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The Cardiovascular System: The Heart Part B

The Cardiovascular System: The Heart Part B. 18. “Heart beat”. http://www.youtube.com/watch?v=ZlB-915CfCg http://www.youtube.com/watch?v=7eFn8Cgcx8g http://www.youtube.com/watch?v=NYB-rJZQt4w&feature=fvw. Know sequence of cardiac cycle. Know sequence of cardiac cycle. - Know.

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The Cardiovascular System: The Heart Part B

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  1. The Cardiovascular System: The Heart Part B 18

  2. “Heart beat” • http://www.youtube.com/watch?v=ZlB-915CfCg • http://www.youtube.com/watch?v=7eFn8Cgcx8g • http://www.youtube.com/watch?v=NYB-rJZQt4w&feature=fvw

  3. Know sequence of cardiac cycle

  4. Know sequence of cardiac cycle

  5. - Know http://www.youtube.com/watch?v=12_nJamoyTk

  6. understand

  7. Cardiac Muscle Contraction - know • Heart muscle: • Is stimulated by nerves and is self-excitable (automaticity) • Contracts as a unit • Has a long (250 ms) absolute refractory period • Cardiac muscle contraction is similar to skeletal muscle contraction http://www.youtube.com/watch?v=IjU81a5TjZs; http://www.dnatube.com/video/317/Beating-Heart-Cell; http://www.youtube.com/watch?v=55tAIOcBg3w&feature=related; http://www.youtube.com/watch?v=_gbGA5il4Sg

  8. Heart Physiology: Intrinsic Conduction System - know • Autorhythmic cells: • Initiate action potentials • Have unstable resting potentials called pacemaker potentials • Use calcium influx (rather than sodium) for rising phase of the action potential http://www.youtube.com/watch?v=Lhl897Mz-h8&feature=related; http://www.interactivephysiology.com/demo/systems/buildframes.html?cardio/actnpot/01

  9. Pacemaker and Action Potentials of the Heart - know

  10. Heart Physiology: Sequence of Excitation - know • Sinoatrial (SA) node generates impulses about 75 times/minute • Atrioventricular (AV) node delays the impulse approximately 0.1 second • Impulse passes from atria to ventricles via the atrioventricular bundle (bundle of His) http://www.smm.org/heart/heart/pumping.htm; http://depts.washington.edu/physdx/heart/demo.html

  11. Heart Physiology: Sequence of Excitation - know • AV bundle splits into two pathways in the interventricular septum (bundle branches) • Bundle branches carry the impulse toward the apex of the heart • Purkinje fibers carry the impulse to the heart apex and ventricular walls

  12. Heart Physiology: Sequence of Excitation - know

  13. Heart Excitation Related to ECG - know

  14. Extrinsic Innervation of the Heart - know • Heart is stimulated by the sympathetic cardioacceleratory center • Heart is inhibited by the parasympathetic cardioinhibitory center

  15. Electrocardiography - know • Electrical activity is recorded by electrocardiogram (ECG) • P wave corresponds to depolarization of SA node • QRS complex corresponds to ventricular depolarization • T wave corresponds to ventricular repolarization • Atrial repolarization record is masked by the larger QRS complex http://www.youtube.com/watch?v=lYMSkGXFoN4&feature=related

  16. Electrocardiography (EKG) - know http://www.youtube.com/watch?v=ew6Jp74vaN4

  17. Heart Sounds - know • Heart sounds (lub-dup) are associated with closing of heart valves • First sound occurs as AV valves close and signifies beginning of systole • Second sound occurs when SL valves close at the beginning of ventricular diastole

  18. Cardiac Cycle - know • Cardiac cycle refers to all events associated with blood flow through the heart • Systole – contraction of heart muscle • Diastole – relaxation of heart muscle http://www.youtube.com/watch?v=ySzCasRhA84

  19. Phases of the Cardiac Cycle - know • Ventricular filling – mid-to-late diastole • Heart blood pressure is low as blood enters atria and flows into ventricles • AV valves are open, then atrial systole occurs

  20. Phases of the Cardiac Cycle - know • Ventricular systole • Atria relax • Rising ventricular pressure results in closing of AV valves • Isovolumetric contraction phase • Ventricular ejection phase opens semilunar valves

  21. Phases of the Cardiac Cycle - know • Isovolumetric relaxation – early diastole • Ventricles relax • Backflow of blood in aorta and pulmonary trunk closes semilunar valves • Dicrotic notch – brief rise in aortic pressure caused by backflow of blood rebounding off semilunar valves

