Term
| What ANS receptors are found on arterioles, and which type of receptor is found where in the body? |
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Definition
Alpha-1 adrenergic Rs are found on skin, splanchnic and renal circulations (divert blood flow away from less vital organs when fight-or-flight).
Beta-2 Rs on skeletal muscle vessels (increase blood flow to muscles). |
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Term
| Velocity of blood flow equation |
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Definition
V = Q/A
Q = blood flow (mL/min)
A = cross-sectional area (cm^2) |
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Term
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Definition
Q = delta-P/R
delta-P = pressure gradient (mmHg)
R = resistance (mmHg/mL/min) |
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Term
| Calculating cardiac output from resistance and pressure values |
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Definition
CO = (MAP - RAP) / TPR
MAP = mean arterial pressure
RAP = right atrial pressure
TPR = total peripheral resistance |
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Term
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Definition
| 2/3 diastolic pressure + 1/3 systolic pressure |
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Term
| Poiseulle's equation (factors that affect resistance) |
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Definition
R = 8(η)l / πr^4
η = viscosity
l = length of blood vessel
r = radius |
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Term
| Adding parallel resistances |
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Definition
| The reciprocal of the total resistance is the sum of the reciprocal of individual resistances. |
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Term
| Adding series resistances |
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Definition
| The total resistance is the sum of individual resistances. |
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Term
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Definition
| Determines whether blood flow will be laminar (organized flow in a straight line) or turbulent (causes audible vibrations called bruits). It is increased (along with turbulence) by increases in blood velocity (i.e. vessel narrowing) or decreases in viscosity (anemia, decreased hematocrit). |
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Term
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Definition
| Blood flow is fastest in the center of a blood vessel and slowest at the wall, thus this type of stress is highest at the vessel wall. |
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Term
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Definition
Describes the distensibility of blood vessels:
C = V/P (mL/mmHg)
V = volume (mL)
P = pressure (mmHg)
Higher for veins (unstressed volume) than arteries so that much more blood volume is contained in them than in the arteries. |
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Term
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Definition
| Represents atrial depolarization (repolarization is buried within the QRS complex). |
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Term
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Definition
| Represents AV nodal conduction, and is increased in cases of slower conduction (as in heart block). Sympathetic stimulation increases velocity and therefore decreases this interval (and vice versa for parasympathetic. |
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Term
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Definition
| Represents depolarization of ventricles. |
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Term
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Definition
| Represents both ventricular depolarization and repolarization. |
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Term
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Definition
| Represents the period when ventricles are depolarized and thus is isoelectric. |
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Term
| Fast (ventricular) action potential |
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Definition
Atria, ventricles and Purkinje system.
Phase 0 = upstroke, increase of Na conductance
Phase 1 = slight repolarization, decrease in Na conductance and outward K current
Phase 2 = plateau, transient increase in Ca inward current balanced by outward K current.
Phase 3 = repolarization, Ca conductance decreases and K outward current dominates.
Phase 4 = resting membrane potential, inward and outward currents are balanced, membrane potential approaches K equilibrium potential. |
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Term
| Slow (pacemaker) action potential |
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Definition
SA and AV nodes.
Phase 0 = depolarization due to inward Ca current
Phase 3 = repolarization with K current
Phase 4 = slow depolarization (automaticity) due to inward Na current that is activated by repolarization during the previous AP. |
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Term
| Order of pacemakers in the heart |
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Definition
| SA node > AV node > His-Purkinje. If the SA node is suppressed the latent pacemakers may take over if they are faster. |
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Term
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Definition
| Affects time required for excitation to spread through heart. Fastest in Purkinje system, slowest at AV node (in order to allow ventricular filling before contraction). |
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Term
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Definition
Absolute = no AP can be initiated
Effective = slightly longer than absolute, APs cannot be propagated
Relative = larger than usual stimulus is required to elicit an AP |
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Term
| Dromotropic vs. Chronotropic effects |
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Definition
| Dromotropy refers to changes in conduction velocity while chronotropy refers to changes in heart rate. |
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Term
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Definition
Vagal nerve releases ACh onto muscarinic receptors.
Negative chronotropic results from decreased Phase 4 Na current.
Negative dromotropic results from decrease Ca current and increased K current (slows conduction and increases PR interval length) |
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Term
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Definition
Norepi acts on beta-1 receptors.
Positive chronotropic results from increased Phase 4 Na current.
Positive dromotropic results from increased Ca current. |
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Term
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Definition
| End-diastolic volume (which is related to right atrial pressure). Determines stretching of ventricular walls before contraction. |
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Term
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Definition
| Aortic pressure (left ventricle) or Pulmonary arterial pressure (right ventricle). |
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Term
| Changes in ventricular pressure volume loops: Increased Preload |
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Definition
| Right boundary of loop extends to the right, as the ventricle is being filled more than usual. |
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Term
| Changes in ventricular pressure volume loops: Increased Afterload |
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Definition
| Top boundary of loop extends upward while left boundary shifts to the right. Ventricle has to pump against a higher aortic pressure so less volume is pumped out. |
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Term
| Changes in ventricular pressure volume loops: Increased Contractility |
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Definition
| Left boundary of loop shifts left; more blood is being pumped out but pressure values remain the same. |
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Term
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Definition
| Volume ejected from the ventricle on each beat, SV = EDV - ESV |
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Term
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Definition
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Term
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Definition
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Term
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Definition
| SW = Aortic pressure x SV |
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