PGY 300: Exam 2
39 Cards in this Set
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Pulmonary circulation
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Right heart, oxygenates blood, low pressure & low resistance
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Systemic circulation
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Left heart, oxygenates tissues, high pressure & high resistance
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System operates on...
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Pressure differences (delta P)
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Arteries
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Take blood away from the heart
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Veins
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Return blood to the hear
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General Flow of Blood through the Heart
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Blood enters Right Atrium through Inferior/Superioir Vena Cavas, travels through AV valve into Right Ventricle, through Pulmonary semilunar valve out Pulmonary artery to Lungs, returns through Pulmonary Vein into Left Atrium, through AV valve into Left Ventricle, through Aortic semilunar …
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Hemoglobin
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Oxygen carrying molecule of RBCs
Average values- Men 14-17, Women 12-16
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Hematocrit
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Volume percentage of RBCs in blood
Average values- Men 40-54%, Women 37-47%
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Blood composition
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Plasma- liquid (top layer after centrifugation) 52%
WBC/Platelets- (middle layer after centrifugation) 1%
RBCs- (bottom layer after centrifugation) 48%
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Blood Flow
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BF = Change in Pressure/Resistance
Systemic blood flow is maintained by a balance between pressure and resistance
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Resistance
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R= 1/r^4 (as radius decreases, Resistance increases)
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Layers of the Heart
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Pericardium- outer sac which protects heart
Myocardium- contracting cardiac muscle of heart
Endocardium- inner layer made of endothelial cells
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3 major regulating systems of the heart
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Autonomic, Sympathetic Nervous, Parasympathetic Nervous
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Autonomic Regulation
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Cardiovascular Control Center in brain, releases epinephrine which circulates throughout system & binds B1 receptors, increasing heart rate and contractility
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Sympathetic Nervous Activity (SNA)
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Excitatory, releases norpepinephrine which binds B1 receptors increasing influx of Na+, followed by vast influx of Ca+ to deploarize the cell, allows for increased heart rate & contractility (reaches threshold faster)
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Parasympathetic Nervous Activity
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Depressant, releases acetylcholine which binds muscarinic receptors, increasing K+ influx and Ca2+ efflux thereby hyperpolarizing the membrane and decreasing heart rate (takes longer to reach threshold)
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Flow of electrical signal
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SA node to AV node to Bundle branches to Purkinje fibers
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SA node
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Pacemaker, located in atrium, pacemaker potential set at 100,
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AV node
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Located in septum between atrium & ventricle,receives action potential from SA node, delays it long enough for the atrium to contract & push blood into ventricles, sends action potential to bundle branches
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Bundle branches & Purkinje Fibers
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Sends action potential through apex to depolarize myocardium to allow for ventricular contraction
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Funny channels (If)
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Channels of the specialized conducting cells which open with Na+ influx, allowing for major Ca2+ influx which depolarizes the cell followed by closing of Ca2+ channels and opening of K+ channels (influx of K+) to hyperpolarize the cell (Absolute Refractory Period)
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Electrocardiogram waves
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P wave- atrial depolarization
--P-R interval- Atrial contraction (systole)
QRS complex- Ventricular depolarization
--Q-T interval- Ventricular contraction
T wave- Ventricular repolarization, opening of If channels
--T-P interval- electrical diastole, lengthens & shortens as HR increa…
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Contraction of cardiac muscle
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Specialized conducting cells excite membrane of cardiac muscle, signal sent through T tubules where sarcoplasmic reticulum releases Ca2+ contracting the heart
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Cardiac Output (CO)
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CO= Stroke volume * Heart rate
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Cardiac cycle
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Late Diastole, Atrial Systole, Isovolumic Ventricular Contraction, Ventricular Ejection, Isolvolumic Ventricular Relaxation
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Late Diastole
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No exictation, blood passively flows into ventricles
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Atrial Systole
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(P wave)atrium contracts pushing final amount of blood in ventricle, SA node depolarizes
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Isolvolumic Ventricular Contraction
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(QRS complex), all 4 valves are closed, ventricle contracts and builds pressure rapidly
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Ventricular Ejection
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(T wave) Pressure opens valves forcing blood from ventricle to aorta & pulmonary artery
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Isolvolumic Ventricular Relaxation
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Ventricle relaxes, all 4 valves closed, pressure in ventricles is greater than atriums but less than arteries
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Peripheral Circulation vessels
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Exits left heart via aorta, arteries, arterioles, capillaries, venules, veins, vena cava, returns to right heart
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Systolic Blood Pressure (SBP)
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Proportional to stroke volume, normal value 120mmHg
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Diastolic Blood Pressure (DBP)
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Proportional to total peripheral resistance, normal value 80mmHg
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Vasoconstriction
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Norephinephrine binds alpha receptors, allows for firing of baroreceptors & narrowing of vessel radius
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Vasodilation
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Epinephrine binds B2 receptors, increasing blood flow to skeletal muscle, heart & liver, widening vessel radius
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Myogenic Autoregulation
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Brain regulates blood flow to prevent over-stretching & swelling, change in pressure is offset by change in resistance and therefore the blood flow in the brain does not change
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Capillary flux
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Capillary fluid flux determines filtration (change of intervascular pressure to interstitial pressure) & absorption (gradient between interstitial & capillary)
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Edema
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Increase in hydrostatic pressure so filtration is greater than absorption & plasma volume increases
*increase in hydrostatic pressure can be due to: increase in mean arterial pressure, damage to capillary wall, decrease in arteriole resistance, increase in venous pressure
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Baroreceptors
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Pressure measuring receptors in aortic arch & carotid body
*Increase SNA to increase firing & decrease MAP
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PGY 300: Cardiovascular Physiology (Exam II)