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27 Cards in this Set
- Front
- Back
autorhythmicity |
1. self-generated action potential 2. 15-20% of heart cells are autorhythmic |
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sinoatrial node |
1. pacemaker cells, upper right of right atrium 2. 120-140 beats/minute 3. action potentials originate in this node |
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prepotential |
1. similar to threshold w/skeletal muscle tissue 2. the heart is always ready to pump again |
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Atrioventricular (AV) node |
1. electrically connects atrial and ventricular chambers 2. electrical signal travels from SA node to AV node |
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Atrioventricular (AV) bundle |
1. embedded in myocardium 2. conductive fibers in septum between the 2 ventricles 3. bundle branches |
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Purkinje fibers |
1. smaller fibers that carry impulse to all cells in myocardium of the ventricles 2. reach papillary muscles which operate valves |
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electrical stimulation path in heart |
1. SA node 2. AV node 3. AV bundle 4. bundle branches 5. Purkinje fibers |
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EKG or ECG: P wave |
1. atria depolarization 2. atria systole 3. contraction |
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EKG or ECG: QRS Complex |
1. depolarization 2. ventricular systole 3. contraction
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EKG or ECG: T Wave |
1. repolarization 2. relaxation 3. diastole |
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end systolic volume |
amount of blood left in left ventricle after contraction |
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If a person exercises |
1. left ventricle can accommodate more blood 2. heart grows, so it can handle larger volume 3. walls of chamber have to get thicker -- denser muscle needed to push extra blood out |
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enlarged heart |
large heart but myocardium can't accommodate extra blood -- not thick enough |
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cardiac output |
how much blood is flowing through left ventricle |
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mean arterial pressure |
collective pressures of body |
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stroke volume |
amount of blood left ventricle pumps each time |
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CO = SV x HR |
1. CO: cardiac output 2. SV: stroke volume 3. HR: heart rate |
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venous return |
amount of blood flowing back to heart |
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cardiac reserve |
amount of blood heart could pump at optimal conditions (at rest or exercise) |
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intrinsic regulation -- preload |
stretching walls of heart in order to contract maximally |
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intrinsic regulation -- reload |
resetting |
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vagus nerves |
1. release ACH onto nervous tissue 2. inhibits heart rate and contractions 3. extrinsic regulation |
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cardiac nerves |
1. secrete epinephrine 2. increase heart rate 3. increase contractions 4. extrinsic regulation 5. long-term regulation |
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baroreceptor reflexes |
1. pressure receptors located in aorta and carotid arteries -- short term regulation 2. vagus and cardiac nerves respond to baroreceptor to adjust blood flow |
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short term regulation of heart functions |
tell yourself to calm down, breathe deep |
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cardioregulatory centers |
medulla oblongata has a visceral reflex |
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adrenal medullary mechanism |
1. increases blood pressure and heart rate 2. increases epinephrine, part of endocrine system |