Physiology Ch. 13 Con.

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Physiology Ch. 13 Con.
2011-09-29 15:28:41
physiology heart

Continued Pulmonary and Systemic Circulations
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  1. Pulmonary Circulation
    Path of blood from right ventricle through the lungs and back to the heart
  2. Systemic Circulation
    Oxygen-rich blood pumped to all organ systems to supplu nutrients
  3. Pulmonary and Systemic Circulations
    Rate of blood flow through systemic circulation = flow rate through pulmonary circulation
  4. Main structures of the heart
    • 4 chambers: 2 atrial/ 2 ventricles (left/right)
    • 2 AV valves: tricuspid (right)/ bicuspid (mitral) (left)
    • 2 semilunar valves: Pulmonary (between right ventricle - pulmonary artery) Aortic (between left ventricle - aorta)
  5. Atrioventricular and Semilunar Valves
    • One way valves
    • Opening and closing of valves occur as a result of pressure differences
  6. Atria and ventricles are separated in 2 functional units by AV valves(connective tissue) they allow blood flow from____ into the____.
    Atria, ventricles
  7. At the origin of pulmonary artery and aorta are_______. They open during_____contraction.
    semilunar valves, ventricular
  8. Cardiac Cycle and blood volume
    Refers to the repeating pattern of contraction and relaxation of the heart
  9. Systole: (ventricle contraction)
    phase of contraction
  10. Diastole:
    phase of relaxation
  11. End-diastolic volume (EDV)
    • Total volume of blood in the ventricles at the end of diastole
    • How much blood are in ventricles
  12. Stroke Volume (SV)
    • Amount of blood ejected from ventricles during systole
    • How much blood pumped out
  13. End systolic volume (ESV)
    • Amount of blood left in the ventricles at the end of systole
    • EDV - SV= ESV
  14. Steps of Cardiac cycle (6 steps)
    • Step 1: Isovolumetric contraction
    • Step 2: Ejection
    • Step 3: Ventricle pressure drops below aortic pressure
    • Step 4: Isovolumetric relaxation
    • Step 5: Rapid filling of ventricles
    • Step 6: Atrial systole----> then cycle repeats back to step 1
  15. Steps of Cardiac cycle
    Step 1: Isovolumetric contraction
    • Contraction of the ventricle causes ventricular pressure to rise above atrial pressure. AV valves close
    • Ventricular pressure is less than aortic pressure. Semilunar valves are closed. Volume of blood in ventricle is EDV
  16. Steps of Cardiac cycle
    Step 2: Ejection
    • Contraction of the ventricle causes ventricle pressure to rise above aortic pressure. Semiluar valves open.
    • Ventricular pressure is greater than atrial pressure. AV valves are closed. Volume of blood ejected: SV
  17. Steps of Cardiac cycle
    Step 3
    Ventricular pressure drops below aortic pressure
  18. Steps of Cardiac cycle
    Step 4: Isovolumetric relaxation
    • Back pressure causes semilunar valves to close
    • AV valves are still closed
    • Volume of blood in the ventricle: ESV
  19. Steps of Cardiac cycle
    Step 5: Rapid filling of ventricles
    • Ventricular pressure decrease below atrial pressure
    • AV valves open
    • Rapid ventricular filling occurs
  20. Steps of Cardiac cycle
    Step 6: Atrial systole
    • Atrial contraction
    • Push 10-30% more blood into the ventricle
    • Then cycle repeats
  21. Heart Sounds
    Caused by the closing of the AV and semilunar valves
  22. Lub (first sound)
    Produced by closing of the AV valves during isovolumetric contraction.
  23. Dub (second sound)
    Produced by closing of the semilunar valves when pressure in te ventricles falls below pressure in the arteries
  24. Heart Murmurs
    Abnormal heart sounds produced by abnormal patterns of blood flow in the heart
  25. Heart Murmurs
    Defective heart valves
    Valves become damaged by antibodies made in response to an infection, or congenital defects
  26. Heart Murmurs
    Mitral Stenosis(Bicuspid)
    • Mitral valve becomes thickened and calcified
    • Impairs blood flow from left atrium to left ventricle
    • Accumulation of blood in left ventricle may cause pulmonary hypertension
  27. Heart Murmurs
    Incompetent valves
    • Damage to papillary muscles
    • Valves do not close properly
    • Murmurs produced as blood regurgitates through valve flaps
  28. Heart Murmurs
    Septal defects
    • Usually congenital
    • Holes in septum between the left and right sides of the heart
    • May occur either in interatrial or interventricular septum
    • Blood passes from left side of the heart to the right side of the heart through the septal holes
  29. Systemic Circulation
    • When oxygen-rich blood pumped to all organ systems to supply nutrients it travels through.
