Chapter 21: Immunity

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What are some examples of innate body defenses?

complement, phagocytosis, lysozyme, inflammation

What is the process by which neutrophils squeeze through capillary walls in response to inflammatory signals?

diapedesis

antibodies released by plasma cells are involved in what?

humoral immunity, immediate hypersensitivity reactions, autoimmune disorders

Which antibodies can fix complement?

IgG and IgM

Which antibody class is abundant in body secretions?

IgA

small molecules that must combine with large proteins to become immunogenic are called what?

haptens

lymphocytes that develop immunocompetence in the bone marrow are called what?

B lymphocytes

cells that can directly attack target cells include what?

macrophages, cytotoxic T cells, and natural killer cells

What substances are involved in the activation of a B cell?

antigen, helper T cell, cytokine

the cell type most often invaded by HIV is what?

helper T cell

complement fixation promotes what?

cell lysis, inflammation, opsonization, and chemotaxis of neutrophils and other cells

Give examples of a phagocyte

neutrophil, macrophage

What releases histamine?

mast cell, basophil

what releases perforins?

natural killer cells, cytotoxic T cell

what are some examples of a lymphocyte?

natural killer cells, cytotoxic T cells, B cells, helper T cells

What are effector cells of adaptive immunity?

cytotoxic T cell and helper T cell

What are antigen-presenting cells?

dendritic cells, B cells, and macrophages

What distinguishes the innate defense system from the adaptive defense system?

the innate defense system is always ready, whereas it takes a lot of time to mount to adaptive defense system. the innate defenses consist of surface barriers and internal defenses, whereas the adaptive defenses consist of humoral and cellular immunity, which rely on B and T lymphocytes

what is the first line of defense against disease?

surface barriers (skin and mucous membranes)

What is opsonization and how does it help phagocytes? give an example of a molecule that acts as an opsonin

the process of making pathogens more susceptible to phagocytosis by decorating their surface with molecules that phagocytes can bind. antibodies and complement proteins are examples of molecules that act as opsonins

under what circumstances are our own cells killed by NK cells?

our own cels are killed by NK cells when they have been infected by viruses or what they have become cancerous

What are the cardinal signs of inflammation and what causes them?

redness, heat, swelling, and pain are the cardinal signs of inflammation. redness and local heat are both caused by vasodilation of arterioles, which increases the flow of blood to the affected area. swelling is due to the release of histamine and other chemical mediators of inflammation, which increase capillary permeability. this increased permeability allows proteins to leave into the ISF, increasing the ISF osmotic pressure and drawing more fluid out of blood vessels and into the tissues, thereby causing swelling. pain is due to the actions of kinins and prostaglandins on nerve ending, and the swelling which can compress nerve endings

name three key characteristics of adaptive immunity

it is specific, it is systemic, and it has memory

what is the difference between a complete antigen and a hapten?

a complete antigen has both immunogenicity and reactivity, whereas a hapten has reactivity but not immunogenicity

what marks a cell as "self" as opposed to "nonself"?

self antigens, particular MHC proteins, mark a cell as self

What event or observation signals that a B or T cell has achieved immunocompetence?

development of immunocompetence of a B or T cell is signaled by the appearance on its surface f specific and unique receptors for an antigen. in the case of a b cell, this receptor is a membrane-bound antibody

What T cell would survive education in the thymus?

the t cell that would survive is one that recognizes MHC but not self-antigen

name three different APCs. which is most important for T lymphocyte activation?

dendritic cells, macrophages, and B cells can all act as APCs. dendritic cells are most important for T cell activation

in clonal selection, "who" does the selecting? what is being selected?

in clonal selection, the antigen does that selecting. what is being selected is a particular clone of B or T cells that has antigen receptors corresponding to that antigen

why is the secondary response to an antigen much faster than the primary response?

the secondary response to an antigen is faster than the primary response because the immune system has already been primed and has memory cells that are specific for that particular antigen

how do vaccinations protect against childhood illnesses?

vaccinations protect by providing the initial encounter to an antigen-the primary response to that antigen. as a result, when the pathogen for that illness is encountered again, the pathogen elicits the much faster, more powerful secondary response, which is generally effective enough to prevent clinical illness

which class of antibody is most abundant in blood? which is secreted first in primary immune response? which is most abundant in secretions?

