MICROBIOLOGY - CHAPTER 13

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Accessory receptor protein on T helper cells that binds to MHC class II molecules

CD4

T cells express with a __________ or a ________ coreceptor

CD4 CD8

Found onles cytotoxic T cells, and it binds MHC class I molecu

CD8

Mature T cells can express:

CD8 coreceptors CD4 coreceptors

______ _______________ play important roles in the immune response, serving to activate different components of immunity.

Cell Markers

Gene code for makers that appear on all nucleated cells. They display unique characteristics of self and allow for the recognition of self molecules and regulation of immune reactions.

Class I

MHC genes also code for immune regulatory makers. These makers are found on macrophages, dendritic cells, and B cells, and involved in present antigens to T cells during cooperative immune reactions.

Class II

MHC genes encode proteins involved with the complement system, among others.

Class III

Distribution in Lymphatic organs B cells

Cortex (in follicles)

Each human produces antibodies with ___ _______ different specificities

10 trillion

Large complex macromolecules approaching a molecular wight (MW) of___________ ______________ are the most immunogenic

100,000 Daltons (a unit of molecular weight)

Acquired specific immunity is the product of a dual system, they are _____ and _____ lymphocytes.

B T lymphocytes

When activated, it divides, giving rise to plasma cells, each with the same reactive profile.

B cells

All cells - both _________ cells and __________ cells have a variety of different markers on their surfaces,

foreign self

Small foreign molecules that are too small by themselves to elicit an immune response are termed

haptens

Naive B cells do what

home in on specific sites (ie. lymph nodes) and circulate through the blood

The process of eliminating any lymphocytes with receptor that recognize self molecules during the development process is

immune tolerance

Specific immunity only occurs after an ____________ event

immunizing

A molecule that stimulates a specific response by T and B cells are called a _________ or ___________

immunogen antigen

B lymphocytes, the receptor genes that undergo the recombination are genes coding for

immunoglobulin

Large glycoprotein moleules that serve as the antigen receptors of B cells and, when secreted, as antibodies.

immunoglobulin

T and B cells in the periphery of the body have mechanisms to prevent reaction with _____________ antigens

innocuous

Specific T - cell areas of circulation

lymph nodes spleen

B cells (lymohocytes) irulate through the blood, "homing" to specific sites in which areas?

lymph nodes, spleen, and gut-associated lymphoid tissue (GALT)

B cells and T cells also constantly circulate between the which areas?

lymphatic and general circulation systems

The property of memory refers to the rapid mobilization of ______________

lymphocytes

B and T cells constantly recirculate through the circulatory system and lymphatics, migrating into and out of the _________ _______

lymphoid organs

Tissue _____________ ingest the pathogen and induce an inflammatory response in the tissue if appropriate.

macrophages

Three different cells can serve as APCs,they are:

macrophages B cells dendritic

One set of genes that codes for human cell makers or receptors is the ______ _________________ _______

major histocompatibility complex (MHC)

B cells that have made it through the maturation process have not yet encountered antigens so they are called _________ B cells and they entered circulation in order to home in on specific sites

naive

PAMPs are molecules shared by many types of microbes that stimulate a _____________ response

nonspecific

Bone marrow stromal cells guide B cell development by:

nurturing lymphocyte stem cells and providing chemical signals that initiate B cell development

These glycoproteins (MHC molecules) are found on all cells except ____ ________ _______

red blood cells

The specific immune response is highly ________ which means that a given antibody, B cell receptor, or T cell receptor only recognizes a specific antigen

selective

During the generation of lymphocyte receptor diversity, any cells that develop a specificity for _________ molecules are eliminated.

self

By the time T and B cells reach the lymphoid tissues, each one is already equipped to respond to a ________ _________ ________

single unique antigen

Two features that most characterize this third line of defense are

specificity memory

These cells are found in bone marrow. This was first discovered in birds.

stromal cells

Bacterial toxins that belong to a group of immunogens are called

superantigens

B cells specific surface markers

Immunoglobulin

Each human ________ a unique combination of class I MHC genes from their parents

Inherits

PAMPs

Pathogen-associated molecular patterns

Release antibodies into the tissue and blood.

Plasma ells

Lymphocyte specificity is

Preprogammed, existing in the genetic makeup before an antigen has ever entered the system

The maturation of T cells and the development of their specific receptors are directed by the __________ _________ and its __________

thymus gland hormones

______ cells are the "mediators" of cell mediated immunity.

T

Which cell receptor is relatively small and never secreted?

T cell receptors

Receptors that bind antigens that have been processed and complexed with MHC molecule on presenting cell surface.

T cells

Secretes cytokines that help destroy pathogens and regulate immune responses.

T cells

Superantigens are potent stimuli for which cells?