    • The role is to direct the flow of blood from the heart to the capillaries, and back to the heart
    • Heart>Arteries>Arterioles>Capillaries>Venules>Veins>Heart
  30. Blood vessels composed of 3 tunics:
    • Tunica externa
    • Tunica media
    • Tunica interna
  31. Tunica externa
    Outer layer comprised of connective tissue
  32. Tunica media
    Middle layer composed of smooth muscle
  33. Tunica interna
    Innermost layer has elastin
  34. Elastic arteries
    • Numerous layers of elastin fibers between smooth muscle
    • Expand when the pressure of the blood rises
    • Act as recoil system when ventricles relax
  35. Muscular arteries
    • Are less elastic and have a thicker layer of smooth muscle
    • Diameter changes slightly as BP raises and falls
  36. Arterioles
    • Contain highest % of smooth muscle
    • Greatest pressure drop
    • Greatest resistance to flow
  37. Most of the blood volume is contained in the____
    venous system
  38. Venules
    • Formed when capillaries unite
    • Very porous
  39. Veins
    • Contain little smooth muscle or elastin
    • Contain 1 way valves that ensure blood flow to the heart
  40. Capillaries
    • Smallest blood vessels
    • 1 endothelial cell thick
    • Provide direct access to cells
    • Permits exchange of nutrients and wastes
  41. Ischemic Heart Disease
    • Ischemia: Oxygen supply to heart tissue if deficient
    • Most common cause is atherosclerosis of coronary arteries (Heart muscle, several of them)
    • Increased lactic acid produced by anaerobic respiration
    • Angina pectoris: Substernal pain....can lead to--->Myocardial infarction (MI)
    • **Cardiac muscle cannot repair itself
  42. Electrical Activity of the Heart
    SA node:
    • Demonstrates automaticity
    • Functions as the pacemaker
    • Spontaneous depolarization (pacemakeer potential)
    • SA node spreads APs to myocardial cells
  43. When myocardial cell reaches threshold, cells depolarize
    Rapid depolarization occurs:
    • VG Na+ channels open
    • Inward diffusion of Na+
  44. Rapid repolarization:
    • VG K+ channels open
    • Rapid outward diffusion of K+
  45. Conducting tissues of the Heart
    APs spread through myocardial cells through____
    gap junctions
  46. Conducting Tissues of the Heart
    Impulses cannot spread to ventricles directly because of______
    Fibrous tissue
  47. Conduction pathway:
    • SA node--> AV node--> Bundle of his--> Purkinje fibers
    • Stimulation of purkinje fibers cause both ventricles to contract simutaneously
  48. Conduction of Impulse
    • APs from SA node spread quickly
    • Time delay occurs as impulses pass through AV node
    • Impulse conduction increases as spread to purkinje fibers
    • Ventricular contraction begins 0.1-.0.2 sec after contraction of the atria
  49. Refractory Periods
    • Heart contracts as syncytium (ie contracts together)
    • Contraction lasts almost 300 msec
    • Refractory periods last almost as long as a contraction
    • Myocardial muscle cannot be stimulated to contract again until it has relaxed. Summation cannot occur
  50. Electrocardiogram (ECG/EKG)
    • The body is a good conductor of electricity
    • Tissue fluids have a high concentration of ions that move in response to potential differences.
    • Measure of the electrical activity of the heart per unit time.
    • Potential differences generated by heart are conducted to body surface where they can be recorded on electrodes on the skin
    • Does not measure the flow of blood through the heart
  51. EKG Waves
    P wave
    Atrial depolarization
  52. EKG Waves
    QRS complex
    • Ventricular depolarization
    • Atrial repolarization (hidden)
  53. EKG Waves
    T wave
    Ventricular repolarization
  54. Correlation of EKG with Heart Sounds
    First Heart sound:
    • Produced immediately after QRS wave
    • Rise of intraventricular pressure causes AV valves to close
  55. Correlation of EKG with Heart Sounds
    Second Heart sound:
    • Produced after T wave begins
    • Fall in intraventricular pressure causes semilunar valves to close
  56. Arrhythmias
    Abnormal heart rhythms
  57. Flutter
    • Extremely rapid rates of excitation and contraction of atria or ventricles.
    • Atrial flutter degenerates into atrial fibrillation
  58. Fibrillation
    • Contractions of different groups of myocardial cells at different times
    • Coordination of pumping impossible
    • Ventricular fibrillation is life threathening
    • Can cause blood clots
  59. Bradycardia
    HR slower < 60 beats/ min
  60. Tachycardia
    HR > 100 beats/min