Immunity The ability of body to resist the infection caused by pathogens. There are two types of immunity 1.Innate (by birth) 2.Acquired 1. Innate- the immunity present is humans by birth innate immunity are of following type i. Physical barrier- also known as first line of defense. skin would be the example. ii. Physiological barrier- also known as second line of defense. tears , saliva which have lysosyme would be the example. iii. Psychological barrier- it includes PMNL cells(poly morphic nucleus leucocytes) like monocytes , neutrophils, leucocytes. They are phagocytes in nature that fed on other cells. iv. Cellular barrier- they consist of INF cells (interferon). They are also known as third line of defense. 2. Acquired immunity- the immunity person acquired during his lifetime is known as acquired immunity. acquired immunity are of two types i. B cell- form in bone marrow and differentiated in bone marrow ii. T cell- form in bone marrow and diff...
