Myocardium The myocardium (from the Greek ldquo;muscle and heartrdquo;, ldquo;middlerdquo;) - is the heart muscle that has a special structure a

Cardiac muscle (myocardium) and arteries of the heart

Myocardium

The myocardium (from the Greek “muscle and heart”, “middle”) — is the heart muscle that has a special structure and properties of both striated and smooth muscle types. According to the microscopic structure, it resembles skeletal muscles, but its contraction is not controlled by consciousness. It changes the frequency, rhythm and strength of its contractions only under the influence of the autonomic nervous and endocrine systems. The muscle of the left ventricle has a thickness of 10-15 mm. This is 2-3 times greater than the thickness of the less intensely working right ventricle muscle (5-7 mm). The thickness of both atrial muscles is about the same — 3 mm.

Heart is an organ that starts to work first even in the body of the embryo, and the last one that dies. The ancient Greek philosopher Aristotle studied the development of the chick embryo. In the egg that was warmed by chicken only one day (chicken egg develops in more than three weeks), he saw a pulsating point. The scientist could not hide his excitement and said: "Living in a living!" He realized that this is the rudiment of the pulsating heart. Much later, scientists found that this pulsing point is the accumulation of future heart cells. Taken from http://worldofschool.org

Heart arteries

A heart that supplies blood to the human body needs a constant and significant supply of oxygen and nutrients. For this purpose it has two coronary (from Latin “crown”) arteries through which flows up to 500 liters of blood per day.

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Questions:
  • Explain the origin of the “myocardium” term.

  • Describe the features of myocardial structure.

  • What are the blood vessels that supply blood to the heart?