How It Works: Science and Technology - Vol. 8

By Wendy Horobin | Go to book overview

Immunology

A colored scanning
electron micrograph image
of a lymphocyte cell
engulfing a yeast cell
in a process called
phagocytosis. The
lymphocyte white blood
cell (here colored blue)
is using pseudopodia
projections of its
cytoplasm to extend
towards the yeast spore
(colored yellow). The
yeast cell will be
swallowed up and
digested. Lymphocytes
circulate in the blood
and play an essential role
in the immune response,
collecting at sites of
infection to repel
foreign invaders.

Immunology is the study of immunity—the body's ability to resist harmful substances, among them such disease-producing organisms as bacteria and viruses. The term immune response refers to the body's production of disease-fighting cells.

Immunity to a particular infectious disease can be given via injections of small quantities of certain parts of the microorganism that causes the disease. They mobilize the immune response, and the body builds up its defenses to that particular disease. The first advances in immunology were due to the English surgeon Edward Jenner, who in 1778, started his investigations into smallpox. He produced the first vaccine. It is ironic that Jenner had no knowledge of viruses, let alone the mechanisms of the immune system, but was still able at least partly to achieve his aims of making his patients immune to the killer disease.

Today, the scope of immunology runs from the study of organs, cells, and molecules in the immune system (those responsible for recognizing alien molecules and disposing of them) to the study of how they respond and interact, the consequences of the immune system's activity, and ways of controlling the responses of the immune system.


Natural and adaptive immunity

The immune system has two kinds of resistance— natural (sometimes termed nonspecific), and adaptive (sometimes termed specific). Both kinds of resistance consist of cellular elements and humoral elements (those that are free in blood serum or other body fluids). Natural resistance is older in evolutionary terms than the adaptive mechanisms of immunity, but many elements of these two different systems interact.


Natural immunity mechanisms

Natural immunity mechanisms are largely indistinguishable from the mechanisms that cause inflammation in reaction to tissue damage. It is because of these mechanisms that natural immunity has been labelled nonspecific, but there are some parts of natural immunity that have specific targets among nonself cells—those cells that do not belong to the host organism.

Almost all cells involved in mammalian immunity have their origins in bone marrow. These cells come from the so-called stem cell, from which all types of blood cell are derived. Those involved in natural immunity include macrophages, large tissue cells that remove damaged tissue and cells, as well as recognizing and disposing of bacteria in a limited capacity. A series of enzymes in blood serum, known collectively as complement, and lysozyme (also known as muramidase), an enzyme secreted by macrophages, also have this limited ability to recognize and dispose of bacteria. Finally, among the specifically acting agents of the natural immunity

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How It Works: Science and Technology - Vol. 8
Table of contents

Table of contents

  • Title Page *
  • Contents *
  • Gold 1013
  • Governor 1017
  • Grass-Cutting Equipment 1018
  • Gravity 1020
  • Gun 1023
  • Gyrocompass 1028
  • Gyroscope 1030
  • Hair Treatment 1032
  • Halogen 1034
  • Hang Glider 1037
  • Head-Up Display 1039
  • Hearing 1041
  • Heart 1045
  • Heart Pacemaker 1048
  • Heart Surgery 1049
  • Heat Engine 1053
  • Heat Exchanger 1054
  • Heating and Ventilation Systems 1056
  • Heat Pump 1063
  • Helicopter 1065
  • Hi-Fi Systems 1071
  • High-Speed Photography 1077
  • Holography 1080
  • Hormone 1084
  • Horticulture 1088
  • Hosiery and Knitwear Manufacture 1090
  • Hurricane and Tornado 1094
  • Hydraulics 1100
  • Hydrocarbon 1105
  • Hydrodynamics 1109
  • Hydroelectric Power 1112
  • Hydrofoil 1116
  • Hydrogen 1118
  • Hydroponics 1120
  • Hygrometer 1123
  • Ignition System, Automobile 1124
  • Image Intensifier 1128
  • Immunology 1132
  • Induction 1138
  • Inertia 1142
  • Information Technology 1147
  • Ink 1151
  • Index i
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