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Give An Account Of The Control Of The Heart Beat And How In Heart Disease The Activity Of The Heart May Be Influenced By Artificial Pacemakers.

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Introduction

Give An Account Of The Control Of The Heart Beat And How In Heart Disease The Activity Of The Heart May Be Influenced By Artificial Pacemakers The mammalian heart is located in the middle of the chest, just beneath the breastbone. A network of blood vessels connects the heart to the other organs. These blood vessels keep blood flowing continuously throughout the body. The heart's functions are: �To provide all of the cells, tissues, and organs with oxygen and nutrient-rich blood �To pump an adequate supply of blood to keep up with the body's demand Each time the heart contracts and relaxes, it flexes its muscle! This flexing creates the pumping action that keeps blood flowing continuously through the blood vessels. It also creates the "heartbeat" that is so very audible. The sequence of events and actions that happen during a heartbeat is referred to as the 'cardiac cycle' and on average lasts a mere 0.8 seconds. This cycle as two major phases; Systole (Say Sis-toll-ee) and Diastole (Say Die-ass-toll-ee). ...read more.

Middle

The pulmonary artery carries the blood to the lungs. There the blood picks up oxygen and is returned to the left atrium of the heart by the pulmonary veins. In the next diastole period, the semi lunar valves close and the atrioventricular valves open. Blood from the pulmonary veins fills the left atrium. (Blood from the vena cava is also filling the right atrium.) The SA node fires again triggering the atria to contract. The left atrium empties its contents into the left ventricle. The mitral valve prevents the oxygenated blood from flowing back into the left atrium. During the systole phase the atrioventricular valves close and the semi lunar valves open. The left ventricle receives impulses from the Purkinje fibres and contracts. Oxygenated blood is pumped into the aorta. The aortic valve prevents the oxygenated blood from flowing back into the left ventricle. The aorta branches out to provide oxygenated blood to all parts of the body. The oxygen-depleted blood is returned to the heart via the vena cava. Whilst it is true that cardiac muscle harbours unfatiguing myogenic properties, meaning that it will contract independently of nervous impulse, it does need regulation. ...read more.

Conclusion

Coronary heart disease arises when the blood supply to the heart muscle is reduced by obstruction in the coronary arteries. This could have a variety of causes. During stress when glucocorticoids, noradrenalin and adrenalin are released into the bloodstream, to aid the fight or flight response. Obviously stress in today's society does not require this sort of response so it is just left to meander about the bloodstream furring up the vessels of the body. Further and perhaps more importantly, LDL cholesterol is a major factor in the furring of vessels. This blockage may then travel toward the heart. An artificial pace maker may be needed if the SA node is damaged. It is a device that uses electrical impulses to regulate the heart rhythm of the patient. An artificial pacemaker will make the heart beat more regularly, ensuring that the patient will live on for many years after the operation. That is of course if they can keep away from electrical interference. On such culprit is the modern microwave. Overall, the heart is a wonderful organ, one that cannot be underestimated in the importance of human survival. Steven Stroud ...read more.

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