Immune System Lines of Defense
A Definition of the Immune System
The immune system, a network of cells, tissues, and organs, protects the body from infection and disease. Invading viruses, bacteria, and other microbes try to invade the body, and the immune system targets them while leaving healthy tissues alone. The immune system does this by recognizing proteins on the surfaces of cells and responding in order to address the problem. When an immune response cannot be activated, an infection can develop. However, if an immune response is activated when there is not a real threat or after the danger passes, the person suffers from allergic reactions and autoimmune disease.
Immune System Lines of Defense
The immune system includes three lines of defense against foreign invaders: physical and chemical barriers, nonspecific resistance, and specific resistance. The first line of defense are the physical and chemical barriers, which are considered functions of innate immunity. The second line of defense is nonspecific resistance, which also is considered a function of innate immunity. The third line of defense is specific resistance, which is considered a function of acquired immunity.
Innate immunity involves nonspecific immune defense 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 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 attacks to specific antigens because it learns, adapts, and remembers them.
Physical and Chemical Barriers (Innate Immunity)
Physical barriers literally provide physical barriers to invaders. These include skin, mucous membranes, hair, cilia, urine, and defecation and vomiting.
- Skin – A thick layer of dead cells in the epidermis provides a physical barrier to viruses, bacteria, and microbes. As the epidermis sheds, microbes are removed
- Mucous membranes – Mucous membranes produce mucus to trap microbes so they cannot spread to the rest of the body
- Hair – Hair within the nose filters microbes, dust, and pollutants from the air to prevent them from invading the body
- Cilia – Cilia lines the upper respiratory tract and traps and propels inhaled debris to the throat so it can exit the body more quickly
- Urine – Urine flushes microbes out of the body via the urethra
- Defecation and vomiting – The body expels microorganisms via bowel movements and vomit
Chemical barriers form another first line of defense against invaders.
- Lysozyme – Lysozyme is an enzyme produced in tears, sweat, and saliva that breaks down cell walls and acts as an antibiotic by killing bacteria
- Gastric juice – Acids in the stomach destroy bacteria and toxins
- Saliva – Saliva dilutes the number of microorganisms in the body and washes the teeth and mouth
- Acidity – Skin acidity inhibits bacterial growth
- Sebum – Unsaturated fatty acids known as sebum provide a protective film on the skin and inhibits growth
- 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 defense of the immune system, also an aspect of innate immunity, is the nonspecific resistance. These defense mechanisms destroy invaders in a general way and do not target specific antigens.
- Phagocytes – Phagocytic cells ingest and destroy microbes that pass into body tissues
- 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
- 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 defense 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 Defense
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 defense even stronger. Supplements such as Del-Immune V® activate cytokines, which act as messengers that alert your body to the presence of harmful germs and bacteria. By using Del-Immune V® supplements, you’ll speed up your body’s response time to foreign invaders from the typical 10 days it takes to recognize harmful invaders to six hours or less.