Download Heart Physiology

CARDIOVASCULAR SYSTEM
Heart Physiology
CARDIAC CYCLE
Systole
*Atria Contract, Ventricles Fill
*Ventricles Contract, Blood Forced
into Aorta and Pulmonary Trunk
Diastole
*Atria Relax & Fill
*Ventricles Passively Receive Blood
from the Atria
BLOOD PRESSURE
BP = pressure blood exerts on inner blood
vessel walls
BP keeps blood moving between heart
contractions
BP rises & falls in response to heart
contraction & relaxation
BLOOD PRESSURE
Systole
- Contraction of ventricles causes arterial
pressure to rise
- Systolic pressure (SBP) is the maximum
pressure during contraction
BLOOD PRESSURE CONTINUED
Diastole
- Relaxation and refilling of ventricles while
semilunar valves are closed
- Arterial pressure drops as blood flows
“downstream”
- Diastolic pressure (DBP) is the minimum
pressure just before the next systole
Average BP = 120/80
Arterial surge in
pressure = Pulse
Pulse rate usually =
heart rate
Average adult pulse =
60-80 BPM
CONDUCTION SYSTEM OF
THE HEART
Specialized Cardiac Muscle Tissue
Capable of Generating & Conducting
Action Potentials
Autorhythmic
Stimulates Contraction of Myocardial
Tissue
CONDUCTION SYSTEM
OF THE HEART continued
5 Components:
- Sinoatrial Node (Pacemaker)
* Right Atrium
* Spontaneously Depolarize
* Activates Atrial Contraction
* Origin of Heart Beat
* Action Potential Spreads to:
CONDUCTION SYSTEM OF
THE HEART continued
- Atrioventricular (AV) Node
* Rt. atrium (interatrial septum)
* Action potential spreads to:
- Atrioventricular Bundle (Bundle of His)
* Only electrical pathway between atria &
ventricles (C.T.Block)
* Interventricular septum
* Carries action potential through
interventricular septum to:
CONDUCTION SYSTEM OF
THE HEART continued
- Bundle Branches (Left & Right )
* Interventricular septum
* Carries action potential toward
respective ventricles
- Purkinje Fibers
* Myocardium of Ventricles
* Conduct action potentials to ventricular
myocardium
ELECTROCARDIOGRAM
(ECG/EKG)
 Record of Electrical Changes in Heart Muscle
 Electrical Changes due to Depolarization &
Repolarization of Cardiac Muscle Fibers
 Metal Electrodes Applied to Skin, Attached to
Physiograph, Pick-up Electrical Activity
 Normal Cardiac Cycle Gives Rise to
Characteristic “Waves”
ELECTROCARIDOGRAM
(ECG/EKG) continued
 P Wave
- SA Node Stimulates Atrial Depolarization
- Occurs Prior to Atrial Contraction
 QRS Complex
- Ventricular Depolarization
- More Tissue, More Electrical Activity, Larger
Wave
- Occurs Prior to Ventricular Contraction
 T Wave
- Ventricular Repolarization
HEART SOUNDS
 Caused by Closing of Heart Valves
 AV Valves
- prevent blood from flowing backwards
into atria
- “Lubb”
 Semilunar Valves
- prevent blood from flowing backwards
into ventricles
- “Dupp”
HEART MURMURS
Abnormal sound
Often indicates valve disorder
Causes:
- Congenital defects
- Scarring
- Insufficiency/Backflow