What is responsible for defending blood against the pathogens?

The primary components responsible for defending blood and protecting it from pathogens are white blood cells, also known as leukocytes. These specialized cells collectively function as the body's immune system within the bloodstream. Here are the main types of white blood cells and their roles in defending blood:

Neutrophils: These are the most abundant type of white blood cells and act as the body's first line of defense. Neutrophils are highly phagocytic, meaning they engulf and destroy harmful microorganisms, including bacteria. They also release antimicrobial substances that help kill pathogens.

Eosinophils: Eosinophils are less common than neutrophils and play a crucial role in defending against parasitic infections. They can directly attack parasites and release toxic substances that damage parasite cells.

Basophils: Basophils are the least common type of white blood cells and are involved in allergic reactions and immune responses to certain infections. They release histamine and other inflammatory mediators, causing vasodilation (widening of blood vessels) and increased blood flow to the affected area.

Lymphocytes: Lymphocytes are a diverse group of white blood cells that include B cells, T cells, and natural killer (NK) cells. B cells produce antibodies that recognize and neutralize specific pathogens. T cells play a central role in cell-mediated immunity, recognizing and destroying infected cells or abnormal cells. NK cells can directly kill infected cells and some tumor cells without prior sensitization.

Monocytes: Monocytes are large white blood cells that circulate in the blood and then migrate into tissues, where they differentiate into macrophages. Macrophages are highly phagocytic and can engulf and destroy pathogens, dead cells, and foreign debris.

These white blood cells work together to provide immune surveillance, detect and eliminate pathogens, and maintain the overall health and integrity of the blood.