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34 Cards in this Set
- Front
- Back
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Cardiac output |
= heart rate x stroke volume |
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Systole |
Contraction (ventricular or atrial) |
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Diastole |
Relaxation (ventricular or atrial) |
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Pacemaker cells |
In sinoatrial node. Regulates and synchronize heart rate |
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Stage 1 |
Filling. Av valves open and atria and ventricles are relaxed in diastole 70% of ventricular filling |
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Stage 2 |
Atrial systole Atria contracts pushing remaining 30 % of blood into ventricles. Atria then relaxes into atria diastole |
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Stage 3 |
Isovolumetric contraction All 4 valves closed First phase of ventricular systole Pressure rises in their interior which exceeds pressure in atria closing av valves Papillary muscles contract preventing av valves from inverting |
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Stage 4 |
Ejection. Pressure in ventricles reaches point where it exceeds pressure in aorta and pulmonary arteries opening semilunar valves passively Blood ejected quickly then at a reduced rate. Ventricular diastole is when ventricles stop contracting. |
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Stage 5 |
Isovolumetric relaxation Pressure drops in ventricles below aorta and pulmonary trunk closing semilunar valves. Pressure in ventricles continues to fall all 4 valves are closed |
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Stage 6 |
Onset of filling. Pressure in ventricles falls below atria and av valves open allowing blood to rush in. |
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Diastasis |
Reduced filling of blood into atria |
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Sphygmomanometer |
Indirectly measure blood pressure. Inflates bag to excess of systolic pressure released til sound which is systolic pressure. Diastolic pressure is when the sounds disappear |
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Korotkoff sounds |
Sounds hear between systolic pressure and diastolic pressure when measuring blood pressure |
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Auscultation |
Hearing the sounds of the cardiac cycle with a stethoscope |
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Normal heart sounds |
S1 - first heart sound occurs at the onset of ventricular systole is closing of av valves S2 - second heart sound occurs when semilunar valves closes and marks end of ventricular systole Aortic closes slightly before pulmonary leaving to a2 and p2 |
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Systolic murmurs |
When tricuspid of mitral valves do not close properly during systole causing blood to regurgitate into ventricles during ventricular systole and during isovolumetric relaxation |
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Diastolic murmurs |
Can occur when aortic or pulmonary valves do not close properly. Allows blood to regurgitate into ventricles during ventricular diastole |
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Stroke volume |
End diastolic volume (at end of fillinh)- end systolic volume ( at end of ejection |
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Ejection fraction |
Stroke volume/ end diastolic volume |
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Cardiac output |
Stroke volume x heart rate |
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Preferred source of energy for the heart |
Fatty acids. Can also use glucose and lactate |
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Creatine phosphokinase |
Enzyme Manufacturers creatine phosphate from atp. Different than that in skeletal muscle. If there is damage to the heart it can be found in the blood |
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Mean arterial pressure |
Diastolic aortic pressure - 1/3 pulse pressure |
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Total peripheral resistance |
Mean blood pressure / cardiac output |
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Ejection fraction |
Stroke volume/end diastolic volume |
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4 factors that affect cardiac output |
Preload- end diastolic volume Afterload - resistance to ejection fraction of blood from ventricles Heart rate Myocardial contractility- strength of cardiac muscle contractility |
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Starlings law of the heart |
Withing limits the greater the preload or stretch the greater will be the force of contraction the smaller will be the end systolic volume and so a large stroke volume. Ensure heart pumps into aorta the same amount it receives from the veins |
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Myocardial contractility |
Force of contraction of cardiac muscles at a given fiber length Does not change during starlings law. |
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Factors that affect myocardial contractility |
Norepinephrine and epinephrine Increased extracellular calcium Digitalis which increases intracellular calcium |
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Sympathetic branch innervation |
Innervated by post ganglionic sympathetic nerve fibers that release norepinephrine which binds to b adrenergic receptors in myocardial cells membranes Stimulates sinus node increasing heart rate Stimulaes Cardiac muscle of ventricles cause it to increase contractile force. |
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Parasympathetic bramch |
Nerve fibers from left and right vagus nerve innervated sinus and av nodes. Not ventricular myocardium. Causes heart to beat more slowly. Preganglionic Parasympathetic nerve endings release acetylcholine which binds to nicotinic receptors on post ganglionic neurons in the heart. Post ganglionic release acetylcholine which binds to Muscarinic receptors on membranes of pacemaker cells. Blocked by atropine |
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Atropine |
Blocks Muscarinic receptors which prevent the Parasympathetic from slowing the heart down. |
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Central control of the heart |
Primarily from region of medulla called Vasomotor center or cardiac center. |
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Heart fuel percentages |
Fatty acids - 67 Glucose - 17.9 Lactate - 16.5 Amino acids- 5.3 Keto acids- 4.3 Pyruvate - .5 |
