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14 Cards in this Set
- Front
- Back
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Factors affecting cardiac output |
PSYM nerve activity- slows the heart rate, lowers CO SYM nerve activity- raises the heart rate, increases CO Arterial pressure- increases afterload, decreases CO Filling pressure- increases preload and increases CO |
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ANS control of the heart- PSYM |
PSYM nerves- cholinergic comes through the vagus and affects the heart by slowing it. also innervates the external genitalia, causes erections |
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ANS control of the heart- SYM |
SYM nerves- adrenergic. wider distribution Affects the adrenal medulla to release NE and EPI, which affect the heart in addition to systemic effects SA/AV nodes and muscle itself is stimulated by the NE SYM causes increased NA and Ca permeability that increases heart rate and contractility vascular smooth muscle- has alpha receptors. SYM activity constricts the arterioles and causes increase in pressure |
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Autoregulation of bloodflow |
smooth muscle will adjust to pressure and try to keep flow going through as constant as possible (due to sympathetic activity) Local metabolic control of blood flow: build up of metabolic waste products acts as vasodilators for smooth muscle. the vascular smooth muscle relaxes and increases blood flow to flush these out. very strong in the heart, brain, skeletal muscle. |
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Mean arterial pressure |
MAP = CO x TPR it is a combination of sytolic and diastolic pressure ( |
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Phase 1 of the cardiac cycle |
atrial contraction AV valves open, semilunar vlaves close Initiated by the p wave S4 MAY be audible due to ventricular vibration |
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Phase 2 of the cardiac cycle |
Isovolumetric contraction All valves closed- no way for blood to get out Closure of the AV valves cause the first sound, S1 initiated by QRS, pressure rises rapidly in ventricular chamber |
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phase 3 of the cardiac cycle |
rapid ejection AV valves closed, aortic and pulmonic valves open ventricular pressure exceed pressure in the aorta and the pulmonary artery, pushing the valves open no sound generated unless there is an ejection murmur passive filling of the atrium |
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phase 4 of the cardiac cycle |
isovolumtric relaxation All valves closed- valve closure of the aortic and pulmonic valve cause S2 A/P valves close when the ventricular pressure drops enough no ECG activity link to this phase atrial pressure contrinues to rise due to venous return |
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phase 6 of the cardaic cycle |
rapid filling AV valves open, AP valves close atrial pressure rapidly decreases as blood flows into the ventricle 3rd sound might be heard if ventricular failure/dilation |
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phase 7 of the cardiac cycle |
reduced filling ventricular filling slows aortic and pulmonary artery pressure continues to fall |
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Degrees of AV block |
1st degree- common in horses and dogs, still a 1:1 ratio of P to QRS, it just takes longer 2nd degree- some action potentials get through 3rd degree- none of the action potentials get through |
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hyperkalemia on the ECG |
Slowed conduction velocity, everything gets wider Very big T wave as repolarization occurs in the ventricle |
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3 categories of wide QRS |
Ventricular hypertrophy Conduction disturbanve (global-hyperkalemia, or focal) Ectopic ventricular activity |
