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87 Cards in this Set
- Front
- Back
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4 Cardiac valves?
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Mitral
Tricuspid Pulmonic Aortic |
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Where does the mitral Valve direct blood?
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Left atrium to left ventricle .....oxygenated blood
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Where does the tricuspid valve direct blood?
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Right atrium to right ventricle ..... unoxygenated
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Myocardium?
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The cardiac muscle layer , produces the contractile force +hat pushes blood through circulatory system
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AV Valve VS semi lunar Valves
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semilunar are thicker
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Normal Pressures in Right atrium and Right ventricle ?
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RA = O-8
RV = 15-28 /o-8 |
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Normal pressure in Left atrium and ventricle ?
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LA = 4-12
LV = 100-120 /4-12 |
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Normal Pressure in Pulmonary Artery and Aorta?
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PA = 15-28/4-12
Aorta = 100 - 120 /60-80 |
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Which chamber is the thickest?
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Left ventricle
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Layers of the heart ?
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Endocardium
Epicardium pericardium |
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Endocordium....
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Smooth surface that prevents clotting
* lines chambers |
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Epicardium
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Attatched directly to heart
-outer surface |
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Pericardium
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Form a sac around the heart
2 layers (visceral + parietal ) - separated by fluid - educes friction during Contractility |
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where does exchange of respiratory gases occur?
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Pulmonary capillaries
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Ventricular Contraction
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Systole
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diastole
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ventricles Relax and blood flows in from the atria through AV valves
* through the end of distole it goes from passive to active because atrium squeeze a little more blood into ventricles |
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What is the importance of the "Atrial Kick" ?
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Important during fast HR
- when the time for ventricular Contraction is shortened the kick helps load ventricle quickly - prevents a decrease in stroke Volume |
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List the Ventricular Events
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Isovolumic Contraction
Ejection Isovolumic RelaXtion |
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Isovolumic Contraction is....
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After systole ,ventricles contract causing intra ventricular pressure to rise and AV Valves to close
* Closure = s 1 sound * Volume remains constant (all 4 valves closed) |
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Ventricular Ejection is....
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Ventricular contraction results in a rapid rise in ventricular pressure
- ventricular pressure exceeds Aortic pressure + value is forced Open |
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the Amount of blood ejected with each Contraction Of ventricles is?
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Stroke Volume
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stroke Volume is ?
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cardiac output / heart rate
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End diastolic volume
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Volume of blood in ventricle before ejection
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End systolic volume
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Blood that remains in Ventricle after ejection
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What is Ejection Fraction ?
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pumping effectiveness
SV / EDV -Normal EF= 60% to 80% |
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Isovolumic Relaxation is.....
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when semi lunar value Closes in response to falling Ventricular pressure nds when values open to allow ventricular filling
* semi lunar valve Closure = S2 sound |
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Lusitropy
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Rate and degree of ventricular relaxation
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Atrial Pressure waves
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A= atrial contraction
C= bulging of AV valves into atrial chambers V= gradual incline, filling of atrium. Drops rapidly when AV Valve opens. Large V wave = inadequate closure of AV valves |
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Central venous pressure (CVP)
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indicator of blood volume in heart
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Systolic BP
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Arterial pressure reaches it's maximum during ventricular ejection
- aorta stretches - energy is released |
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Diastolic BP
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Arterial Pressure drop just before semi-lunar valves open
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Food supply to Heart muscles is Supplied by?
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Coronary Arteries
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Blood flow through Coronary vessels is determined by.....
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driving Pressure and Vascular resistance to flow
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Ohm's Law
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Increase in driving pressure (p) increases blood flow (Q)
Increase in resistance (R) reduces blood Flow |
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Autoregulation
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Ability of arteries to adjust blood flow
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Vasodilaton
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increased tissue metabolism uses arteries to Open for more blood flow
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Vasoconstriction
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Decreased metabolic activity Causes arteries to narrow
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ATP-sensitive Potassium Channel
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mechanism for auto regulation Of Coronary blood flow
increased Coronary blood flow = increased ATP levelchannel Closes-vasoconstriction-reduce blood Flow * Opposite effect for vasodilation |
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Autonomic Nervous system in autoregulation
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SNS- NE - vasoconstriction
PNS- NO - vasodilator |
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2 important Uasodilating Chemicals
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Adenosine (ATP)
Nitric Oxide (CNS) |
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2 types of cardiac muscle Cells?
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1. working cells 2. Electrical cells *able to produce and transmit Action potentials |
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working Cells
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Mechanical pumping functions
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Electrical cells
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Transmit electric impulses
-function to initiate + Coordinate contraction of Working cells |
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What are Gap Junctions ?
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How rapid passages of electric impulses from one cell to the next
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What is a functional syncytium ?
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How intercalated disks allow the cells of myocardium to Function together in a Coordinated manner
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Excitation-Contraction coupling
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contraction - action potential traveling down conduction system
Depolarization- ion channels and t tubeles to open - sodium and calcium entry- free calcium results in contraction |
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How is Contraction of cardiac muscle accomplished?
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Shortening of individual sarcomeres
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What is lusitrophy due to?
