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Cardiovascular :<3: System (Electrical Conduction (PR interval- time…
Cardiovascular :<3: System
Clinical Terms
Cardiac Output: Volume of blood ejected by ventricles in 1 minute
Stroke Volume: volume ejected from a ventrical during a single contraction.
Heart rate # of cardiac cycles that occur in 1 minute
Blood flow:Volume/min throught vessel, organ and the rest of body
Blood pressure: Force blood is exerting on blood vessel walls.
Ventrical Systole
Electrical impluse generated by SA node continues through the ICS.
.5 seconds, both AV & semilunar valves closed (Isovolumetric)
1 more item...
CO=SVxHR
The Cardiac Cycle
ECG:
Begins at SA Node {right atrial wall}
-Generates action Potentials 75 t/m
AV Node {interatrial septum}
-slow speed electrical transmission
AV Bundle {interventricular septum to apex} .. Only place where electrical transmission can occur
Purkinkje Fibers {walls of heart and papillary muscles}
-Stimulates contraction of Ventricular myocardium and Pap. muscles
R&F Bundle Branches- Conduct action potential to apex & initiate contraction in interventricular septum.
Cardiac Muscle Contraction
Depolarization: Voltage gated Na+ channels open, membrane polarity is +
Plateau: Opening of voltage gated Ca2+ channels open in Sarcolemma, maintaining depolarization
Repolarization: Cardiac AP decreases, membrane becomes negative...Ca2+ channel closes= K+ channel opens .
*Absolute refractory period for cardiac muscle= 200ms
*Skeletal Muscle refractory period= 1-2ms, these can contract one after another with no relaxation.
Structural Differences In Blood Vessels
Arteries
Thick walls
NO VALVE: contains 2 elastic membranes
Small lumen (higher pressure throughout vessel)
Tunica media- thickest
Veins
Thinner walls;
CONTAINS VALVES: no elastic membrane
Tunica externa
Larger lumen: decrease in friction= decrease peripheral resistance
Heart Anatomy
External structures:
Left Coronary Sulcus
Right Coronary Sulcus
Right Coronary Artery(supplies O2 blood to right side of heart)
Left Coronary Artery (supplies O2 blood to left side of heart)
Circumflex Artery (curves around superior part of left ventrical)
Anterior Interventicular Artery (located in in anterior interventricular sulcus)
Apex & Base
Epicardium
Auricles (increases atrial volume)
Internal Structures:
Ventrials: Left .... pump for systemic circut
Ventrical: Right .... pump for pulmonary circut
Atria: Left & Right
Myocardium
Endocardium (deepest layer, reduces friction of blood flow)
Atrioventricular Valves:
Right: Tricuspid
Left:Bicuspid
Semilunar Valves:
Left: Aortic
Right: Pulmonary
Chordae Tendineae
Papillary Muscles
Fossa Ovalis
Interventricular Septum
Great Vessels:
Inferior Vena Cava (empties into right atrium)
Superior Vena Cava (empties into right atrium)
Aorta (Delivers blood to the body)
Pulmonary Trunk
Pulmonary Arteries
Pulmonary Veins
Electrical Conduction
P-Wave: Recording electric act.
-atrial contractions occurs aprox. 1/s after P-Wave starts.
QRS -Wave -Recording electrical act. with ventricular depolarization. Ventricular contractions follows.
T-Wave- Ventricular repolarization -Ventricular relaxation occurs following wave.
PR interval- time from beginning of atrial depolarization to start of ventricular depolarization
S-T Segment-End of QRS complex to end of the T-wave
Q-T interval- beginning of QRS complex to end of T-wave
Time it takes for ventricles to depolarize, contract and repolarize (Q-T)
Represent time when ventricular myocardium is depolarizing & contracting (S-T)
Time taken for cardiac action potential to get from SA Node to Purkinje fibers (PR)