Term
| allows for easy travel of AP between cells and almost free diffusion of ions creating a syncytium of the heart |
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Definition
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Term
| atrial and ventricular syncytium are separated by fibrous tissue called |
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Definition
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Term
| contractility is directly related to |
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Definition
| intracellular Ca concentration/ handling |
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Term
Have you ever been so frightened that you felt your heart pounding so hard that you thought it would jump out of your chest?
What system mediates this response?
How does this system affect cardiac contractility? |
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Definition
Norepinephrine activates beta-adrenergic receptor /Gs-mediated activation of adenylate cyclase
NE increases cAMP levels
Increased cAMP promotes Ca influx via L-type Ca Channels
Increased cAMP promotes increased cytosolic Ca from SR.
NE effect on Ca++ induces increased cardiac contractility |
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Term
| IIf Ca++ handling is so important to cardiac contractility; what do you predict will happen if you increase Ca influx via L-type Ca channels in cardiac myocytes through genetic engineering? |
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Definition
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Term
| IIf Ca++ handling is so important to cardiac contractility; what do you predict will be the inotropic effect (positive or negative) of a drug that blocks L-type Ca channels in cardiac myocytes? |
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Definition
Verapamil (L-type Ca channel blocker)
Reduces heart rate (negative chronotropic effect)
Reduces contractility (negative inotropic effect) |
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Term
| on the frank starling curve a drug that blocks l type calcium channels would shift the curve |
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Definition
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Term
| on the frank starling curve an increase in the intrinsic ability of the heart to contract due to beta adrenergic stimulus shifts the curve |
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Definition
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Term
| the period of contraction that ejects blood to the lungs or the rest of the body |
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Definition
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Term
| the period of relaxation when the heart fills with blood |
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Definition
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Term
| the volume of blood ejected from one ventricle in one beat |
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Definition
| stroke volume which is about 70 ml |
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Term
| end-diastolic volume - end systolic volume equals |
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Definition
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Term
| the volume of blood left in the ventricle after normal filling during diastole |
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Definition
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Term
| volume of blood remaining in the ventricle after systole |
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Definition
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Term
| the fraction of the end-diastolic blood volume from one ventricle in one beat. which is a good index of heart contratility (normal range= 55-70% |
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Definition
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Term
| stroke volume/ end-diastolic volume equals |
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Definition
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Term
| the ventricular wall tension at the end of diastole, AKA the stretch on the muscle fibers just prior to contraction |
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Definition
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Term
| clincial way to increase preload |
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Definition
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Term
| the ventricular wall tension during contraction AKA the resistance that must be overcome to eject the stroke volume |
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Definition
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Term
| increased afterload in the mean aortic presure is a marker for |
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Definition
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Term
| decreased afterload in the mean aortic pressure a marker for |
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Definition
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Term
| peak left ventricular pressure, increased afterload is an indicator of |
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Definition
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Term
| property that accounts for changes in strength of contraction that is independent of preload and afterload, often affected by NT or hormonal influences and the contractility effect is mediated by hanges intercelluar Calcium |
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Definition
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Term
| the 2 main factors the regulate CO |
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Definition
1. Intrinsic: venous return- ventricular filling pressure-preload (Frank-Starling mechanism)
2. ANS (sympatheitc and parasympatheitc nerves) regulate heart rate and strength of contraction |
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Term
| Stroke volume X Heart rate = |
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Definition
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Term
| the cardiac output in an average healthy man |
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Definition
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Term
| expresses the functional ability of the ventricles to pump blood according to frank-starling mechanism |
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Definition
| ventricular function curve |
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Term
| An inrease in right and left atrial pressure leads to |
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Definition
| increase in ventricular volume output on the right and left sides |
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Term
| THe part of the ANS that causes an increase cardiac output at any given right atrial pressure |
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Definition
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Term
| The part of the ANS that leads to a decrease CO at any given right atrial pressure |
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Definition
| parasympathetic stimulation |
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Term
| way to measure the right atrial pressure |
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Definition
| by measuring the length of the right jugular vein |
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Term
| what tool can be used to measure the patient's cardiac pressure and cardiac output |
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Definition
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Term
| the method of measuring cardiac output |
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Definition
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Term
In steady state:
Rate of O2 consumption in the body equal amount of O2
leaving the lung (pulmonary veins) minus amount of O2
returning to the lung (pulmonary artery) |
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Definition
| Conservation of mass Fick's principle |
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Term
| oxygen consumption/the change in arteriovenous oxygen concentration = |
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Definition
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