Learning Objectives
·
Introduction
·
Definition
·
Events
o
Electrical
o
Mechanical
§
Atrial Systole
§
Atrial Diastole
§
Ventricular Systole
§
Ventricular Diastole
o
Hemodynamic
§
Pressure changes
§
Volume changes
o
Acoustic events
§
Heart sounds
Introduction
·
Heart
o
is a double pump, i.e. it consists of 2 separate
pumps connected in series
o
Right heart pumps blood through lungs
o
Left heart pumps blood through peripheral organs
·
Right heart
o
Right atrium
o
Right ventricle
·
Left heart
o
Left atrium
o
Left ventricle
·
Atrium – Primary pumps for ventricles
·
Ventricles - Pumps blood through pulmonary
and systemic circulation
·
Systole – contraction phase
·
Diastole – relaxation phase
·
Autorhythmicity – Pacemaker – SA Node
Definition
·
The sequential cardiac events that occur from
the beginning of one heart beat to the beginning of the next
·
Duration – 0.8 sec (HR = 75)
Events
·
Electrical
·
Mechanical
·
Hemodynamic
·
Acoustic
Phases of Cardiac cycle
·
Two cycles
o
Atrial Cycle
§
Atrial contraction / systole (0.1 s)
§
Atrial relaxation /diastole (0.7 s)
o
Ventricular Cycle
§
Venticular contraction / systole (0.3 s)
§
Ventricular relaxation / diastole (0.5 s)
Pressure and Volume changes
Significant changes
during events of cardiac cycle are
•
Pressure
changes
–
Atrial
pressure changes
–
Ventricular
pressure changes
–
Aortic
pressure changes
•
Volume
changes
–
Ventricular
volume changes
Atrial systole
Atrial depolarization
↓
Atrial contraction
↓
Atrial pressure rises
↓
Blood flows across AV valves
