The ECG Flashcards
What is a heartbeat?
It is a single contraction of the heart starting with the atria and then the ventricles
What are the two types of cardiac muscle cells?
Contraction cells and Conducting system
What causes a contraction of a cardiac muscle cell?
Increase in calcium ion concentration around the myofibrils
Why are calcium ions important?
They are important as they enter the Plasma membrane during plateau phase and allow for contraction
What is the conducting system?
It is a system of specialized cardiac muscle cells and they initiate and send out electrical impulses that stimulate contraction
What are the structures of the conducting system?
SA node
AV node
Conducting cells
What are the conducting cells?
They connect the SA and AV nodes
And send out stimulus through the myocardium
What is a Ectopic pacemaker?
Abnormal cells and generate a high rate of action potentials and disrupt ventricular contractions
What is an ECG?
It’s a machine that records electrical events of the heart and parts of the body is connected to electrodes
What are the features of the ECG?
P wave
QRS Complex
T wave
What is the Cardiac Cycle?
Events during a complete heartbeat that make up the Cardiac cycle
From the start of one heartbeat to the beginning of the next and includes both contraction and relaxation
What is systole?
Contraction
What is Diastole?
Relaxation
What happens during the Cardiac cycle?
It starts with atrial systole which causes the additional blood to go into the relaxed ventricles and then soon after atrial diastole follows thus causing the 1st phase of ventricular systole and then creates pressure but isn’t enough to open the SV so they stay closed then the 2nd phase of Ventricular Systole happens where now there’s enough pressure created which open the SV which eject blood then ventricular diastole follows relaxing the ventricles and pressure dropping causing cusps to have blood flow against then and close the SV and blood flowing into atria.All chambers of the heart fill passively
What are the heart sounds?
Sound 1 is produced by AV valves
Sound 2 Produced by SV
Sound 3 and 4 is where blood flow into ventricle and atrial contraction
