Pictur from:- www.faculty.weber.edu 
Pictures from:- http://www.cdle.ca/
3.3 Explain The Electrical Activity Of The
Heart During A Heart Beat
---------------------------------------
Our heart as a pace maker of it's own and this is what helps keep our heart beating at a regular rate. The natural pace maker is situated in the upper part of the right atrium and it is a group of specialised electrical cells known as the Sinus or Sino - Atrial node.
The electrical system Carry's sparks that stimulate the muscle wall of the four chambers of the heart, those being the left atrium, right atrium, left ventricle and right ventricle to contract and then empty, this is done in a certain sequence. The first parts of the heart to be stimulated is the upper parts and the atria, after this there is a small delay which allows the two atria to empty, then the two ventricles are stimulated.
For the stimulation to happen adrenaline needs to be built up causing the sinus node to increase the amount of sparks per minute, this then increases the heart rate, how much adrenaline is released is determined by our nervous system. Our heart beats on average 72 times a minute (heartsite web) and when we carry out exercise or are stressed then the sinus node speeds up, this also occurs when our body needs an extra boost of blood supply.
The way in which the electrical activity takes place in the heart is as follows. When the sino - atrial node fires the electrical impulse goes through both the left and right atrium, this then causes both chambers to contract. When this happens this activity on an ECG would be known as the 'P' wave. From here the impulse then goes to the atrio- ventricular node which is just above the ventricules, it is then held here shortly. The reason it is help is to allow the left and right atrium to carry on emptying there blood into the ventricles, on an ECG this would then show as the 'PR interval'. The atrio - ventricular node is then acting as a rest area which is delaying the stimulation of the ventricles whilst the two atria empty. Once the delay is over the impulse then travels through both the ventricles, this then causes them to contract and blood is then sent into the pulmonary artery and the aorta, this is shown as the 'QRS complex' on an ECG. Once the ventricles have then recovered from the impulse it generates an 'ST segment' and T wave on an ECG.
The thing that makes the heart make the 'Lub' sound is when the impulses are in the ventricular systole stage and the pressure of the blood is causing the ventricular valves to close, the valve is opened during atrial systole and when it makes the 'Dub' sound it is during the diastole stage and due to the pressure of the blood being so high in the arteries that it causes the semi lunar valve to shut, the semi - lunar opens during ventricular systole.
Overall again our heart with help from our nervous system is playing a major part in our body and it enables us to breath without having to think about doing it.
Heart During A Heart Beat
---------------------------------------
Our heart as a pace maker of it's own and this is what helps keep our heart beating at a regular rate. The natural pace maker is situated in the upper part of the right atrium and it is a group of specialised electrical cells known as the Sinus or Sino - Atrial node.
The electrical system Carry's sparks that stimulate the muscle wall of the four chambers of the heart, those being the left atrium, right atrium, left ventricle and right ventricle to contract and then empty, this is done in a certain sequence. The first parts of the heart to be stimulated is the upper parts and the atria, after this there is a small delay which allows the two atria to empty, then the two ventricles are stimulated.
For the stimulation to happen adrenaline needs to be built up causing the sinus node to increase the amount of sparks per minute, this then increases the heart rate, how much adrenaline is released is determined by our nervous system. Our heart beats on average 72 times a minute (heartsite web) and when we carry out exercise or are stressed then the sinus node speeds up, this also occurs when our body needs an extra boost of blood supply.
The way in which the electrical activity takes place in the heart is as follows. When the sino - atrial node fires the electrical impulse goes through both the left and right atrium, this then causes both chambers to contract. When this happens this activity on an ECG would be known as the 'P' wave. From here the impulse then goes to the atrio- ventricular node which is just above the ventricules, it is then held here shortly. The reason it is help is to allow the left and right atrium to carry on emptying there blood into the ventricles, on an ECG this would then show as the 'PR interval'. The atrio - ventricular node is then acting as a rest area which is delaying the stimulation of the ventricles whilst the two atria empty. Once the delay is over the impulse then travels through both the ventricles, this then causes them to contract and blood is then sent into the pulmonary artery and the aorta, this is shown as the 'QRS complex' on an ECG. Once the ventricles have then recovered from the impulse it generates an 'ST segment' and T wave on an ECG.
The thing that makes the heart make the 'Lub' sound is when the impulses are in the ventricular systole stage and the pressure of the blood is causing the ventricular valves to close, the valve is opened during atrial systole and when it makes the 'Dub' sound it is during the diastole stage and due to the pressure of the blood being so high in the arteries that it causes the semi lunar valve to shut, the semi - lunar opens during ventricular systole.
Overall again our heart with help from our nervous system is playing a major part in our body and it enables us to breath without having to think about doing it.
No comments:
Post a Comment