Term
| What is the pathway of blood through the heart and lungs? |
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Definition
| right atrium to the tricuspid valve to the right ventricle to the polmunary semilunaar valve to the polmonary arteries to the lungs to the polmonary veins to left atrium to the bicuspid valve to left ventricle to aortic semilunar valve to aorta |
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Term
| What is the mechanisms of cardiac contraction. |
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Definition
| cardiac muscle is stimulated by nerves and is self excitable (automacity). contracts as unit. similar to skeletal muscle. uses autorythmic cells to initiate action potentials. has unstable resting potential called pacemaker potentials. uses calcium influx rather sodium for rising phase of action potentials. |
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Term
| How is cardiac muscle contracted? |
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Definition
| Depolarization opens up voltage gated fast Na channels in the sarcolemma. reversal of resting potential from -90 mV to +30mV. Depolarization wave in T tubules causes the SR to release Ca2. Depolarization also opens up slow Ca channels in the sarcolemma. Ca surge prolongs the depolorization phase(platuea) |
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Term
| Electrical activity in the heart is recorded by ??? |
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Definition
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Term
| Tell me about P wave, QRS complex, and T wave |
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Definition
| P wave coressponds to depolarization of the SA node. QRS complex corresponds to ventricular depolarization and T wave corresponds to ventricular repolarization |
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Term
| Atrial repolarization is masked by _______ |
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Definition
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Term
| What are heart sounds associated with? |
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Definition
| heart sounds are associated with the closing of heart valves. the first sound is when av valves close and systole starts. the second sound is when SL valves close at beginning of ventricular diastole |
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Term
| what is the sequence of excitation? |
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Definition
Sa node generates 75 times per minute.
atrioventricular node delays the response about 0.1 seconds.
impulses passes from atria to ventricles via the atrioventricular bundle (bundle of his) |
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Term
| what is the extrinsic innervation of the heart? |
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Definition
| heart is stimulated by the sympathetic cardioacceletory center and heart is inhibited by the cardioinhibitory center |
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Term
| List three phases of the ECG? |
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Definition
| 1. Atrial depolorazation initiated by the SA node causes the P wave. QRS depolarization of ventricular(atrial repolarization) ventricular |
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Term
| What is cardiac output, stroke volume and heart rate? |
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Definition
| Cardiac output is the amount of blood pumped by each ventricle in one minute. Cardiac output is stroke volume x heart rate. heart rate is the number of heart beats per minute. stroke volume is the number of blood pumped by ventricles per each heart beat. |
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Term
| what is the regulation of stroke volume? |
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Definition
| Stroke is End diastolic volume minus end systolic volume. |
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Term
| What is End diastolic volume and end systolic volume? |
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Definition
| end diastolic volume is the amount of blood collected in a ventricle whereas end systolic volume is the reminaing of blood in a ventricle |
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Term
| factors affecting stroke volume? |
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Definition
Preload - the amount ventricles are stretched before they contract
Contractility - cardiac cell contractile force due to factors other than EDV.
Afterload |
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Term
| what does the frank starlin law state? |
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Definition
| that the preload or stretch of the heart cardiac muscles before they contract is a critical factor determining the stroke volume. Slow heart beat and exercise increase venous return to the heart , increasing SV. Blood loss and extremely rapid heart beat causes lower stroke volume |
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Term
| what are the extrinsic factors influencing stroke volume? |
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Definition
| contractility which is the increase in contractile strength, independent of stretch and EDV. |
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Term
| where does increased contractility come from? |
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Definition
| increased symphatetic stimuli. certain hormones Ca2 and some drugs |
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Term
| what are the agents/factors that decrease contractility include |
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Definition
| acidosis, incresaed extracellular K, calcium channel blockers |
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