Chapter 21 The Immune System: Innate and Adaptive Body Defenses

Describe the two intrinsic systems of the immune system.

The innate (nonspecific) defense system and the adaptive (specific) defense system.

Explain the primary role of the immune system.

To provide resistance to disease and protect the body from pathogens.

Identify the first line of defense in innate immunity.

External body membranes such as the skin and mucous membranes.

What constitutes the second line of defense in innate immunity?

Antimicrobial proteins, phagocytes, natural killer cells, inflammation, and fever.

Characterize the third line of defense in the immune system.

Adaptive (specific) immunity that attacks particular foreign substances.

"Define phagocytes and their function in the immune system."

"Phagocytes are white blood cells that ingest and digest foreign invaders, including neutrophils and macrophages."

"Describe the role of natural killer (NK) cells in the immune response."

"Natural killer (NK) cells patrol the blood and lymph to kill cancer and virus-infected cells before the activation of adaptive immunity."

"List the four cardinal signs of acute inflammation."

"The four cardinal signs of acute inflammation are redness, heat, swelling, and pain."

"What is a possible fifth sign of inflammation?"

"A possible fifth sign of inflammation is impairment of function if movement or use of the affected area is hindered."

"Explain the cause of redness and heat in an inflamed area."

"Redness and heat in an inflamed area are caused by local hyperemia due to vasodilation."

"Identify the main antimicrobial proteins involved in innate immunity."

"The main antimicrobial proteins involved in innate immunity include various proteins that help to fight off pathogens."

"Describe the role of fever in innate immunity."

"Fever inhibits pathogen growth and enhances immune system efficiency."

"Define the three main characteristics of adaptive immunity."

"Specificity (targets specific antigens), systemic action (not limited to infection site), and memory (stronger response upon re-exposure)."

"Explain the two main branches of adaptive immunity."

"Humoral (antibody-mediated) immunity and cellular (cell-mediated) immunity."

"Do B cells mediate humoral or cellular immunity?"

"B cells mediate humoral immunity by producing antibodies."

"How do T cells contribute to immunity?"

"T cells mediate cellular immunity, attacking infected or abnormal body cells."

"Identify the cell type that produces antibodies."

"Plasma cells, which are differentiated B lymphocytes, produce antibodies."

"Describe the basic structure of an antibody."

"An antibody is composed of two heavy chains and two light chains forming a Y-shaped molecule."

"Name the five major classes of antibodies."

"IgM, IgA, IgD, IgG, and IgE."

"What is the first antibody released during an immune response?"

"IgM, which is a pentamer and larger than other antibodies."

"Where is IgA found and what is its primary function?"

"IgA is found in mucus and secretions; it helps prevent pathogen entry."

"What is the function of IgD in the immune system?"

"IgD acts as a B cell receptor on B cell surfaces."

"Explain the significance of IgG in the immune response."

"IgG is the most abundant antibody in plasma (75–85%) and crosses the placental barrier."

"Describe the role of IgE in the immune system."

"IgE is active in allergies and parasitic infections; it triggers histamine release from mast cells and basophils."

"Define active humoral immunity."

"Active humoral immunity is developed by exposure to an antigen, either from infection or vaccination, leading to antibody production."

"Explain passive humoral immunity."

"Passive humoral immunity is gained from receiving antibodies, such as through injection or from a mother to child."

"What is a vaccine and its purpose?"

"A vaccine is a biological preparation containing weakened or killed microbes or their components that stimulate active acquired immunity."

"How do vaccines prime the immune system?"

"Vaccines work by priming the adaptive immune system with a harmless primary exposure to elicit a faster and more efficient secondary response upon actual infection."

"Discuss the reason for seasonal flu vaccinations compared to polio vaccinations."

"The flu vaccine needs to be given seasonally because the flu virus has multiple strains that change seasonally, while the polio virus is more stable."

"What are immunodeficiency diseases?"

"Immunodeficiency diseases are conditions where the immune system is unable to combat infections effectively, examples include AIDS and severe combined immunodeficiency (SCID)."

"How do autoimmune diseases occur?"

"Autoimmune diseases occur when the immune system mistakenly attacks the body's own tissues, as seen in conditions like rheumatoid arthritis and multiple sclerosis."

"Define hypersensitivity in the context of the immune system."

"Hypersensitivity is an abnormally intense immune reaction to a harmless antigen; immediate hypersensitivities (allergies) involve IgE antibodies."