in Biology
Notes
IMMUNOBIOLOGY: AN
INTRODUCTION
We all get infections, but some of us fall sick more frequently than others. This is
related to the immune system. Proper functioning of immune system protects us
from the infections. On the other hand, its malfunctioning provides opportunity to
infectious agents for causing diseases. Besides protection from infection, immune
system also performs several other functions. It is about all this that you will learn
in this lesson.
OBJECTIVES
After completing this lesson, you will be able to:
define the term immunity.
explain the concept of “self” and “non-self”.
describe the types of defense mechanisms in the body.
describe the types of immunity.
list and describe various cells of the immune system.
differentiate between cellular and humoral immunity; innate and
acquired immunity.
describe various components of the immune system.
explain the concept of immunization (vaccination) and list various types
of vaccines.
31.1 IMMUNITY
Immunity is broadly defined as “the capacity of the body to recognize materials as
foreign to itself and to neutralize, eliminate or metabolize them with or without
injury to its own tissues”.
Immunobiology is the study of organization and functioning of 319
immune system. Immune system provides ‘immunity’ (protection
against diseases).
BIOLOGY
,MODULE - 5 Immunobiology: An Introduction
Emerging Areas
in Biology
Jenner, the father of immunology
Edward Jenner (1749-1823) is the father of modern immunobiology.
He demonstrated that inoculation of cowpox crusts afforded protection to
humans against smallpox. He observed that milkmaids who recovered
from cowpox never contracted the disease smallpox. Hence the name
vaccination from the Latin word “Vacca” for cow came into beng. The
Notes milkmaids and the vaccinated individuals were protected from smallpox
virus. Such protection gave them what is called `immunity’ to smallpox,
although Jenner neither knew the actual causative agent of this disease nor
the actual mechanism of protection.
Concept of “Self” and “Non-Self”
The basis of the above-mentioned protection was the ability of the immune system
of the milkmaid and vaccinated individuals to distinguish between ‘self (their own
tissues) and ‘non-self’ components of the outsiders i.e., the smallpox virus) in this
context.
An individual induces a physiological response (immune response) to substances
that are different from self-components. For example, an immune response is
induced against pathogens (bacteria, virus, fungi, and parasites) attacking the body
of the host.
Let us now learn about the different ways by which the body defends itself from
pathogens and other harmful substances.
31.2 DEFENCE MECHANISMS IN THE BODY
There are four defense mechanisms in our body:
1. Immunity to defend the body from infections.
2. Metabolic defense to metabolize and detoxify foreign chemicals.
3. Stoppage of bleeding (Haeostasis) to prevent to blood loss.
4. Resistance to stress mainly through release of hormone.
Immunological defense is the most important defense mechanism. It provides
protection against various infective agents e.g., virus, bacteria, fungi, and parasites
and against the development of a tumor.
Thus, immunological defense serves three main functions:
1. Defense against microorganisms.
2. Recognition and destruction of mutant cells (Surveillance).
3. Removal of damaged or nonf unctional cells to maintain normal state
(Homeostasis).
320 BIOLOGY
, Immunobiology: An Introduction MODULE -
5
Emerging Areas
in Biology
INTEXT QUESTIONS 31.1
1. Who is considered as the father of immunobiology?
............................................................................................................................
2. What are the three main functions of immunological defense?
Notes
(i) ..................................................................................................................
(ii) ..................................................................................................................
(iii) ..................................................................................................................
3. Define immunology.
............................................................................................................................
31.3 IMMUNE SYSTEM
By now, you are aware that immunity to infection is one of the most important
factors facilitating survival of an individual. Immunity is mainly provided by a
complex network of cells, tissues, and soluble factors. This network is collectively
referred to as the ‘immune system’. Cells participating in the immune response
are organized into discrete ‘lymphoid tissues and organs.
1. Tissues and Organs involved in the Immune System
Lymphoid organs are divided into two groups:
(i) Central lymphoid organs or primary lymphoid tissue. Example: Thymus and
bone marrow.
Fig. 31.1 Major lymphoid organs and tissues.
