1. SECTON IV CIRCULATION
Chapter 9~11

2. Introduction Definition of circulation Function of circulation
Circulatory system is made up of the heart and vessels in which blood is flowing in certain direction, going round and begin again
Function of circulation
Cardiovascular system transport the blood flow circulating the whole body, maintain the homeostasis
Heart---- as a blood pump
Vessels---- distributing and collecting the blood flow
SECTON VI CIRCULATION Chapter 9~11

3. Introduction Pulmonary circulation Gases exchange in the lungs
Systemic circulations
Metabolic substances exchange in every well of the body
SECTON VI CIRCULATION Chapter 9~11

4. Introduction Non-circulation function
The heart and vessels as the endocrine organs
Atrial natriuretic peptide (ANP)…
Endothelin (ET)…
SECTON VI CIRCULATION Chapter 9~11

5. Content of the course
CHAP 9 ELECTRICAL PROPERTIES OF THE CARDIAC MUSCLE
CHAP 10 THE ELECTROCARDIOGRAM
CHAP 11 THE HEART AS A PUMP
CHAP 12 DYNAMICS OF BLOOD AND LYMPH FLOW
CHAP 13 CARDIOVASCULAR REGULATORY MECHANISMS
CHAP 14 CIRCULATION THROUGH SPECIAL REGIONS
SECTON VI CIRCULATION Chapter 9~11

6. CHAP 9 ELECTRICAL PROPERTIES OF THE CARDIAC MUSCLE
9.1 INTRODUCTION
9.2 RESTING MEMBRANE POTENTIAL AND ACTION POTENTIAL
9.3 ORIGIN AND SPREAD OF CARDIAC EXCITATION
9.4 EFFECT OF CARDIAC INNERVATION STIMULATION
SECTON VI CIRCULATION Chapter 9~11

7. 9.1 INTRODUCTION Physiologic properties Conducting system
Electrophysiological properties
Excitability
Autorhythmicity
Conductivity
Mechanical property
Contractility
Conducting system
SECTON VI CIRCULATION Chapter 9~11

8. 9.1 INTRODUCTION Cardiac myocyte Electrical activity of myocardium
Contractile myocardium
Atrial muscles, ventricular muscles
Autorhythmic myocardium
S-A node, A-V node, bundle of His and its branches, Purkinje fibers
Electrical activity of myocardium
SECTON VI CIRCULATION Chapter 9~11

9. 9.2 RESTING MEMBRANE POTENTIAL AND ACTION POTENTIAL
EK＝61.5·log [K+]o/ [K+]i
＝61.5·log [4]o/ [135]I
＝－90mv
SECTON VI CIRCULATION Chapter 9~11

10. 9.2 RESTING MEMBRANE POTENTIAL AND ACTION POTENTIAL
9.2.2 The ion currents responsible for the action potential
Ventricular action potential
Depolarizing phase
Phase 0 : INa, IK , ICa(L)
Repolarizing phase
Phase 1 : Ito
Phase 2 : ICa (L) , IK
Phase 3 : IK
Phase 4 :resting state, active ion exchange
SECTON VI CIRCULATION Chapter 9~11

11. 9.2 RESTING MEMBRANE POTENTIAL AND ACTION POTENTIAL
Factors affecting excitability of myocardium
Relationship of resting potential and threshold level
Characters of Na+ channel
Resting:
Active:
Inactive: effective refractory period
SECTON VI CIRCULATION Chapter 9~11

12. 9.2 RESTING MEMBRANE POTENTIAL AND ACTION POTENTIAL
9.2.3 The pacemaker potentials
S-A node action potential
Auto-depolarizing phase—4: IK, ICa(T), INa(F), Ca2+ sparks
Depolarizing phase—0: ICa(L)
Repolarizing phase—3: IK
Purkinje fibers
4: INa(F), IK
SECTON VI CIRCULATION Chapter 9~11

13. 9.2 RESTING MEMBRANE POTENTIAL AND ACTION POTENTIAL
Factors affecting autorhythmicity of myocardium
Maximum diastolic potential
Spontaneous depolarization
Threshold potential
SECTON VI CIRCULATION Chapter 9~11

14. 9.3 ORIGIN AND SPREAD OF CARDIAC EXCITATION
9.3.1 Anatomic consideration
Spetial conductive system in heart
SA node: normal pacemaker
Autonomic innervations
Right vagus and sympathetic nerve→ SA node
Left vagus and sympathetic nerve→ A-V node
SECTON VI CIRCULATION Chapter 9~11

