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2013-01-19 17:56:18

second half of lecture
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  1. What is the Pericardium?
    it is lined by serous membrane that is subdivided into parietal and visceral
  2. What is the Visceral Pericardium?
    it covers closely to the heart, (like skin)
  3. What is the Parietal Pericardium?
    it lines the surface of the pericardial sac
  4. What is the Fibrous Pericardium?
    it is made of dense connective tissue, it also stabilizes the heart within the mediastinum
  5. How do Gap junctions help optimize cell function? What does it mean?
    Intercellular communication, it communicates through small openings between each of the cells, it helps with action potential-polarization of ions
  6. Intercalcated discs do what? What do they connect?
    They convey the farce of the contractions from cell to cell. The connect cardiac muscles
  7. Desmosomes
    help move neighboring cells as one unit (syncytium)

  8. HEART FUNCTION: Prevent mixing oxygenated and deoxygenated blood
    HEART ANATOMY (used): Interventricular septum, interatrial septum
  9. HEART FUNCTION: Overcome resistance
    HEART ANATOMY: Ventricles
  10. HEART FUNCTION: Prevent backflow of blood
    HEART ANATOMY: Chordae teninae, bicuspid/tricuspid valves, papillary muscles, pulonary & aortic semilunar valves
  11. HEART FUNCTION: Coordination of contraction
    HEART ANATOMY: Nodal cells (conducting system)
  12. 3 Main circulation circuits
    pulmonary, coronary, systemic
  13. The difference between Contractile and Conduction.
    • Produce powerful contractions, has a long plateau phase, long slow twitch, long refractory period
    • Controls and coordinates heartbeat
  14. Cardiac Cycle
    • Atria contract > push blood to ventricles > ventricles contract > push blood out of the heart
    • SA node generates impulses at regular intervals with a brief pause
  15. Similarities between cardiac and skeletal muscle
    • Action potentials to release Ca++ to bind to troponin
    • Expose active sites on the actin
    • Cause sarcomere shortening and muscle contraction
  16. Differences between cardiac and skeletal muscle
    • Action Potentials
    • Length of the contractions
  17. Cardiac Contractions
    • Ca++ enters from extracellular fluid during the plateau phase of action potential
    • This arrival of Ca++ causes the release of Ca++ from the SR
    • Skeletal muscle fiber contraction quickly, however cardiac muscles contracts longer and will continue until the plateau ends
  18. Depolarization between Cardiac and skeletal muscle 
    • Cardiac > rapid due to fast channels and massive influx of Na+
    • Skeletal > same thing
  19. Resting Potential for cardiac and skeletal muscle
    • Cardiac > Resting potential -90mV threshold -75mV
    • Skeletal > Resting potential -85mV threshold -50mV
  20. Depolarization/Plateau between cardiac and skeletal muscle
    • Cardiac > voltage regulated @ +30mV > slow voltage; plateau Ca++ open, will remain open at 0mV of 175 m/sec
    • Skeletal > voltage regulated +30mV; no plateau
  21. Repolarization of Cardiac and Skeletal muscle
    • Cardiac > slow K+ channels, open to restore resting potential
    • Skeletal > same
  22. Absolute Refractory period between Cardiac and Skeletal muscle
    • Cardiac > During depolarization; plateau and portion of repolarization, very long
    • Skeletal > During depolarization; normal length
  23. Relative Refactory Period between Cardiac and Skeletal muscle
    • Cardiac > Takes place during repolarization
    • Skeletal > takes place during repolarization & hyperpolarization
  24. 2 types of conducting cells
    • Nodal cells > Stop watch; reaches threshold first and sets heart rate
    • Conducting cells > conductor; distributes stimuli to myocardium
  25. Sinoatrial (SA) Node
    impulse spreads across atria to atrioventricular (AV) node > AV bundle and bundle branchs via Purkinje fibers to ventricles
  26. Autorhythmicity
    The heart can conduct impulses without external stimulation unlike that of the skeletal muscles
  27. Prepotential
    Each time the heart will repolarize it and will gradually move toward threshold, (always ready to start again)
  28. Difference between Bradycardia and Trachycardia
    • Bradycardia is too little K+; slower than normal heart rate
    • Trachycardia is too much K+; faster than normal heart rate
  29. Cardiac Action Potential
    • protein channels > sodium, potassium, calcium
    • Started by the prepotential but it is initiated by massive influx of sodium
    • The plateau is caused by calcium channels remain open for 175 m/sec at 0 mV
    • Repolarization > uses potassium channels that open & calcium channels close
    • (no leak channels=no hyperpolarization)
  30. Sodium and potassium pump in heart
    Potassium helps restore resting potential
  31. Phases in the cardiac cycle
    • Systole > contraction phase; ventricles together
    • Diastole > Relaxation phase
  32. Stroke Volume equation
    SV (stroke volume)= EDV-ESV
  33. 3 factors that affect ESV
    • Preload: filling with blood EDV
    • Contractility: force produced during contraction
    • Afterload: resistance in circulation ESV
  34. Cardiac output equation
    CO(ml/min)=heart rate(beats/min) * stroke volume(ml/beat)
  35. Frank-Starling Principle
    • "more in"="more out"
    • Larger EDV=larger stroke volume
  36. CNS Control of the Heart
    • Basic control in the medulla oblongata(brain stem)
    • Cardioacceleratory center > accelerate heart rate (sympathetic neurons)
    • Cardioinhibitory center > lower heart rate (parasympathetic neurons)
    • Blood pressure sensors (baroreceptors)
    • Oxygen, carbon dioxide receptors (cemoreceptors)
  37. Hormone and autonomic regulation of heart
    • Parasympathetic release of Ach which extends repolarization and decrease of heart rate
    • Sympathetic release of NE or E which shortens repolarization and accelerates the rate of spontaneous repolatization
  38. Hormone effects on Cardiac Output
    • Adrenal medulla hormones (E/NE)
    • Thyroid hormones
    • Glucagon
  39. Blood Vessels
    Arteries > Arterioles > Capillaries > Venules > Veins
  40. Properties of Arteries
    • Contain layers of tissue: Tunica externa(connective tissue) > Tunica media (smooth muscle) > Tunica intima (epithelium)
    • Thicker walls
  41. Specialized vessels
    • Fenestrated Capillaries
    • >contain pores or windows
    • >rapid exchange of water and solutes between plasma and interstitial fluid
  42. Properties of capillaries
    • Exchange between blood and cells take place
    • organized into interconnected capillary beds
    • vasomotion of precapillary sphincters(bands of smooth muscle) controls flow
  43. Properties of veins
    • collect blood from capillaries
    • merge into medium-sized veins
    • merge then into large veins
    • BP is low and valves keep blood flowing to the heart
  44. Fetal Circulation
    • Fetus > umbilical arteries > placenta > umbilical vein > fetus
    • Umbilical vein > ductus venous
    • Hepatic veins > ductus venous > inferior vena cava > right atrium > foramen ovale > left atrium > pumonary trunk > ductus arteriosus > arota > umbilical arteries