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fribrous perdicardium
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The Heart CH 20
| Question | Answer |
|---|---|
| location | in thoracic cavity in mediastenum; in pericardium sack |
| fribrous perdicardium | tough outer layer; prevents over distention; anchor |
| serous pericardium | thin inner layer; simple squamous epithelium |
| heart wall | epicardium= smooth outermyocardium= middle layer w/cardiac muslce for heart contractingendocardium= smooth inner |
| pectinate muscles | muscluar ridges in auricles and right atrial wall |
| trabecular carnae | muscular ridges on inside of ventricles |
| coronary artery | exit aorta just superior to where it exits heart |
| tricuspid valve | on right side |
| bicuspid/mitral valve | on left side |
| SA node | pacemaker; generate spontaneous APs, medial to opening of superior vena cavae |
| AV node | APs conducted slower to ensure ventricles recieve signal to contract after atria have contracted |
| AV bundle | pass thru hole in cardiac skeleton to reach interventricular septum |
| bundle branches | extend beneath endocardium to L & R ventricles apices |
| purkinje fibers | conduct APs to ventricular muscle cells; contain gap junctions |
| P wave | depolarization of atrial myocardium, signals onset of atrial contraction |
| QRS complex | ventricular depolarization, signals onset of ventricular contraction and repolarization of atria |
| T wave | repolarization of ventricles |
| systole | period of isovolumic contraction; ventricle muscles contract & AV valves closes |
| diastole | period of isovolumic relaxation; ventric pressure falls rapidly; pulm trunk/aorta pressure > ventricles; elastic recoil causes blood to flow towards ventricles and semilunar valves close |
| end diastolic volume | amt of blood left after previous distole when atria emptied into ventricles (120-130 ml blood) |
| period of ejection | when pressure in ventricles is greater than pressure in pulm trunk/aorta, the semilunar valves are opened and blood ejects from ventricles; left ventricle has more than right |
| end systolic volume | amt of blood left after period of ejection (50-60 ml) |
| passive ventricular filling | while ventricles were in systole, atrials filled with blood; atrial pressure >ventricular, AV valves open and blood flows into ventricles (70% of filling) |
| active ventricular filling | depol of SA node causes APs to spread over atrias (P wave) & atria contract, which completes filling; this type unnecessary when at rest |
| lubb sound | AV vales and surrounding fluid vibrate as valves close at beginning of systole |
| dupp sound | closure of semilunar valves at beginning of distole |
| Mean Arterial Pressure | CO x PR |
| stroke volume (sv) | amt of blood pumped during each heartbeat |
| heart rate (hr) | # times heart beats per minute |
| cardiac reserve | difference between CO at rest and maximum CO |
| CO | amt of blood pumped by heart per minute; SV xHR |
| PR | total resistance against which blood must be pumped |
| intrinsic regulation | results from normal functional characteristics of heart |
| preload | amt of stretch of ventricular walls |
| starlings law | the greater the preload the greater the force of the contraction |
| afterload | pressure contracting muslce have to produce to overcome pressure in aorta and move blood into aorta |
| extrinsic regulation | involves neural and hormonal control |
| sympathetic stimulation | supplied by cardiac nerves; innervate SA & AV nodes, coronary vessels and atrial and ventricular myocardium. Increases heart rate and force of contraction. Increased heart rate-> increased cardiac output; lower end systolic volume bc of greater force; |
| parasympathetic stimulation | supplied by vagus nerve, decreases heart rate; acetycholine hyperpolarizes heart |
| hormonal control | epinephrine and norepinephrine released my adrenal medulla in response to high physical activity or stress |
| homeostasis of heart | baroreceptors monitor blood pressure and send info to medulla oblongata. low oxygen levels causes increase heart rate and BP so more oxygen can be delivered. heart rate increases when body temp increase. |
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