15. 9.3 ORIGIN AND SPREAD OF CARDIAC EXCITATION
Sequence of cardiac excitation
Normal pacemaker: S-A node function as the pacemaker for the entire heart
Latent or sub ordinary pacemaker
Ectopic pacemaker
Factors affecting conductivity
Speed and amplitude of depolarization
Excitability of neighbor cell
SECTON VI CIRCULATION Chapter 9~11

16. 9.4 EFFECT OF CARDIAC INNERVATIONS STIMULATION
9.4.1 Effect of vagal cardiac nerves stimulation
The parasympathetic postganglionic fibers release primarily acetylcholine (ACh), which binds to M2-receptors →G(γ)
Inhibiting the heart actions
9.4.2 Effect of sympathetic cardiac nerves stimulation
The sympathetic postganglionic fibers release primarily norepinephrine (NE), which binds mainly to 2-receptors →Gs
Exciting the heart actions
SECTON VI CIRCULATION Chapter 9~11

17. CHAP 10 THE ELECTROCARDIOGRAM
10.1 RECORDING LEADS OF ECG
10.2 NORMAL ECG (EKG)
SECTON VI CIRCULATION Chapter 9~11

18. 10.1 RECORDING LEADS OF ECG Basic principle Body is a volume conductor
The heart is a current source in the center of a volume conductor (Einthoven's triangle)
The ECG may be recorded by using an exploring electrod
Depolarization moving toward an active electrode in a volume conductor produces a positive deflection, whereas depolarization moving in the opposite direction produces a negative deflection
SECTON VI CIRCULATION Chapter 9~11

19. 10.1 RECORDING LEADS OF ECG Recording lead Waves of the ECG
Bipolar recording
Standard limb leads
leads I, II, and III
Augmented limb leads
aVL, aVR, aVF
Unipolar recording
Precordial leads
Waves of the ECG
P, Q R S, T (,U)
SECTON VI CIRCULATION Chapter 9~11

20. 10.2 NORMAL ECG (EKG) Duration of the ECG PR interval: 0.18s
Atrial depolarization and conduction through AV node
QRS duration: 0.08s
Ventricular depolarization and atrial repolarization
QT interval: 0.40s
Ventricular depolarization plus ventricular repolarization
ST interval: 0.32s
Ventricular repolarization
ST segment
SECTON VI CIRCULATION Chapter 9~11

21. CHAP 11 THE HEART AS A PUMP CHAP 11 THE HEART AS A PUMP
11.1 MECHANICAL PROPERTIES OF THE CARDIAC MUSCLE
11.2 MECHANICAL EVENTS OF THE
CARDIAC CYCLE
11.3 CARDIAC OUTPUT
11.4 CARDIAC RESERVE
SECTON VI CIRCULATION Chapter 9~11

22. 11.1 MECHANICAL PROPERTIES OF THE CARDIAC MUSCLE
Contractile response
Dependent upon [Ca2+]o
[Ca2+]i↑ triggered by Ca2+o
No tetanus
Contractile response lasts about 1.5 times as long as the action potential
Long ERP: phase 0 →3(repolarization -50mv)
Contraction in synchronism
SECTON VI CIRCULATION Chapter 9~11

23. 11.1 MECHANICAL PROPERTIES OF THE CARDIAC MUSCLE
Relation between muscle fiber length and tension
Starling‘s law of the heart (Frank-Starling law )
Energy of contraction is proportional to the initial length of the cardiac muscle fiber.
The length of the muscle fibers (ie, the extent of the preload) is proportionate to the end-diastolic volume
Heterometric regulation: dependent on initial length of myocardium fibers
SECTON VI CIRCULATION Chapter 9~11

24. 11.1 MECHANICAL PROPERTIES OF THE CARDIAC MUSCLE
Contractility— inotropic effect
Homometric regulation: independent of initial length
Active regulation by the organism
SECTON VI CIRCULATION Chapter 9~11

25. 11.2 MECHANICAL EVENTS OF THE CARDIAC CYCLE
Pumping function is periodicity action
Heart rate: 60~100 beats/min
Cardiac cycle: 0.8s (~72 beats/min)
Systole and diastole
Atria systole and diastole
Ventricular systole and diastole
Whole cardiac diastole
SECTON VI CIRCULATION Chapter 9~11

26. 11.2 MECHANICAL EVENTS OF THE CARDIAC CYCLE
Mechanism events: filling and ejection: driving the blood flow from vein to artery in certain direction
Difference pressure between atria, ventricles and arteries
Valves status: opened or closed
Change of volume in ventricular chambers
Direction of blood flow
SECTON VI CIRCULATION Chapter 9~11

