Chapter 21, Problem 16TYR

Summary Introduction

Introduction:

One of the most survival challenges for all living organisms is to fight with the pathogen that includes viruses, bacteria, fungi, protozoa and other microbes. The human body consists of three lines of defense mechanism to fight against the pathogenic microbes. In the first line of defense mechanism includes the skin, mucous membranes and epithelial cells that act as barriers. In the second line of defense mechanism, immune cells like macrophages and leukocytes, natural killer cells, inflammation, fever are involved in the protection against the pathogenic microbes. In the third line of defense mechanism which is involved not only to clear the microbes and but also leaves the body with its memory.