Bio Test 2 Chapter 43

Plasma cells, which are derived from B cells, are responsible for the secretion of antibodies. Antibodies are proteins that are produced in response to the presence of antigens, which are foreign substances that can trigger an immune response. Antigenic determinants, also known as epitopes, are specific regions on antigens that bind to receptors on B cells. When B cells encounter antigens, they undergo a process called clonal selection, where they are activated and differentiate into plasma cells. These plasma cells then secrete antibodies that can specifically bind to the antigenic determinants on the antigens, helping to neutralize or eliminate the foreign substances.

When there are no more memory cells, the type of immune response that occurs is the innate response. The innate immune response is the first line of defense against pathogens and does not require prior exposure or memory cells. It is a non-specific response that includes physical barriers like the skin, as well as cellular and chemical components such as phagocytes and inflammatory mediators. In the absence of memory cells, the innate immune response plays a crucial role in recognizing and eliminating pathogens to prevent infection.

The given statement is true because the influenza virus has the ability to express alternative envelope proteins, which helps it evade the immune system and infect individuals who may have developed immunity to previous strains. Additionally, none of the memory cells in the human population completely recognize the strain, meaning that even if someone has been previously infected or vaccinated, they may still be susceptible to the virus.

Lysozome is an enzyme that is capable of breaking down the cell walls of certain types of microorganisms. It does this by hydrolyzing the bonds between the sugar molecules in the cell wall, leading to the lysis or destruction of the microbial cell. This process is an important defense mechanism in the innate immune system, as it helps to prevent the growth and spread of harmful bacteria.

Antigen presentation is the process by which cells display antigens on their surface using the major histocompatibility complex (MHC) molecules. This allows the immune system to recognize and respond to foreign substances such as viruses. In this case, the correct answer suggests that viruses can infect cells and interfere with the normal antigen presentation process, potentially evading immune detection and leading to immune evasion.

The given correct answer suggests that the process described is the assembly of different antigen receptors. This process involves the association of the variable region of the heavy chain and the light chain combined. It is through this assembly that different antigen receptors are formed, allowing the immune system to recognize and respond to a wide range of antigens. This explanation highlights the key concept of antigen receptor assembly and its role in diversifying the immune response.

The correct answer is that each T cell receptor consists of two different types of polypeptide chains, specifically an alpha chain and a beta chain. This is different from B cell receptors, which consist of an alpha chain and a beta chain. The heavy chain structure of T cell receptors is distinct from that of B cell receptors.

Natural killer cells are part of the immune system and are responsible for targeting and eliminating cells that are damaged or infected. In this case, the correct answer is "and eliminates damaged cells that have stopped expressing the class I MHC molecule following a viral infection or conversion to a cancerous state." This is because class I MHC molecules are responsible for presenting antigens on the surface of cells, allowing the immune system to recognize them as "self" or "foreign." When cells become damaged or infected, they may stop expressing class I MHC molecules, making them a target for natural killer cells.

autoimmune disease is when lymphocytes produce receptors for epitopes in the body's own molecules

Clonal selection is the process by which the immune system selectively activates and expands specific B cells that produce antibodies against a particular antigen. When an antigen enters the body, it binds to specific B cell receptors, triggering their activation and proliferation. This process leads to the production of a large number of identical B cells (clones) that produce antibodies targeting the antigen. The selected B cells then differentiate into plasma cells, which release large amounts of antibodies into the bloodstream. Therefore, clonal selection is the process that induces high levels of specific antibodies to fight against an invading pathogen.

Immunological memory refers to the ability of the immune system to remember and recognize specific pathogens it has encountered before. When someone recovers from the plague, their immune system develops a memory of the pathogen responsible for the disease. This memory allows the immune system to respond more effectively and rapidly if the person is exposed to the plague again. As a result, individuals with immunological memory are better equipped to care for others with the disease, as their immune system can mount a stronger defense and potentially prevent reinfection or severe illness.

The humoral immune response refers to the production of antibodies by B cells during both the primary and secondary immune responses. During the primary immune response, when the body encounters a pathogen for the first time, B cells are activated and differentiate into plasma cells that produce specific antibodies to target the pathogen. These antibodies help in neutralizing the pathogen and marking it for destruction. During the secondary immune response, if the same pathogen is encountered again, memory B cells quickly produce a larger amount of antibodies, leading to a faster and more effective immune response. Therefore, the humoral immune response is responsible for the production of antibodies during both primary and secondary immune responses.

T cells use MHC molecules to detect self because MHC molecules are responsible for presenting antigens to T cells. These molecules bind to peptide fragments derived from pathogens or self-proteins and display them on the cell surface. T cells have receptors that recognize these peptide-MHC complexes, allowing them to distinguish between self and non-self antigens. This recognition is crucial for the immune system to mount an appropriate response against foreign pathogens while avoiding attacking healthy cells.

When a pathogen enters the body, it can be recognized by Toll-like receptors (TLRs). This recognition triggers a series of internal defenses, including an increase in the activity of phagocytes in the infected area. Phagocytes are immune cells that engulf and destroy pathogens. By increasing their activity, the body can effectively eliminate the pathogen and prevent the infection from spreading. Therefore, the statement "recognition by TLR triggers series of internal defenses" explains how TLR activation leads to an increased activity of phagocytes in an infective area.

Cytotoxic cells, also known as killer cells, are a type of lymphocyte that directly attack pathogens. They are a crucial part of the immune system and play a key role in defending the body against infections. These cells are able to recognize and destroy infected cells or cells that have been invaded by pathogens. By releasing toxic substances, such as perforin and granzymes, cytotoxic cells cause the death of the targeted cells, eliminating the threat posed by the pathogens. Therefore, cytotoxic cells are responsible for directly attacking and eliminating pathogens in the body.

Helper T cells interact with both B cells and cytotoxic T cells because they play a crucial role in the immune response by coordinating and regulating the activities of these cells. Helper T cells recognize antigens presented by B cells and cytotoxic T cells, and they release chemical signals called cytokines that help activate and enhance the immune response. This interaction is essential for the effective elimination of pathogens and the production of antibodies by B cells, as well as the killing of infected cells by cytotoxic T cells.

T cell receptors (TCRs) are proteins found on the surface of T cells, which are a type of immune cell. TCRs are responsible for recognizing and binding to antigens, which are foreign substances that can trigger an immune response. The given answer suggests that T cell receptors differ in their heavy chain structure. This means that different T cell receptors have variations in the structure of the heavy chain component, which can affect their ability to recognize and bind to specific antigens. This diversity in heavy chain structure allows T cells to recognize a wide range of antigens, enhancing the immune response.