Final answer:
Antigens can enter the body through inhalation, ingestion, or breaks in the skin. The immune system responds with an innate immune response for immediate defense and an adaptive immune response for targeted elimination, involving various immune cells and mechanisms.
Step-by-step explanation:
Routes of Antigen Entry and Immune System Response
Antigens can enter the human body through several routes, including:
- Inhalation, where pathogens enter through the respiratory tract.
- Ingestion, where pathogens are introduced via the digestive system.
- Breaks in the skin, where direct entry into the bloodstream or tissues occurs.
The immune system generally responds to antigens through a series of mechanisms depending on whether the immune response is part of the innate or adaptive immune system. The innate immune system is the first to respond and includes barriers like skin and mucous membranes, inflammations, and cells like macrophages and natural killer cells. The adaptive immune system provides a specific response to each type of pathogen, producing tailored responses including the production of antibodies by B cells and the action of cytotoxic T cells.
When an antigen enters the body, the immune system initiates a response that can include:
- The innate immune response, which acts quickly but without specificity, involving inflammation and phagocytosis.
- An adaptive immune response that targets specific pathogens with antibodies and memory cells for future defenses.
- The activation and cooperation of various immune cells, including T cells, B cells, macrophages, and others, all working in concert to eliminate the threat.