Systole/ Diastole | Systole~ Contraction of the heart muscles. Diastole~ Relaxation of the heart muscles |
Papillary Muscles | Contract & generate tension on chordae tendineae |
Cardiac Reserve | Difference between resting and maximal cardiac output |
Angina Pectoris | Pain due to deficient blood supply to the myocardium. Caused by transient stress-induced spasms of coronary arteries, increased physical demands on the heart or arteriosclerosis. Cells are weakened. |
Myocardial Infract | Hear Attack. Prolonged coronary blockage= prolonged lack of oxygen to the heart muscles= cardiac muscle cell death. These cells are AMITOTIC; replaced with non-contractile scar tissue. May be repairable depending on the extent of the damage and time |
Layers of the Heart | Epicardium aka visceral pericardium- visceral layer of the serous pericardium. Myocardium- Spiral bundles of cardiac muscle cells held together by elastic & collagen fibers that form a dense network called the Fibrous Skeleton of the heart. Endocardium innermost- Endothelial layer of the inner myocardial surface that is continuous with blood vessel linings. Creates a smooth surface for easy blood flow. |
Contraction of the Heart | Sinoatrial node (SA Node-Pacemaker) 60-100 beats/min. Atrioventricular node (AV Node) 40-60 beats/min. Atrioventricular (AV) bundles (Bundle of His) 0-40 beats/min Right and Left bundle branches 0-40 beats/min Ventricular Purkinje Fibers 0-40 beats/min |
Lub/Dub sounds | Caused by the closing of heart valves. First Sound~ occurs as AV valves close and signifies beginning of systole (contraction). Second Sound~ occurs when SL valves close at the beginning of ventricular diastole (relaxed) |
Pathway of blood through Heart (Pulmonary circuit) | Right atrium-tricuspid valve-right ventricle-pulmonary semilunar valve-pulmonary arteries-Lungs-pulmonary veins-left atrium |
Pathway of blood through Heart (Systemic circuit) | Left atrium-bicuspid (mitral) valve-Left ventricle-aortic semilunar valve-aorta-to the body-vena cavas-right atrium |
Isovolumetric contraction/relaxation | isovolumetric Contraction~ All 4 valves are closed. Atria relax; ventricles contract (0.3 seconds) Isovolumetric Relaxation~ All 4 valves are closed. Occurs in early diastole. Ventricles relax. Backflow of blood in aorta and pulmonary trunk closes semilunar valves. Quiescent period (0.4 seconds) |
Ventricular Filling | Takes places mid-to-late diastole. Atrial contraction (0.1 seconds). AV valves are open. 80% of blood passively flows into ventricles. Remaining 20% delivered with atrial systole. Heart blood pressure is low as blood enters atria and flows into ventricles. |
Development aspects of the heart | Fetal heart structures that bypass pulmonary circulation. Forman Ovale~ connects the two atria. After birth this closes and becomes the Fossa Ovalis. Ductus Arteriosus~ connects pulmonary trunk and the aorta. After birth this closes and becomes the Ligamentum Ateriosum |
Cardiac Output Equation | CO= SV (Stroke Volume) X HR (Heart Rate) If HR or SV goes up so does CO; same is true for going down |
Stroke Volume Equation | SV= EDV (End Diastolic Volume) - ESV (End Systolic Volume) EDV~ amount of blood collected in a ventricle during diastole (120ml) ESV~ amount of blood remaining in a ventricle after contraction (50ml) Average Stroke Volume~ 70ml |
Norepinephrine | Sympathetic neuron activation releases Norepinephrine |
Acetylcholine | Parasympathetic fibers in the vagus nerves release Acetylcholine. If vagus nerves are cut= inc HR by ~ 25 bpm (THIS IS CALLED VAGAL TONE) |
Congestive Heart Failure (CHF) | The heart is a "double pump" and each side can initially fail independently of the other. LEFT SIDE~ Pulmonary congestion~ blood backing up into the lungs > pulmonary edema. Can lead to suffocation. RIGHT SIDE~ Peripheral Congestion~ blood backs up at the tissue level > edema in the extremities. Can lead to tissue hypoxia. |
Commotio Cordis | Often lethal disruption of heart rhythm that occurs as a result of a blow to the area directly over the heart, at a critical time during the cycle of a heart beat causing cardiac arrest. It is a form a ventricular fibrillation, not mechanical damage to the heart muscle or surrounding organs, and not the result of heart disease. |
Normal blood pressure in Pulmonary Trunk | 24/8 mmHg |
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