Final answer:
White blood cells are responsible for fighting off pathogens, and their numbers can increase within hours in response to an infection, thanks to the bone marrow's ability to produce them rapidly. These cells form an integral part of the immune system and vary in type and function, with changes in their numbers potentially indicating specific health conditions.
Step-by-step explanation:
White blood cells fight pathogens such as bacteria, viruses, and other foreign organisms that may pose a threat to the body. These cells are a vital component of the immune system. Given their crucial role, when a person has an infection or an inflammatory process going on, the number of white blood cells can increase significantly within hours to counter the threat. The variable number of white blood cells is part of the body's sophisticated adaptive response to infectious diseases and aids in providing a robust defense mechanism.
The bone marrow plays a critical role in this process as it is the primary site for the production of white blood cells. When an infection occurs, signals are sent to the bone marrow to ramp up leukocyte production. The different types of white blood cells, including neutrophils, eosinophils, basophils, lymphocytes, and monocytes, each serve distinct functions in the body's defense system. Certain diseases or conditions can be associated with an increase or decrease in specific types of white blood cells, providing diagnostic clues to medical professionals.