Pathophysiology Ch. 7 Evolve

What is the difference between central tolerance and peripheral tolerance?

Central tolerance is the mechanism by which developing T cells in the thymus and B cells in the bone marrow are against foreign antigens and "tolerant" to self-antigens. Peripheral tolerance is developed when T cells and B cells reach maturity and enter the lymphoid organs and other tissues.

Which is a function of cytotoxic T lymphocytes?

Direct killing of foreign and abnormal cells

Which is the portion of the antigen that is configured to recognize and bind?

Epitope

Inactivation or blocking of the antigen binding to the receptor is best described as:

neutralization

Define acquired immunity.

Acquired or adaptive immunity develops in response to exposure to a foreign or nonself substance. The cells involved are memory cells that provide long-term protection against specific antigens. Acquired immunity is obtained from the development of antibodies when the human is exposed to an antigen or is obtained as the result of a vaccination or an attack of an infectious disease. Acquired immunity can be the result of the transmission of antibodies from mother to fetus via the placenta.

Which is characteristic of humoral immunity?

Antibodies are primarily responsible for protection.

What are antigen-presenting cells?

Antigens that cannot induce the immune response independently must first interact with several populations of cells including T helper (Th) cells and antigen-presenting cells (APCs). APCs are usually macrophages or macrophage-like cells in tissue, B cells, and endothelial cells. The immune response begins after the antigen interacts with Th cells and APCs.

What are the differences among antigens, immunogens, and haptens?

Any molecule that induces an immune response is an immunogen. An antigen is a molecule or molecular fragment that can bind with antibodies or antigen receptors on B and T cells and produce an immune response. Haptens are antigens that are too small to be immunogens by themselves but become immunogenic after combining with larger molecules that function as a carrier for the hapten. All immunogens are antigens, but not all antigens are immunogens, as there are antigens that do not stimulate an immune response.

Which statement best characterizes humoral response?

Becoming activated upon recognition of an antigen

Why are cytokines important to the immune response?

Cytokines are secreted by cells participating in the immune response and function as messengers, providing communication between APCs and various lymphocytes. During an immune response, one participant may produce a cytokine that is then released, binds to a specific receptor on a neighboring cell, and instructs that cell to respond in a genetically programmed fashion. Cytokines regulate adaptive or innate immunity.

Which is a characteristic of the immune response in humans?

Generation of clonal diversity occurs in primary lymphoid organs.

Distinguish between humoral and cell-mediated immunity.

Humoral immunity: The lymphocytes that migrate through bone marrow become B lymphocytes, or B cells. When B cells encounter antigens, they are stimulated to develop into mature plasma cells that secrete antibodies. B cells are responsible for humoral immunity. In the presence of humoral immunity the whole body is affected. Symptoms often affect different body systems. Cell-mediated immunity: The lymphocytes that migrate through the thymus gland become T lymphocytes, or T cells. T cells are capable of becoming sensitized to and recognizing specific antigens, which they attack directly. T cells are responsible for cell-mediated immunity. Symptoms in the presence of cell-mediated immunity are usually localized to specific areas or tissues.

The molecular classes of immunoglobulins include: (select four that apply)

IgG, IgM, IgE, IgA

Distinguish between innate and acquired immunity.

Natural or innate immunity is not produced by an immune response. It is the immunity present at birth and is species dependent. A second type of innate immunity is host-dependent immunity and involves the specific individual's genetic characteristics. Acquired immunity develops in response to initial exposure to an antigen. After initial exposure, subsequent exposures do not manifest into disease. It can also be the result of a vaccination or transmission of antibodies from the mother to the fetus via the placenta.

What is the role of T-helper cells?

T-helper cells emerge from the thymus with a characteristic cell surface protein, called CD4 (CD4-positive cells). Antigen-presenting cells present antigen to T-helper cells, whether an antigen primarily induces a cellular or humoral immune response. T-helper cells undergo differentiation into Th1, Th2, or Th17 cells. Th1 cells appear to support developing cell-mediated immunity, Th2 cells provide support for humoral immunity, and Th17 cells activate macrophages. The T-helper subsets differ considerably in the spectrum of cytokines they produce.

Define BCR and TCR

The B-cell receptor (BCR) is a complex of antibodies bound to the cell surface that recognizes antigen and communicates this information to the cell nucleus. The T-cell receptor (TCR) complex is composed of an antibody-like protein and a group of accessory proteins that are involved in signaling to the nucleus; all TCRs on a single T cell are identical in structure and specificity.

What are the major functions of antibodies?

The chief functions of antibodies are to protect the host by (1) neutralizing bacterial toxins, (2) neutralizing viruses, (3) opsonizing bacteria to promote phagocytosis, and (4) activating components of the inflammatory response.

What is the difference between the secretory and systemic immune systems?

The major differences between the secretory and systemic immune systems are as follows: (1) their lymphocytes follow different paths of migration and pass though different lymphoid tissues; (2) the secretory immune response is one of the body's first lines of defense; the systemic response is the body's last line of defense; (3) the secretory response occurs locally and externally in the body's secretions; the systemic response occurs systemically and internally through the blood and tissues.

What are the different types of T cells, and what function does each have?

There are several types of mature T cells, each with a different immune function. Memory cells induce the secondary immune response. Lymphokine-producing cells (Td) transfer delayed hypersensitivity and secrete proteins that activate other cells such as macrophages. Cytotoxic cells (Tc) attack antigens directly and destroy cells that bear foreign antigens. Helper T (Th) cells are regulatory cells that control both the cell-mediated and humoral immune responses.

The IgE antibody is correctly described as: (select two that apply)

a common cause of common allergies, capable of protecting the host from parasites.

It is true that aging affects self-defense mechanisms by:

decreasing immune function, diminishing T-cell function, reducing antibody response to antigenic challenges, decreasing thymic hormone production

Which is true regarding an IgA antibody? An IgA antibody: (select all that apply)

is found in blood as IgA-1, is primarily found in the body's secretions IUgA-2, has dimers anchored together by a J chain.

The excessive production of cytokines and Th-cell activation and proliferation is a result of:

superantigen