IgG antibody is the most abundant in blood. igM is secreted first in a primary immune response. igA is most abundant in secretions

list four ways in which antibodies can bring about destruction of a pathogen

antibodies can bring about destruction of pathogen via PLAN- phagocytosis, lysis (via complement), agglutination, or neutralization

Class II MHC proteins display what kind of antigens? what class of T cell recognizes antigens bound to class II MHC? what types of cells display these proteins?

class II MHC proteins display exogenous antigens. class II MHC proteins are recognized by CD4 T cells (which usually become helper T cells). APCs display class II MHC proteins

what happens when antigens are bound in the absence of co-stimulators?

when antigens are bound in the absence of co-stimulations this causes the lymphocyte to develop anergy, a state of permanent unresponsiveness to that antigen

which type of T cell is the most important in both cell-mediated and humoral immunity? why?

helper t cells are central to both humoral and cell-mediate immunity because they are required for activation of both cytotoxic t cells and most b cells

describe the killing mechanism of cytotoxic T cells that involves perforins

the cytotoxic t cell releases perforins and onto the identified target cell. perforins form a pore in the target cell membrane, and granzymes enter through this pore, triggering apoptosis

which proteins must be carefully matched before an organ transplant?

MHC proteins and blood type antigens are carefully matched before an organ transplant

What makes HIV particularly hard for the immune system to defeat?

HIV is particularly hard for the immune system to defeat because it destroys helper t cells, which are key players in adaptive immunity and it has a high mutation rate and so it rapidly becomes resistant to drugs

What event triggers the release of histamine from mast cells in an allergic response?

binding of an allergen onto specific igE antibodies attached to mast cells triggers the mast cells to release histamine

Special lymphatic vessels called lacteals absorb what that are not absorbed by the blood capillaries?

lipids

What are factors that help to move lymph?

the thoracic pump, the skeletal muscle pump, arterial pulsations squeezing lymphatic vessels, and rhythmic contractions of lymphatic vessels.

What are some things involved in the second line of defense?

inflammation, natural killer cells, interferon and the complement system, the macrophage system

What is one antimicrobial protein?

Interferons

What don't antibodies do?

differentiate into memory antibodies, which upon reexposure to the same pathogen would mount a quicker attack.

What is a cardinal sign of inflammation?

edema

What are some examples of autoimmune diseases?

multiple sclerosis, rheumatoid arthritis

What does aspirin inhibit?

prostaglandins

Which of the following is important for activation of a B-cell during the antigen challenge?

the antigen, a helper T cell, and chemicals that stimulate the B-cells to divide

Class II MHC proteins are found on what cell-surfaces?

macrophages, activated B lymphocytes, some T cells

What do interferons do?

interfere with viral replication within cells

B cells respond to the initial antigen challenge by doing what?

producing progeny cells that include plasma cells and memory cells

What is true about T cells?

their proliferation is enhanced by interleukins 1 and 2

What is not an autoimmune disease?

type 2 diabetes

In clonal selection of B cells, which substance is responsible for determining which cells will eventually become cloned?

antigen

The chief antibody-mediated mechanism used against cellular antigens, such as bacteria, is what?

agglutination

What is a characteristic of complete antigens?

reactivity with an antibody

delayed hypersensitivities include what?

allergic contact dermatitis

What is associated with passive immunity?

passage of IgG antibodies from a pregnant mother to her fetus

the process whereby neutrophils and other white blood cells are attracted to an inflammatory site is called what?

chemotaxis

Before a B lymphocyte can secrete antibodies it must transform into what?

plasma cell

Complement fixation enables foreign cells to be destroyed by what?

lysis

T cells become immunocompetent during their stay where?

thymus

Cytotoxic T cells can destroy cancer cells by means of a secretion called what?

perforin

It is allergy season, and you have tremendous nasal congestion, watery eyes, and a runny nose. These symptoms are caused when allergens bind to IgE on the membranes of ______ and stimulate them to release __________?

mast cells and basophils; histamine

Neutrophils are the chief enemies of bacteria. They exhibit what steps in fighting bacteria?

margination → diapedesis → chemotaxis → phagocytosis

What is NOT a cardinal sign of inflammation?

heat

Antibodies are what?

proteins

The only T cells that can directly attack and kill other cells are what?

cytotoxic cells

cancer cells and virus-infected body cells can be killed before activation of the immune system by what?

natural killer cells

Natural killer (NK) cells can do what?

kill cancer cells before the immune system is activated

What do cytotoxic T cells require during activation?

require the double recognition signal of I MHC plus II MHC on the target cell in order to function

What is immunocompetence?

the ability of individual cells to recognize a specific antigen by binding to it

These are "identification tags" that label every cell of your body as belonging to you

major histocompatibility complex proteins

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