Bradycardia was defined as a heart rate less than 60 beats per minute when textbooks asserted that the normal range for heart rates was 60â100 BPM. The normal range has since been revised in textbooks to 50â90 BPM for a human at total rest.he normal resting adult human heart rate ranges from 60â100 bpm. Tachycardia is a fast heart rate, defined as above 100 bpm at rest. Bradycardia is a slow heart rate, defined as below 60 bpm at rest.
âEndothelial cell contraction leads to intercellular gaps in venules. This is the most common form of increased vascular permeability, endothelial cell contraction is a reversible process elicited by histamine, bradykinin, leukotrienes and many other classes of chemical mediators.
endothelial cell. The type of epithelial cell that lines blood vessels and lymph vessels; these cells are usually squamous (flattened) and form sheets one layer thick. Endothelial cells are derived from mesenchyme cells of the embryo. A sheet of endothelial cells is called an endothelium.See also: cell.he type of epithelial cell that lines blood vessels and lymph vessels; these cells are usually squamous (flattened) and form sheets one layer thick.