Exercise 2. Read and complete the missing words. shields, direct, effective, stores, become unwell, protection, hinder

as the first line of defense against pathogens and other harmful substances. It is present from birth and provides immediate, non-specific protection. This type of immunity includes physical barriers such as the skin, mucous membranes, and certain chemicals found in tears, saliva, and sweat. These physical barriers create a protective shield that prevents pathogens from entering the body.

In addition to physical barriers, the innate immune system also includes specialized cells that can recognize and eliminate pathogens. These cells, such as macrophages and neutrophils, can engulf and digest bacteria and other foreign invaders. They act as the body"s initial response to infection, working to eliminate pathogens before they have a chance to spread and cause illness.

On the other hand, adaptive immunity is a more specific and targeted defense mechanism. It develops throughout our lives as we are exposed to different pathogens. Adaptive immunity involves the production of antibodies, which are proteins that can recognize and neutralize specific pathogens. These antibodies are produced by a type of white blood cell called B cells. When a pathogen enters the body, B cells produce antibodies that bind to the pathogen and mark it for destruction by other immune cells.

The adaptive immune response is highly effective in targeting specific pathogens and providing long-term protection. It also has the ability to "remember" previous encounters with pathogens, which allows for a faster and more efficient response upon subsequent exposures. This is the basis of immunization, where the body is exposed to a weakened or inactivated form of a pathogen to stimulate the production of antibodies and develop immunity.

In conclusion, our immune system is a complex network of cells, tissues, and proteins that work together to defend our bodies against harmful invaders. It has both innate and adaptive components, which provide immediate and targeted protection, respectively. This defense system is essential for our survival and well-being, as it helps to prevent and fight off infections and diseases.