(How Your Lymphatic System Defends Your Body and Keeps You Safe)
Several years ago I came across my grandfather’s old Navy manual. He enlisted in the Navy underage, determined to join, near the time of Pearl Harbor. The attack against Pearl Harbor forced the United States into World War II. His subsequent years saw a lot of action – events he would never talk about. Only in reading his journal entries years later (in the front and back pages of his handbook) did I gain greater insight into what he experienced. He wrote of being attacked by bombers and torpedo planes in the early morning hours. “[A]bout two o’clock they dived at us just missed us with a torpedo.” He continued, “May our luck hold out and God watch over us in time of battle which is very often.” I knew he had a fear of water but only understood why later: He had been knocked into the ocean during an enemy attack against his destroyer warship. Ultimately, he was honorably discharged after developing post-traumatic stress disorder (PTSD).
Many times we go about our daily lives not giving thought to the sacrifices those in our military make (in order that we might remain free and live each day as we do). Their sacrifices include missing the comfort of home; separation from loved ones; missing birthdays, anniversaries and holidays; missing a child’s milestones; potentially sustaining lifelong mental, emotional and physical trauma; and, some even sacrifice their very life on our behalf. May President Reagan’s words ring true this month (and every month), “We will always remember. We will always be proud. We will always be prepared so we may be always free.” 8
To all who have served (and presently serve) in our armed forces: Thank you.
In honor of Veterans Day, how does your lymphatic system play a role in defending your body and keeping you safe?
Men and women in the Air Force, Army, Navy, Marine Corps, Coast Guard, and recent Space Force as well as the National Guard preserve our freedom by securing our country, protecting our interests, preventing potential attacks and fighting on our behalf when we do go to war. We even have elite special operations forces (highly trained and skilled individuals with specialized knowledge). To best perform these functions, the military must be strong, healthy and able to respond swiftly. In his 1793 State of the Union Address, President George Washington said, “[I]f we desire to secure peace …it must be known that we are at all times ready for war.” 1 The best way to prevent an opportunist from gaining a foothold is to always be strong, prepared, and willing to act, if necessary.
Your body’s defense system is similarly made up of various branches creating its own armed forces: Your skin, stomach (acid) and digestive system, tears, mucus, cilia (hair-like projections), saliva and lymphatic system make up your “armed forces.” The lymphatic system has structural components made of vessels and organs. These include:
- lymph vessels – lymph capillaries, precollectors, collectors (lymphangions) and trunks
- primary lymph organs – red bone marrow (housing stem cells that become lymphocytes) and the thymus gland
- secondary lymph organs – spleen, lymph nodes (such as tonsils) and mucosa-associated lymphatic tissue (membranes that line the GI tract like Peyer’s patches, respiratory airways, urinary tract and reproductive tract). 3,4
Your body fends off attacks from an enemy such as a pathogen or microbe (like a virus or bacteria) by neutralizing it, repairing damage (from bumps, cuts, burns, chemicals, etc.) and eliminating abnormal or degenerative cells (like cancer). The body provides two types of defense:
Nonspecific3 – A general protection against invasion by pathogens through physical barriers (skin and mucus membranes), production of antimicrobial chemicals to inhibit microbe growth, natural killer cells (a.k.a. white blood cells or lymphocytes), phagocytosis (ingesting a pathogen), fever and inflammation.
Examples: Thick mucus and cilia filter air and trap microbes, dust and pollutants. Tears bathe the eye surface, washing away microbes as you blink. Cells that get infected with a virus produce messages (proteins called interferons) that signal other cells of the invasion. Many lymphatic cells (macrophages, B and T lymphocytes) produce these proteins. Non-infected cells get the message and ready themselves for attack (i.e. they make proteins to inhibit their own invasion of a virus which replicates itself using the cell). The blood contains a group of soldiers (i.e. inactive proteins) that activate themselves to bolster defenses (by enhancing immune, allergic and inflammatory reactions). Some soldiers even combine forces to punch holes in the plasma membrane of a microbe (cytolysis) causing it to rupture. How awesome is that?
If physical barriers and antimicrobial chemicals don’t work, the next lines of defense are natural killer cells and phagocytes (WBCs or lymphocytes) which destroy intruders. Killer cells patrol the body, interacting with other cells (checking “ID cards”). If a cell doesn’t match up (like a cancer cell)? It’s “Hasta la vista, Baby.” 6 Some phagocytes also patrol the body while others remain stationed at a post (in tissue). They ingest (imprison) an invader, unleash chemicals to kill the microbe and digest the remains. What a rough way to go! Anything that can’t be degraded is contained in residual bodies (mini-prisons) which are expelled into the interstitial space and cleaned up by the lymph capillaries.
Finally, there is inflammation and fever. If invaders have caused tissue damage, the body responds with an inflammatory response (a loud siren) resulting in widening of roads (enlarging blood vessels, a process called vasodilation) and more eagerly opening gates (increasing blood vessel permeability), to allow soldiers, clean up personnel and paramedics (antibodies, phagocytes and clot-forming chemicals in blood) to enter the trauma zone.
Specific3 – A specific, adapted defense response (immunity) to a particular pathogen (called an antigen) is launched by the lymphatic system (T and B lymphocytes) and is the most potent.5 This takes some smarts! It is sort of like profiling (antigens are external molecular structures or characteristics that identify the pathogen). The lymphatic system not only recognizes the invader but remembers it next time around and responds even faster. These are your “elite special operations forces.” T and B cells develop in red bone marrow. B cells remain there while T cells migrate to the thymus to complete their training (development). Before either cell leaves their training base, it becomes highly trained and skilled with specialized knowledge (in the form of distinctive surface proteins) in order to recognize specific enemies. In fact, “[b]efore a particular antigen ever enters the body, T and B lymphocytes that can recognize and respond to that intruder are ready and waiting.”7 That kind of preparedness would make President George Washington proud!
When an antigen is recognized, B and T cells respond in two ways: cellular or humoral. In cellular, some T cells become killer cells and directly attack. This is sort of like a reconnaissance mission during which T cells scout the body for enemies and once identified, attack. In humoral, B cells become plasma cells which make and secrete proteins (antibodies or immunoglobulins). These bind to and inactivate a particular antigen. This is sort of like a reconnaissance mission during which B cells disable and neutralize the enemy.
How can your lymphatic system “always be strong, prepared, and willing to act?” By you following a healthy regimen: Get plenty of rest. Eat healthy. Reduce stress. Practice good hygiene and wash your hands often. Exercise. Maintain a healthy weight. Don’t do unhealthy things (drinking too much, smoking, etc.). And, given that lymphatics slow down as we age (restricting the transport of antibodies), 2 consider getting a manual lymph drainage massage from time to time.
2Verlag, K. (1998). Compendium of Dr. Vodder’s Manual Lymph Drainage, p. 22-23. Germany: Huthig GmbH.
3Tortora, G., Grabowski, S. (1996). Principles of Anatomy and Physiology (8th ed.), p. 671-706. New York: HarperCollins College Publishers.
4Foldi, M, Foldi, E. (2006). Foldi’s Textbook of Lymphology (2nd ed.), p. 2-8. Germany: Urban and Fisher.
6Cameron, J. (Producer, Director). 1991. Terminator 2: Judgment Day. United States: TriStar Pictures.
7Tortora, G., Grabowski, S. (1996). Principles of Anatomy and Physiology (8th ed.), p. 688. New York: HarperCollins College Publishers.
8Reagan, Pres. Ronald. “Normandy Speech.” June 6, 1984.