Immune Response Mechanisms

First Two Barriers: - Physical Barriers: Include skin and mucous membranes that prevent pathogen entry. - Chemical Barriers: Include secretions (e.g., mucus, enzymes) that destroy pathogens.
Biological Barriers Activation: - Activated when a pathogen bypasses the physical and chemical defenses.

Langerhans Cells: - Definition: Specialized dendritic cells located in the dermis of the skin. - Function: - Identify pathogens upon entry. - Seize the pathogens and transport them to local lymph nodes for further immune action.
Lymphocytes: - Types include B cells and T cells that respond to pathogens presented by Langerhans cells. - They carry out specific immune defense roles in the adaptive immune response.

Definition: - A system comprising about a dozen different proteins that circulate in the blood.
Role in Immune Response: - Important in the first nonspecific immune response, known as inflammation: - Signs of inflammation: - Redness, heat, swelling at the site of infection (e.g., a scratch). - Attracts killer T cells that assist in fighting the infection. - Functions of Complement Proteins: - Attach to pathogens, enhancing visibility and targeting for immune cells. - Some complement proteins can directly kill pathogens, such as bacteria, through lysis.

Process: - When tissues are damaged (e.g., scratched), inflammation is initiated: - Increased blood flow leads to redness and heat. - Accumulation of fluids leads to swelling in the affected area. - The primary purpose of inflammation is to contain and eliminate infections.

Combined Actions: - Langerhans cells present pathogen information to lymphocytes in lymph nodes, initiating a tailored immune response. - The complement system acts as an early defense mechanism, responding quickly to calls for help when infection is detected.