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Chapter 17
Heart
| Term | Definition |
|---|---|
| Alveoli | balloon shaped air sacks where gas exchange happens; when you inhale these fill up |
| Pulmonary Capillaries | branches in lungs that surround alveoli |
| ANP | secretes the hearts atria in response to increased blood pressure; produces cardiomyocytes; lowers blood pressure by influencing sodium ion retention in kidneys |
| Kidneys | ANP secretes sodium and water which widens blood vessels, inhibiting a chain reaction |
| Fibrous Layer | tough outer layer (prevents chambers from over filling) |
| Cardiac Tamponade | excess fluid in pericardial cavity, making cavity go inward toward heart |
| Serous Pericardium | houses thin layer of serous fluid called pericardial fluid |
| Parietal Layer | outer layer/fused to fibrous pericardium |
| Visceral Layer | also called epicardium; inner layer; adheres directly to heart; superficial layer of heart wall |
| Myocardium Layer | second layer of heart wall and the thickest |
| Fibrous Skeleton | myocytes pull on during contraction; structural support; electrical insulator |
| Endocardium Layer | third layer of heart wall and the deepest layer |
| Endothelium | what the endocardium layer is made of, simple squamous epithelium |
| Coronary Circulation | vessels that supply myocardium with blood |
| Anastomose | system of channels formed between blood vessels; form when blood flow to myocardium is insufficient |
| Collateral Circulation | alternate routes for blood flow |
| Plaque | fatty material built up in coronary arteries |
| Angina Pectoris | chest pains |
| Myocardial Ischemia | heart muscle does not get enough oxygen-rich blood |
| Angioplasty | procedure to open blocked/narrow arteries |
| Stenosis | closure of a blood vessel or spinal canal |
| Heart Murmur | audible swooshing sound when heart beats; usually effects the mitral and aortic valves (AV valves) |
| Pacemaker Cells | generate action potentials (1%) |
| 1: Initial Depolarization | begins in hyperpolarized state (minimum membrane potential)/ non-specific cation channels open/sodium ions enter cell, potassium ions exit |
| 2: Full Depolarization | membrane reaches threshold/ voltage-gated calcium ion channels open, calcium enters cell |
| 3: Repolarization | calcium ion channels time-gated for closing/potassium ion channels open, potassium ions exit cell/membrane repolarizes |
| 4: Minimum Potential | potassium ion channels stay open until membrane reaches minimum potential/cation channels reopen and process begins again |
| Contractile Cells | stimulate action potentials in other cardiac muscle cells (99%) |
| 1: Depolarization | voltage-gated sodium ion channels open, sodium enters cell, voltage of membrane goes from negative to positive |
| 2: Initial Repolarization | inactivation of sodium ion channels, some potassium channels open, flow out of K+ |
| 3: Plateau | sustained depolarization/allows calcium channels to stay open, calcium enters cell, potassium continues to exit |
| Plateau | maintains heart rate (time for heart to fill up), prevents tetany (sustained contractions, lengthens refractory period, forces heart to relax between contractions |
| 4: Repolarization | sodium and calcium ion channels close, remaining potassium ion channels open, potential returns to -85mV |
| Cardiac Conduction System | group of interconnected pacemaker cells, make action potential throughout the heart |
| Ectopic Pacemaker | contractile cells or other pacemaker cells attempt to pace heart at same time as SA node (irregular heart rhythm) |
| Dysrhythmia | disturbance of normal heart rhythm, disturbance of conduction pathway, and fibrillation |
| Fibrillation | parts of heart depolarizing and contracting while parts repolarizing and not contracting |
| Arrhythmia | no rhythm (flatline) |
| Atrial Fibrillation | not life-threatening irregular heartbeat |
| Ventricular Fibrillation | immediately life-threatening irregular heartbeat (needs defibrillation - electric shock) |
| Ventricular Filling Phase | pressure in left and right ventricles, SL valves closed, no change in volume of heart in ventricles |
| Isovolumetric Contraction Phase | ventricular systole begins, increase in ventricular pressure, AV valves close (S1 produced), SL valves closed, no change in volume in ventricles |
| Ventricular Ejection Phase | begins when ventricular pressure exceeds aortic and pulmonary trunk pressures, SL valves open, blood is ejected from ventricles, aortic and pulmonary trunk pressure rises to match ventricular pressure |
| Isovolumetric Relaxation Phase | ventricular diastole begins, ventricular pressure drops, SL valves close (S2 sound heard), ventricular pressure is still higher than atrial pressure, AV valve remains closed |
| Wiggers Diagram | shows what is happening in the heart at each stage of cardiac cycle |
| Cardiac Output | amount of blood pumped into the pulmonary and systemic circuits in one min |
| Heart Rate | number of cardiac cycles the heart undergoes in one min |
| Stroke Volume | amount of blood pumped with each heartbeat |
| Preload | length of sarcomeres in ventricular muscle cells before contraction |
| Frank-Starling Law | the more ventricular muscle cells are stretched the more forcefully they contract, more actin-myosin overlap, |
| Contractility | increase in stroke volume and decrease in end-systolic volume |
| Afterload | force ventricles must overcome to eject blood, increase corresponds with decrease in stroke volume and increase in end-systolic volume |
| Ventricular Hypertrophy | enlargement of ventricular muscle, heart enlargement which increases other cardiac conditions |
| Chronotropic Agents | influence heart rate |
| Positive Chronotropic Agents | increase heart rate, sympathetic nerves |
| Negative Chronotropic Agents | decreases heart rate, parasympathetic nerves |
| Inotropic Agents | factors that influence contractility, speed up |
| Cardiomyopathies | diseases of the heart muscle |
| Pulmonary Congestion | pulmonary edema |
| End-diastolic Volume | how much blood will hold in ventricles |
| End-systolic Volume | blood remaining in ventricle after it contracts |
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