Blood Flow Through the Heart

Deoxygenated blood is returned to the heart from the arms and head by a large vein called the superior vena cava. Deoxygenated blood is returned to the heart from the legs and trunk by a large vein called the inferior vena cava. The blood empties into a chamber called the right atrium. Upon contraction of the right atrium, blood flows over a valve called the tricuspid valve. This valve consists of three cusps or flaps. Attached to the inferior aspect of the tricuspid valve are fine tendon-like cords called chordae tendineae. The chordae tendineae attach to papillary muscles located in the right ventricle. The papillary muscles are made up of cardiac muscle fibers.

Upon contraction of the right ventricle, blood flows over a valve called the pulmonary semilunar valve. This valve is made up of three half-moon-shaped cusps. After passing through the pulmonary semilunar valve, the blood enters the pulmonary trunk. The pulmonary trunk divides into the right pulmonary artery and the left pulmonary artery. These two arteries take blood to the lungs to be oxygenated.

After oxygenation, the blood is returned to the heart by four veins called pulmonary veins that empty into the left atrium. Two of these veins enter each side of the left atrium. Upon contraction of the left atrium, blood flows over a valve called the mitral valve. This valve consists of two cusps or flaps. Attached to the inferior aspect of the mitral valve are chordae tendineae attached to papillary muscles.

Upon contraction of the left ventricle, blood flows over a valve called the aortic semilunar valve. This valve is made up of three half-moon-shaped cusps. After passing over the aortic semilunar valve, the blood enters the aorta. The aorta is the largest artery in the body and is responsible for blood distribution to the various body structures. The portion of the aorta just past the aortic semilunar valve is called the ascending aorta. It curves to the left forming the aortic arch. The aortic arch then descends and is called the descending aorta.

Originating from the aortic arch are three arteries. These three arteries distribute blood to the arms and the head. The one closest to the right side of the heart is called the innominate artery. The middle one is called the left common carotid artery. The one closest to the left side of the heart is called the left subclavian artery.

Connecting the aortic arch and the pulmonary trunk is a ligament called the ligamentum arteriosum. The lig-amentum arteriosum is the remains of a fetal structure called the ductus arteriosus (see chapter 29).

Supplements For Diabetics

Supplements For Diabetics

All you need is a proper diet of fresh fruits and vegetables and get plenty of exercise and you'll be fine. Ever heard those words from your doctor? If that's all heshe recommends then you're missing out an important ingredient for health that he's not telling you. Fact is that you can adhere to the strictest diet, watch everything you eat and get the exercise of amarathon runner and still come down with diabetic complications. Diet, exercise and standard drug treatments simply aren't enough to help keep your diabetes under control.

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