Chapter 21

• Immune system protects the body from foreign invaders

  (e.g., bacteria) that could cause disease or death
• The lymphatic and immune systems function together
• Lymphatic system consists of vessels, cells, and organs

  ○ Carries excess fluid back to bloodstream

  ○ Filters potential pathogens from blood
• Interstital fluid becomes lymph once it enters lymphatic

  system
• Lymphatic vessels transport lymph
• It is the fluid between cells that becomes lymph when absorbed by lymphatic capillaries. interstitial fluid
• They are small, bean-shaped structures that filter lymph for pathogens and support immune responses. lymph nodes
• It is caused by excess accumulation of interstitial fluid when lymphatic drainage is insufficient. edema
• A sac-like chamber that collects lymph from the lower body before it is drained into the thoracic duct. cisterna chyli
• What are the two primary lymphatic ducts. The right lymphatic duct and the thoracic duct
• What is the role of the spleen in the lymphatic system? . The spleen recycles old red blood cells, stores platelets, and initiates immune responses against blood-borne pathogens.
• Tonsils are lymphoid tissues that protect against inhaled or ingested pathogens
• Mucosa-associated lymphoid tissue helps protect mucosal surfaces like the digestive and respiratory tracts from pathogens.
• What are the three lines of defense in the immune system? Barrier defenses, innate immune response, and adaptive immune response.
• Phagocytes are immune cells like macrophages and neutrophils that engulf and digest pathogens.
• Cytokines are signaling molecules that mediate and regulate immunity, inflammation, and hematopoiesis.
• Inflammation is triggered by the release of histamine and prostaglandins in response to infection or tissue damage.
• What are the four signs of inflammation? Redness, heat, pain, and swelling
• A group of proteins that enhance immune responses through opsonization, inflammation, and cytolysis. complement system?
• Antigens are substances recognized by the immune system as foreign and capable of triggering an immune response.
• What are the two main types of lymphocytes in the adaptive immune system? B cells and T cells
• B cells produce antibodies that bind to specific antigens and neutralize or mark them for destruction.
• Helper T cells assist in activating other immune cells by secreting cytokines and enhancing the immune response
• TCRs are molecules on T cells that recognize and bind to specific antigens presented by antigen-presenting cells (APCs).
• Cytotoxic T cells kill infected or cancerous cells by inducing apoptosis
• Antibodies are proteins that bind to antigens, neutralizing pathogens or marking them for destruction by other immune cells.
• What are the five classes of antibodies? IgM, IgG, IgA, IgD, and IgE
• IgG is the most abundant antibody, providing long-term protection and crossing the placenta to protect the fetus.
• IgA is found in mucosal areas like the gut and respiratory tract and provides localized protection against pathogens.
• Active immunity is acquired when the immune system responds to a pathogen, producing memory cells for long-term protection.
• Passive immunity is gained through the transfer of antibodies from another individual, such as from mother to child.
• major histocompatibility complex molecules present antigens on cell surfaces, allowing T cells to recognize and respond to them.
• Regulatory T cells help suppress the immune response once an infection has been cleared to prevent autoimmunity.
• Clonal expansion is the rapid multiplication of specific B or T cells after they encounter their specific antigen.
• Memory cells are long-lived immune cells that provide a faster and stronger response upon subsequent exposure to a previously encountered pathogen.