Final answer:
Macrophages are white blood cells that act as phagocytes and can be divided into two main types: free macrophages, which move throughout the tissues, and fixed macrophages, which remain in a specific location within the tissues to defend against pathogens.
Step-by-step explanation:
Phagocytes come in different varieties, including macrophages, which are a type of white blood cell that moves out of the bloodstream and into tissues.
There are two main types of macrophages: free macrophages, which roam through the connective tissues looking for pathogens and damaged cells, and fixed macrophages, which are stationed in a single spot within tissues, such as the Kupffer cells in the liver or histiocytes in connective tissue.
Macrophages play a crucial role in the immune system by phagocytizing foreign particles and pathogens, releasing cytokines to recruit other immune cells, and presenting antigens to activate the adaptive immune system. Free macrophages, also known as roaming macrophages, are highly mobile and hunt for foreign invaders throughout the tissues. In contrast, fixed macrophages remain in one location within the tissues and form an important defense in specific areas of the body.