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Cardiovascular System

Cardiovascular System. Week 10 Dr. Walid Daoud A. Professor. Cardiac Cycle ___________________________________________________________________________________________________________________________________________.

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Cardiovascular System

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  1. CardiovascularSystem Week 10 Dr. Walid Daoud A. Professor

  2. Cardiac Cycle___________________________________________________________________________________________________________________________________________ It is the events that occur in the cardiac muscle during systole and diastole. It consists of depolarization of atria followed by depolarization of ventricles then repolarization of the whole heart. 1-Atrial systole. 2-Ventricular systole. 3-Diastole of the whole heart.

  3. Phases of Cardiac Cycle___________________________________________________________________________________________________________________________________________ Cardiac cycle duration is 0.8 sec. (7 phases): 1-Atrial systole. 2-Isovolumetric ventricular contraction. 3-Rapid ejection phase. 4-Reduced ejection phase. 5-Isovolumetric relaxation phase. 6-Rapid ventricular filling. 7-Reduced ventricular filling.

  4. Comparison between Isovolumetric Phases____________________________________________________________________________________________________________________________________________

  5. Differences between the two audible sounds____________________________________________________________________________________________________________________________________________

  6. Pulse____________________________________________________________________________________________________________________________________________Pulse____________________________________________________________________________________________________________________________________________ It is due to propagation of waves of blood in arteries during max. ejection phase (systole). It is felt from any superficial artery e.g. radial. Clinical significance of arterial pulse palpation: - Counting heart rate / min. (rate). - Detection of regularity of heart (rhythm). - Detection of blood volume. - Equality on both sides. - Blood pressure. - State of arterial wall.

  7. Cardiac Output (CO)____________________________________________________________________________________________________________________________________________ It is volume of blood pumped by each ventricle per minute. Stroke volume (SV): Volume of blood pumped by each ventricle per beat. SV = EDV – ESV = 135 – 65 = 70 ml. CO = SV x HR = 70 x 70 = about 5 L/min. Cardiac index: = CO / square meter surface area of the body. = 3.2 L / min / m2

  8. Cardiac Output (CO)____________________________________________________________________________________________________________________________________________ CO increases in: Excitement (50-100%), eating (30%), exercise (700%), inspiration, adrenaline, high temperature, end of pregnancy. CO decreases in: Sitting or standing from lying position. Rapid arrhythmia. Heart failure.

  9. Cardiac Output (CO)___________________________________________________________________________________________________________________________ Measurement: O2 consumption = CO x (A-V) O2 difference CO = O2 consumption per min. (A-V) O2 difference = 250 = 250 = 5 L / min. 180-130 50

  10. Regulation of Cardiac Output __________________________________________________________________________________________________________________________________________ 1-Intrinsic mechanism: It is ability of heart to ↑ force of contraction i.e, ↑ SV while heart rate is unchanged. It is independent on nerves or hormones. SV = EDV – ESV SV can be ↑ either by ↑ EDV or ↓ ESV

  11. Stages of intrinsic regulation___________________________________________________________________________________________________________________________________________

  12. Stages of intrinsic regulation___________________________________________________________________________________________________________________________________________

  13. Regulation of Cardiac Output __________________________________________________________________________________________________________________________________________ 2-Extrinsic regulation: This mechanism adjusts both HR and SV through: - Nervous regulation (Autonomic nerves). - Hormonal regulation.

  14. Nervous Regulation of CO____________________________________________________________________________________________________________________________________________

  15. Nervous Regulation of CO___________________________________________________________________________________________________________________________________________

  16. Nervous Regulation of CO___________________________________________________________________________________________________________________________________________ Vagal and Sympathetic Tones: Tone is a continuous discharge of both sympathetic and vagi to the heart but vagal tone is stronger so cutting all nerves to the heart, HR increases to 90/min which is the original SAN rate of discharge i.e, the vagus inhibits the inherent rhythm of SAN.

  17. Nervous Regulation of CO___________________________________________________________________________________________________________________________________________ Vagal Escape Phenomenon: Powerful vagal stimulationslows the heart up to stopping. After short period of time the ventricles start to beat again, but at a slower rate known as idioventricular rhythm. This is due to: 1-Ventricles are not supplied by the vagus. 2-They contain automatic cells.

  18. Effects of Hormones & Drugs on Contractility of cardiac muscle________________________________________________________________________________________________________________________________________________________________

  19. Arterial Blood Pressure____________________________________________________________________________________________________________________________________________ ABP: pressure of blood on the arterial wall. Systolic pressure (SP): It is the maximal pressure reached during systole 120 mmHg (90-160). Diastolic pressure (DP): It is the maximal pressure reached during diastole 70 mmHg (60-90). Pulse Pressure = SP-DP = 50 mmHg. Mean Systemic Arterial Pressure: = DP + 1/3 Pulse pressure = 90 mmHg.

  20. Arterial Blood Pressure____________________________________________________________________________________________________________________________________________ Measurement: 1- Direct:by cardiac catheter. 2- Indirect:by sphigmomanometer. - Palpatory method. - Auscultatory method.

  21. Arterial Blood Pressure____________________________________________________________________________________________________________________________________________ Physiological Variation in ABP: 1- Age. 2- Sex. 3- Race. 4- Emotions. 5- Exercise. 6- Gravity 7- Respiration.

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