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67 Cards in this Set

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  • Back
Site of highest resistance in the cardiovascular system?
Poiseuille's equation for resistance
R = 8*n*l / pi*r^4
Blood flow equation (hint: analogous to Ohm's law)
Q = change in pressure / resistance
Reynolds number predicts whether blood flow will be laminar or turbulent. What two factors increase Reynolds number?
Decrease in viscosity (anemia, decrease in hematocrit) or increasing blood velocity (narrowing of vessel)
Capacitance describes the ___ of blood vessles
What is unstressed volume?
The blood volume within the venous system. Arterial blood volume is known as the stressed volume.
What is the pressure in: aorta, arterioles, capillaries, and vena cava
100, 50, 20, 4
What is the most important determinant of pulse pressure?
Stroke volume
How do you calculate Mean Arterial Pressure
Diastolic pressure plus 1/3 pulse pressure
What gives the SA-node, AV-node, and His-Purkinje system its automaticity character?
Funny (I Na) channels
What causes the A2:P2 split of S2 heart sound?
Inspiration decreases intrathoracic pressure. Increased VR. Increased Preload to RV. Prolonged RV ejection phase. There is also a small decrease in ejection phase of LV.
How does the parasympathetic nervous system effect the heart?
Acts on SA node, atria, and AV node via vagal innervation. The neurotransmitter is ACh that acts on muscarinic receptors. Negative chronotropic (decrease I f), ionotropic and dromotropic (decrease Ca current and increase K current) effects.
What is the S3 heart sounds?
Ventricular gallop in mid-diastole. Rapid ventricular filling. Normal in young and athletes.
How does the sympathetic nervous system effect the heart?
Norepinephrine acts on Beta 1 receptors. Positive chronotropic, ionotropic and dromotropic effects.
What is the S4 heart sound? What is the clinical correlation.
Atrial gallop in late diastole. Clinical correlation: myocardial infarction causes a stiff ventricle.
How does digitalis work?
Increases the force of contraction by inhibiting Na/K ATPase in the myocardial cell membrane. Intracellular Na increases which decreases the Ca/Na exchange. Intracellular Ca increases.
What heart sound could a brief period of exercise cause?
Increased VR leads to an S3 sound.
What is the first heart sounds, S1? When is it increased?
Closure of AV valves in early systole. Loudest at the apex. It is increased in tachycardia and mitral stenosis.
Cardiac output. Give two equations.
= SV * HR (5 L/min)
What is the second heart sounds, S2?
Closure of the semilunar valves in early diastole. Physiological A2:P2 split
What is Fick's principle?
CO is related to whole body oxygen consumption. O2 consumption / (O2a - O2v) = CO
What happens to the stroke volume in: aortic regurgitation and aortic stenosis
Regurgitation - increased SV (normally there is still a decrease in effective stroke volume)
Stenosis - decreased SV
Below what % of Ejection fraction indicates heart failure?
What heart sound could a brief period of exercise cause?
Increased VR leads to an S3 sound.
Determinants of Stroke Volume?
Preload, contractility, afterload
What is the LaPlace equation?
sigma = P * r / 2h
sigma is wall tension
h = wall thickness
r = intralumenal radius
P = intralumenal pressure
Increased afterload causes __1__ hypertrophy. Fluid overload causes __2__ hypertrophy.
1 - concentric (mycoardial thickening)
2 - eccentric (sarcomeres are added in series)
Stroke work equation.
= aortic pressure x stroke volume. Fatty acids are the primary energy source for stroke work.
How does aortic stenosis change the ventricle pressure-volume loops?
Afterload (pressure required to open aortic valve) increases. Longer phase II (isovolumeic contraction). Shorter ejection phase III. Therefore, stroke volume decreases.
Aortic regurgitation (insufficiency) ____ pulse pressure due to a ____ diastolic pressure.
Increases, low.
What clinical diseases are associated with arotic regurgiation?
Ehlers-Danlos, Marfans, syphilitic aortitis
What does Rheumatic fever do to the heart?
Causes Mitral stenosis. Symptoms develop 20 years later.
When would a mitral valve prolapse be heard?
Mid-systolic click.
Above what Reynolds number does turbulent flow occur?
When is an aortic stenosis murmur heard? What does it sound like? Where?
Ejection type of murmur with a crescendo-decrescendo. Heard at 2nd right intercostal space and radiates to carotids.
When is an aortic regurgitation murmur heard? What does it sound like?
