The inner layer of the heart wall is the endocardium, composed of endothelial cells that provide a smooth, elastic, non-adherent surface for blood collection and pumping. The endocardium may regulate metabolic waste removal from heart tissues and act as a barrier between the blood and the heart muscle, thus controlling the composition of the extracellular fluid in which the cardiomyocytes bathe. This in turn can affect the contractility of the heart.
This tissue also covers the valves of the heart and is histologically continuous with the vascular endothelium of the major blood vessels entering and leaving the heart. The Purkinje fibers are located just beneath the endocardium and send nervous impulses from the SA and AV nodes outside of the heart into the myocardial tissues.
The endocardium can become infected, a serious inflammatory condition called infective endocarditis. This and other potential problems with the endocardium may damage the valves and impair the normal flow of blood through the heart.
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the inner part of my heart attaches the bold, raw pieces of myself to the cold-blooded creature slumbering in the hidden depths of misery and despair i carry
this part of my heart is the wreckage of the hurt and the toxicity caused by parental fallout, the burden of unexpected disappointments, of following footsteps too big for my feet, the fear of being a soldier in a war that is not your own, of discovering depression sleeping beside you in the bed, of bruised lips and bloodied knuckles, crooked shoulders, broken whispers, left alone in the barren wilderness that is my mind
this chapter is dedicated to the part of my heart that is the collateral damage of growing up