Electrocardiogram (ECG) Flashcards
What is a ECG
Measurement of electrical activity of the heart
How is the heart a conducting system
Specialised Heart muscles able to initiate and conduct nerve impulses action potential
What does impulses allow the heart to do
Pump blood to the atria and ventricles
Also into the pulmonary and systemic circuit
What is the node that is the pacemaker
Sinoatrial node
What is a normal ECG look like
Heart rate that is between 60 to 100 beats per minute
be able to see the p wave, QRS complex and T wave
What happens in the first step of the mechanical activity of the heart
Depolarisation
- ion gates opens that allow sodium ions into the cell
- the membrane potential will go from -90millivolts to become positive due to the sodium ions
- membrane potential now being 30millivolts
- cause a message for the muscle to contract
step 2 of the mechanical activity of the heart
Plateau phase
Another channel opens which allow calcium channels to rush in
- some sodium ions are being pumped out and the sodium channels close
Step 3 of the mechanical activity of the heart
Repolarisation
Potassium gated channels open
Potassium ion flow outside of cell more positive outside than inside of cell.
What happens at the p wave
Atrial depolarisation
Atria contact
What happens at the QRS complex
Ventricular Depolarisation
Ventricle contract
What happens at the t wave
Ventricular repolarisation
What is depolarisation
stimulus cause a reponse in the muscle cells which is contracting the cell
A wave of contraction appears
What is the repolarisation
Is the depolarised cells returning to the resting position and getting ready for the next contraction
What depolarisation and repolarisation not seen on a ECG
Atrial repolarisation
What nerve increase heart rate and force contractions
Sympathetic nerve
