SESSION 02

Immunology: Is the study of body defence mechanisms

Immunoglobulin: Is a glycoprotein, composed of H and L chains, that functions as antibodies.(NB All antibodies are immunoglobulin but not all immunoglobulin have antibody functions)

Immunity is the way in which the body can protect itself from invasion by pathogenic micro-organisms and provide a defence against their harmful effects

Antigen: Is a substance which when introduced parenterally into the body stimulates the production of an antibody with which it reacts specifically in observable manner

Antibody: Is a protein substance produced in response of antigenic stimulus and reacts specifically with antigen produced

Definitions of Terms cont…

Natural immunity(non-specific): Is provided by all the mechanisms that form an immediate non specific barrier to infection

Artificial immunity (specific): refers to all the mechanisms that are involved when the body actively responds to a foreign substance as an infecting micro organism

Types of Immune System

This is the body’s first line of defense against germs that entering the body.

It responds in the same way to all germs and foreign substances, which is why it is sometimes referred to as the “nonspecific” immune system.

It acts very quickly, As it makes sure the bacteria that have entered the skin through a small wound are detected and destroyed on the spot within a few hours

The innate immune system consists of

Protection offered by the skin and mucous membranes

Protection offered by the immune system cells (defense cells) and proteins

INNATE IMMUNITY SYSTEM cont..

The adaptive immune system takes over if the innate immune system is not able to destroy the germs. It specifically targets the type of germ that is causing the infection. But to do that it first needs to identify the germ. This means that it is slower to respond than the innate immune system, but when it does it is more accurate. It also has the advantage of being able to “remember” germs, so the next time a known germ is encountered, the adaptive immune system can respond faster.

This memory is also the reason why there are some illnesses you can only get once in your life, because afterwards your body becomes “immune.” It may take a few days for the adaptive immune system to respond the first time it comes into contact with the germ, but the next time the body can react immediately. The second infection is then usually not even noticed, or is at least milder.

The adaptive immune system is made up of

T lymphocytes in the tissue between the body’s cells

B lymphocytes, also found in the tissue between the body’s cells

Antibodies in the blood and other bodily fluids

ADAPTIVE IMMUNUTY SYSTEM

Immunity that develops after a person receives immune system components, most commonly antibodies, from another person. Passive immunity can occur naturally, such as when an infant receives a mother’s antibodies through the placenta or breast milk, or artificially, such as when a person receives antibodies in the form of an injection (gamma globulin injection). Passive immunity provides immediate protection against an antigen, but does not provide long-lasting protection.