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Heart valve surgery – operation for replacement heart valves

Heart valve surgery – operation for replacement heart valves

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heart valves maintain the unidirectional flow of blood in the heart by opening and closing depending on the difference in pressure on each side. They are mechanically similar to reed valves.

Atrioventricular valves

These are small valves that prevent backflow from the ventricles into the atria during systole. They are anchored to the wall of the ventricle by chordae tendineae, which prevent the valve from inverting.

The chordae tendineae are attached to papillary muscles that cause tension to better hold the valve. Together, the papillary muscles and the chordae tendineae are known as the subvalvular apparatus. The function of the subvalvular apparatus is to keep the valves from prolapsing into the atria when they close. The subvalvular apparatus have no effect on the opening and closure of the valves, however. This is caused entirely by the pressure gradient across the valve.

The closure of the AV valves is heard as the first heart sound

Echocardiography — The echocardiogram is an ultrasound of the heart. Using standard ultrasound techniques, two-dimensional slices of the heart can be imaged. 

Heart — The heart is a hollow, muscular organ in vertebrates that pumps blood through the blood vessels by repeated, rhythmic contractions, or a similareart. Veins form part of the circulatory system. The vessels that carry blood …

Vein — In biology, a vein is a blood vessel which carries blood toward the heart. Veins form part of the circulatory system

The tricuspid valve is the three flapped valve on the right side of the heart, between the right atrium and the right ventricle which stops the backflow of blood between the two. It has three cusps.

Semilunar valves

These are located at the base of both the pulmonary trunk (pulmonary artery) and the aorta, the two arteries taking blood out of the ventricles. These valves permit blood to be forced into the arteries, but prevent backflow of blood from the arteries into the ventricles. [1] These valves do not have chordae tendineae, and are more similar to valves in veins than atrioventricular valves.

Aortic valve

Main article: aortic valve

The aortic valve lies between the left ventricle and the aorta. The aortic valve has three cusps. During ventricular systole, pressure rises in the left ventricle. When the pressure in the left ventricle rises above the pressure in the aorta, the aortic valve opens, allowing blood to exit the left ventricle into the aorta. When ventricular systole ends, pressure in the left ventricle rapidly drops. When the pressure in the left ventricle decreases, the aortic pressure forces the aortic valve to close. The closure of the aortic valve contributes the A2 component of the second heart sound (S2).

The most common congenital abnormality of the heart is the bicuspid aortic valve. In this condition, instead of three cusps, the aortic valve has two cusps. This condition is often undiagnosed until the person develops calcific aortic stenosis. Aortic stenosis occurs in this condition usually in patients in their 40s or 50s, an average of over 10 years earlier than in people with normal aortic valves.

Pulmonary valve

Main article: pulmonary valve

The pulmonary valve (sometimes referred to as the pulmonic valve) is the semilunar valve of the heart that lies between the right ventricle and the pulmonary artery and has three cusps. Similar to the aortic valve, the pulmonary valve opens in ventricular systole, when the pressure in the right ventricle rises above the pressure in the pulmonary artery. At the end of ventricular systole, when the pressure in the right ventricle falls rapidly, the pressure in the pulmonary artery will close the pulmonary valve.

The closure of the pulmonary valve contributes the P2 component of the second heart sound (S2). The right heart is a low-pressure system, so the P2 component of the second heart sound is usually softer than the A2 component of the second heart sound. However, it is physiologically normal in some young people to hear both components separated during inhalation.

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Sexy Aerobics

Lucy_Liu

Sexy Aerobics

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Aerobics is a form of physical exercise that combines rhythmic aerobic exercise with stretching and strength training routines with the goal of improving all elements of fitness (flexibility, muscular strength, and cardio-vascular fitness).

It is usually performed to music and may be practiced in a group setting led by an instructor, although it can be done solo and without musical accompaniment. With the goal of preventing illness and promoting physical fitness, practitioners perform various routines comprising a number of different dance-like exercises.

Formal aerobics classes are divided into different levels of intensity and complexity.

Aerobics classes may allow participants to select their level of participation according to their fitness level. Many gyms offer a wide variety of aerobic classes for participants to take. Each class is designed for a certain level of experience and taught by a certified instructor with a specialty area related to their particular class.

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Late-night snacks could pack on the pounds: study

in.reuters.com

Late-night snacks could pack on the pounds: study

Midnight raids on the refrigerator may have worse consequences than indigestion — a study in mice boosts the theory that when you eat affects whether the calories go to your hips or get burned off.

Mice fed during the daytime — when they normally would be sleeping — gained more weight than mice fed at night, Fred Turek of Northwestern University in Illinois and colleagues found.

They ended up weighing 7.8 percent more than night-fed mice. This held even though the mice were fed identical amounts of food and exercised the same amount, they said in the study published on Friday in the International Journal of Obesity.

“Simply modifying the time of feeding alone can greatly affect body weight,” they wrote.

“Mice fed a high-fat diet only during the ‘right’ feeding time (i.e., during the dark) weigh significantly less than mice fed only during the time when feeding is normally reduced (i.e., during the light).”

The finding might help people trying to lose weight, the researchers said.

It may be possible to simply change the timing of meals and snacks, they said. That could mean eating more in the daytime and cutting back on the late-night ice cream.

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