Final answer:
The immune system defends the body from threats much like a castle with layered defenses. It has both nonspecific (innate) and specific (adaptive) subsystems, with the lymphatic system supporting these responses. Physical barriers, inflammation, and a memory of specific pathogens characterize the immune response.
Step-by-step explanation:
The immune system protects the body from disease by developing immunities, destroying pathogens, and neutralizing toxins. It acts as the body’s defense mechanism against various threats, akin to a castle with multilayered defenses. The first line of defense includes physical barriers such as skin and mucus, while the second involves inflammation and fever responses along with mobilization of protective cells. The third line of defense is the immune response which is specific to each pathogen, providing a targeted attack and memory for future defenses.
The immune system comprises two major subsystems: the innate immune system and the adaptive immune system. Innate immunity provides a quick, non-specific response, while adaptive immunity is characterized by its specificity and memory, leading to a more robust response upon reencounter with a pathogen. The lymphatic system plays a crucial role in both the distribution of immune cells and the removal of foreign substances from the body.