Chapter 9, Problem 11TY

Summary Introduction

Introduction:

The overall ability of an organism to fight off foreign disease-causing organisms is known as immunity. It is of two types, including innate and the acquired immunity. Innate immunity is the nonspecific type of defense, providing barriers for foreign agents that may enter the organism. In humans, innate immunity consists of skin, mucous coating the epithelium lining of the urogenital, respiratory and gastrointestinal tract, cytokine barriers, and acid in the stomach, natural killer T-cells, macrophages, and the complement system.

Acquired immunity is the pathogen-specific type of defense. Whenever the human body encounters a pathogen for the first time, a primary response is generated, which is of low intensity as no past memory of this pathogen exists. The primary response also generates memory cells so as to counter the pathogen better in case of future invasion. This secondary response is of high intensity. Both of these responses are carried out by B and T lymphocytes. In response to the antigens, the B cells produce antibodies and the T cells help them. Acquired immunity mediated by antibodies is known as a humoral response. The cell-mediated response is the other type of response, governed by the T-cells.