Innate and Adaptive Immunity Innate immunity is the first line of defense against infection. It is present from birth and serves to protect the body from...
Innate immunity is the first line of defense against infection. It is present from birth and serves to protect the body from infection regardless of prior exposure.
Key components of innate immunity include:
Physical barriers: Skin, mucous membranes, and epithelial barriers prevent pathogens from entering the body.
Pattern recognition receptors (PRRs): These receptors recognize specific molecules on the surface of pathogens, triggering an immune response.
Cytokines: These chemicals released by immune cells communicate with other immune cells and activate inflammatory responses.
Natural killer cells: These cells are part of the immune system and can recognize and kill infected or abnormal cells.
Adaptive immunity develops later in life and is specific to each individual. It involves the activation of lymphocytes, which are specialized cells that recognize and attack foreign invaders.
Adaptive immunity has three main stages:
Primary response: The immune system responds to a pathogen by producing antibodies that bind to it and mark it for destruction.
Secondary response: Antibodies produced during the primary response bind to and neutralize the pathogen, preventing it from infecting cells.
Memory response: After the pathogen is cleared, memory B cells and T cells remain in the body and provide long-term immunity.
Examples:
Skin: The skin's physical barrier prevents pathogens from entering the body. PRRs on the skin, such as those recognized by dendritic cells, trigger the immune response.
Mucous membranes: Mucous membranes lining the respiratory tract and digestive tract trap and filter pathogens, preventing infection.
Cytokines: Cytokines released by immune cells like macrophages and dendritic cells activate other immune cells to initiate inflammation and defense against infection.
Natural killer cells: These cells recognize and kill cells infected with viruses or cancer cells.
Innate and adaptive immunity work together to provide a robust defense against infection.