  22. Phases of the Cardiac Cycle - detail

  23. Cardiac Output (CO) and Reserve - know • CO is the amount of blood pumped by each ventricle in one minute • CO is the product of heart rate (HR) and stroke volume (SV) • HR is the number of heart beats per minute • SV is the amount of blood pumped out by a ventricle with each beat • Cardiac reserve is the difference between resting and maximal CO

  24. Cardiac Output: Example – understand how to calculate • CO (ml/min) = HR (75 beats/min) x SV (70 ml/beat) • CO = 5250 ml/min (5.25 L/min)

  25. Regulation of Stroke Volume - know • SV = end diastolic volume (EDV) minus end systolic volume (ESV) • EDV = amount of blood collected in a ventricle during diastole • ESV = amount of blood remaining in a ventricle after contraction

  26. Factors Affecting Stroke Volume - know • Preload – amount ventricles are stretched by contained blood • Contractility – cardiac cell contractile force due to factors other than EDV • Afterload – back pressure exerted by blood in the large arteries leaving the heart

  27. Frank-Starling Law of the Heart - know • Preload, or degree of stretch, of cardiac muscle cells before they contract is the critical factor controlling stroke volume • Slow heartbeat and exercise increase venous return to the heart, increasing SV • Blood loss and extremely rapid heartbeat decrease SV http://www.youtube.com/watch?v=Y7cjyb5oLIM

  28. Preload and Afterload - understand

  29. Extrinsic Factors Influencing Stroke Volume - know • Contractility is the increase in contractile strength, independent of stretch and EDV • Increase in contractility comes from: • Increased sympathetic stimuli • Certain hormones • Ca2+ and some drugs

  30. Extrinsic Factors Influencing Stroke Volume - know • Agents/factors that decrease contractility include: • Acidosis (pH < 7) • Increased extracellular K+ • Calcium channel blockers

  31. Contractility and Norepinephrine - understand • Sympathetic stimulation releases norepinephrine and initiates a cyclic AMP second-messenger system

  32. Regulation of Heart Rate – know definitions • Positive chronotropic factors increase heart rate • Negative chronotropic factors decrease heart rate

  33. Regulation of Heart Rate: Autonomic Nervous System - know • Sympathetic nervous system (SNS) stimulation is activated by stress, anxiety, excitement, or exercise • Parasympathetic nervous system (PNS) stimulation is mediated by acetylcholine and opposes the SNS • PNS dominates the autonomic stimulation, slowing heart rate and causing vagal tone

  34. Atrial (Bainbridge) Reflex – know what it is • Atrial (Bainbridge) reflex – a sympathetic reflex initiated by increased blood in the atria • Causes stimulation of the SA node • Stimulates baroreceptors in the atria, causing increased SNS stimulation

  35. Chemical Regulation of the Heart - understand • The hormones epinephrine and thyroxine increase heart rate • Intra- and extracellular ion concentrations must be maintained for normal heart function

  36. Factors Involved in Regulation of Cardiac Output - detail

  37. Congestive Heart Failure (CHF) - know • Congestive heart failure (CHF) is caused by: • Coronary atherosclerosis • Persistent high blood pressure • Multiple myocardial infarcts • Dilated cardiomyopathy (DCM) http://youtube.com/watch?v=XFmFpwOvcn8&feature=related

  38. Coronary Bypass surgery – understand what it is http://www.youtube.com/watch?feature=related&v=1SBMgh7IVGg; http://www.youtube.com/watch?v=u43dVSsG-54&feature=related; http://www.youtube.com/watch?v=HW-6SlIako0

  39. Developmental Aspects of the Heart - understand • Embryonic heart chambers • Sinus venous • Atrium • Ventricle • Bulbus cordis

  40. Developmental Aspects of the Heart - detail Know what “foramen ovale” is, and why it closes

  41. Developmental Aspects of the Heart - know • Fetal heart structures that bypass pulmonary circulation • Foramen ovale connects the two atria • Ductus arteriosus connects pulmonary trunk and the aorta http://www.youtube.com/watch?v=NIbL5eMwG04; http://www.videospider.tv/Videos/Detail/4141862558.aspx

  42. Examples of Congenital Heart Defects - understand

  43. Age-Related Changes Affecting the Heart - know • Sclerosis and thickening of valve flaps • Decline in cardiac reserve • Fibrosis of cardiac muscle • Atherosclerosis

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