T cells

Which cells do not produce antibodies

T cells

PAMPs and antigens share the following characteristics

They are parts of foreign cells They provoke an immune response

MHC Class I molecules on host cell display unique characteristics of self which is important tot he process of:

Tissue rejection

Any exposed or released protein or polysaccharide is a potential _________ for specific immunity.

antigen

Any exposed or released protein or polysaccharide is potentially an

antigen

During their developmental process, B and T lymphocytes undergo a selective process that specializes them for reacting only to one specific

antigen

The ends of the forks formed by the light and heavy chains contain pockets called

antigen binding sites

Perceived as foreign, meaning that it is not a normal constituent of the body is an

antigen or immunogen

In most immune reactions, the antigen must be further acted upon and formally present to lymphocytes by called called

antigen-presenting cells (APCs)

Highly individual and stimulate specific immunity are ___________

antigens

Mature lymphocytes eventually populate the lymphatic organs where they encounter

antigens

The _________ __________ theory is a conceptual explanation for the development of lymphocyte specificity and variety during immune system maturation.

clonal selection

The mechanism by which the exactly correct B or T cell is activated by an incoming antigen is a process called

clonal selection

Each genetically unique line of lymphocytes arising from the extensive recombination of surface proteins is termed a

clone

The entire ____________ region of an antibody has an amino acid content that does not vary greaty.

constant

Tissue ____________ cells ingest the antigen and migrate to the nearest lymphoid organ.

dendritic

Cytotoxic T cells that lead to the destruction of infected host cells and ___________ cells

foreign

It is acceptable to think of antigens as ____________ molecules that stimulate the immune response

foreign

Most materials that serve as antigens fall into these chemical categories:

*Proteins and polypeptides ( enzymes, cell surface structures, exotoxins)*lipoproteins (cell membranes) * glycoproteins (blood cell makers) * nucleoproteins (DNA complexed to proteins but not pure DNA)*polysaccharides (certain bacterial capsules) and lipopolysaharides

When comparing the T and B cell antigen-specific receptors they both:

1. Are formed by genetic rearrangements 2. Contain variable and constant regions 3 Are inserted into the lymphocyte cell membrane 4. Belong to the same protein family

The presence of Superantigens in infection activates T cells at a rate of _______ times greater than ordinary antigens.

100

____________ is a process by phagocytic cells

Antigen

Huge cells nurture the lymphocyte stem cell an provide chemical signals that initiate which cell development.

B

Receptors that bind antigens

B cells

T cell receptor for antigen belongs to the same protein family as the __ ______ receptor.

B-cell

Receptors for antigen - B cells

B-cell receptor (immunoglobulin)

Some diseases (autoimmunity) are thought to be caused by the loss of immune tolerance through the survival of

Forbidden clones

Circulation in blood - T cells

High numbers

MHC is also known as the _________ _____________ _________ (HLA) ____________

Human Leukocyte Antigen System

The ability of the body to react with countless foreign substances, develops

Immunocompetence

Circulation in blood - B cells

Low numbers

Markers that "accept" or "grasp" antigens in some form are called

Lymphocyte Receptors

MHC gene complex gives rise to a series of glycoproteins called _____ ___________

MHC Molecules

Lymphocytes arise from the same basic stem cell type, they also diverge into two distinct type

Maturation of B cells in specialized bone marrow sites. T cells occurs in the thymus.

Distribution in Lymphatic organs T cells

Paracortical sites (interior to the follicles)

Which cells produce antibodies?

Plasma cells

Memory is important to specific immunity in that it allows:

Rapid mobilization of antigen specific memory lymphocytes

Antigens or immunogens are defined as molecules that stimulate a response by which cells ______ and _____

T Cells and B Cells

T cell specific surface markers

T cell receptor several CD molecules

Specific immunity is the product of

a dual system of B and T lyphocytes

Each genetically distinct lymphocyte expresses only

a single specificity and can react to only one type antigen

The third line of immunity is not innate, it is____________

adaptive

Cell surface markers and molecules that occur in some member of the same species but not in other are called

alloantigens

A T cell gives rise to one of three different type of progeny, each involved in a ______-___________ immune function

cell-mediated

T-lymphocyte response is

cell-mediated immunity

After activation, the B or T cell multiplies rapidly in a process called

clonal expansion

T cells secrete soluble mediators called ________ that help destroy pathogens and regulate immune responses.

cytokines

When plasma cells release the antibodies, they attach to the antigen for which they are specific, the antigen is marked for____________ or _________________

destruction or neutralization

Lymphocytes capacity to discriminate differences in molecular shape is so fine that it recognizes and responds to only portion of hte antigen molecule called

epitope

The T cell antigen-specific receptor differs from the B cell antigen-receptor in that it has

fewer antigen binding sites

Antigen receptor diversity in lymphocytes is due to

genetic rearrangement events

The specificity for a single antigen molecule is programmed into the lymphocyte and is set for the life of a

given cell

immunoglobulins are large ________ __________ that serve as the antigen receptors of B cells and, when secreted, as antibodies.

glycoprotein molecules

The multiplication of a particular lymphocyte creates a clone, or a group of genetically identical cells, some of which are __________ cells

memory

When foreign cells cross the first line of defense and enter the tissue, resident _____________ migrate to the site.

phagocytes

When foreign cells or pathogens first enter a tissue, resident ____________ migrate to the site of antigen entry

phagocytes

Antigens are usually

proteins polysaccharides

During lymphocyte stem cell differentiation, random gene ______________________ occur that results in the generation of a large arry of antigen receptor diversity

rearrangement events

Lymphocytes have been programmed to "_______" their first engagement with the invader

recall

MHC genes have been identified in how many classes?

three

There are how many import features of clonal selections?

two

The __________ regions found on both the heavy and light chains in an antibody molecule come together to form the antigen binding site

variable

Extreme versatility in antigens is due to

variable regions (V)


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