STRUCTURE  

STRUCTURE
FUNCTION
DISEASES
CORONARY HEART
CONGENITAL DEFECTS
VALVE MALFUNCTION
ARRHYTHMIAS
HEART DISEASE
HEART FAILURE
RESEARCH

 

 

STRUCTURE OF THE HEART

Cardiac Muscle Cardiac muscle is a unique muscle tissue found only in the heart. Unlike most forms of muscle, which are stimulated to contract by nerves or hormones, certain cardiac muscle cells can contract spontaneously. Without a constant supply of oxygen, cardiac muscle will die, and heart attacks occur from the damage caused by insufficient blood supply to cardiac muscle. Tony Stone Images /G.W. Willis 

 

The human heart has four chambers. The upper two chambers, the right and left atria, are receiving chambers for blood. The atria are sometimes known as auricles. They collect blood that pours in from veins, blood vessels that return blood to the heart. The heartís lower two chambers, the right and left ventricles, are the powerful pumping chambers. The ventricles propel blood into arteries, blood vessels that carry blood away from the heart.

False-Color Angiogram of a Healthy Human Heart The coronary arteries, named because of the way they encircle the heart muscle like a crown, provide a constant supply of oxygen and nutrients to the heart. In this angiogram, the main coronary arteries appear as yellow ribbons across the heart.Photo Researchers, Inc./Science Source 

 

A wall of tissue separates the right and left sides of the heart. Each side pumps blood through a different circuit of blood vessels: The right side of the heart pumps oxygen-poor blood to the lungs, while the left side of the heart pumps oxygen-rich blood to the body. Blood returning from a trip around the body has given up most of its oxygen and picked up carbon dioxide in the bodyís tissues. This oxygen-poor blood feeds into two large veins, the superior vena cava and inferior vena cava, which empty into the right atrium of the heart.

 

The right atrium conducts blood to the right ventricle, and the right ventricle pumps blood into the pulmonary artery. The pulmonary artery carries the blood to the lungs, where it picks up a fresh supply of oxygen and eliminates carbon dioxide. The blood, now oxygen-rich, returns to the heart through the pulmonary veins, which empty into the left atrium. Blood passes from the left atrium into the left ventricle, from where it is pumped out of the heart into the aorta, the bodyís largest artery. Smaller arteries that branch off the aorta distribute blood to various parts of the body.

Heart Valves

Myocardium

Pericardium

Endocardium

Coronary Arteries

 


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