ECG summary Flashcards
What does ECG stand for?
Electrocardiogram
What does action potential do?
These are nerve impulses and they allow for blood to be pumped through the atria and ventricles into pulmonary and systemic circuits.
What is action potential?
These are nerve impulses (small electrical currents) that travel through the body to the surface and is then detected by an electrocardiograph to produce an electrocardiogram.
What is the difference between electrocardiograph and electrocardiogram?
An electrocardiograph is the machine used to pick up the signals and produce the tracing and an electrocardiogram is the actual tracing that is produced.
What is the process of the conduction system?
1) Depolarisation- Na+ is flowing into the cell causing the voltage to increase inside the cell to +30mV (at rest, it is -90mV)
2) Plateau phase- this is where some Na+ leak out of the cell through leakage tunnels and cause mV to drop slightly
3) Repolarisation- as Na+ move out of cell, the mV return back to the resting amount of -90mV
What is the membrane potential at rest?
-90mV
What is the refractory period?
The period where cell cannot produce a new action potential (prevents summation/ tetanus)- build up of lots of potentials.
What causes change in electrical current?
The movement of ions from the outside to inside of cell.
What is the SA node?
This is known as the pacemaker cell as it has an unstable resting membrane and this starts the flow of electrical activity.
What does depolarisation mean?
Need for muscle to contract (causes a response). Depolarisation in one cell can be stimulus for another cell and leads to knock on effect (wave of contraction).
What does depolarisation mean?
Need for muscle to relax and return to resting position (getting ready for the next contraction).
What creates a P wave?
The SA node sending out an impulse across the atria.- atrial depolarisation
What creates the PR interval?
The impulse being delayed at the AV node.
What causes the QRS complex?
The impulse being passed onto the ventricles- ventricular depolarisation
What causes the ST segment?
The interval between ventricular depolarisation and repolarisation.
