Introduction to Physiology (Course # 72336) 1 עקרונות בסיסיים (הכנה למעבדת לב) הלב Adi Mizrahi mizrahia@cc.huji.ac.il Textbook Chapter 12
2 The circulatory system To the heart Away from the heart 3 L 2.5 L ~ 70 Beats/min (24/7) Within reach of almost every cell in the body ~5.5 Liter THE SYSTEMIC AND PULMONARY CIRCULATION
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Hemodynamics - Pressure, Flow, and Resistance 5 F = P R flow R= 8L r 4 Blood flows from regions of high pressure to low pressure
Resistance and flow 6 F = P R R= 8L r 4
THE HEART 7
THE HEART 8
THE HEART 9
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THE CARDIAC CYCLE 11 Systole Diastole
Mid/late-diastole THE CARDIAC CYCLE 1= Ventricular filling 2= Isovolumetric ventricular contraction 3= ventricular ejection 4= Isovolumetric ventricular relaxation
Early Systole 1= Ventricular filling 2= Isovolumetric ventricular contraction 3= ventricular ejection 4= Isovolumetric ventricular relaxation
Systole 1= Ventricular filling 2= Isovolumetric ventricular contraction 3= ventricular ejection 4= Isovolumetric ventricular relaxation
Early Diastole 1= Ventricular filling 2= Isovolumetric ventricular contraction 3= ventricular ejection 4= Isovolumetric ventricular relaxation Stroke volume
HEART SOUNDS 16 AV valve Aorta-V Sounds: valve Where / who?
17 Cardiac Output = HR X SV Liters/min beats/min Liters/beat
18 Resting Well trained athlete 5 lit/min 35 lit/min Cardiac Output = HR X SV
CO = Heart Rate x SV 19 The inherent (autonomous) rhythm of the heart s pacemaker is ~100 beats/min Which is under neuronal and hormonal control Sympathetic stimulation Parasympathetic stimulation So why does our heart beat at 70 beats/min? Autonomic nervous system
CO = Heart Rate x SV 20 The inherent (autonomous) rhythm of the heart s pacemaker is ~100 beats/min Sympathetic stimulation Parasympathetic stimulation Only 70 because under normal conditions parasympathetic ti rules
CO = Heart Rate x SV 21 The SA node is the normal pacemaker of the heart!
CO = Heart Rate x SV 22
CO = Heart Rate x SV 23 Epinephrine acts on beta-adrenergic receptors of the SA node to accelerate heart rate Epinephrine HR
CO = Heart Rate x SV 24
CO = Heart Rate x SV 25 Stroke volume is affected by: 1. End diastolic volume (preload). 2. Sympathetic input to the ventricles. 3. Afterload.
END DIASTOLIC VOLUME (PRELOAD) 26 Stroke volume Skeletal l muscle Heart muscle Starling s law of the heart The higher the end diastolic volume The stronger is the contraction ti
THE SYMPATHETIC NERVES (and epinephrine) 27 Stroke volume Epinephrine and norepinephrine change the contractility of the heart s muscle Ejection fraction= SV/EDV Independent of the end diastolic volume!!!
THE SYMPATHETIC NERVES (and epinephrine) 28 Stroke volume Epinephrine and norepinephrine shorten the duration of cardiac cycle
CO = Heart Rate x SV 29 Stroke volume is affected by: 1. End diastolic volume (preload). 2. Sympathetic input to the ventricles. 3. Afterload.
לסיכום... 30 Cardiac output
Pressure in the vessels 31
Blood vessels are structurally t and functionally different 32 Pressure Size Resistance arteries low arterioles veins high low Number Composition Endothelium - common Smooth muscle Connective tissue variable
הלב עקרונות בסיסיים (הכנה למעבדה ( ARTERIES They have thick walls and lots of elastic tissue. Large diameter (low resistance). Act as blood reservoir for maintaining flow. 33
הלב עקרונות בסיסיים (הכנה למעבדה ( ARTERIES Blood pressure in a vessel is determined by: Volume of blood Compliance ( stretchability ) Compliance = volume / pressure 34
הלב עקרונות בסיסיים (הכנה למעבדה ( ARTERIES Input does not equal output (that s why arteries stretch during systole ) Output exceeds input (that s why arteries relax during diastole)
הלב עקרונות בסיסיים (הכנה למעבדה ( ARTERIES Pulse Pressure is determined by: SV, speed of SV ejection and contractility of the artery PP Pulse Pressure (PP) = P sys P dia Mean Arterial Pressure (MAP) = P dia + 1/3 (PP) 36
הלב עקרונות בסיסיים (הכנה למעבדה ( ARTERIOLES Determine the relative blood flow into organs Main factor in determining the MAP 37
הלב עקרונות בסיסיים (הכנה למעבדה ( ARTERIOLES Determine the relative blood flow into organs The arterioles diameters determine the flow into the organs (by changing g their resistance) F = P R flow 38
הלב עקרונות בסיסיים (הכנה למעבדה ( ARTERIOLES Determine MAP MAP (Mean Arterial Pressure) CO = X (Cardiac Output) TPR (Total Peripheral resistance) 39
הלב עקרונות בסיסיים (הכנה למעבדה ( ARTERIOLES Determine MAP When things are calm Inflow = outflow But when priorities change
הלב עקרונות בסיסיים (הכנה למעבדה ( ARTERIOLES P F = R Determine MAP 41
הלב עקרונות בסיסיים (הכנה למעבדה ( ARTERIOLES Determine MAP P F = R TPR a TPR b TPR a =TPR b =1/r 1 +1/r 2 +1/r 3 +1/r 4 +1/r 5
הלב עקרונות בסיסיים (הכנה למעבדה ( ARTERIOLES Determine MAP P F = R P= F X R MAP = CO X TPR 43
MAP = CO X TPR??? = CO X??? equal??? = CO X??? 44