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lusitrophy (muscle relaxation)
- due to removal of calcium |
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Sliding Filament / Cross-Bridge Theory of Muscle Contraction
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Muscle shortening is accomplished by increasing the amount of overlap of actin and myosin
- this causes z discs to move closer together |
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Cross bridge
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Each time a myosin head binds an actin bead
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IS the breaking of cross bridge an active process?
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Yes, it requires 1 ATP molecule
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ATP Hydrolysis
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Hydrolysized w/ each contraction
• occurs at myosin head • Affects Capability of myosin to bind actin |
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2 functional States Of Myosin
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1. low affinity state in which it binds weakly (ATP bound)
2. High affinity state in which it avidly binds actin ( ATP or inorganic phosphate) |
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Role of Calcium in Muscle contraction
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Presence of Calcium = increased contractions
- Binding of Ca to troponin induces the movement of tropomyosin to expose actin-binding sites And allow cross-bridge Formation |
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Energy of Muscle Relaxation
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Relation requires energy to Pump calcium ions out
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What does the heart use When ATP is low ?
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stored creatine phosphate (cp) from excess ATP is an immediate Source of energy and is converted back to ATP by creative kinase (ck)
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What are the primary Substrates for the heart?
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Fatty Acids and glucose
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what is the primary determinant of the resting membrane potential ?
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Potassium Ion Concentration
• increase in potassium = hypopolarize (less negative) • decrease in potassium = Hyperpolarize (more negative) |
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What is a common source of cardiac dysrhythmias?
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Abnormal t.es in serum potassium levels
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Rhythmic ity
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Regular spontaneous generation Of action potentials
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What is the rate of rhythmic discharge determined by ?
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Influx of Na + ca vs the efflux Of K
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What is a requirement of Rhythmicity?
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Cell membrane has Channels that open as membrane becomes more negative during repolarization allowing Pacemaker cells (Na, CA, and K)
These positive cells offset the replacing currents and Depolarize the membrane, resulting in generation of an action potential |
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Which cells become the Pacemakers of the heart?
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Cell W/ the fastest rate of spontaneous depolarization
* normally the cells of SA node |
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Conduction system of the heart
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myocardial cells special red To conduct action potentials throughout the heart in an Organized rapid manner
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Conduction pathway
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1. SA Node
2. Atrial internodal pathways 3. AV Node 4. Bundle of His 5. Ventricular bundle branches 6. Purkinje Fibers |
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Sympathetic Regulation of Rhythmic ity
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increases HR, increases speed of Conduction, inducing heart muscles to Contract more forcefully, and relax more quickly
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Parasympathetic Regulation or Rythmicity
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Reduction in heart rate and speed of action potential Conduction because acetylcholine is released opening pottasium iOn Channels allowing more K in which e polarizes heart muscles
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How does a ECG work?
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As action potentials spread from cell to Cell throughout myocardium, an electrical current is transmitted to body surface and can be detected by electrodes Placed on skin
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What does the ECG indicate?
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Abnormalties of the heart's Conduction system
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What are the major wave Complexes?
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p wave = atrial depolarization
QRS complex = ventricular depolarization T wave = ventricular repolarization U wave = low HR + decrease potassium PR interval = atrial, AU node, + Purkinje depolarization R wave = apical depolarization S wave = depolarization of lateral walls (base) |
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What is Cardiac Output?
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measure of the amount of blood pumped out of the heart each minute
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Cardiac Output is a product of what?
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Heart rate and stroke volume
* increase in HR t SV will result in increased CO |
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Normul resting cardiac Output is?
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5-6 L/min
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What is cardiac output Usually adjusted to?
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Body surface
* normal range of index = 2.8 -3.3 L/min |
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What is the HR primarily influenced by?
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ANS, Release of norepinephrine causes an increase in HR
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Baroceptors
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Respond to changes in BP and send signals to the brain
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what might activate the SNS ?
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Anxiety
Fear Stress Excitement Trauma Fever |
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What determines Stroke Volume? ,
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preload (volume of blood in heart)
Contractility fterload ( impedance opposing ejection Of blood from ventricle) |
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Frank-Starling Law
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increase in preload results in a greater contraction
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What factors does contractility depend on?
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1. the amount of contractile proteins
in the muscle cells 2. Availability of ATP 3. Availability of free calcium ions in the cytoplasm |
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Afterload
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- determined by aortic BP
- Reducedblood Pressure can decrease after load - increase work load |
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Cardiac Workload can be increased by?
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Any of the determinants Of stroke Volume
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Endocrine Function of the heart
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When the heart is stretched in secretes ANP
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Electrocardiography
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indicates electrical currents generated by cardiac cells
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Echocardiography
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reflected sound waves to provide an image of cardiac Structures
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Nuclear Cardiography
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Radioactive substance injected into bloodstream can be used to trace the patterns of blood flow
• areas Of impaired perflesion = Cold spots PET scans used to evaluate Cardiac perfusion and metabolism |
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Cardiac Catheterization\ coronary Aniogruphy
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measures direct pressures within Cardiac Chambers
Evaluate the Right side : introduced through femoral vein then through inferior vena cava Evaluate the Leftside : introduced through femoral artery into aorta |