27. 11.2 MECHANICAL EVENTS OF THE CARDIAC CYCLE
Atria systole
Events in late diastole
The mitralis and tricuspid are opened and the aortic and pulmonary valves are closed
Blood flows: into the heart from caval vein, filling the atria and ventricles
Pressure in the ventricles remains low
SECTON VI CIRCULATION Chapter 9~11

28. 11.2 MECHANICAL EVENTS OF THE CARDIAC CYCLE
Atria systole
Atrial systole starts after the P wave of the ECG
Propels some additional blood into the ventricles
Vena cava and pulmonary veins narrowed
Vome regurgitation of blood into the veins during atrial systole
SECTON VI CIRCULATION Chapter 9~11

29. 11.2 MECHANICAL EVENTS OF THE CARDIAC CYCLE
Ventricular systole
Ventricular systole starts near the end of the R wave and ends just after the T wave of the ECG
Isovolumetric ventricular contraction
lasts about 0.05 s
Mitral and tricuspid (AV) valves all closed
Intraventricular pressure rises sharply as the myocardium presses on the blood
No blood into or out the ventricles
SECTON VI CIRCULATION Chapter 9~11

30. 11.2 MECHANICAL EVENTS OF THE CARDIAC CYCLE
Ventricular ejection
the ventricular pressures exceed aorta (80 mm Hg; 10.6 kPa) and pulmonary artery (10 mm Hg)
The aortic and pulmonary valves open
Propels blood into the large arteries more rapidly
SECTON VI CIRCULATION Chapter 9~11

31. 11.2 MECHANICAL EVENTS OF THE CARDIAC CYCLE
Ventricular diastole
Isovolumetric ventricular relaxation
Ventricular pressure continues to drop rapidly
The aortic and pulmonary valves are closed
Ventricular filling
Pressure falls below the atrial pressure
the AV valves open, permitting the ventricles to fill
SECTON VI CIRCULATION Chapter 9~11

32. 11.2 MECHANICAL EVENTS OF THE CARDIAC CYCLE
Heat sounds
1st sounds: 0.15 s, Hz
Myocardium contraction
Flow impacting the cardiac wall
Vibration set up by closure of A-V valves
2nd sounds: 0.12 s, 50 Hz.
Vibrations associated with closure of arterial valves
Arterial roots vibration
SECTON VI CIRCULATION Chapter 9~11

33. 11.3 CARDIAC OUTPUT 11.3.1 Cardiac output in various conditions
Stroke volume & ejection fraction
Cardiac output (CO, minute cardiac output)
CO=Stroke volume × Heart rate
CO=70mL/beat×72/min=5.0L/min
Cardiac index=CO/m2
SECTON VI CIRCULATION Chapter 9~11

34. 11.3 CARDIAC OUTPUT 11.3.2 Factors controlling cardiac output
Control of stroke volume：the major factors influencing force of contraction
Intrinsic regulation: the Frank-Starling mechanism
Venous flow returned →changes in end-diastolic volume →heterometric autoregulation
SECTON VI CIRCULATION Chapter 9~11

35. 11.3 CARDIAC OUTPUT
Extrinsic regulation: sympathetic stimulation, epinephrine
To increase myocardial contractility (inotropic status)→ the force of contraction at any given end-diastolic volume → hotmometric regulation
SECTON VI CIRCULATION Chapter 9~11

36. 11.3 CARDIAC OUTPUT Afterload: the arterial pressures
Against which the ventricles pump
Increasing pressures decrease the strength of contraction
SECTON VI CIRCULATION Chapter 9~11

37. 11.3 CARDIAC OUTPUT Control of heart rate Cardiac nerves Epinephrine
Parasympathetic nerves (Cardiac Vagus) :  heart rate
Sympathetic nerves:  heart rate
Epinephrine
 heart rate
SECTON VI CIRCULATION Chapter 9~11

38. 11.4 CARDIAC RESERVE During exercise CO →20~25L/min→35L/min
Heart reserve
Stroke volume reserve
Systolic reserve
Diastolic reserve
SECTON VI CIRCULATION Chapter 9~11

39. Pumping procedure Atria systole and diastole Ventricular systole
Isovolumetric ventricular contraction
Ventricular ejection
Ventricular relaxation
Isovolumetric ventricular relaxation
Ventricular filling
SECTON VI CIRCULATION Chapter 9~11

40. SECTON VI CIRCULATION Chapter 9~11