Chapter 17 Cardiovascular System: The Heart
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40 terms
Terms | Definitions |
|---|---|
 3 layers of the heart | Epicardium, myocardium, and endocardium |
| Epicardium | visceral layer of serous pericardium |
| Myocardium | cardiac muscle cells connected by connective tissue fibers |
| Endocardium | simple squamous epithelium that lines chambers of heart and covers valves |
| Right Atrium | receives deoxygenated blood from superior and inferior vena cavae coming from systemic circulation |
| Left Atrium | receives oxygenated blood from pulmonary veins coming from pulmonary circulation |
| Right Ventricle | pumps deoxygenated blood to lungs via pulmonary arteries |
| Left Ventricle | pumps oxygenated blood to rest of body via aorta |
| Pulmonary arteries | carry deoxygenated blood |
| Pulmonary veins | carry oxygenated blood |
| Pulmonary Circulation | blood moves from right side of heart to the lungs to pick up oxygen; low pressure side |
| Systemic Circulation | blood moves from the left side of the heart to all the body; high pressure side |
| Pathway of Blood | Superior/Inferior vena cavae carry deoxygenated blood to the right atrium>tricuspid valve>right ventricle>pulmonary arteries that branch off the pulmonary trunk>LUNGS>oxygenated blood enters the left atrium by the 4 pulmonary veins>bicuspid valve>left ventricle>aorta>end organs |
| Atrioventricular (AV) Valves | right ventricle valve called tricuspid; left ventricle valve called bicuspid |
| Chordae tendinae | anchor the AV valves to papillary muscles during ventricular systole. |
| Semilunar Valves | aortic valve and pulmonary valve |
| Heart Muscle Anatomy | Intercalated discs, automaticity (no input from nervous system) |
| Heart is made up of 2 types of muscle fibers | Contractile cells and cells of the conducting system (autorhythmic cells) |
| Contractile Cells | Similar to skeletal muscle (action potential, release of calcium into cells, and binding of calcium to troponins) |
| Cells of the conductive system (autorhythmic cells) | initiate action potentials, pacemaker potentials, calcium influx for rising phase, rate of depolarization varies |
| Electrical Events | SA>AV>bundle of His >breaks into right and left branch>purkinje fibers |
| Regulation of Heart Rate | Sympathetic - HR and contractility increase Parasympathetic - slows HR thru vagus nerve |
| Electrocardiography | P wave - depolarization of SA node (first little bump in wave) QRS wave - ventricular depolarization (big spike) T wave - ventricular repolarization (bump after spike) Atrial repolarization is masked by QRS wave |
| Cardiac cycle | all events associated with blood flow through the heart |
| Systole | contraction of heart muscle |
| Diatole | relaxation of heart muscle |
| Phases of cardiac cycle | Ventricular filling, ventricular systole and isovolumetric relaxation |
| Ventricular filling | - mid to late diastole - Heart blood pressure is low as blood enters atria and fills ventricles - AV valves are open, then atrial systole occurs |
| Ventricular systole | - Atria relax - rising ventricular pressure results in closing of AV valves - Isovolumetric contraction phase - ventricular ejection opens semilunar valves |
| Isovolumetric relaxation | - early diastole - ventricles relax - backflow of blood in aorta & pulmonary trunk closes semilunar valves |
| Dicrotic notch | brief rise of aortic pressure caused by backflow of blood rebounding off semilunar valves |
| Heart sounds | associated with closing of valves |
| Cardiac Output | amount of blood pumped by each ventricle in one minute |
| Formula for calculating CO | CO = HR x SV |
| Heart rate | the number of heart beats per minute |
| Stroke volume | amount of blood pumped out by a ventricle with each beat; end diatolic volume (EDV) minus end systolic volume (ESV) |
| Cardiac reserve | difference between resting and maximal CO |
| End diastolic volume (EDV) | amount of blood collected in a ventricle during diatole |
| End systolic volume (ESV) | amount of blood remaining in a ventricle after contraction |
| Factors Affecting Stroke Volume | Preload - Volume of blood Contractility - how efficient the squeeze is Afterload - how much pressure to squeeze the heart |
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