by activating other immune cells; recognize antigens presented by MHC class II molecules 

cytotoxic T cells (CD8+)

directly kill infected or abnormal cells; recognize antigens presented by MHC class I molecules 

regulatory T cells (Treg)

suppress immune responses to prevent autoimmunity 

memory T cells

remember past infections for a faster response next time 

how B lymphocytes develop immunocompetence

Originate from stem cells in the bone marrow > mature in the bone marrow by developing unique B cell receptors on the surface which are particular to certain antigens > are tested for self-tolerance (this prevents autoimmunity by getting rid of B cells that react strongly to self-antigens > is immocompetent when it can recognize and bind to a specific antigen using the BCR and not react to the body’s own cells > travel to lymphoid tissues once they are immunocompetent 

inflammatory response

the body’s way of protecting itself from infection, injury, or harmful stimuli 

signs of inflammatory response

redness (rubor), heat (calor), swelling (tumor), pain (dolar), and sometimes loss of function

stages of inflammatory response

blood vessels dilate and become permeable (vascular change) > WBCS move to site of injury (cellular response) > histamine and cytokines help coordinate response (chemical mediators) 

composition of an antibody

Made of four protein chains (two heavy chains which are longer, two light chains which are shorter), which are arranged in a “Y” shape. The chains are held together by disulfide bonds (strong covalent bonds between sulfur atoms in cysteine amino acids). The disulfide bonds link the heavy chains to each other and each heavy chain to a light chain 

clonal selection

the process by which a specific B cell is chosen to multiply in response to an invading antigen 

which substance is responsible for determining which cells will eventually become cloned

The antigen is the substance responsible for determining which B cells will be selected due to the unique receptor that binds to a specific antigen 

characteristics of NK cells

do not require activation by specific antigens, recognize abnormal cells by detecting changes in surface proteins, and release perforins (create pores in target cell membrane) and granzymes (trigger programmed cell death) to kill target cells 

chemotaxis

the movement of cells toward or away from a chemical signal, important in inflammatory response 

how does chemotaxis work

chemical signals are released at the site of infection or damage, and immune cells detect these signals and migrate toward higher concentrations helping immune cells reach and attack pathogens quickly 

haptens

small molecules that, by themselves, cannot trigger an immune response  

how do haptens work

are able to trigger an immune response when they attach to a larger carrier molecule like a protein; hapten + carrier is recognized as foreign by immune system which causes it to produce antibodies 

sequence of phagocytosis

Chemotaxis > adherence > ingestion > digestion > exocytosis 

cytotoxic cells

immune cells that can directly kill infected, cancerous, or damaged cells 

main types of cytotoxic cells

Cytotoxic T cells which recognize and destroy cells presenting foreign antigens with MHC I molecules 

Natural Killer (NK) cells which kill abnormal cells without needing prior activation by antigens 

how do cytotoxic cells kill

release perforins and granzymes 

cell-mediated immunity

a type of adaptive immune response that relies on T cells (not antibodies) to defend the body against infected or abnormal cells using Cytotoxic T cells and helper T cells 

how does cell-mediated immunity work

antigen-presenting cells display foreign antigens on surface using MHC molecules, T cells recognize these antigens through T cell receptors, activated T cells multiply and carry out their functions 

what determines what specific foreign substances our adaptive immune system will be able to recognize and resist

Genetically encoded receptors on lymphocytes (genetic makeup of each lymphocyte) 

function of regulatory T cells

prevents the immune system from attacking the body’s own tissues (autoimmunity); limits excessive immune reactions to keep inflammation in check

autografts

tissue is transplanted from one part of your body to another part of your body 

isografts

tissue is transplanted between two genetically identical individuals 

allografts

tissue is transplanted between two people who are not genetically identical 

xenografts

tissue is transplanted from a different species 

antigen

any substance that can trigger an immune response by being recognized as foreign by the body’s immune system 

characteristics of antigens

not produced by your body (foreign), stimulate the production of antibodies or activate T cells, can react with antibodies or immune cells that are produced in response to them 

function of antigens

trigger immune response, help body recognize and eliminate pathogens or abnormal cells, serve as flags that mark invaders for destruction by the immune system 

cytokines

small proteins released by immune cells that act as chemical messengers to regulate immunity, inflammation, and blood cell formation 

