Quizlet Lecture Exam II- The Circulatory System- The Heart

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  1. anastomoses: points where two arteries come together and combine their blood to points where two arteries come together and combine their blood flow to points farther downstream
  2. arrhythmia: any abnormal cardiac rhythm
  3. atrioventricular mode: node, located near the right AV valve at the lower end of the interarterial septum, which acts as an electrical gateway to the ventricals. The fibrous skeleton acts as an insulator to prevent currents from getting to the ventricles by another route
  4. atrioventricular valves: regulate the openings between the atria and the ventricles. right is the tricuspid, and left is the bicuspid
  5. autorhythmic: label of cardiac myocytes because they are able to depolarize spontaneously at regular time intervals
  6. bundle of His: aka the atrioventricular (AV) bundle, a pathway by which signals leave the AV node
  7. cardiac conduction: cells that control the route and timing of electrical conduction to ensure that the four chambers are coordinated with each other
  8. cardiac nerves: sympathetic nerves that arise from the cervical ganglia and lead to the venticular myocardium. the parasympathetic pathway to the hear is through the vagus nerves. The ventricles receive little or no vagal stimulation, the vagus nerve is what slows the heartbeat. These sympathetic and parasympathetic nerves are not what make it bear; the heart beat is set off by the heart's internal pacemaker and is simply modified by these nerves
  9. cardiology: scientific study of the heart and treatment of its disorders
  10. cardiovascular system: consists of the heart and the blood vessels that carry the blood to and from the body's organs. two major sytems include the pulmonary and systemic circuit.
  11. chordae tendineae: tendonous cords that conncect the valve cusps to conical papillary muscles on the floor of the ventricles
  12. collateral circulation: provided by anastomoses, an alternate route that can supply the tissue with blood if the primary route becomes obstructed
  13. coronary circulation: blood vessels of the heart wall constitute this system. provides blood to the myocarium and all of its muscle cells. approximately 5% of the circulating blood goes to meet the metabolic needs of the heart
  14. diastole: relaxation in the cardiac cycle`
  15. ectopic focus: any region of spontaneous firing other than the SA node. If the SA node is damaged, this may take over the governance of the heart rhythm. Most common is the AV node
  16. electrocardiogram: a composit recording of all the action potentials produced by the nodl and myocardial cells. a moving paper chart that records the simultaneous recordings made from electrodes at different distances from the heart. it provides a comprehensive image of the heart's electrical activity.
  17. endocardium: layer of tissue that lines the interior of the heart chambers
  18. epicardium: a serous membrane on the surface of the heart
  19. fast calcium channels: when the pacemaker potential reaches a threshold of -40mV, these channels open and Ca2+ flows in from the ECF. this produces a rising (depolorizing) phase of the action potential which peaks slightly above 0mV. this causes the K+ channels to open and the K+ leaves the cell. which makes the cytosol increasingly negative and creates a falling (repolorizing) phase of the action potential. When the repolarization is complete, the K+ channels close and the pacemaker potential starts over. each depolorization of the SA node sets off one heartbeat
  20. fibrous skeleton: meshwork of collagenous and elastic fibers, concentrated in the walls between the heart chambers, in fibrous rings around the openings of the heart valves, and in sheets of tissues that interconnect these rings. This functions as: structural support for the heart, an anchor for the myocyte and gives something to pull against, an electrical insulation between the atria and the ventricles, the elastic recoil aids in the refilling after each beat
  21. glycogen: a stored energy source, found in cardiac muscle for aerobic respiration
  22. heart block: failure of any part of the cardiac conduction system to transmit signals, usually as a result of disease and degeneration of conduction system fibers. examples include: bundle branch block-due to damage of one/both bundle fibers, total heart block- damage to the AV node, the atria fail to reach the ventricles and the ventricles beat their own intrinsic rhythm
  23. intercalated discs: thick connections that join the myocytes end to end. three distinctive features: interdigitating folds, mechanical junctions (fascia adherens and desmosomes), and gap junctions
  24. left coronary artery: travels through the coronary sulcus and under the left auricle where it divides two branches...one of which is the cirfumflex branch which gives rise to the marginal artery
  25. myocardial infarction: aka heart attack, caused by a fatty deposit or blood clot in a coronary artery
  26. myocardium: layer of tissue of the heart that is composed of cardiac muscle, the thickest layer, and performs the work of the heart
  27. myoglobin: a short-term source of stored oxygen for aerobic respiration, very rich in the cardiac cells for aerobic respiration
  28. nodal rhythm: the slower heartbeat of about 40-50 bpm by the AV node, which is sufficient to sustain life. other ectopic foci fire at rates of about 20-40 bpm but this is too little blood flow to the brain to be able to sustain life
  29. P wave: produced when a signal from the SA node spreads through the atria and depolarizes them. atrial systole begins about 100 msec after the p wave begins
  30. pacemaker potential: the SA node's unstable resting membrane potential starts at about -60mV and drifts upward, showing a gradual depolarization as a result of a slow inflow of Na+ without compensating outflow of K+
  31. parietal pericardium: the outer, tough, superficial fibrous layer of dense irregular connective tissue and a deep, thin serous layer.
  32. pectinate muscles: internal ridges of myocardium
  33. pericardial cavity: the space betwen the visceral and parietal membranes, and contains pericardial fluid
  34. pericardial fluid: found in the pericardial cavity, exuded by the serous pericardium, lubricates the membranes and allows the heart to beat almost without friction; isolates the heart from other organs, allows the heart room to expand and yet prevents excessive expansion
  35. pericardium: a double-walled sac that encloses the heart
  36. premature ventricular contraction: aka extrasystole, stimuli can cause other parts of the conduction system to fire before the SA node does, setting off an extra heart beat
  37. pulmonary circuit: carries blood to the lungs for gas exchange and returns it to the heart
  38. Purkinje fibers: nervelike processes that arise from the lower end of the bundle branches and turn upward to spread throughout the ventricular myocardium. THey distribute the electrical excitation to the myocytes of the ventricles; they form an elaborate network in the left ventricle than in the right
  39. QRS complex: consists of a small downward deflection, followed by a tall, sharp peak, and a final downward deflection. This is the result of the signal as it spreads from the AV node through the ventricular myocardium. the shape is due to the complex shape of the ventricles and the different times required for them to depolarize. ventricular systole begins soon after this segment. Atrial repolarization and diastole also occur during this interval.
  40. Right and Left bundle branches: after the fork in the AV bundle, these enter the interventricular septum and descend toward the apex
  41. right coronary artery: supplies the right atrium and the sinoatrial node. gives off two branches...one of which is the posterior interventicular branch
  42. semiulnar valves: rgulate the flow of blood from the ventricles into the great arteries. the pulmonary and aortic valves
  43. sinoatrial node: a patch of modified monocytes in the right atrium, under the epicardium near the superior vena cava, this is the pacemaker that initiates each heartbeat and determines the heart rate. the signals spread throughout the atria
  44. sinus rhythm: the name of the normal heart beat, triggered by the SA node
  45. systemic circuit: supplies blood to every organ of the lungs and the wall of the heart itself
  46. systole: contraction in the cardiac cycle
  47. T wave: generated by ventricular repolorization immediately before diastole. ventricles take longer to repolorize than to depolorize, therefore this wave is more spread out than the QRS complex and has a rounded peak.
  48. trabculae carneae: intenal ridges in both ventricles
  49. vagal tone: the steady background firing of the vagus nerves
  50. venous drainage: route which blood leaves an organ
  51. visceral pericardium: covering of the heart surface that is anchored by ligaments to the diaphrogm below and the sternum anterior to it