Immunity

• T lymphocytes (T cells) play a role in cell-mediated immunity and can differentiate into helper T cells or cytotoxic T cells.
• The immune system is the body's defense against foreign substances.
• B lymphocytes (B cells) produce antibodies specific to antigens encountered by the body.
• Innate immunity includes physical barriers such as skin and mucous membranes, chemical defenses like stomach acid and tears, and inflammation caused by histamine release from mast cells.
• Plasma cells secrete large amounts of antibodies that bind to the same antigen on other pathogens, marking them for destruction by phagocytosis.
• Memory cells are produced during adaptive immunity and remain in the bloodstream even after the infection has been cleared.
• Memory cells remain in circulation even after infection has been cleared, providing rapid response upon reexposure to the same antigen.
• Antigens are molecules that stimulate an immune response, while antibodies are proteins produced by B cells to neutralize antigens.
• Helper T cells secrete cytokines that activate other immune system components, while cytotoxic T cells directly kill infected host cells.
• Adaptive immunity is characterized by its ability to recognize and respond specifically to different types of pathogens, resulting in the production of antibodies and memory cells.
• Antibody production occurs when an antigen stimulates B cells to divide rapidly and form clones of identical daughter cells called plasma cells.
• Agglutination involves the formation of clusters of bacteria due to the binding of multiple antibodies to one bacterium.
• Phagocytes engulf and destroy foreign substances using lysosomes containing digestive enzymes.
• Immune responses involve phagocytosis, where white blood cells engulf pathogens, and complement activation, which involves enzymes that destroy pathogens.
• Adaptive immunity involves B and T lymphocytes that recognize specific pathogens through their receptors.
• Adaptive immunity involves B cells producing plasma cells that secrete antibodies and memory cells that remember the antigen and respond quickly if it enters again.
• The binding of antibodies to antigens can lead to various effects such as agglutination (clumping), opsonization (marking for destruction), complement activation, and neutralization.
• B lymphocytes produce antibodies against specific antigens, while T lymphocytes kill infected host cells directly or indirectly.
• T lymphocytes play a role in cellular immunity, which involves direct killing of infected host cells through cytotoxic T cells.
• Adaptive immunity involves the production of memory cells that can rapidly respond to repeated exposure to the same antigen.
• Effector cells produce large amounts of antibodies against the antigen, while memory cells remain dormant until they encounter the same antigen again.