B cell response to initial antigen

B cell encounters and binds to its specific antigen using its BCR > B cell enlists help from a helper T cell to become fully activated > activated B cell divides rapidly, producing many clones > clones become plasma cells (produce and secrete large amounts of antibodies specific to the antigen) and memory B cells (remain in the body to respond quickly if the same antigen appears again) > antibodies circulate in the blood and bind to the antigen 

opsonization

a process where pathogens (like bacteria) are tagged to make them easier for immune cells to recognize and destroy 

role of complement proteins

C3b binds to the surface of pathogens and acts as a signal that attracts phagocytes; phagocytes have receptors for C3b making it easier for them to attach and destroy 

characteristics of adaptive immune system

Targets particular pathogens or foreign substances using specific receptors of B and T cells, remembers the pathogen after initial exposure, recognizes and responds to millions of different antigens due to variety of receptors, can distinguish between the body’s own cells and foreign invaders, and provides protection throughout the entire body instead of just the site of infection 

characteristics of diabetes

Impaired immune response due to high blood sugar levels, chronic inflammation, autoimmunity in type 1 diabetes, and increased susceptibility to infections 

delayed hypersensitivity reaction

An immune response that takes 24-72 hours to develop after exposure to an antigen; involves T cells which recognize an antigen and release cytokines that attract and activate other immune cells 

innate immune system

Responds to all pathogens the same way without targeting specific invaders, acts quickly, has no memory of previous encounters with pathogens 

class I MHC molecules

found on all nucleated cells in the body, present from inside the cell to cytotoxic T cells, help the immune system detect and destroy infected or abnormal cells 

class II MHC molecules

found only on antigen-presenting cells, present exogenous antigens (from outside the cell) to helper T cells, help activate other immune cells to mount a coordinated immune response 

fever

An increase in body temperature above the normal range in response to infection or inflammation; helps the body fight off pathogens by making the environment less favorable for their growth 

immunocompetence

The ability of the immune system to recognize and respond to specific antigens; only immunocompetent cells can launch a proper immune response against pathogens while avoiding attacks on the body’s own tissues 

immune tolerance 

the process by which your immune system learns to recognize your own body’s cells and does not attack them

when is immune tolerance developed

during early life while immune cells are maturing in the thymus and bone marrow 

active immunity

your own immune system produces antibodies and memory cells after exposure to an antigen, you get active immunity through infection or vaccination, it is long-lasting since memory cells are formed

passive immunity

you receive ready-made antibodies from another source; your immune system does not make them, you receive passive immunity from mother to baby or by infection of antibodies, it is short-term 

immunodeficiency

A condition where the immune system’s ability to fight infections and diseases is weakened or absent making the body vulnerable to infections and certain cancers 

immediate hypersensitivity

A rapid allergic reaction that occurs minutes after exposure to an allergen  

how does immediate hypersensitivity occur

During the first exposure, the immune system produces IgE antibodies against the allergen, IgE binds to mast cells and basophils; during later exposure the allergen binds to the IgE antibodies causing the cels to release histamine; this leads to symptoms like sneezing, itching, swelling, and sometimes serve reactions 

primary immune response

The body’s first reaction to a new antigen; occurs when the immune system encounters an antigen for the first time. B cells are activated and start producing antibodies, mainly IgM at first. It then takes several days (lag phase) because the body needs time to recognize the antigen and produce specific antibodies. Memory cells are formed helping the body respond faster if the same antigen appears again 

what is considered to be the most critical cell in immunity

Helper T cells (CD4+ T cell) 

number of binding sites on IgG, IgE, and IgD

2 binding sites

number of binding sites on IgA

4 binding sites

number of binding sites on IgM

10 binding sites

mechanisms for the development of autoimmune disorderes

loss of selt tolerance, molecular mimicry, genetic factors, envrionmental triggers, and abnormal activation of immune cells

antibody function

Neutralization, opsonization, activation of complement proteins, agglutination, and antibody-dependent cellular cytotoxicity 

toll like receptors (TLRS)

special proteins found on the surface of immune cells (macrophages and dendritic cells) that help the immune system recognize pathogen-associated molecular patterns which are unique molecules found on microbes but not on human cells

what activates TLRS

bacterial cell wall components, viral RNA or DNA, flagellin, and fungal molecules