Lect 18 - Cardiology Flashcards
Electrocardiogram
Measures electrical activity of the heart
What functions as a conductor in an electrocardiogram?
The body
Distance and amplitude of spread depend on what two factors?
Size of action potentials
Synchronicity of potentials from other cells
Heart Electrical Activity is synchronized
Electrical Activity Waves of an Electrocardiogram
P Wave: Atrial Depolarization
QRS Complex: Ventricular Depolarization and Atrial Repolarization
T Wave: Ventricular Repolarization
Electrical Activity Segments of an Electrocardiogram
PQ Segment (How fast AP travels):
AV Nodal Delay
QT Segment (End of Signal to Next Signal):
Ventricular Systole
QT Interval (Time it takes to contract and recover):
Ventricular Diastole
Effects of a prolonged QT interval, how can this occur
Can lead to Tachycardia
Caused by problems with ion channel (K+ not properly increasing)
ECG Arrhythmias
Heart has an abnormal rate
Arrhythmias can be deduced by ECGs
Sinus Rhythem
Pace that is generated by SA node
Tachycardia
Fast Rhythm
Bradycardia
Slow Rhythm
Extra Contraction effect on ECG
Causes extra systole
Premature atrial contraction
Ventricular Fibrillation effect on ECG
Loss of coordination of electrical activity of heart
Death can happen within minutes
Systole
Period of Contraction
Diastole
Period of Relaxation
Cardiac cycle at rest is mostly in ______
Diastole
Benefits of longer diastole
Allows for optimal filling of relaxed ventricles
Cardiac Cycle
Atriums contract ventricles are passively filled (Atrial Systole)
Atrial Systole ends and Atrial diastole begins until the next cardiac cycle
Isovolumetric Ventricular Contraction
AV valves close (no more filling)
Semilunar valves remain closed (no blood leaving)
When ventricle pressure > artery pressure
Semilunar valves open and blood is ejected into arteries
Isovolumetric Relaxation
Ventricles relax and ventricle pressure
decreases (Ventricles Diastole)
AV and Semilunar valve are closed
When atrial pressure > ventricle pressure
AV valves open and ventricles fill passively
Summarize the 4 Phases of Cardiac Cycle
Atrial Contraction –> Ventricle Filling
AV Open, Semilunar Close
Isovolumetric Ventricular Contraction
AV Close, Semilunar Close
Ventricular Pressure increases from contraction
Ventricular Ejection
AV Close, Semilunar Open
Isovolumetric Ventricular Relaxation
AV Close, Semilunar Close
Ventricular Pressure decreases from relaxation
What are the 4 valves in the heart
2 Atrioventricular Valves:
Tricuspid and Bicuspid Valves
2 Semilunar Valves:
Aorta and Pulmonary Valves
Aortic Pressure (Diastole)
Ventricular Relaxation
Aortic (Semilunar) Valve closes as ventricle pressure decreases
No new blood ejected into aorta and Blood is leaving aorta
–> Aorta Pressure starts to fall
Lowest Point = Diastolic Pressure
Aortic Pressure (Systole)
Aortic (Semilunar) Valve opens are ventricle pressure increases
Pressure of Aorta rises from ejected blood from the ventricle
–> Aorta Pressure starts to rise
Highest Point = Systolic Pressure
Aortic Pressure (Dicrotic Notch)
At the beginning of diastole aortic valve closes, backflow of blood hits the closed valve causing a slight increase in aortic pressure
Aortic Pressure (MAP)
Mean Arterial Pressure
Mean pressure in aorta over cardiac cycle
Heart Sounds (First Heart Sound, Why?)
Soft Lub
Both AV closes simultaneously
