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PHYS3
Heart II
| Question | Answer |
|---|---|
| MECHANICAL EVENTS OF THE CARDIAC CYCLE | MECHANICS OF THE CARDIAC CYCLE |
| Systole: What contracts/relaxes and what de/polarize? | Ventricular contraction/depolarization |
| Diastole: What contracts/relaxes and what de/polarize? | Ventricular relaxation; repolarization |
| SYSTOLE | SYSTOLE |
| What happens to the AV valves to make them close? Is this in systole or diastole? | In the beginning of systole, ventricular pressure is greater than atrial pressure to make them close |
| What is this phenomena called? | Isovolumetric ventricular contraction |
| What is this AKA? | Isobaloonic ventricular contraction |
| Does an ejection of blood occur from the ventricles? Why> | No, because the pulmornary and aortic valves aren't open due to a lack of pressure in chambers |
| When do the aeortic and pulmonary valves open? | When the ventricular pressure is over the aortic and pulmonary trunk pressure |
| DIASTOLE | DIASTOLE |
| What happens to the ventricles at the onset of diastole? | They releax |
| What happens with respect to pressure to get the aeortic and pulmonary trunk to close> | The ventircular pressure fall below the pressure of the aeortic and pulmonary trunk |
| Does blood move here? So what is this phenonema called? | No blodo moves, so it is like the isovolumentric or isobaloomic ventricular relaxation |
| When do the AV valves open? | When ventricular pressures is BELOW the pressure int eh right and left atria, AV open |
| What is diastole? | the ventircular filling phase |
| What is the speed of filling? | Very fast first |
| How much blood does atrial contraction at the very end of diastole add? | Very small amount is added to ventricle |
| VOLUMES | VOLUMES |
| End diastolic volume is? | The amount of blood in the ventricles just before systole |
| End sytolic volume? | The volume remaining after ejection |
| Storked volume: | Volume ejected |
| How is it caclulated? What is it in an adult? | End diastolic -- end systolic, it is about 70mV |
| PRESSURES | PRESSURES |
| Does the right heart or the left heart have lower pressure? | The right heart! |
| What does this lead to? | The fact that the right heart wall lis much thinner |
| CARDIAC OUTPUT | CARDIAC OUTPUT |
| Define cardiac output: | Volume of blood pumped by each ventricle |
| What is the equation to calculate cardiac output? | Heart rate x stroke volume |
| What is the cardiac output when you're excercising? When you're REALLY excercising? | 25-35 and increases to 200 beats a minute |
| HEART RATE CONTROL | HR |
| What is the intrinsic HR? | 100 beats a minute |
| Resting heart rate? | 72 beats a minute |
| What kind of nerve fibers innervate the heart? | Parasympathetic and sympathetic |
| What happens when you increase parasympathetic nerve stimulation? | Decrease HR |
| What happens when you increase syjmpathetic nerve stimulation | increase HR |
| What happens when you increase ciruclating EPI? Why? | Increase HR; b/c beta 1 receptors are bound |
| What does parasympathetic stimulation do to the membrane potential? Why? | causes it to be more negative before teh pacemaker potential begins |
| CHANGES IN STORKE VOLUME | CHANGES IN STROKE VOLUME |
| How can you cause an increase in strroke volume? | More forceful contraction |
| What are the two factors that cause this? | Changes in enddiastolic volume and changes in the magnitude of sympathetic nervous sytem input ot he ventricles |
| When do you fill up the end diastolic volume? | Before diastole, |
| What does happen at the end of diastole? | Filling ventricles up |
| How do you increase end diastolic volume? | Increase ventricular filling pressure |
| STARLING'S LAW OF THE HEART | STARLING OF THE HEART |
| What is the law? | Increasing end-diastolic volume will have a greater force of contraction and will yeild a higher stroke volume |
| What is venous return? | Flow of blood from veins to the heart |
| What is the eraltionship of venous return and CO? | Direct, as one increases, so does the other |
| Laying down on stage | see mandy |
| Getting up | mandy! |
| Define intrinsic return? | Venous return |
| So blood is flowing from what to what? | from veins to heart |
| How can increased venous return increase CO? | by increasing stroke volume and DISTENDING the ventricles |
| How would one distend the ventricles? | Laying down on stage |
| AFTERLOAD | AFTERLOAD |
| What is afterload? What is pre-load? | The resistance to ventricular ejection during sytole to ejection; pre-load is the volume of blood in teh ventricles before contraction |
| What does an increase in afterload lead to? | increase end systolic volume and decrease in stroke volume |
| What happens to cardiac muscles and blood flow in this case? | They shorten more slowly; there's less blood in ventrricles |
| When would this happen? (2 reasons) | When you've got high arterial pressure and stiffening of the arteries |
| SYMPATHIETIC NERVES | SYMPATHETIC NERVES |
| What're the components of the syjmpathtic nerves? | Conducting system and myocardial tissue |
| What is the conducting system purpose? | Inrease HR and conduction Rate |
| What is the myocardial system prupose? | Increase contractilitity |
| How would the curve be measured? | Measure force of muslce independent of filling |
| What does starling measure? | After filling |
| SUMMARY | SUMMARY |
| What 3 things determine stroke volume? | Preload, afterload, and contractility |
| What is pre-load? | Cardiac filling during diastole |
| What is it a reflection of? what releationshiop, that is? | Length-tension erlationship |
| What is AFTERLOAD? | Load on heart during ejection |
| What is it a reflection of? | Force velocity relationsihp |
| What is contractility? | Force of contractions as modified by sympathetic activity |
| What is the sympathetic activity due to? | EPI and NE |
| SUMMARY OF EFFECTS OF AUTONOMIC NERVES ON THE HEART | summary again |
| SA NODE | SA NODE |
| What does sympathetic nerves affect? | Heart rate |
| What do sympathetic nerves cause? | Increase heart rate |
| What do parasympathetic nerves cause? | decrease heart rate |
| AV NODE | AV NODE |
| What does the AV node cause WRT conduction rate? | Increasse conduction rate |
| parasymp? | Decrease conduction rate |
| ATRIAL MUSCLD | ATRIAL MUSCLE |
| Symp nerves? | Increase contractility |
| Parasympathetic | Decrease contractilty |
| VENTRICULAR MUSCLE | VENTRICULAR MUSCLE |
| Symp nerves? | Increase contractilty |
| Parsymp nerves | Decrease contractilyt |
| So...what is the effect of sympathetic and parasympathetic? | INDIRECT |
| At which point of diastole does atrial contraction occur? | At the end of diastole |
Created by:
talkglitter2486