BIOLOGY 321
Notes
IMMUNOBIOLOGY: AN
INTRODUCTION
We all get infections, but some of us fall sick more frequently than others. This is
related to the immune system. Proper functioning of immune system protects us
from the infections. On the other hand, its malfunctioning provides opportunity to
infectious agents for causing diseases. Besides protection from infection, immune
system also performs several other functions. It is about all this that you will learn
in this lesson.
OBJECTIVES
After completing this lesson, you will be able to:
define the term immunity.
explain the concept of “self” and “non-self”.
describe the types of defense mechanisms in the body.
describe the types of immunity.
list and describe various cells of the immune system.
differentiate between cellular and humoral immunity; innate and
acquired immunity.
describe various components of the immune system.
explain the concept of immunization (vaccination) and list various types
of vaccines.
31.1 IMMUNITY
Immunity is broadly defined as “the capacity of the body to recognize materials as
foreign to itself and to neutralize, eliminate or metabolize them with or without
injury to its own tissues”.
Immunobiology is the study of organization and functioning of 319
immune system. Immune system provides ‘immunity’ (protection
against diseases).
BIOLOGY
,MODULE - 5 Immunobiology: An Introduction
Emerging Areas
in Biology
Jenner, the father of immunology
Edward Jenner (1749-1823) is the father of modern immunobiology.
He demonstrated that inoculation of cowpox crusts afforded protection to
humans against smallpox. He observed that milkmaids who recovered
from cowpox never contracted the disease smallpox. Hence the name
vaccination from the Latin word “Vacca” for cow came into beng. The
Notes milkmaids and the vaccinated individuals were protected from smallpox
virus. Such protection gave them what is called `immunity’ to smallpox,
although Jenner neither knew the actual causative agent of this disease nor
the actual mechanism of protection.
Concept of “Self” and “Non-Self”
The basis of the above-mentioned protection was the ability of the immune system
of the milkmaid and vaccinated individuals to distinguish between ‘self (their own
tissues) and ‘non-self’ components of the outsiders i.e., the smallpox virus) in this
context.
An individual induces a physiological response (immune response) to substances
that are different from self-components. For example, an immune response is
induced against pathogens (bacteria, virus, fungi, and parasites) attacking the body
of the host.
Let us now learn about the different ways by which the body defends itself from
pathogens and other harmful substances.
31.2 DEFENCE MECHANISMS IN THE BODY
There are four defense mechanisms in our body:
1. Immunity to defend the body from infections.
2. Metabolic defense to metabolize and detoxify foreign chemicals.
3. Stoppage of bleeding (Haeostasis) to prevent to blood loss.
4. Resistance to stress mainly through release of hormone.
Immunological defense is the most important defense mechanism. It provides
protection against various infective agents e.g., virus, bacteria, fungi, and parasites
and against the development of a tumor.
Thus, immunological defense serves three main functions:
1. Defense against microorganisms.
2. Recognition and destruction of mutant cells (Surveillance).
3. Removal of damaged or nonf unctional cells to maintain normal state
(Homeostasis).
320 BIOLOGY
, Immunobiology: An Introduction MODULE -
5
Emerging Areas
in Biology
INTEXT QUESTIONS 31.1
1. Who is considered as the father of immunobiology?
............................................................................................................................
2. What are the three main functions of immunological defense?
Notes
(i) ..................................................................................................................
(ii) ..................................................................................................................
(iii) ..................................................................................................................
3. Define immunology.
............................................................................................................................
31.3 IMMUNE SYSTEM
By now, you are aware that immunity to infection is one of the most important
factors facilitating survival of an individual. Immunity is mainly provided by a
complex network of cells, tissues, and soluble factors. This network is collectively
referred to as the ‘immune system’. Cells participating in the immune response
are organized into discrete ‘lymphoid tissues and organs.
1. Tissues and Organs involved in the Immune System
Lymphoid organs are divided into two groups:
(i) Central lymphoid organs or primary lymphoid tissue. Example: Thymus and
bone marrow.
Fig. 31.1 Major lymphoid organs and tissues.
BIOLOGY 321
