Содержание
- 2. Plan:
- 3. Functions of the Heart Generating blood pressure Routing blood: separates pulmonary and systemic circulations Ensuring one-way
- 4. The cardiovascular system is divided into two circuits Pulmonary circuit blood to and from the lungs
- 6. Cardiac Muscle Elongated, branching cells containing 1-2 centrally located nuclei Contains actin and myosin myofilaments Intercalated
- 7. Heart chambers and valves Structural Differences in heart chambers The left side of the heart is
- 8. Cardiac Muscle Contraction Heart muscle: Is stimulated by nerves and is self-excitable (automaticity) Contracts as a
- 9. Differences Between Skeletal and Cardiac Muscle Physiology Action Potential Cardiac: Action potentials conducted from cell to
- 10. The Action Potential in Skeletal and Cardiac Muscle Figure 20.15
- 11. 1. Rising phase of action potential Due to opening of fast Na+ channels 2. Plateau phase
- 12. Conducting System of Heart
- 13. Conduction System of the Heart SA node: sinoatrial node. The pacemaker. Specialized cardiac muscle cells. Generate
- 14. Heart Physiology: Intrinsic Conduction System Autorhythmic cells: Initiate action potentials Have unstable resting potentials called pacemaker
- 15. Depolarization of SA Node SA node - no stable resting membrane potential Pacemaker potential gradual depolarization
- 16. Pacemaker and Action Potentials of the Heart
- 17. Heart Physiology: Sequence of Excitation Sinoatrial (SA) node generates impulses about 75 times/minute Atrioventricular (AV) node
- 18. Impulse Conduction through the Heart
- 19. An Electrocardiogram
- 20. Electrocardiogram Record of electrical events in the myocardium that can be correlated with mechanical events P
- 21. ECGs, Normal and Abnormal
- 22. ECGs, Abnormal Extrasystole : note inverted QRS complex, misshapen QRS and T and absence of a
- 23. ECGs, Abnormal Arrhythmia: conduction failure at AV node No pumping action occurs
- 24. The Cardiac Cycle Cardiac cycle refers to all events associated with blood flow through the heart
- 25. Phases of the Cardiac Cycle Atrial diastole and systole - Blood flows into and passively out
- 26. Phases of the Cardiac Cycle Ventricular systole Atria relax Rising ventricular pressure results in closing of
- 27. Phases of the Cardiac Cycle Ventricular diastole Ventricles relax Backflow of blood in aorta and pulmonary
- 28. Pressure and Volume Relationships in the Cardiac Cycle
- 29. Cardiac Output (CO) and Cardiac Reserve CO is the amount of blood pumped by each ventricle
- 30. A Simple Model of Stroke Volume Figure 20.19a-d
- 31. Cardiac Output: An Example CO (ml/min) = HR (75 beats/min) x SV (70 ml/beat) CO =
- 32. Factors Affecting Cardiac Output Figure 20.20
- 33. Extrinsic Innervation of the Heart Vital centers of medulla 1. Cardiac Center Cardioaccelerator center Activates sympathetic
- 34. Regulation of the Heart Neural regulation Parasympathetic stimulation - a negative chronotropic factor Supplied by vagus
- 35. Basic heart rate established by pacemaker cells SA node establishes baseline (sinus rhythmn) Modified by ANS
- 36. Pacemaker Function
- 37. Chemical Regulation of the Heart The hormones epinephrine and thyroxine increase heart rate Intra- and extracellular
- 38. Regulation of Stroke Volume SV: volume of blood pumped by a ventricle per beat SV= end
- 39. Factors Affecting Stroke Volume EDV - affected by Venous return - vol. of blood returning to
- 40. Frank-Starling Law of the Heart Preload, or degree of stretch, of cardiac muscle cells before they
- 41. Factors Affecting Stroke Volume
- 42. Extrinsic Factors Influencing Stroke Volume Contractility is the increase in contractile strength, independent of stretch and
- 43. Effects of Autonomic Activity on Contractility Sympathetic stimulation Release norepinephrine from symp. postganglionic fiber Also, EP
- 44. Contractility and Norepinephrine Sympathetic stimulation releases norepinephrine and initiates a cyclic AMP 2nd-messenger system Figure 18.22
- 45. Preload and Afterload Figure 18.21
- 46. Effects of Hormones on Contractility Epi, NE, and Thyroxine all have positive ionotropic effects and thus
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