Immunity:Non specific defense: Introduction

IMMUNITY:

Immunity is the ability of body to resist any change from foreign particle and the harmful chemical release by them

IMMUNOLOGY:

"The science which deals with study of immune system,working mechanism,disorders etc"
                                  OR
"Immunology is the study of foreign partice that cause damage to the living body and defence mechanism taken by the body to eleminate them"
Father of immunolgy is EMIL VON BEHRING(He discovered antibody)

NON-SPECIFIC DEFENSE:

It is generalzed responce of body which is similar for most of the infection. In this antibodies not involved mean it fight with pathogens without antibodies. It is present from birth. It is also known as INNATE immunity
It consist of
1-External defence(First line of defence)
2-Internal defence(Second line of defence)
External defence prevent the pathogen from entering into the blood. When pathogen enter into the blood then internal defence take action against pathogen.

FIRST LINE OF DEFENSE:

It consist of physical and chemical barriers such
Mucous membrane which is found in
1-Buccal cavity
2-GI tract
3-Respiratory tract
4-Urenogenital tract
5-Exposed part of eyeball etc
and skin. Both mucous membrane and skin prevent the pathogen from entering into the body and act as physical barrier

Chemical barriers of external defense include

1-Saliva
2-HCL( Present in stomach)
3-Sweat
4-Ear wax(Present in ear)
5-Bile juice and intestinal juice
Chemical barrier also known as Functional or Physiological barrier

SKIN:

Intact skin is the largest defensive organ, Skin is also the largest excretery organ. Skin consist of two major layers
1-Epidermis
2-Dermis
Epidermis is the superficial multiple cell thickned layer.Most cells of epidermis are kartinocytes(they produce a protein mixture keratin. The outer surface of skin also consist of dead and dry cell. Consequently microbes that land on skin cannot obtain water and nutrients they need
 Dermis is the inner comparatively thick layer consist of sweat and sabaceous gland,hair follicles,receptors,blood vessels,nerves etc. Skin secretions include sebum(an oily substance which is released  by sabaceous gland) and sweat(salty fluid released by sweat gland. It provide cooling effect). Secretions of skin also contain natural antibiotic such as LACTIC ACID which inhibits the growth of bacteria and fungi.
PH of skin is little bit acidic

MUCOUS MEMBRANE:

It consist of epithelium connective tissue. It involves in trapping the foreign particles
Chemical barrier:
It includes secretions from skin,mucous membrane and glands. Sweat keep skin PH acidic. Acidic PH minimize the growth of harmful pathogens. Oil gland produce sebum which keep skin soft. Tears,saliva and mucous secretion lysozyme. Lysozyme break cell wall of gram positive bacteria. Lysozyme is bacteriocidal.Saliva also contain Lactoferrin(It binds with ironand stops bacterial multiplication. Lactoferrin is bacteriostatic. Ltsozyme also found in urine,brast milk. Oxyntic or parietal call of stomach produce HCL that kill pathogen enter from food. HCL is a potent killer of typhoid bacteria

INTERNAL DEFENSE:

If pathogen breaks first line of defence and enter into the blood then internal defence or second line of defence take action against pathogen. It consist of
1-Killing cells of blood and natural killer cells
2-Protective proteins of complement system
3-Interferons
4-Inflammatory response
5-Fever or temperature response
To understand second line of defence or immunity you must have basic knowledge of white blood cells.

WHITE BLOOD CELLS OR LEUKOCYTES:

White blood cells also known as leukocyte devided into two types
1-Granulocyte 68%
It consist of
1-Neutrophills(Stain with acidic as well as basic dye)
2-Basophills(Stain with basic dye)
3-Eosinophills(Stain with acidic dye)
2-Agranulocyte32%
It consist of
1-Monocytes
2-Lymphocytes
When any infection occur number of WBCs increases and this process is known as LEUCOCYTOSIS. WBCs are colourless. During infection WBCs come out of blood vessels mainly to fight pathogen.

