Cardiac cycle and ECG Flashcards
Electrocardiogram
Is a test to check for difficulties with the electrical activity of your heart
P wave
on the graph, it looks like a small bump from the baseline. It represents the depolarization of the atria. This happens right before the atria contract and push blood into the ventricles.
QRS complex
is a much larger wave than the P wave, and it represents the depolarization of the ventricles.
Impulse spread through the ventricles from the AV node to the purjinke fibers.
PQ segment
AV nodal delay
QT segment
Ventricular contraction, where ventricular pressure is high in the ventricles, as it pumps blood out of the aortic valve and to the rest of the body.
TQ interval
Ventricular relaxation
RR interval
time between heart beats
A condition of the heart in which the heart beat is fewer than 60 beats per minute is called
bradycardia
Tachycardia
A condition to describe a rapid heart rate of greater than 100 beats per minute
arrhythmia
deviation from a normal heart rhythm
Myocardial ischemia
Acute myocardial infarction
is inadequate delivery of oxygenated blood to the heart tissue. This can lead to death of heart muscle clles when a blood vessel supplying that rea of the heart becomes blood or ruptured. This can lead to a heart attack (acute myocardial infarction)
Systole
is the period of the heart cycle where the ventricles are contracting
dystole
is the period of ventricular relaxation
Cardiac cycle
is the mechanical events of the heart associated with blood flow during a single heartbeat. The cycle is divided into systole and diastole. It can also be divided into four phases.
end-diastolic volume
the volume of blood in the ventricle at the end of diastole an average of 135 millilitres.
Ventricular filling
a phase in the cardiac cycle where the pressure in the atria is greater than the pressure in ventricles.
Initially, during the passive phase, all four chambers are momentarily relaxed, and the AV valves are open due to greater Atria pressure.
During the active phase, the atria contract
Isovolumetric ventricular contraction
is the event occurring in early systole, the ventricles contracts without corresponding volume change (isovolumetrically). This brief moment in time within the cardiac cycle takes place when the heart valves are closed because the onset of ventricular contraction forces apply a backward pressure that forces the AV valves to close.
Ventricular ejection phase
In this phase of the cardiac cycle, the pressure of the ventricles is greater than the pressure in the atria, and the semilunar valves open as the blood is pumped out of the ventricles
Describe the two phases of the Ventricular Diastole during a cardiac cycle
Ventricular diastole= Phase 4, and phase 1:
In phase 4, The pressure in the ventricle decreases to below that of the aorta and the aortic valve closes
In Phase 1: ventricular filling begins once the pressure in the ventricle is less than that of the atria, and the AV valves open. In the beginning, the ventricle fills passively as the AV valves are open … and then the atria contracts, and actively fill the ventricle
Describe the phases in Ventricular Systole during a cardiac cycle
Ventricular systole occurs in phase 2 & phase 3
In phase 2: the increasing pressure within the ventricles causes the AV valves to close. This stage corresponds to isovolumetric ventricular contraction.
In Phase 3
The pressures in the ventricle exceeds those in the aorta, the aortic valve opens - blood is ejected out of the ventricles
End systolic volume (ESV)
End systolic volume (ESV) - the volume of blood in the right/left ventricle at the end of contraction, or systole, and the beginning of filling or diastole. ESV is the lowest volume of blood in the ventricle at any point in the cardiac cycle.
End diastolic volume (EDV)
End diastolic volume (EDV) - the volume of blood in the right or left ventricle at the end of filling.
Stroke volume
How is it calculated?
is the volume of blood ejected from the heart during the cardiac cycle,
SV = EDV - ESV
