Chapter 24, Problem 1SQ

Summary Introduction

Concept introduction:

Immune system of the human body is divided into two main branches namely the innate immunity and the adaptive immunity. Innate or the body’s first defense mechanism is present since birth, and this defense mechanism is non-specific, which means that it acts as a barrier in for every foreign body irrespective of its structure. Adaptive immunity of the body comes in later stages, when the body is introduced to pathogens. It is a specific type of defense mechanism. The adaptive immune system or the acquired immune system is a subsystem of all immune systems that is the association of highly specialized systematic cells. Adaptive immunity influences immunological memory after an initial response toward a specific pathogen.

Answer to Problem 1SQ

Correct answer:  Molecules that elicit a response from lymphocytes are called antigens. Proteins secreted by lymphocytes that bind to these molecules are antibodies.

Explanation of Solution

Antigens:

In immunity of the body, an antigen is a molecule able to trigger an immune response in the body. Antigen is a substance that the immune system perceives as being a foreign material. Any molecule in the immune system that is able to extract an adaptive immune response is referred to as an antigen. In most of the cases, such responses are seen to the nontoxic foreign molecules, such as a foreign protein. The lymphocytes recognize and respond to the specific invading pathogens. Most of the antigens are surface molecules of many viruses or foreign cells.

Antibodies:

In immune systems of the body, antibody is a protein molecule that is produced to deal with invaders, such as microbes and bacteria. It is a blood protein that counteracts the responses to specific antigens.

Lymphocyte carries adaptive immune responses. There are two classes of immune responses seen in lymphocytes, one is antibody-mediated response and the other is cell-mediated response, which is carried out by two different classes of lymphocytes namely B cells and T cells, respectively. In antibody responses, B cells are stimulated to emit antibodies; these proteins are called as immunoglobulin. These antibodies travel throughout the bloodstream and activate the other body fluids, where they attach particularly with the foreign antigens that initiate their production.