Early in diastole. Decrease in intensity.
When is an mitral regurgitation murmur heard?
When is an mitral stenosis murmur heard? What does it sound like?
Snap and rumble in diastole.
Coronary artery blood flow depends on what three things?
Length of diastole. Diastolic pressure of aorta, vascular resistance of coronary arteries.
What is demand-ischemia?
Persons with severe anemia may have elevated cardiac enzymes due to an ischemic heart.
What is angina pectoris? Stable vs unstable?
Chest pain caused by myocardial hypoperfusion (ischemia). Stable is due to exertion. Unstable is due to unfixed plaque, a medical emergency, chest pain at rest.
What are the clinical features of diastolic heart failure?
Increase afterload - concentric hypertrophy (sacromeres added in parallel) - leads o diastolic heart failure. Lead to backwards symptoms: dyspnea, shortness of breath, paroxsysmal nocturnal dyspnea.
Name some forward heart failure symptoms.
Related to systolic congestive heart failure. Fatigue, malasie.
What is hypertrophic cardiomyopathy?
Myocardium hypertrophies without a physiological stimulus. Occurs asymmetrically. Results in LV outflow obstructions. Results in syncope or sudden death. Tx with negative ionotropics.
What murmur increases in intensity with the Valsalva manuver?
Hypertrophic cardiomyopathy murmurs. Decrease LV preload. LV has to contract more strongly.
What is the most common cause of dilated cardiomyopathy unrelated to volume overload?
Excessive alcohol. Eccentric hypertrophy (minimal increase in wall thickness).
What two important physiological roles does the refractory period of an action potential have?
Prevents tetany and places an upper limit on heart rate.
Force of contraction of the myocardial cells is proportional to intracellular ___ levels. What drugs effect these levels.
Calcium. Digatalis increases Ca levels. Calcium channel blockers decreased Ca levels.
Why must calcium must be pumped back into sarcoplasmic reticulum?
So the cardiac muscle relaxes. This requires ATP.
What causes vasovagal syncope? Why do patients survive?
PNS outflow to heart during emotional upset. Ventricular escape rhythm saves the pt.
What ECG abnormality could you see with an acute MI?
ST segment elevation
What ECG abnormality could you see with a bundle branch block?
Split R wave
What ECG abnormality could you see with an heart block?
PR interval > 200 msec
What ECG abnormality could you see with an old MI?
Pathological Q wave
What ECG abnormality could you see with an LVH?
Deviation of mean QRS
What ECG abnormality could you see with heart ischemia?
Inverted T wave
Define heart failure.
Inadequate CO to meet metabolic demand (forward)
Adequate CO maintained only at elevated filling pressures (backward failure)
Systolic heart failure results in decreased stroke volume and cardiac output. What is the pathogenesis (2)?
Impaired contractility: MI's, regurgitations, dilated cardiomyopathy
Pathological increase in afterload: HTN, aortic stenosis
Diastolic heart failure results in an increase in LA filling pressure and pulmonary edema. What is the pathogenesis (2)?
Impaired relaxation: LVH, HCM, RCM, transient MI
Obstruction of LV filling: mitral stenosis, tamponade
Thyrotoxicosis, severe anemia, and large AV fistulas can cause what type of heart failure?
High output
What is the most common cause of death in Duchenne muscular dystrophy?
This X-linked disorder is caused by a defect in the gene for dystrophin, a protein necessary for sarcolemma stability. Muscle necrosis occurs. Death is due to fibrosis of the myocardium which leads to heart failure, pulmonary congestion, and arrhythmias.
What condition causes a pathological S3?
Aortic regurgitation. Early-mid diastole.
Describe the action of nitrates and nitrites on the molecular level.
Nitrates activate guanylate cyclase and increase cyclic guanine nucleotides. This activates cGMP dependent kinases that dephosphorylates myosin light chains. Vessels dilate.
Nitrates are used to treat the symptoms of ____.
Angina. Through the improvement of hemodynamics.
Why do nitrates have a large first-pass effect?
High-capacity organic nitrate reductase in the liver inactivates the drug.
How are the following drugs administered?
1 - Nitroglycerin
2 - Amyl nitrite
1 - sublingually for rapid delivery and short duration
2- volatile liquid that is inhaled
What are the adverse effects of nitrates and nitrites?
Orthostatic hypotension, reflex tachy, blushing, burning sensation. Methemoglobinemia and cyanosis.