PNB Heart

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PNB Heart
2013-02-19 23:30:09

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  1. Layers of the heart (deepest to superficial)
    • Endocardium (covers heart wall)
    • myocardium (middle layer, consists of cardiac muscle)
    • epicardium (visceral layer of serous pericardium)
    • pericardial cavity (paricardial fluid-prevents friction and heat)
    • Parietal Pericardium
    • Fibrous Pericardium (fibro-serous membrane, covers heart-made of collagen=high tensile strength/NO compliance)
  2. Sequence starting with LT atrium
    • 1.Aortic Semilunar valve 
    • 2.Coronary artery  
    • 3.Systemic Capillary bed 
    • 4.Coronary vein  
    • 5.Coronary sinus 
    • 6.Tricuspid valve
    • 7.Pulmonary trunk 
    • 8.Pulmonary vein
  3. Function of Papillary muscles
    • -prevent eversion of bicuspid valve
    • -contract during ventricular systole
  4. Sequence of Depolarization
    • -SA node depolarizes
    • -depolarization of atrial myocytes (AP spreads through gap junctions in intercalated disks)
    • -AV node depolarizes
    • -signal is slowed down/delayed
    • -signal reaches bundle of His
    • -two bundle branches (right/left)
    • -signal reaches APEX of ventricles
    • -Purkinje fibers (originate from the bundle branches--spread superiorly and laterally; also spreads into the ventricular muscle.
  5. Order of Systemic circulation (include structures)
    OXYGENATED BLOOD: LT atrium-->AV valve-->LT ventricle-->aortic SL valve-->aorta-->elastic arteries-->muscular arteries-->arterioles-->capillaries (bed)-->

    O2 blood out the aorta,--> elastic arteries-->muscular arteries--> to arterioles, to capillaries for exchange, back to heart via Vena Cava
  6. structures for PULMONARY circulation
    DEOXYGENATED: RT ATRIUM-->RT VENTRICLE --> pulmonary trunk-->pulmonary arteries-->lungs-->arterioles-->pulmonary capillaries-->OXYGENATED venules-->pulmonary veins-->left Atrium
  7. What do veins have that arteries do not?
    • -valves
    • -compliance, stretch
  8. ventricles vs. atria-- do what with blood?
    • VENTRICLES: blood AWAY from heart
    • ATRIA: RECEIVES blood
  9. Pulmonary Valves
    • tricuspid (right AV)-- supported by papillary musc/choridae tendon 
    • pulmonary SL 
    • SA node
  10. Systemic Valves:
    • Bicuspid (Left AV) --- supported by papillary musc/choridae tendon 
    • Aortic SL
  11. Explain ventricular systole (pre-and systole)
    BLOOD FLOW: vena cava OR pulmonary veins-->atrium-->AV valve-->Ventricle

    -->AV/SL valves CLOSE (leading to isovolumetric)-->ventricular filling-->ventricular pressure EXCEEDS aortic or pulmonary trunk-->SL valves open-->ventricular ejection
  12. Ventricular Diastole:
    BEGINS: when ventricle relaxes after ejection, blood flowing back to ventricle causes SL to close. BOTH VALVES CLOSED
  13. How does ventricular filling occur? (atrial systole)
    atrial pressure GREATER than ventricular pressure, AV VALVES OPEN-->ventricular filling
  14. When does Atrial contraction occur?
    end of ventricular systole
  15. Epicardium
    visceral pericardium, squamous epithelium, areolar CT, fat
  16. Myocardium
    • cardiac muscle attached to fibrous skeleton of heart
    • "wringing" contraction
    • made of collagen and elastin
  17. endothelium
    • areolar CT and squamous endothelium
    • anchored by thing CT layer
  18. Explain coronary (heart) circulatory system
    • -Coronary artery delivers O2 blood to cardiac muscle  (branching off aorta)
    • -capillary within cardiac muscle, blood drains into coronary veins
    • -coronary vein--empty into coronary sinus
    • -blood returned to RIGHT atrium
  19. RT atrium receives blood from.....
    • inferior vena cava-systemic circ.
    • superior vena cava-systemic circ. 
    • coronary sinus
  20. What is another word for the "bundle of his"
    AV bundle
  21. compare/contrast angina with MI
    angina: ischemia (cut off blood flow), vasospasm, short-lived, no cell death

    MI: blockage of O2 to cardiac muscle, cell death
  22. what is another word for "discharge rate" in the pacemaker
    sinus rhythem
  23. equation for Stroke volume
  24. Ejection fraction equation and normal range

  25. MAP equation
    Diastolic + 1/3 pulse pressure
  26. Cardiac reserve equation
    CO(max) - CO (rest)
  27. EDV determined by:
    • length of ventricular DIASTOLE
    • venous return (inc. EDV)
  28. ESV determined by:
    • Mean Arterial Pressure
    • contractility (harder contraction, dec. ESV)
  29. Factors affecting stroke volume-PRELOAD:
    • increased EDV (main INTRINSIC factor)
  30. Frank-Starling Law of heart
    • any factor that increases volume or speed of venous return, thus increasing EDV --> increase stretch and force of contraction to pump out "extra blood"INTRINSIC (ESV&EDV)
    • due to length tension curve...
    • the more the heart is filled with blood, the more blood will be pumped out.
  31. Factors affecting stroke volume: Contractility
    • EXTRINSIC: ANS/hormones
    • -sympathetic stimulation
    • -EPI from adrenal medulla (increase Ca2+)
    • -increase force of contraction and rate-->more blood ejection
    • (Independent to EDV/muscle stretch)
    • -lower ESV, higher stroke volume
  32. diameter calculation
    radius(to the 4th power) THEN divide 1/R4
  33. Factors affecting stroke volume: Afterload
    • ventricular pressure must exceed arterial pressure
  34. Mean arterial/aortic pressure
  35. Stroke volume with hypertension has what affect?
    afterload increases, affecting ESV and lowering stroke volume

    heart must increase force of contraction-->DAMAGE longterm
  36. Blood flow equation
    Flow=change of pressure/radius
  37. Which node is more negative? SA or AV?
    • AV....
    • SA pushes AV to threshold
  38. P-Wave
    Depolarization of atria (following by Atrial contraction)
  39. QRS complex
    depolarization of ventricles (followed by ventricular contraction
  40. T Wave:
    Repolarization of ventricles
  41. P-R complex
    atria contract and begin to relax
  42. Q-T
    appx length of time it takes for ventricles to contract (depolarization) and relax (repolarization)
  43. Ectopic pacemaker
    Pacemaker in the wrong place
  44. Sympathetic NS is controlled by:
    • Medulla/cardioacceleratory
    • inc rate and inc force
  45. Paraympathetic NS is controlled by:
    • Medulla/cardioinhibitory by G-protein inhibiting adenyl cyclase, decrease in cAMP, decrease activity of HCN acting on channels
    • (vagus nerve)
  46. parasympathetic affects...
    heart rate ONLY
  47. sympathetic affects...
    heart rate AND ventricular muscle strength of contraction (stroke volume)
  48. baroreceptors control....
    blood pressure regulation
  49. BP regulation
    • increased MAP/BP-->
    • increased strength of wall-->
    • stimulate baroreceptors -->
    • inhibit sympathetic
    • increase parasympathetic .....
  50. chemoreceptors control...
    pH and O2 level