NaimExplain

Describe a plausible explanation for the increased incidence of cancer in the elderly. The increased incidence of cancer in the elderly may result from a decline in immune surveillance, which results in reduced elimination of tumor cells as they arise.

Describe immunosuppression. Immunosuppression is the partial or complete reduction of the immune response in a person. It is also induced to enhance the survival of organ transplant recipients.

Define autoimmune disorders. Autoimmune disorders are diseases that result from the production of antibodies (called autoantibodies) directed against normal substances in the body (self-antigens).

Which cells can be activated by direct contact with virus-infected cells? Cytotoxic T cells and NK cells can be activated by direct contact with virus-infected cells.

Which cells product antibodies? Plasma cells produce antibodies.

Identify the type of T cell whose plasma membrane contains CD8 markers and the type with CD4 markers. CD8 markers are found on cytotoxic T cells, memory Tc cells, and suppressor T cells; CD4 markers are on all helper T cells.

Which chemicals do mast cells and basophils release when stimulated in an allergic reaction? Histamines, leukotrienes, and other chemicals that cause pain and inflammation are released when mast cells and basophils are stimulated in an allergic reaction.

What is anaphylaxis? In anaphylaxis, an immune response to a circulating antigen stimulates mast cells throughout the body to release chemicals that prompt the inflammatory response.

Define allergy and allergen. An allergy is an inappropriate or excessive immune response to an allergen, which is an antigen that triggers an allergic reaction.

Which would be more affected by a lack of memory B cells and memory T cells: The primary response or the secondary response? The secondary response would be more affected by a lack of memory cells, which are produced in response to an initial exposure to an antigen during the primary response.

Define antigenic determinant site. An antigenic determinant site is the part of an antigen molecule to which an antibody molecule binds.

Describe the structure of an antibody. An antibody molecule consists of two parallel pairs of polypeptide chains: a pair of long, heavy chains and a pair of short, light chains. Each chain contains both constant segments and variable segments. The constant segments of the heavy chains form the base of the antibody molecule; the free tips of the two variable segments form the antigen binding sites.

If you observed a higher-than-normal of plasma cells in a sample of lymph, would you expect antibody levels in the blood to be higher or lower than normal? Plasma cells produce and secrete antibodies, so observing an elevated number of plasma cells in the lymph would lead you to expect higher than normal antibody levels in the blood.

Explain the function of cytokines secreted by helper T cells. Cytokines secreted by the activated T cells aid in coordinating specific and nonspecific defenses and regulate cell-mediated and antibody-mediated immunity.

Define sensitization. Sensitization is the process by which a B cell prepares to undergo activation after encountering a specific antigen. During sensitization, the specific antigens are brought into the cell where they become bound to Class II MHC proteins. Together, they then appear at the cell surface.

How do abnormal antigens attached to Class I MHC proteins initiate an immune response? Abnormal antigens attached to Class I MHC proteins of an infected cells are displayed on the surface of the cell's plasma membrane. The recognition of such antigens by CD8 T cells initiates an immune response.

Identify the three major types of T cells activated by Class I MHC proteins. The three major types of T cells activated by Class I MHC proteins are cytotoxic T cells, memory Tc cells, and suppressor T cells.

Describe CD markers. T cell membranes contain proteins called CD (cluster of differentiation) markers. Cells with CD8 markers respond to antigens presented by Class I MHC proteins and are on cytotoxic T cells, memory Tc cells, and suppressor T cells. Cells with CD4 markers respond to antigens presented by Class II MHC

Where are class I MHC proteins and Class II MHC proteins found? Class I MHC proteins are in the plasma membranes of all nucleated body cells. Class II MHC proteins are only in the plasma membranes of antigen-presenting cells (APCs) and lymphocytes.

What is the major histocompatibility complex (MHC)? The major histocompatibility complex (MHC) is a portion of chromosome 6 containing genes that control the synthesis of membrane glycoprotiens.