Coronary Vessels (right side)
VIII. Coronary Vessels
y Coronary vessels branch off of the
Aorta just above the Aortic
Semilunar Valve
Coronary Vessels (left side)
y B. Left coronary artery
1. circumflex coronary artery
-feeds the left atrium & left ventricle
2. anterior descending coronary
artery
- feeds the left & right ventricles
Left
Coronary
Artery
Coronary Vessels
Left
Coronary
Artery
Right
Coronary
Artery
To: Anterior Descending
Coronary Artery
Coronary Vessels
Right
Coronary
Artery
To:
Circumflex
Branch
y A. Right coronary artery branches feed right atrium
1. marginal artery
- feeds right ventricle
2. posterior descending coronary
artery
- feeds the right & left ventricle
To:
Marginal
Artery
Left
Coronary
Artery
Coronary
Vessels
Right
Coronary
Artery
To: Posterior
Descending
Coronary
Artery
1
Conduction System:
Components of Conduction System
O Specialized
cardiac muscle tissue
(contraction)
O Generates & distributes electrical
impulses (conduction)
O as a result heart can contract
without neural stimulationintrinsic rhythm.
Sinoatrial
Components of Conduction System
Components of Conduction System
† Atrioventricular
(AV) node –
O Rt. Atrial wall/inferior interatrial
septum
O Last portion to receive impulse
from SA node
O Stimulated & passes on impulse
‡ Atrioventricular
Components of Conduction System
Components of Conduction System
a) right branch of AV bundles (Bundle
Bundle of
His)
His
b) left branch of AV bundles (Bundle
Bundle of
His)
His
O Carry impulse down the
interventricular septum
ˆ Purkinje
(SA) node
O Right Atrial wall, inferior to opening
of superior vena cava
O Initiates cardiac cycle – sets pace
(pacemaker)
O Impulse spreads over both atria
resulting in contraction
Bundle (Bundle of His)
O Carry the impulse from AV node to
superior part of interventricular
septum
fibers – lateral branches that
pass through the walls of the
ventricles
O stimulate myocardial cells in ventricles
to contract.
O After short delay SA node fires again
– cycle repeats.
2
Cardiac Cycle:
O Complete
series of events
occurring within the heart
beginning with depolarization of
SA node.
O Involves specific length of time,
pressure & volume changes,
electrical activity & heart sounds.
I. Electrocardiogram (ECG) (EKG)
O Impulses
through the conduction
system generate electrical currents –
O detected at body surface.
O ECG is the recording of this
electrocardiograph is the instrument.
O Each part of cardiac cycle produces a
different electrical impulse.
ECG
First
wave: P (small upward)
O atrial depolarization, (excitation)
passage of impulse from SA node
through both atria = result atrial
contraction
ECG
’PR
interval
O start of P wave to start of Q wave
O from the start of atrial excitation to
start of ventricular excitation, passage
of impulse from the SA node to AV
node to Purkinje fibers in ventricles
ECG
† QRS
complex – small downward
deflection, large triangular upward
deflection, ends w/ small downward
deflection.
O Depolarization of ventricles,
(excitation) § ventricular contraction.
ECG
† ’ST
segment – end of S to start of
T wave
O end of ventricular depolarization
(spread of impulse through vent.) to
start of repolarization of ventricles
3
ECG
‡T
wave
O ventricular repolarization
O atrial repolarization occurs in the
midst of the QRS complex & is
masked by that event
O This cycle of events repeats.
II. Heart & Blood Pressure
O Systole:
contraction phase of cardiac
cycle – atria/ ventricles
O Diastole: relaxation phase of cardiac
cycle – atria/ ventricles
O Pressure changes: related to 1) chamber
size & 2.) volume of blood it contains
O Greater vol = higher pressure
O Blood flow: Higher to lower pressure
Blood Pressure
O B.P.
= pressure exerted by blood on
wall of any blood vessel
O Clinically: pressure in arteries exerted
by left ventricle (systole) and pressure
remaining when ventricle is in diastole
O Systolic
= (Force of left vent. Contraction)
Diastolic = (Pressure in blood vessel walls
during left vent. relaxation)
III. Heart Sounds
O Typically
2:
closing of AV valves – longer
(ventricle contraction) “Lubb”
† closing of semilunar valves – shorter,
sharper “Dupp”
O Provide information about valves:
O Lubb
Dupp Pause Lubb Dupp Pause
1
2 3&4
1
2
3&4
IV. Pulse
O Pulse:
expansion & recoil of artery
due to:
rhythmic injections of blood from Left
ventricle into aorta -> arteries
† expansion and contraction of arterial
walls
Pulse
O Pulse:
farther from heart = fainter
O Related to ventricular contraction/
does not coincide.
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