What is the Immune System and How Does It Work? Part One: Organs and Cells

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Healthy cells of the Immune System

In the human body, microbes outnumber human cells 10:1. 

The term human being is being replaced with the term human organism by microbiologists to reflect the reality that the human genome is one of a myriad genomes dictating the human experience in both health and disease.

The human immune system is a multi-layered, sophisticated, and highly-adaptive defence system of structures, and mechanical, chemical, and biological processes that protect us from pathogens such as viruses, bacteria, parasites, toxins, fungus, allergens, and carcinogens. Let's have a closer look.

Organs of the Immune System

The Lymphatic System

The adenoids are lumpy clusters of spongy lymphatic tissue that help protect children from getting sick. They sit in the back of the nasal cavity and are above the roof of the mouth.

Like tonsils, adenoids help keep your body healthy by trapping harmful bacteria and viruses that you breathe in or swallow. Adenoids also contain cells that make antibodies to help your body fight infections.

Adenoids do important work as infection fighters for babies and young children. They become less important once a child gets older and the body develops other ways to fight germs. Adenoids usually shrink after about age 5, and by the teenage years they often practically disappear.

The thymus is a specialized organ of the immune system. The only known function of the thymus is the production and education of T-lymphocytes (T cells), which are critical cells of the adaptive immune system. The thymus is composed of two identical lobes and is located anatomically in the anterior superior mediastinum, in front of the heart and behind the sternum. 

The thymus is largest and most active during the neonatal and pre-adolescent periods. By the early teens, the thymus begins to atrophy and thymic stroma is replaced by adipose (fat) tissue. Nevertheless, residual T lymphopoiesis continues throughout adult life.

The spleen is the immunological conference centre and filter of the blood and it is made up of B cells, T cells, macrophages, dendritic cells, natural killer cells and red blood cells. In addition to capturing antigens (foreign material) from the blood, macrophages and dendritic cells bring antigens to the spleen via the bloodstream. 

An immune response is initiated when they present the antigen to the appropriate B or T cells, which then become activated and produce large amounts of antibodies. The spleen also produces red blood cells, destroys old red blood cells, synthesizes antibodies and removes antibody-coated red blood cells and bacteria from the bloodstream and stores reserves of monocytes and platelets that promote wound healing.

Lymph fluid, ducts, and vessels are a network of conduits that carry a clear fluid called lymph unidirectionally toward the heart. Blood plasma exits vascular capillaries to become interstitial fluid (between cells) and comes into contact with the functional parts of all organs and then enters lymphatic vessels to become lymph fluid.  Unlike blood, there is no heart pressure to move this fluid. It is moved by intrinsic (internal) contractions of the lymph passages or extrinsic (external) compression caused by breathing and muscle movement or contraction.

A lymph node is a small ball-shaped organ distributed widely throughout the body including the armpit and stomach and linked by lymphatic vessels. Lymph nodes are garrisons of B, T, and other immune cells. Lymph nodes are found all through the body, and act as filters or traps for foreign particles. They are important in the proper functioning of the immune system.

The lymph fluid contains lymphocytes which defend against infection and the spread of tumours, absorbs and transports fatty acids and fats to the circulatory system, transports immune cells to and from lymph nodes in to bones, transports antigen-presenting cells to lymph nodes where an immune response is stimulated and is a part of the inflammatory response of the body.  

Peyers Patches are located in the lowest portion of the small intestine, the ileum and contain macrophages, dedritic cells, B-lymphocytes and T-lymphocytes. Because the gastrointestinal tract is exposed to the external environment, it is populated with potentially pathogenic microorganisms and toxins. Peyers patches are an important part of immune surveillance and the generation of the immune response.

All cells of the immune system are initially derived from bone marrow. They form through a process called hematopoiesis. During hematopoiesis, stem cells from bone marrow differentiate into either mature immune cells or into precursors of cells that migrate out of the bone marrow to continue their maturation eslewhere. Bone produces B cells, natural killer cells, granulocytes, immature thymocytes in addition to red blood cells and platelets. 

 

Cells of the Immune System

Cells of the Immune System

T Helper cells augment and increase the effect of lymphocytes (white blood cells) and the immune response by the secretion of specialized factors that activate other white blood cells to fight infection. 

  

T Killer/Suppressor cells directly killer tumour cells, viral-infected cells, some parasites, and are important in the down-regulation of the immune response. Both T cells are found throughout the body and depend on lymph nodes and the spleen for activation. T cells are also found in the liver, lungs, blood, intestine and reproductive tracts. 

Natural Killer cells function as effector cells that directly kill certain tumours such as melanomas and lymphomas, and viral-infected cells. They do not depend on lymphoid tissue (spleen, lymph nodes) for activation. Natural killer cells that have been activated by T helper cells will kill tumours and infection more effectively.

B (lymphocyte) cells main function is the production of antibodies in response to foreign proteins of bacteria, viruses and tumour cells. Antibodies are specialized proteins that specifically recogize and bind to an antigen and is critical as a means to signal other cells to engulf, kill or to remove it from the body.

A Healthy B Cell

Granulocytes or polymorphonuclear leukocytes are a group of white blood cells composed of three cell types: neutrophils, eosinophils, and basophils that are important in the removal of bacteria and parasites from the body. They engulf and degrade foreign microbes by using their powerful enzymes.

Macrophages regulate the immune response and are referred to as scavengers or antigen-presenting cells because they pick up and ingest foreign material and present these antigens to other cells which is one of the first steps in the immune response. Stimulated macrophages exhibit increased levels of phagocytosis and are also secretory.
 

Dendritic cells originate in the bone marrow and function as antigen-presenting cells and are more efficient than macrophages. They are found in the thymus, lymph nodes, spleen, bloodstream and other tissues. Dendritic cells capture antigens and transport these to lymphoid organs where an immune response is initiated.

Please visit: 

Immune System: Innate and Adaptive

HEALTH COACH Health Dictionary

The Immune System in Action

Is it time to tune up your Basic Health Habits? 

• Frequent fatigue
• Sleep disturbances 
• Low energy
• Flatulence, gas and bloating (also at issue: food combining, see Part Two: Basic Health Habit No. 2 :: Digestive Health)
• Excess weight
• Food allergies
• Impaired digestion
• Irritability, mood swings
• Bad breath and foul-smelling stools
• Parasites in stool
• Frequent colds
• Recurring headaches
• Chronic constipation
• Irritable Bowel Syndrome
• Protruding belly
• Powerful food cravings
• Skin problems, rashes, acne etc.
• Impaired wound healing 
• Metallic taste in mouth
• Chronic diarrhea
• Mental fog
• Inflamed joints
• Physical aches and pains 

Healthy ways to help your body detoxify:

• Increase Basic Health Habits 
• Reduce and eliminate processed foods from your diet 
• Calibrate Basic Health Habit No. 3 :: Hydration
• Eat more fresh vegetables and fruit 
• Increase the fibre in your diet 
• Green leafy vegetables 
• Green tea 
• Drink lemon (fresh-squeezed) water 
• Broccoli and cabbage aid liver function 
• Seaweed and kelp 
• Sweat 
• Fresh air walk 
• Sleep between 9:30 PM. and 7:30 AM. 

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