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The SA node triggers an impulse that causes both atria to do what?
SA node sends an impulse for the atria to contract. AV node is then activated which contracts the ventricles.
Do the ventricles contract at the apex or at the base of the heart?
Not really sure what you mean by the base, the ventricles contract from the Apex (which is at the bottom) upwards.
When does the human heart rest?
The electrical impulse reaches all the muscle tissue in the ventricles, and the ventricles contract. This electrical conduction pattern occurs approx. every 0.8 seconds.
What are AV nodes?
AV node is biologically an inhibitor of the conduction across the atrium to ventricles. The conduction of impulse is delayed across the AV node. This buys time for the atria to contract, to be fallowed by ventricles.
When an electrical impulse reaches the AV node it is slowed for a brief period of time so that?
blood can pass from the atria to the ventricles.
What structure conducts the contraction impulse from the atria to the ventricles?
the purkinje fibers um no!!! wrong answer!!
What are AV nodes biologically?
AV node is biologically an inhibitor of the conduction across the atrium to ventricles. The conduction of impulse is delayed across the AV node. This buys time for the atria to contract, to be fallowed by ventricles.
Can someone help you decipher your EKG report It says sinus tachycardia borderline AV conduction delay and probable left atrial abnormality.?
sinus tachycardia = rapid heartbeat borderline av conduction delay = a slight delay in the conduction of electrical impulse from the atria, at the top of the heart, to the ventricles, at the base of the heart. The ventricles are the chambers that do the pumping of blood to the lungs and to the body. The atria are the two "collecting" chambers for the blood returning to the heart from the lungs and from the body. The electrical impulse of a heartbeat starts in the right atrium, travels across to the left atrium and down to the top of the ventricles. This causes the atria to contract and push blood through heart valves into the chambers of the heart called Ventricles. The contraction then has a slight pause as the impulse "stimulates" the atrioventricular node to pass the impulse down to the base of the right and left ventricles. When the impulse passes the AV node, the ventricles contract and push the blood out to the lungs to be oxygenated and to the body. A slight delay in the conduction of the impulse is normal but it is only a fraction of a second. Any delay in the conduction which is longer than the "normal" fraction of a second is considered an abnormal av conduction delay. Probable Left Atrial abnormality = some kind of abnormal size, shape, structure, or electrical conduction in the chamber at the top of the left side of the heart. Remember that the atria are chambers for collecting blood returning to the heart. The left atrium is the chamber for collecting blood which is returning from the lungs. This is freshly oxygenated blood. The blood travels from the lungs to the left atrium. When the atria contract, the blood is pushed from the left atrium into the left ventricle. When the ventricles contract, the blood is then pumped from the left ventricle out into the aorta (the largest artery in your body) and then on to the furthest reaches of your body.
Which part of the heart delays the electrical impulse to allow for atrial emptying of blood before ventricular contraction?
The AV node slows down the impulse giving the atria time to contract before the ventricles contract.
How does the impulse to contract slow down slightly before it is transferred into the ventricles?
junctional fibers leading into the AV node have very small diameters
How does movement of electrical impulse relate to the contraction of the chambers of the heart?
The impulse shocks the left and right atria of the heart. This pumps blood into the left and right ventricle. The ventricles then receive the impulse and pump the blood. The movement of the electrical impulse allows the blood to move through multiple areas of the heart with only one impulse.
What are junctional fibers?
On the Net, you can find different things being said about the cardiac "junctional fibers". I am going to offer what I understand makes the most sense. The junctional fibers are cardiac muscle cells which are specialized for slowing down the cardiac impulse just before it goes into the atrioventricular node. This delay gives the atria time to empty their blood into the ventricles before the cardiac impulse goes on to stimulate the ventricles to contract. Notes: (1) These junctional fibers are not nerve cells, but are muscle cells which are specialized for conducting the cardiac impulse. You may know how more-narrow nerve axons are slower at passing on an action potential, while wider axons can pass on an action potential faster. Well, these junctional fibers are like nerve fibers, in this way > because these junctional fibers are very narrow, they can slow down the cardiac impulse. (2) So, where do you think these narrow junctional fibers need to be, in order to slow down the cardiac impulse at the right place and time? If the cardiac impulse were to go from the atria right on to to the ventricles, then the ventricles would be stimulated to contract while the atria were still trying to empty blood into the ventricles. And so, the ventricular blood pressure would be pushing back against the blood that was trying to get from the atria into the ventricles. This would not be good. So . . . the heart needs to slow that impulse, just after it leaves the atria . . . slowing it long enough so the ventricles stay relaxed while they receive blood from the atria. (3) And, lo and behold . . . the junctional fibers are located right after the atria; and they receive the impulse which comes from the atrial muscles; then it delays the impulse before letting it go into the atrioventricular node. This slow-down gives the atrial muscles just enough time to finish contracting before the atrioventricular node sends on the cardiac impulse to stimulate the ventricles to contract. (4) You might notice on an EKG how there is the P wave showing atrial depolarization. Then the line goes flat for a little bit before the QRS complex. At the beginning of that flat time at the end of the atrial depolarization, this is where the junctional fibers are slowing down the cardiac impulse before it shows as the QRS which shows the impulse being fired by the atrioventricular node to the ventricles, I understand.
