Who supports your support system? An unsung hero — connective tissue

Connective tissue, the inner part of the wall that conveys the body's infrastructure

If you’ve been reading this blog, by now you’ll know that the oxygen and nutrients your cells depend upon first enter the cell’s neighborhood by means of your crowded capillaries.  Molecules then diffuse outward across the interstitial fluid to reach most cells in your body.  The cardiovascular system is the most obvious “support system” in the body because it circulates the blood that keeps your cells alive.  It also works with the kidneys to remove wastes.  I’d also add the lymphatic system (see lymph nodes) which drains excess interstitial fluid and filter pathogens from it.  And, I’d include the nervous system which carries a crucial pipeline of information that many cells depend on to do their job.

But who supports the “support system”?  Do your blood vessels, lymph vessels and nerves simply meander through the body, or is there a structure – a scaffolding — that holds them in place?  Yes, there is – our unsung hero, the connective tissues of the body.

In a typical organ like your stomach, lungs, or skin, you’ll have one or more layers of epithelium at the surface (shown in yellow) to interact with your food, air, or the external environment.  Always behind that epithelium you’ll have connective tissue (shown in brown) which carries the blood vessels, lymph vessels, and nerves that serve that region of the body.  Even a muscle layer (for example in the stomach), as seen at far right, actually contains, between the muscle cells, a great deal of intervening connective tissue, which is where the vessels and nerves travel.  (This is the endomysium, the “first class seat” that supplies all the muscle cell’s needs.)

As you go about your business indoors, at work or home, think of the wall surfaces as an epithelium.  They provide electrical outlets, faucets, heating vents and other necessities for life.  But all of these things come to you through an infrastructure of electrical wires, water and sewage pipes, ventilation ducts, and internet cables that travel, unseen, through the walls.  Inside your body, that role of the “internal wall space”, which supports and conceals the “support system” of the body, is served by connective tissue.

Endomysium: A first-class seat for your muscle cells

Endomysium is like a first-class airplane seat for your muscle cells

Strapped into an economy seat as we fly across the country for the holidays, it’s hard not to appreciate life’s basic necessities — a cup of soda, a bag of pretzels, the relief of seeing “vacant” on the lavatory door. It’s also a good time to remember that the real protagonists in this story are your trillions of cells, each of whom has the same basic needs you have. Each muscle cell, for example, needs an oxygen supply, nutrients, a way to eliminate wastes, a command system telling it whether to contract (or just relax), and a physical attachment allowing it to work with the rest of the muscle. All of these things are provided by a thin sheath of connective tissue called the endomysium which surrounds each muscle cell. The endomysium, in effect, acts as a scaffolding to support the infrastructure of blood vessels and nerve cells that allow the muscle cell to function. What kind of airplane seat does a muscle cell occupy? Considering that the bloodstream keeps the cell supplied with a constant stream of goodies, I imagine it’s got to be a first-class seat.