EXAM 1 Flashcards
~At base of aorta
~Open during systole - blood flow from L ventricle to systemic circulation
Aortic valve
~Two small, thin-walled chambers of heart
~Low pressure
~Receive blood from systemic and pulmonary circulation
~Deliver blood to ventricles
Atria
~On floor of R atrium
~Delaying effect on electrical impulses
AV node
~Anterior interatrial band of internodal conduction tracts
~Transmits impulses to L atrium
Bachmann’s bundle
~Two cusp valve - separates L atrium from L ventricle
~Prevents backflow during systole
~Connected to papillary muscles via cordae tendinae
Bicuspid (mitral) valve
~Splitting ventricle septum
~Moves through R and L ventricles
~Transmits impulses to Purkinje fibers
Bundle branches
~Combines with AV node to make AV junction
~Speeds up impulses and delivers to bundle branches
Bundle of His
~Received from the veins
~Transported through R side of heart to lungs
Deoxygenated blood
~Innermost layer of the heart
Endocardium
~Outermost layer of the heart
Epicardium
~Anchors heart to mediastinum
~Attaches to diaphragm surface
~Continuous with CT of great vessels
Fibrous pericardium
~Vessels that provide blood supply to heart muscle
~Right coronary artery
~Left coronary artery
~Supplies oxygenated blood to anterior aspect of both ventricles
~1 major branch of LCA
Left anterior descending (LAD)
~Supplies oxygenated blood to lateral aspect of L ventricle and L atrium
~1 major branch of LCA
Left circumflex (LCX)
~Middle layer of heart
~Made of actual cardiac muscle tissue
Myocardium
~Returns to L side of heart from lungs
~Pumped through systemic circulation
Oxygenated blood
~Releases acetylcholine
~Decreases all 4 properties of cardiac muscle cells
~Through vagus nerve
~AKA Cholinergic
Parasympathetic nervous system
~Surrounds the heart and protects it
~Double-walled closed sac
Pericardium
~At base of pulmonary artery
~Open during systole - blood flow from R ventricle to pulmonary circulation
Pulmonic valve
~Thin filaments embedded in endocardium
~Conduct impulses rapidly through ventricular muscle - assist in depo and contraction
Purkinje fibers
~2 major branches of RCA
~Supply oxygenated blood to inferior aspect of both ventricles
~Marginal branch
~Posterior interventricular branch (PIV)
~In superior aspect of R atrium
~Natural pacemaker that initiates electrical impulse
SA node
~Rate of SA node
60-100 bpm
~Transparent, delicate, thin inner layer of pericardium
Serous pericardium
~Outer layer that lines fibrous pericardium
Parietal pericardium
~Inner layer that covers cardiac muscle tissue
Visceral pericardium
~Nerves of thoracic and lumbar
~Stimulators: epinephrine and norepinephrine
~Produces vasodilation
~AKA Adrenergic
Sympathetic nervous system
~Three cusps
~Separates R atrium and R ventricle
~Connected to papillary muscles via chordae tendinae
Tricuspid valve
~2 larger, thick-walled (muscular) chambers of heart
~Pump blood through pulmonary and systemic circulations
~Separated by a septum
Ventricles
~Useful diagram to correlate cardiac electrical cycle and events that take place during cycle
Wiggers diagram
~Only used when HR is regular
~Most accurate way to calculate HR from ECG
1500 method: find 2 consecutive R waves, count number of small boxes between, divide 1500 by number = bpm
~Used when HR intervals are regular or irregular
6 second method: determine 6-sec period, count number of cycles, multiply by 10
~Used to fill ventricles with blood before ventricular systole
~Increases end diastolic volume
Atrial kick
~Determines direction of ventricular depo
~Axis used to determine flow of atrial depo
Axis deviation
~Only used when HR is regular
Dark line method: find one R wave on dark line, find next R wave, determine HR range
~Associated HRs for dark lines
300, 150, 100, 75, 60, 50, 44, 38…
~Triangle that forms leads I, II, III
~Shows movement of electricity from - to + poles
Einthoven’s triangle
~Leads I, II, III are called…
Bipolar limb leads
~Records the electrical potentials (depo and repo) via electrodes placed on the chest wall
Electrocardiogram (ECG)
~Diagram showing relationship of 6 limb leads in frontal plane
~Determines heart’s electrical axis
Hexaxial reference system
~R wave + in lead I, - in aVf
Left axis deviation (LAD)
~Direction of ventricular depo
~Calculated by using hexaxial reference system and limb leads
Mean QRS axis (vector)
~Measured from beginning of P wave to beginning of QRS complex
~Time for impulse to move from SA node to AV node and through Purkinje fibers
~Beginning of atrial depo to beginning of ventricular depo
PR interval
~Produced using horizontal plane
~Produce chest leads
~Directly measure heart’s activity
Precordial leads
~What are the precordial leads?
V1, 2, 3, 4, 5, 6
~Generated by atrial depo
~Represents conduction of electrical activity from SA node to AV node
P wave
~Generated by ventricular depo
~Represents conduction of electrical activity through L ventricle
QRS complex
~Time between start of QRS complex and end of T wave
QT interval
~R wave - in lead I, + in aVf
Right axis deviation (RAD)
~Period between end of S wave and start of T wave
~No electrical activity occurring
~Correlates with early systole and high ventricular systolic pressures
ST segment
~Evidence of potential CAD or old myocardial injury (possible myocardial ischemia)
~Electrical signal is moving slower through myocardium
ST segment depression
~Evidence of recent or impending myocardial infarction
~Myocardium not receiving blood to supply oxygen and other nutrients
ST segment elevation
~Ventricular repo
~End of ventricular systole
T wave
~Time from end of QRS complex to peak height of T wave
Absolute refractory period
~Time from peak height of T wave to end of T wave
Relative refractory period
~Rarely seen in normal ECG
~If seen, represents last stages of ventricular repo
U wave
~Developed from a combination of leads
~Movement of electricity from one limb leads towards the other two
Augmented vector leads (unipolar limb leads)
~Measured from LL -> RA and LA
aVf
~Measured from RA -> LA, LL
aVr
~Measured from LA -> RA, LL
aVl
