The walls of the chambers of the heart consist of three layers:
• The endocardium
• The epicardium
• Myocardium
Page 2 Endocardium and Epicardium
The chambers themselves are lined with a simple epithelium known as the endocardium.
Likewise, the epicardium is a simple epithelium tissue. It surrounds the outside of the heart.
The epicardium is also referred to as the visceral pericardium.
Page 3 Myocardium
By far the most important of the three layers in the heart walls is the myocardium, the middle layer.
It is made up of cardiac muscle tissue.
Cardiac muscle tissue consists of fibers formed by the fusion of many individual cells (syncytium). These cardiac fibers are striated and branched.
Page 4 Myocardium of Ventricles
The myocardium is thicker in the walls of the ventricles than the atria.
This is because greater pressures are needed for the ventricles to perform their function. The wall of the left ventricle is especially thick, since it has to drive the blood throughout the body.
The inner surfaces of the ventricular walls have ridges of muscle known as the trabeculae carneae, with spaces between them.
Page 5
When the musculature within a chamber wall contracts, the lumen (cavity) decreases in diameter. This is particularly true of the left ventricle.
There is also a twisting or wringing action of the left ventricle that causes the apex of the heart to
hit against the inner surface of the chest wall--the apex beat.
Page 6
The stroke volume is the amount of blood forced out of each ventricle in one contraction.
The cardiac output is the volume of blood pumped out of the ventricles (RT into the lungs, LT into the systemic circulation) in one minute (expressed in liters per minute).
These volumes will change according to the needs of the body.
English
Spanish
French
Italian
Myocardium of ventricles has thinker walls than the arteries because more pressure are need for ventricles to function.
What is stroke volume?
The heart consists of how many layers?
if the apex of ventricles while contracting and relaxing touches the chest wall,, then how do we not get sensed for that.?
How many times the left ventricle do 'twisting' ? What stimulate it to twist ?
What will happen if the left ventricle cannot twist anymore ? Does it mean the person dies ?
The heart is equipped with an anatomical function at its apex that allows it to twist and beat against the chest wall -- the apex beat.
elaborate on wall layers