Physical barrier : Mucus coating :: Physiological barrier : ________
The human body has two types of immune defence i.e. specific and non-specific defence. Physical barriers, physiological barriers and cellular barriers are the types of non-specific defence.
Physiological barriers include HCl acid in the stomach, lysozyme in tears and saliva. Lysozyme functions as an antimicrobial agent by cleaving the peptidoglycan component of bacterial cell walls, which leads to cell death.
Interferons are chemical barriers that are produced when cells are infected by viruses. The infected cells produce interferons that provide a signal to uninfected cells and protect them from further viral infections.
Monocytes and Neutrophils are cellular barriers. Monocytes are the largest of all leukocytes. They are amoeboid in appearance, and have non-granulated cytoplasm; their nucleus is bilobed. Monocytes get differentiated into macrophages when they leave the circulation and enter any of the specialized tissues of the body.
Neutrophils are the most abundant type of granulocytes and make up 40% to 70% of all white blood cells in humans. They help to heal damaged tissues and resolve infections. They prevent infections by blocking, disabling, digesting, or warding off invading particles and microorganisms.