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Unformatted text preview: Final Review Cardiac Material 1. What is a HEARTBEAT? -A single contraction of the heart 2. In what order do the parts of the heart contract?- first the ATRIA and then the VENTRICLES 3. What does the EKG measure?-The electrical events in the heart 4. What are the P-waves, QRS complex, and the T-wave?-P-waves- atrial depolartization-QRS complex- ventricle depolartization-T-Wave-ventricles repolarize 5. What are the main differences between action potentials in the heart and skeletal muscles?- The length of cardiac action potential in the ventricles is 30 times longer than skeletal muscle. The long refractory period prevents summation and tetany. 6. What are the 3 steps in a cardiac action potential? A. Rapid depolarization-voltage gated sodium channels open B. Sodium channels close and voltage gated calcium channels open(slowly to create a “plateau”.) C. Repolarization- Calcium channels close and Potassium channels open to restore resting membrane potential. 7. What role does calcium play in heart contraction?- Contraction of a cardiac muscle cell is produced by an increase in calcium ion concentration around myofibrils. 8. Where is Calcium mostly concentrated (intra or extra cellular)?-Most of the calcium is concentrated extracellularly in order to maintain resting membrane potential.-The sarcoplasmic reticulum stores calcium intracellularly and releases it once depolarization occurs. 9. What is the difference between systole and diastole?- systole (contraction)- diastole (relaxation) 10. What is the relationship between blood pressure and systole/diastole?- In any chamber Blood Pressure: – rises during systole – falls during diastole 11. What are the 8 steps of the cardiac cycle and what happens in each? 1. Atrial systole: – atrial contraction begins – right and left AV valves are open 2. Atria eject blood into ventricles: – filling ventricles 3. Atrial systole ends: – AV valves close – ventricles contain maximum volume – end-diastolic volume (EDV) 4. Ventricular systole: – isovolemic ventricular contraction – pressure in ventricles rises – AV valves shut 5. Ventricular ejection: – semilunar valves open – blood flows into pulmonary and aortic trunks 6. Ventricular pressure falls: – semilunar valves close – ventricles contain end-systolic volume 7. Ventricular diastole: – ventricular pressure is higher than atrial pressure – all heart valves are closed – ventricles relax (isovolumetric relaxation) 8. Atrial pressure is higher than ventricular pressure: – AV valves open – passive atrial filling – passive ventricular filling – cardiac cycle ends 12. What do the following terms mean?-End-Diastolic Volume (EDV)- the volume of blood in a ventricle at the end of filling ( diastole )-End-Systolic Volume (ESV)- the volume of blood in the left ventricle at the end of contraction, or systole , and the beginning of filling, or diastole ....
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This note was uploaded on 04/28/2008 for the course ZOOL 2404 taught by Professor Hanson during the Spring '08 term at Texas Tech.
- Spring '08