Final answer:
The human body's immune system includes various cell types and proteins that protect against pathogens.
Step-by-step explanation:
The human body is equipped with a complex immune system that plays a crucial role in protecting against diseases and maintaining overall health. Epithelial cells act as a physical barrier, lining the body's surface and internal organs, thus preventing pathogen invasion. Bone cells are instrumental in providing structural support and safeguarding delicate tissues. Immune system cells, including various white blood cells such as lymphocytes and phagocytic cells, actively fight off invading pathogens. Lymphocytes, which include B and T cells, are central to the adaptive immune response, effectively targeting and remembering specific pathogens. Phagocytic cells such as macrophages engulf and destroy pathogens, while cells containing cytoplasmic granules mediate responses against parasites. Protective proteins like interferon impede viral replication and heighten immune response, while major histocompatibility class (MHC) molecules on cell surfaces play a pivotal role in the immune system's recognition of foreign cells.
Barrier defenses such as skin and mucous membranes provide instantaneous protection against pathogens, and epithelial tissues engage in the secretion and absorption of substances critical to the body's defense mechanisms. Inflammation, a component of the innate immune response, is a way the body combats infection. Proteins like complement and various types of white blood cells, including natural killer (NK) cells and mast cells, contribute to the thorough protection offered by the immune system.