Growth and Renewal
Humans are born with a set number of heart muscle cells, or cardiomyocytes, which increase in size as our heart grows larger during childhood development. Recent evidence suggests that cardiomyocytes are actually slowly turned over as we age, but that less than 50% of the cardiomyocytes we are born with are replaced during a normal life span. The growth of individual cardiomyocytes not only occurs during normal heart development, it also occurs in response to extensive exercise (athletic heart syndrome), heart disease, or heart muscle injury such as after a myocardial infarction. A healthy adult cardiomyocyte has a cylindrical shape that is approximately 100μm long and 10-25μm in diameter. Cardiomyocyte hypertrophy occurs through sarcomerogensis, the creation of new sarcomere units in the cell. During heart volume overload, cardiomyocytes grow through eccentric hypertrophy. The cardiomyocytes extend lengthwise but have the same diameter, resulting in ventricular dilation. During heart pressure overload, cardiomyocytes grow through concentric hypertrophy. The cardiomyocytes grow larger in diameter but have the same length, resulting in heart wall thickening.
Read more about this topic: Cardiac Muscle Cell
Famous quotes containing the words growth and, growth and/or renewal:
“The idealists dream and the dream is told, and the practical men listen and ponder and bring back the truth and apply it to human life, and progress and growth and higher human ideals come into being and so the world moves ever on.”
—Anna Howard Shaw (1847–1919)
“Sensuality often accelerates the growth of love so much that its roots remain weak and are easily pulled up.”
—Friedrich Nietzsche (1844–1900)
“My hope is ... that we may recover ... something of a renewal of that vision of the law with which men may be supposed to have started out with in the old days of the oracles, who communed with the intimations of divinity.”
—Woodrow Wilson (1856–1924)