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Cardiac Physiology I
Cardiac Fall 2
| Question | Answer |
|---|---|
| What are the 2 types of circulation in the body? | Pulmonary & systemic |
| List the order of the cardiac conduction system from start to finish. | SA Node to AV Node to atrioventricular bundle/Bundle of His to right & left bundle branches to fasciculi to Purkinje fibers |
| The SA node also sends electrical impulses across the IAS to the LA. What are the branches in the LA called? | Bachman's Bundle |
| Where is the SA node located? | posterior wall of the RA near the opening of the SVC |
| What's another name for the SA node? | pacemaker |
| How are myocardial cells different from skeletal muscle cells? | they contain high speed conduction pathways called intercalated discs; they don't require external stimulus to contract; they have a long refractory period |
| What is special about intercalated discs? | only located in the heart & they contain gap junctions to allow communication between the cells for contraction |
| What causes contraction of the myocardium? | excitation contraction-coupling |
| What sets up excitation contraction-coupling? | Depolarization |
| What does repolarization allow for? | relaxation & uncoupling |
| What generates the P wave on the EKG? | atrial depolarization |
| What generates the QRS wave on the EKG? | ventricular depolarization |
| What generates the T wave on the EKG? | ventricular repolarization |
| What does the Q wave represent? | end diastole & beginning of systole |
| What does the end of the T wave represent? | end of systole |
| What is the order of gate opening during cardiomyocyte action potentials? | sodium channels open/potassium channels close; then calcium channels open/sodium channels close; then potassium channels open/calcium channels close |
| What happens in Phase 0 of the action potential? | sodium rushes into the cell causing rapid depolarization |
| What happens during Phase 1 of the action potential? | calcium quickly enters the cell causing initial repolarization |
| What happens during Phase 2 of the action potential? | calcium slowly enters the cell causing a plateau phase |
| What happens during Phase 3 of the action potential? | calcium channels close & potassium channels open; potassium leaves the cell causing repolarization |
| What happens during Phase 4 of the action potential? | resting phase |
| What is the smallest contractile unit within a myocyte? | sarcomere |
| What is the thick filament in a sarcomere? | myosin |
| What is the thin filament in a sarcomere? | actin |
| What is important to note about calcium & muscle contraction? | the greater the amount of calcium, the greater the force of contraction |
| What releases the calcium necessary for contraction? | sarcoplasmic reticulum |
| What is the absolute refractory period? | period during which no amount of stimulation will cause another contraction response |
| What is the relative refractory period? | period where only a strong stimulus can evoke contraction |
| What does the heart's ability to stretch & regain shape refer to? | elasticity |
| What is the change in volume for a given change in pressure referred to? | compliance |
| What does the contraction strength of cardiac muscle refer to? | contractility |
| What does Frank Starling's Law state? | the force of ventricular contraction is determined by the myocardial fiber length at the onset of contraction (rubberband) |
| What is the load imposed on the ventricle at the end of diastole? | preload |
| What is the predominant determining factor for preload? | venous return |
| What is the load imposed on the ventricle during systole? | afterload |
| What are determining factors of afterload? | aortic pressure & resistance of the arterial system |
| How could you describe the relationship between BP & heart rate? | they are reciprocals |
| What are the 5 phases of the cardiac cycle? | Rapid filling, atrial contraction, isovolumic contraction, systolic ejection, & isovolumic relaxation |
| Where is rapid filling represented on an EKG? | right after the T wave |
| Where is atrial contraction represented on an EKG? | the P wave |
| Where is isovolumic contraction represented on an EKG? | QRS wave |
| Where is systolic ejection represented on an EKG? | S-T segment |
| Where is isovolumic relaxation represented on an EKG? | T wave |
| What heart sound is generated during atrial contraction (late diastole)? | S4- atrial gallop |
| What heart sound is generated during isovolumic contraction? | S1- Lubb (MV & TV closing) |
| What heart sound is generated during isovolumic relaxation? | S2- Dubb (AV & PV closing) |
| What heart sound is generated during rapid filling of the ventricles? | S3- ventricular gallop |
| How do you figure MAP (mean arterial pressure)? | 2(DBP) + SBP/3 |
| How do you figure pulse pressure? | SBP-DBP |
| What is the dip on an arterial pulse pressure graph? | dicrotic notch |
| Coronary blood flow happens predominantly during what phase of the cardiac cycle? | diastole |
| In what part of the cardiac cycle do we find the least coronary flow? | isovolumic contraction |
Created by:
ginaliane
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