KILLING CELLS OF BLOOD:

Two type of white blood cells are Phagocytes(mean they destroy pathogen by eating ot engilfing them. This process of eating is known as phagocytosis)
1-Monocytes
2-Neutrophills

MACROPHAGE:

Macrophage are derived from monocyte or monocyte that leave blood is known as macrophage. Monocytes are formed in born marrow. From born through blood macrophages are transported to the area of body where they are needed. Macrophages are generally found in the organs such as liver,lungs,spleen,lymph nodes,kidney etc. In these organ they patrol within the free spaces among the cell and provide protection by engulfing the pathogen enter in the tissue. Macrophage not only perform the phagocytosis of cells but also display some part of pathogen on their surface to inform other cells that some pathogen enter into the blood. They also release some chemicalls during phagocytosis of microorganism. Some of the chemicals triggers the maturation of monocytes into macrophage increasing the number of macrophage. They secrete Interleukin-1 during phagocytosis that signals brain to increase temperature. Some of the chemicals stimulate specific immune response

NEUTROPHILS:

Neutrophills are the type of agranulocte. They are most abundant type of white blood cells. They are highly mobiled orshort lived. They can enter into the part of tissue wher othercells/molecules don't able to enter. They die after single phagoctic event. They move like amoeba. They also relerase lysosomal enzymes and certain chemicalls that kill microorganism and cause inflammation

NATURAL KILLER CELLS:

Natural killer cells are the fraction lymphocytes. They kill the self cell that ultered and become dangerous for body. It kill their target by striking it and release protein called PERFORINS which make hole through the membrane of infected cells. The pores formed by perforin allow the passive diffusion of certain apoptic proteases known as GRANZYMES, into the target cell

PROTECTIVE PROTEIN OF COMPLEMENT SYSTEM:

The complement system consist of over 30 different protein made by liver and circulating in blood in inactive state. They are activated when certain pathoen enter into blood. Once a complement protein activated it activates other protein and so on. The result of complement activation is stimulation of phagocytes to clearforeign and damged  material, Development of inflammation and the activation of cell killing membrane complex. An example of protective protein of complement system is perforin

INTERFERON:

Interferons belong to large class of proteins called CYTOKINES,molecules used for communication between cells during infection. Interferon release by host cell in response of certain virus. Interferon are named due to thier ability as they interfere with viral replication by activating molecules which prevent the virus from producing and replicating its genome. It also activates certain immune cells

INFLAMMATORY RESPONSE:

The inflammatory response is a major component of non-specific defence. Any damage to the tissue caused by certain microorganism or by any physical injury, insect bite triggers this response. Inflammation may be of two type
1-Local inflammation
2-Widespread inflammation
The classical signs of inflammation are
1-Heat
2-Pain
3-Reedness
4-Swelling
5-Loss of function

TEMPERATURE RESPONSE:

Fever or pyrexia is the condition in which body temperature raised then the normal. The invaded microorganism release certain chemicals called PYROGENS. These pyrogen can increase the set point of hypothalmic thermostat. As a result all the mechanism brough into play to increase the body temperature. Increased temperature then normal can facilate microbial growth in the body, That's why payhogen want to increase host body temperature
On the other hand, in response to these microorganism certain white blood cells also release chemical known as ENDOGENOUS PYROGEN that further increase the body temperature because higher body temperature then the normal increase the ability of phagocytic white blood cells that attack upon bacteria. These pyrogen cause other cell to decrease iron concentration in blood because pathogen that grow at a temperature higher then normal required more iron. Fever also increase the production of interferon. So fever is very effective against microbial inavasion but high body temperature becomes destructive for body own metabolic system. So that's why physician recommend antipyretic drug to the patient of high degree

QUIZ:

Q-Natural killer cells are fraction of
1-Basophils
2-Neutrophils
3-Monocyte
4-Lymphocyte
Q-Complement system consist of
1- 40 PROTEINS
2- 100 PROTEINS
3- 30 PROTEINS
4- 75 PROTEINS
Q- Fevers
1- Decrease the concentation of iron in the blood
2- Decrease the inflammation
3- Decrease the activity of phagocytes
4- Decrease interferon production
Q- HCL secreted by
1- Pareital cell
2- Oxyntic cell
3-Principle cell
4-Zymogen cell

ANSWERS

Q1: Lymphocytes
Q2: 30 Proteins
Q3: Decrease the concentration of iron in the blood
Q4: parietal and oxyntic both cells release HCL

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