As we see in the previous post, human (mammal) heart has septum, The function of septum is to separate the chambers at left and right. Septum of the heart is not complete until birth. Hence, during foetal development, oxygenated blood comes from the placenta and goes directly to the aorta of the foetal's heart, through a small vessel called ductus arteriosus. It usually closes after the infant's birth. However, in some cases, the vessel do not close completely, and the infant will suffer from 'hole in the heart'.
The whole heart, or an isolated cardiac muscle cell is provided with enough nutrient, mineral salts and oxygen of course, it will contract and relax simultaneously without and nerve impulse or hormonal stimulation.
Heart valves will harden sometimes as we get old, The closing and opening of the valve can be heard like the sound of a slammed door, instead of gentle 'lup-dup' sound. Moreover, in certain cases, valves do not close properly, resulting the sound of breezing or gushing of wind. These sounds can be heard through stethoscope.
Cardiac output varies with volume of blood returning to the heart through main veins. When return is high, wall of right atrium are stretched and heart rate increases. Such a condition is known as Bainbridge Reflex. The Frank Starling Effect is another condition where stroke volume of heart is increased when walls of left ventricle is stretched, causing ventricles to to contract even stronger due to high venous return of blood to heart. This effect enables the heart to automatically adjust its output to match the flow.
Cardiac output is determined by heart rate. It is the total amount of blood that flows out of the heart per minute. Cardiac output can be obtained through ,
Cardiac Output = Heart rate x Stroke volume.
Some people suffers from heart block,a condition where the conduction of the electrical impulses from SA node is impaired. In this case, normal heart rhythm can be maintained by battery powered artificial pacemaker, which is implanted under the muscles in upper thorax. The device delivers regular electrical impulses to the heart, to control the cardiac cycle.
Some people encounters high heart rate, restlessness, and irritability. This could be because of hyperthyrodism, a disorder where thyroid hormones are excessively secreted, more than the needed amount.
Not only ruptures of blood capillary in brain causes cerebrovascular accident ( CVA ), but also a clot in artery that supplies blood to the blood. Blood supply to the brain will be interrupted, and this may cause death of brain cells in a few seconds of time. Dead brain cells cause impairments of certain body functions that is controlled by the affected area. 100% recovery is impossible as dead brain cells cannot be replaced. Degree of impairment and the level of recovery depends to the extensiveness of the damage occurred.
The whole heart, or an isolated cardiac muscle cell is provided with enough nutrient, mineral salts and oxygen of course, it will contract and relax simultaneously without and nerve impulse or hormonal stimulation.
Heart valves will harden sometimes as we get old, The closing and opening of the valve can be heard like the sound of a slammed door, instead of gentle 'lup-dup' sound. Moreover, in certain cases, valves do not close properly, resulting the sound of breezing or gushing of wind. These sounds can be heard through stethoscope.
Cardiac output varies with volume of blood returning to the heart through main veins. When return is high, wall of right atrium are stretched and heart rate increases. Such a condition is known as Bainbridge Reflex. The Frank Starling Effect is another condition where stroke volume of heart is increased when walls of left ventricle is stretched, causing ventricles to to contract even stronger due to high venous return of blood to heart. This effect enables the heart to automatically adjust its output to match the flow.
Cardiac output is determined by heart rate. It is the total amount of blood that flows out of the heart per minute. Cardiac output can be obtained through ,
Cardiac Output = Heart rate x Stroke volume.
Some people suffers from heart block,a condition where the conduction of the electrical impulses from SA node is impaired. In this case, normal heart rhythm can be maintained by battery powered artificial pacemaker, which is implanted under the muscles in upper thorax. The device delivers regular electrical impulses to the heart, to control the cardiac cycle.
Some people encounters high heart rate, restlessness, and irritability. This could be because of hyperthyrodism, a disorder where thyroid hormones are excessively secreted, more than the needed amount.
Not only ruptures of blood capillary in brain causes cerebrovascular accident ( CVA ), but also a clot in artery that supplies blood to the blood. Blood supply to the brain will be interrupted, and this may cause death of brain cells in a few seconds of time. Dead brain cells cause impairments of certain body functions that is controlled by the affected area. 100% recovery is impossible as dead brain cells cannot be replaced. Degree of impairment and the level of recovery depends to the extensiveness of the damage occurred.
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