Download Cardiovascular System

Cardiovascular System
Heart Conduction System
Heart Function
• Primary function of the heart is to impart
energy to the blood in order for it to be
dispersed throughout the body.
Cardiac Cycle
• Cardiac Cycle- one complete heart beat
• Diastole = relaxation of the ventricles
• Systole = contraction of the ventricles
Heart Function Terminology
• Amount of blood pumped out of one ventricle
during one beat is known as Stroke Volume
(ml/stroke)
• Number of times ventricles beat per minute is
known as Heart Rate
• Cardiac output (Q) = SV x HR (l/min)
• Together SV and HR gives to volume of blood
pumped in 1 minute by one ventricle
Cardiac Cycle
• 1. Atrial systole- A-V valves open
-semi lunar valves closed
-atria contract
1 2. Isovolumetric Contraction- All valves
closed
-ventricular wall tension increases as
ventricles are being filled
Cardiac Cycle
3. Rapid Ejection- Aortic and Pulmonary valves
open
-A-V valves closed
- Intraventricular pressure forces aortic and
pulmonary valves to open
4. Reduced Ejection- aortic and pulmonary valves
open
-A-V valves closed
-ventricular pressure decreases
Cardiac Cycle
5. Isovolumetric Relaxation- all valves closed
-atrial pressure rises from venous
return
6. Rapid Ventricular Filling- A-V valves open
-atrial pressure greater than ventricular pressure
7. Reduced Ventricular Filling- ventricles continue to
fill
-pressure difference between atrium and ventricles decreases
Conduction System
• A specialized electrical conduction system
controls the mechanical contraction of the
heart.
Conduction System
Control center in the brain is the medulla oblongata
• The Sinoatrial Node (SA Node) in which rhythmic electrical impulses are
initiated is Located in the upper lateral wall of the right atrium
• The internodal pathways, which conduct the impulse from the SA node to
the Atrioventricular Node (AV Node)
• The AV Node , in which the impulse is delayed before passing into the
ventricles
• The Atrioventricular bundle (AV Bundle) which conducts the impulse to
the ventricles
• The left and right bundle of branches of the Purkije fibers, which conduct
the impulse to all parts of the ventricle
• The electrical system of the heart regulates Depolarization and
Repolarization of the Atrium and Ventricles during the Cardiac Cycle.
Conduction System
Conduction System
• This process is illustrated through the use of
the ECG (electrocardiograph)
Cardiac Cycle
Cardiac Cycle-Diastole
Cardiac Cycle-Atrial Systole
Cardiac Cycle-Ventricular
Systole
Conduction System
• P-wave- atrial depolarization
-signal sent from the SA node through the
Atria
• QRS-complex- Left ventricular wall
depolarization
• T-wave- ventricular repolarization
• U- wave- Purkinje Fibre repolarization
Conduction System
Cardiac review and Conduction
System
• Cardiac Cycle illustration