Term
| What ion is the most integral to cardiac contraction? |
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Definition
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Term
| Describe the steps in excitation contraction coupling |
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Definition
1) Ca2+ enters cell during depolarization and triggers release of Ca2+ from terminal cisternae
2) Ca2+ binds to troponin-C inducing conformational change in troponin complex
3) Myosin binds actin – cross bridge cycling occurs
4) Ca2+ is sequestered by SR via SERCA pumps
5) Ca2+ leaves troponin-C, myosin cannot bind actin.
6) Sarcomere returns to original relaxed length |
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Term
| The three necessary mechanisms for relaxation of cardiac muscle are what? |
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Definition
| Extrusion of Ca++ into ECF, re-uptake of Ca++ by SR, dissociation of Ca++ from troponin-c |
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Term
| How do you calculate the duration of a heartbeat? |
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Definition
Duration (s/bt) = __60(s/min)_____
heart rate (bts/min) |
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Term
| An average heart rate of 75 bt/min is equivalent to how many seconds per beat? |
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Definition
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Term
| How do you calculate cardiac output? |
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Definition
Heart rate (HR) x Stoke volume (SV) |
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Term
| What is the first phase of filling/emptying of the heart pump and does it occur during systole or dyastole? |
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Definition
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Term
What is the second phase of filling/emptying of the heart pump and does it occur during systole or dyastole?
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Definition
| Iso-volumetric contraction, systole |
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Term
What is the third phase of filling/emptying of the heart pump and does it occur during systole or dyastole?
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Definition
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Term
What is the fourth phase of filling/emptying of the heart pump and does it occur during systole or dyastole?
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Definition
| Iso-volumetric relaxation, diastole |
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Term
| What forces the aortic valve open? |
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Definition
| Ventricular pressure is greater than pressure in aorta |
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Term
| Peak flow out of the left ventricle and into the aorta marks the beginning of what phase? |
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Definition
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Term
| A small backward flow from the aorta to the ventricles just before the the aortic valve snaps shut is responsible for what? |
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Definition
| Dichrotic notch in aortic pressure wave |
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Term
| What is the result of ventricular pressure falling bellow atrial pressure? |
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Definition
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Term
| The end volume of the ventricles at the end of the relaxation period is known as what? |
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Definition
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Term
| Volume at the end of contraction is referred to as what? |
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Definition
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Term
| The amount of blood that is ejected during systole is known as what? |
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Definition
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Term
| On a graph of the pressure volume loop during cardiac performance, the diastolic pressure curve is representative of what? |
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Definition
| Initial (passive) tension |
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Term
| On a graph of the pressure volume loop during cardiac performance, the systolic pressure curve is representative of what? |
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Definition
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Term
On a graph of the pressure volume loop during cardiac performance, the area between the diastolic and systolic pressure curve represents what?
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Definition
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Term
| Cardiac work is defined by what part of a pressure-volume loop? |
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Definition
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Term
| The phrase "the greater the heart fills, the greater the force development of the heart" describes what? |
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Definition
| Frank-starling relationship |
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Term
| The normal heart usually operates on what portion of the Frank-Starling curve? |
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Definition
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Term
What is Frank-Starling's law? |
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Definition
| The mechanical energy set free in the passage from the resting to the active state is a function of the length of the fiber |
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Term
| What intrinsic control mechanism can alter stroke volume? |
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Definition
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Term
| What provides extrinsic regulation of stroke volume? |
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Definition
| Sympathetic nervous system |
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Term
| What is the definition of contractility? |
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Definition
The capacity of the heart to do work with a constant pre-load and a constant after-load. |
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Term
| Preload is defined as what? |
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Definition
Ventricular filling pressure just before ventricular contraction, end-diastolic pressure provides a good index |
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Term
| Afterload is defined as what? |
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Definition
Resistance in the vasculature, aortic pressure provides a good index |
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Term
| What is the relationship between contractility and sympathetic drive? |
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Definition
| Change in sympathetic drive is directly proportional to change in contractility |
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Term
| The slope of the curve (dP/dt) on a left ventricular pressure curve is an index for what? |
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Definition
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Term
| Max dP/dt of a left ventricular pressure curve indicates what? |
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Definition
| Max rate of force development by the ventricle |
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Term
| Max slope on a left ventricular pressure curve occurs during what phase? |
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Definition
| Isovolumic phase of systole |
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Term
| How is ejection fraction calculated? |
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Definition
| Systolic volume/End Diastolic volume |
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Term
| What is the relationship between stroke volume and pre-load? |
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Definition
| Increased pre-load = increased stroke volume |
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Term
| What is the relationship between stroke volume and after-load? |
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Definition
| Increased after-load decreases stroke volume |
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Term
| What is the relationship between stroke volume and contractility? |
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Definition
| Increased contractility increases stroke volume |
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Term
| What is the relationship between systolic Ca++ and contractile force of skeletal muscle? |
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Definition
| Calcium is responsible for contractile force |
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Term
| What Ca++ regulator can be found in cardiac uscle in addition to the SERCA pump? |
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Definition
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Term
| What is phospholamban's effects on the activity of the SERCA pump? |
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Definition
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Term
| What is the effect of the activation of b1 adrenergic receptors in cardiac muscle? |
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Definition
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Term
| What kind of pathway is activated by B1 adrenergic receptors? |
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Definition
| PKA phosphorylation pathway |
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Term
| How does activation of B1 adrenergic receptors in myocardial tissue increase the strength of contraction? |
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Definition
| Phosphorylation of L-type Ca++ channels lead to an increase in Ca++ influx |
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Term
| How does the activation of B1 adrenergic receptors in myocardial tissue shorten the time to relaxation following contraction? |
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Definition
| Phosphorylates phospholambam and troponin-I subunits |
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Term
| What is the primary role of the Baroreceptor reflex? |
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Definition
| Regulation of blood pressure, though it typically increases heart rate when activated |
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Term
| Where are baroreceptors located? |
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Definition
| High pressure areas (aortic arch, carotid sinus) |
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Term
| Do baroreceptors increase or decrease their firing in response to a decrease in pressure? |
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Definition
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Term
| The Bainbridge reflex (aka trial reflex) is an increase in heart rate due to an increase in what? |
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Definition
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Term
| Where are stretch receptors involved in the Bainbridge reflex located? |
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Definition
| Both atria at the venoatrial junctions |
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Term
| How does the increase in heart rate due to the Bainbridge reflex decrease pressure in the superior and inferior vena cava? |
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Definition
| Draws more blood out of the right atrium |
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Term
| While baroreceptors are high pressure receptors, Bainbridge receptors respond to what? |
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Definition
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Term
| An elevation of contractile force due to increased heart rate in healthy hearts is known as what? |
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Definition
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Term
| What causes the Treppe effect? |
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Definition
| Inc Ca++ influx due to increased number of APs, greater filling of SR and higher amount of Ca++ available for release |
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Term
| What can be used to augment the positive inotropic effect of the Treppe effect? |
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Definition
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