The immune system protects organisms from invading organisms and toxic materials. Defenses include non-specific barrier (skin), cellular, and protein defenses as well as specific T and B cells that target particular bacteria and viruses. The lymphatic system plays a key role in immunity and contains the spleen, thymus, adenoids, tonsils, lymph nodes, and the lymphatic fluid. Nonspecific cellular defenses include phagocytes, neutrophils, macrophages, natural killer cells, the inflammatory response, complement proteins, and interferon proteins. Specific defenses (acquired immunities) involve T lymphocytes and B lymphocytes. Each has a slightly different receptor that can bind to a different antigen and then divide or clone itself to make millions of copies. T cells stimulate this division and kill infected cells. Antibodies also assist in the immune response.
The first line of defense is
barrier to entry. The skin, mucus membranes and tears are barrier
The second line of defense
includes nonspecific cellular defenses such as neutrophils,
macrophages and natural killer cells. Proteins such as complement
and interferon also play a role in nonspecific defense.
B cells are produced and mature
in the bone marrow. B cells are responsible for humoral immunity,
which is mediated by antibodies secreted by plasma cells.
mature in the thymus and are responsible for cell-mediated immunity.
Cytotoxic T cells destroy cells
that are infected by a pathogen or that are abnormal.
Helper T cells assist in
activating the production of antibodies by B cells and by
stimulating cytotoxic T cells.
Antigens are presented to T
cells by Major Histocompatibility Complex (MHC) Molecules on the
surface of cells.
Passive immunity is conferred
when an individual is given pre-formed antibodies. Active immunity
requires the stimulation of a person's own immune system.
The Immune System
Lecture Slides are screen-captured images of important points in the lecture. Students can download and print out these lecture slide images to do practice problems as well as take notes while watching the lecture.
The book and CD package include two full length practice exams that are presented with all questions answered and explained. The author also presents detailed reviews of all test topics and includes multiple-choice and free-response questions with answers at the end of each topic's chapter.
This book includes a review of the AP Biology exam format and scoring, proven strategies for answering multiple-choice questions, and hints for tackling the essay questions. The practice tests include answers and explanations and there is also proven test-taking strategies for both the multiple choice and essay parts.