Lymphatic organs and tissue: Immunoglobin and its types

Lymph

Lymph is a clear-to-white fluid made of white blood cells, especially lymphocytes, the cells that attack bacteria in the blood. Fluid from the intestines are called chyle, which contains proteins and fats.

Formation of Lymph

Because lymph capillaries are permeable, interstitial fluid is converted into lymph. When blood travels through blood capillaries in the tissues, 90% of the fluid moves from the arterial end of the capillaries into the venous end. And since lymph capillaries are more permeable than blood capillaries, the remaining one-tenth of the fluid enters them.

As a result, when lymph travels through lymph capillaries, its makeup resembles that of interstitial fluid, including its protein content, more or less. Because of their larger size, proteins found in interstitial fluid cannot enter blood capillaries. Because lymph vessels are permeable to large particles as well, these proteins enter them.

About 120 mL of lymph flows into blood per hour. Out of this, about 100 mL/hour flows through thoracic duct and 20 mL/hour flows through the right lymphatic duct.

Composition of Lymph

Usually, lymph is a clear and colorless fluid. It is formed by 96% water and 4% solids. Some blood cells are also present in lymph. The solid contents in lymph includes:

• Organic Substances: protein, lipids, carbohydrate and nitrogenous waste product.
• Inorganic Substances: sodium, calcium, potassium, chloride and bicarbonate.
• Cellular Content: lymphocytes, monocytes, macrophages, and plasma cells.

Functions of the Lymph

• The return of proteins from tissue gaps into blood is a crucial role of lymph.
• It is in charge of the body's fluid redistribution.
• Lymph helps eliminate bacteria, poisons, and other foreign substances from tissues.
• The preservation of tissue's structural and functional integrity is accomplished by lymph flow. Myocardium, nephrons, and hepatic cells are significantly impacted by lymph flow obstruction.
• An essential pathway for intestinal fat absorption is lymph movement. Because of this, lymph after a fatty meal appears milky.
• It contributes significantly to immunity by moving lymphocytes.

Body Defense Mechanism

Mechanisms that our body employs to defend against pathogens and toxin are called defense mechanism. Defense is provided by immune system in two ways.

• The nonspecific (innate) mechanism
• The specific (adaptive) mechanism.

Nonspecific (Innate) Mechanism

The nonspecific, also called innate defense mechanism lacks specific response to specific invaders. It consists of mechanism that acts against a wide variety of pathogens. These mechanism are present at births and are effective against pathogens to which the body has never been exposed before. The nonspecific resistance mechanisms include the external physical and chemical barriers provided by the skin and mucous membranes. These defense mechanism are also called first line defense mechanism. Non specific defense mechanism also include defense such as antimicrobial proteins natural killer cells and phagocytes, inflammation and fever. These defense mechanism are also called second line defense mechanism.

• Physical Barrier: Physical barrier make it mechanically difficult for pathogenic organism to inter the body or travel in the tissue. The surface of the protein make the pathogen hard to penetrate. Most of the skin lacks sufficient moisture and nutrients and does not suppo exterior; but then mucus traps microbes. Bacteria trapped in the respiratory system are move by cilia to the pharynx, swallowed and are destroyed by stomach and intestinal juices. Bacteria microbial growth. The digestive, respiratory, urinary and reproductive tracts are open to the are flushed from the upper digestive tract by saliva and from the lower urinary tract by urine,
•  Chemical Barrier: Certain body secretion in human body inhibits the multiplication, survival a pathogens. Lactic acid in the skin and mucus membrane also inhibit microbial growth in the urethra spread of micro-organism. Hydrochloric acid (HCL), secreted by stomach, destroys most ingested and vagina. Similarly, tears, saliva and mucus contain lysozymes, that dissolve bacterial cell walls.
• Antimicrobial Proteins: Blood and interstitial fluids contain three main types of protein that discourage or inhabit microbial growth. There three antimicrobial proteins are interferon, complement system and transferrins.
• Phagocytes: Phagocytic cells (monocytes, tissue macrophages, dendritic cells, and neutrophils phagocytose infecting organisms; Phagocytosis is the process by which invaders are recognized, ingested, and killed. The two major types of phagocytes are Neutrophils and macrophages. When the infection occurs, neutrophils and monocytes enlarge and develop int active phagocyte macrophages. Some of the microphages are histiocytes, reticular cells alveolar macrophages, endothelial cell, and Kupffer cells.

These phagocytes play important roles in both non specific and specific immunity.

• Inflammation: Inflammation is a nonspecific defensive response of the body to tissue damage Words ending in the suffix - itis denote inflammation of specific organs tissue. Examples arthritis (inflammation of the bone) peritonitis (inflammation of the peritoneum). The general purposes of inflammations are to limit the spread of pathogens and ultimately destroy, the remove the debris of damaged tissue and repair.

These processes are mediated by the different inflammatory chemicals such as bradykinin histamine, leukotrienes, complement, and prostaglandins by damaged cell.

• Fever: Fever is an abnormally high body temperature that can result from trauma, drug reaction, inflammation or infection and several other causes. Fever is also recognized as an adapting defense mechanism.

Specific (Adaptive) Mechanism

The ability of the body to defend itself against specific agents such as bacteria, toxins, viruses and foreign body or tissue is called specific defense mechanism or adaptive or acquired immunity. Immunity may be defined as the ability to destroy pathogens or other foreign material and to prevent certain infectious diseases. Specific immunity is different from non specific resistance because of two important features:

• Specificity: Immunity is directed against a particular pathogens and immunity to one pathogen does not give immunity to others.
• Memory: Immune response on subsequent exposure to the same antigen is generally faster and more powerful.

Types of Specific Immunity

There are two types of specific immunity:

•  Humeral (Antibody-Mediated) Immunity

It involves the action of soluble plasma protein called antibodies. Circulating antibodies bind to the antigen (virus, bacteria, toxins) and binding mark them for destruction by other cell types.

It is an acquired immunity in which the role of circulating antibodies is predominant. The B lymphocytes is predominant in this type of Immunity.

• Cellular (Cell-Mediated) Immunity

It is based on direct attack of diseased cells by a type of lymphocytes. These lymphocytes kill/ break these cells directly or by activating other defense such as inflammation. It is an acquired immunity in which the role of T lymphocytes is predominant.

Types of Acquired Immunity

There are two basic mechanisms for acquiring immunity - active and passive.

Passive Immunity: The protection an individual acquires by receiving antibodies produced by another person or animal is called passive immunity. Passive immunity provides protection against some infections, but this protection is temporary. The antibodies will degrade during a period of weeks to months and the recipient will no longer be protected. The most common form of passive immunity (naturally acquired passive immunity) is that which an infant receives mother's antibodies during intrauterine life and use of antiserum for the treatment of snakebite (artificially acquired passive immunity)

Active Immunity: The production of one's own antibodies against the antigen is called active immunity in which the protection is produced by the person's own immune system. This type of immunity is usually permanent, often for a lifetime. One way to acquire active immunity is to have the natural disease such as measles, chickenpox. Once exposed with these diseases, the individual will be immuned for the rest of his/her live. Another way to produce active immunity is by vaccination.

Antibody ( Immunoglobulin)

An Antibody is defined as a protein by B Lymphocytes in response to the presence of an antigen. Antibody is gamma globulin in nature and it is also called immunoglobulin (Ig). Immunoglobulins form 20% of the total plasma proteins. Antibodies enter almost all the tissues of the body.