Organization of Immune System Flashcards

Three Lines of Defense

• First line: Barriers at body surfaces, such as skin layers and chemicals in saliva and tears.
• Second line: Innate immunity, which is nonspecific and activated when the first line fails, involving inflammation and immune organs.
• Third line: Adaptive immunity, characterized by a specific response and the ability to remember past infections.

1st Line of Defense

• Comprises physical barriers like skin and chemical barriers in bodily fluids.
• Harbors beneficial bacteria that help exclude harmful pathogens.

2nd Line of Defense

• Employs nonspecific mechanisms like inflammation and swelling.
• Involves components such as complement proteins and lymphatic organs, including lymph nodes, spleen, and tonsils.

Inflammation Mechanism

• Body's response to infection increases blood flow to the affected area.
• White blood cells are recruited to localize and eliminate pathogens, often accompanied by fever.

Fever Response

• Represents systemic inflammation, beneficial for a short duration.
• High temperatures hinder bacterial survival and growth, giving the immune system time to react.
• Prolonged fever can damage healthy cells and impair enzyme function.

Complement Proteins

• Attack bacterial cells by piercing their membranes, leading to cell death.
• They remain inactive in circulation until they encounter a pathogen.

Lymphatic System

• Comprises lymph nodes and vessels that filter and return tissue fluid to the bloodstream.
• Functions in fat transport and immune defense, evident when lymph nodes swell in response to infection.

Areas for Blood Cells

• Blood cells reside primarily in lymph nodes, spleen, and tonsils before being activated in response to infection.

3rd Line of Defense

• Involves a highly specific adaptive immune response, functioning with memory and rapid response capabilities.
• Engages effector T and B cells for effective immune action.

Effector T Cells

• Stimulate the proliferation of white blood cells.
• Release signaling chemicals to enhance the immune response in the lymph nodes.

Effector B Cells

• Produce antibodies tailored to specific pathogens such as bacteria and fungi.
• The antibody response takes time as the immune system must identify the correct type.

Memory T and B Cells

• Store information about specific antibodies needed for previously encountered pathogens.
• Remain inactive until re-exposure, leading to a quicker response and preventing future illness.
• Memory duration varies, affecting immunity against specific diseases.

Reasons for Recurring Illness

• Pathogen evasion occurs through mutations that alter receptor types and markers on cells.
• Previous antibodies may be ineffective against new strains, necessitating the generation of new antibodies.