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60 Cards in this Set
- Front
- Back
what are the three structures in the carotid sheath?
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internal jugular vein (lateral)
common carotid artery (medial) vagus nerve (posterior) |
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in most cases, what supplies the SA and AV nodes?
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RCA
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80% of the time, what supplies the inferior portion of the LV via the PD artery?
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RCA (right dominant)
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when do the coronary arteries fill?
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during diastole
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what supplies the anterior interventricular septum?
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LAD
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what is the most posterior part of the heart? enlargment can cause what?
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left atrium; dysphagia
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what artery gives off large obtuse marginal branches that supply the lateral and posterior walls of the LV?
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circumflex
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what supplies the anterior 2/3 of IV septum, apical portion of anterior papillary muscle, and the anterior surface of the LV?
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LAD
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where does the RCA travel?
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in the right AV groove
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what supplies the inferior and posterior wals of the ventricles and the posterior 1/3 of the IV septum?
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posterior descending (typically a branch of RCA)
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Cardiac output = ?
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stroke volume x heart rate
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what is the Fick principle?
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CO = rate of O2 consumption/ (arterial O2 content - venous O2 content)
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how do you calculate mean arterial pressure?
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CO x TPR
also: 1/3systolic + 2/3diastolic |
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pulse pressure = ?
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systolic - diastolic
(approximates stroke volume) |
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stroke volume = ?
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CO/HR
EDV - ESV |
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what variables affect stroke volume?
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contractility, afterload, and preload - SV CAP
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what effect does increased intracellular calcium have on contractility and SV?
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increases contractility and SV
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how does decreased extracellular sodium affect contractility and SV?
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increases contractility and SV
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5 things that decrease contractility and SV?
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1. B1 blockade
2. heart failure 3. acidosis 4. hypoxia/hypercapnea 5. Ca2+ channel blockers |
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what effect does digitalis have on contractility and SV?
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increases them
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preload is equal to what volume?
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end diastolic volume
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afterload is equal to what presure?
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systolic arterial pressure (proportional to peripheral resistance)
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what effect do venous dilators (e.g. nitroglycerin) have?
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decrease preload
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what effect do vasodilators (e.g. hydralazine) have?
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decrease afterload
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this increases slightly with exercise, increased blood volume (overtransfusion), and excitement (sympathetics)
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preload
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ejection fraction = ?
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SV/EDV
(EDV-ESV)/EDV (index of ventricular contractility) |
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ejection fraction is normally greater than or equal to?
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55%
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resistance is directly proportional to what?
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viscosity
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resistance is inversely proportional to what?
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radius to the 4th power
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delta P = ?
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Q x R
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resistance = ?
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driving pressure (delta P)/flow (Q)
8(vicosity)xlength/pir4 |
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what does viscosity mostly depend on? when is it increased?
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hematocrit
incrased in polycythemia, hyperproteinemic states (e.g. multiple myeloma), hereditary spherocytosis |
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when in the cardiac cycle is O2 consumption highest?
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isovolumetric contraction
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this is the period between mitral valve closing and aortic valve opening
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isovolumetric contraction
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this is the period between aortic valve opening and closing
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systolic ejection
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this is the period between aortic valve closing and mitral vale opening
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isovolumetric relaxation
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when does rapid filling occur?
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just after mitral valve opens
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when does slow filling occur?
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just before mitral valve closes
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when is JVD seen?
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right heart failure
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what is cardiac muscle contraction dependent on?
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extracellular calcium, which enters the cells during plateau of action potential and stimulates calcium release from the sarcoplasmic reticulum (calcium-induced calcium release)
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what is the plateau in the cardiac muscle action potential due to?
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calcium influx
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where does the pacemaker action potential occur?
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SA and AV nodes
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what accounts for the automaticity of the SA and AV nodes?
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slow diastolic depolarization - membrane potential spontaneously depolarizes as Na+ conductance increases (funny channel)
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what determines heart rate?
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slope of phase 4 in the SA node
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what are the peripheral chemoreceptors? what do they respond to?
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carotid and aortic bodies - they respond to decreased (less than 60 mmHg)/increased PCO2, decreased pH of blood
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what do central chemoreceptors respond to?
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changes in pH and PCO2 of brain interstitial fluid, which in turn are influenced by arterial CO2
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what does the aortic arch respond to? how does it transmit and to where?
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responds to increased BP; transmits via vagus to medulla
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how and to where does the carotid sinus transmit information?
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via glossopharyngeal to the medulla
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how do the central chemoreceptors respond to increased intracranial pressure?
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hypertension (sympathetic response) and bradycardia (parasympathetic response)
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what organ receives the larges share of systemic cardiac output?
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liver
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what organ receivest eh highest blood flow per gramof tissue?
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kidney
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how does the heart meet increased O2 demand?
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incrased coronary blood flow, not by increased extraction of O2
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hypoxia in the pulmonary vasculature causes what?
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vasoconstriction (unique because in other organs hypoxia causes vasodilation)
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what are the local factors in the heart that determine autoregulaton?
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O2, adenosine, NO
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what are the local factors in the brain that determine autoregulation?
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CO2 (pH)
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how do the kidneys determine autoregulation?
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myogenic and tuboglomerular feedback
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what local factors determine autoregulation in skeletal muscle?
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lactate, adenosine, K+
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what is the most important mechanism for determining autoregulation in the skin?
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sympathetic stimulation - temperature control
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what is the effect of carotid massage?
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incrases pressure on carotid artery - increasing stretch and leading to decreased HR
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what is the ultimate consequence of baroreceptors sensing hypotension?
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vasoconstriction, incrased HR, contractility, and BP - important in the response to severe hemorrhage
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