Readers would like you to visualise your High school Biology classes wherein you have read about the various systems of our body. You also remember the story of an African fable where all the body parts began complaining against the stomach and went on strike. Let me retell the story in case some have forgotten.

"Look at me," says the hand, "I till the soil to plant the seeds, I harvest the crops, I prepare the food. All that the stomach ever does is lie there waiting to be fed. This is unfair," The feet agreed, "Me too, I carry the heavy stomach around all day, I carry him to the farm to get food, I carry him to the river to get water, I even carry him up the palm tree to get palm wine, and all the stomach ever does is lie there and expect to get his ration of food, water and wine whenever he needs them. This is unfair, "The head too complained about how he carries all the heavy load from the farm and the river, all to feed the stomach who does nothing to help. The parts of the body decided that this injustice must stop. To force the issue, they decided to embark on protest action. They agreed to stop working and feeding the lazy stomach until the stomach learns to be a responsible citizen of the body.

A whole day went by and the stomach was not given any food or water or wine. All that the stomach did was groan from time to time while the others taunted him. By the second day of starving the stomach, the head said that he was beginning to feel dizzy. By the third day, the hands reported that they were feeling weak, and the feet were wobbly and could not stand straight. Then it dawned on them that, much as they were visibly supporting the stomach, the stomach was also supporting them in a less obvious but equally important way. It dawned on them that by feeding the stomach they were feeding themselves without knowing it. So they called off their strike action and went back to work to feed the stomach. Their strength returned and together with the stomach they lived happily together after. So it's very important that you eat the right food and keep your digestive system along with other body organs fit and healthy.

Here I will dwell upon a little bit about how our body defends against the various Pathogens (Virus, Bacteria, Parasites, Fungi, Yeasts) present in the environment. If not for this defence mechanism all these pathogens will eat up your body in no time. Without your knowledge like the heartbeats, similarly, the body defence system is also at work from birth. The most important organs which contribute to your body defence can be put as follows.

Immune System: Lines of Defence

Let me introduce the word Immune which has become a household word during this pandemic. It's a Latin word and it means exempt from public service, and in English, it means resistance to particular infection or toxins. The immune system or the defence system of our body includes three lines of defence against foreign invaders: physical and chemical barriers, nonspecific resistance, and specific resistance. The first line of defence is the physical and chemical barriers, which are considered functions of innate immunity. The second line of defence is nonspecific resistance, which also is considered a function of innate immunity. The third line of defence is specific resistance, which is considered a function of acquired immunity.

Innate immunity involves nonspecific immune defence mechanisms that activate immediately or within hours of an antigen's invasion of the body. Innate immunity is present at birth. Innate immunity activates when the immune system recognizes the chemical properties of the antigens. Acquired immunity, also referred to as adaptive or specific immunity, is not present at birth but is learned. The immune system encounters antigens and the acquired immunity's components learn how to attack each antigen and develop a memory for it. Specific immunity tailors attack to specific antigens because it learns, adapts, and remembers them.

Physical and Chemical Barriers (Innate Immunity)

1. Skin - The intact skin provides a physical barrier to viruses, bacteria, and microbes. Healthy skin has bactericidal (killing of bacteria) activity.
2. Mucous membranes - Mucous membranes produce mucus to trap microbes so they cannot spread to the rest of the body
3. Hair - Hair within the nose filters microbes, dust, and pollutants from the air to prevent them from invading the body
4. Cilia - Cilia lines the upper respiratory tract and traps and propels inhaled debris to the throat so it can exit the body more quickly. Cough reflex is a protective mechanism
5. Urine - Urine flushes microbes out of the body via the urethra
6. Defecation and vomiting - The body expels microorganisms via bowel movements and vomit

Chemical barriers form another first line of defence against invaders.

1. Lysozyme - Lysozyme is an enzyme produced in tears, sweat, and saliva that breaks down cell walls and acts as an antibiotic by killing bacteria
2. Gastric juice - Acids in the stomach destroy bacteria and toxins
3. Saliva - Saliva dilutes the number of microorganisms in the body and washes the teeth and mouth
4. Acidity - Skin acidity inhibits bacterial growth
5. Sebum - Unsaturated fatty acids known as sebum provide a protective film on the skin and inhibits growth
6. Hyaluronic acid - A gelatinous substance, hyaluronic acid slows the spread of microorganisms that can harm the body

Nonspecific Resistance (Innate Immunity)

The second line of defence of the immune system, also an aspect of innate immunity, is the nonspecific resistance. These defence mechanisms destroy invaders in a general way and do not target specific antigens.

1. Phagocytes - Phagocytic cells eat and destroy microbes that pass into body tissues
2. Inflammation - Inflammation is a localized response in the tissue that occurs when tissues are damaged or in response to other stimuli. Inflammation occurs when white blood cells flood an area of invasion by microbes. The response includes swelling, redness, heat, and pain
3. Fever - Fevers inhibit bacterial growth and increase the rate of tissue repair when an infection is present in the body

Specific Resistance (Acquired Immunity)

The final line of defence is specific resistance, which is a component of acquired immunity. Specific resistance relies on antigens, or specific substances that are found in foreign microbes. Most antigens are proteins; they act as a stimulus to produce an immune response.

.Lymphocytes- Specific white blood cells, T cells and B cells, are responsible for acquired immunity. A specific immune response occurs when antibodies produced by B cells encounter antigens.

Probiotics Can Boost the Body's Lines of Defence

These complex physiological processes are sophisticated and, in most cases, pretty adept at defending your body from disease-causing bacteria. But that doesn't mean there's nothing you can do to make your immune system lines of defence even stronger. Now you realise that how important is a healthy skin to your body defence mechanism. Also, there are important cells in your body defence mechanism

which by different mechanisms protect you from the pathogens.

The level of innate immunity in an individual depends on several factors like age, the two extremes of life carry a higher susceptibility to infectious diseases as compared to adults. Hormonal disorders like Diabetes, thyroid problems, state of pregnancy and stress, all contribute to heightened susceptibility to many infections.

Nutrition is an important component of a healthy immune system. Malnutrition reduces immune responses. Hence a balanced diet is important. There are certain micronutrients that are needed for the immune system. ZINC is one such micronutrient. Now a day one hears a lot about the Immune Booster diet. If you remember the story at the beginning, one needs to eat a healthy balanced diet on a regular basis so that the stomach does it work properly.

A previous article here at "Karuwaki Speaks" dealt in detail regarding what should be eaten to strengthen your Body defence mechanism.

Ask these three questions for yourself:

1. What are you eating?
2. How are You eating?
3. When are you eating?

You deliberate with these questions with your other family members and prepare the plate. What are you eating should answer the constituents of your plate, how are you eating should answer the hygiene and preparation, and when are you eating should answer the timings and regularity.

Chalk yourself the perfect balance plate and make your body defence system strong.

Watch this space for next on Vaccines which are closely related to your Immune system.

Reference: Text Book of Microbiology, Ananthanarayan and Paniker's From researched papers on Immunity, Source Internet