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Circulatory Responses

Circulatory Responses. Purpose. transport oxygen to tissues transport of nutrients to tissues removal of wastes regulation of body temperature. Organization. arteries - away from heart (oxygenated) veins - to heart (deoxygenated) arterioles - branches capillaries - smallest arteries

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Circulatory Responses

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  1. Circulatory Responses

  2. Purpose • transport oxygen to tissues • transport of nutrients to tissues • removal of wastes • regulation of body temperature

  3. Organization • arteries - away from heart (oxygenated) • veins - to heart (deoxygenated) • arterioles - branches • capillaries - smallest arteries • venules - smallest veins • mixed venous blood - from entire body

  4. Structure of the Heart

  5. pulmonary - pumps blood to the lungs and back to the left side of the heart from the lungs systemic - pumps blood to the rest of the body and back to the right side of the heart The Heart has Two Pumps

  6. The Myocardium

  7. Cardiac Cycle • Systole • contraction phase • 0.3 sec at rest down to 0.2 sec during heavy exercise • Diastole • relaxation phase • 0.5 sec at rest down to 0.13 sec during heavy exercise

  8. Systole Contraction phase Diastole Relaxation phase The Cardiac Cycle

  9. Pressure Changes During the Cardiac Cycle

  10. Insert fig 9.4 • two heart sounds • 1st closing of the atrioventricular valves • 2nd closing of the aortic and pulmonary valves

  11. Blood Pressure • arterial blood pressure estimated using sphygmomanometer • systolic/diastolic • males 120/80 • females 110/70 • Hypertension • resting BP of 140/90 • primary or secondary

  12. Blood Pressure Determination • Pulse pressure • difference between systolic and diastolic • Mean arterial pressure (MAP) • product of cardiac output and total vascular resistance (sig?) • average pressure during cardiac cycle • determines rate of blood flow through system • MAP = DBP +.33 (pulse pressure)

  13. Factors Affecting Blood Pressure • Blood pressure can be increase by • increase in blood volume • increase in heart rate • increase in blood viscosity • increase in stroke volume • increased peripheral resistance

  14. Anterior View of the Heart

  15. Normal electrocardiogram at rest

  16. Use of ECG for Diagnosis (ST depression)

  17. Q = HR x SV Q = cardiac output HR = heart rate SV = stroke volume Implications during exercise??? Cardiac Output

  18. Insert table 9.1

  19. Regulation of Heart Rate • Parasympathetic control • cardiovascular control center (medulla oblongota) • vagus nerve • acetylcholine decreases activity of both SA and AV nodes • can increase HR by removal

  20. HR Regulation cont’d • Sympathetic control • cardiac accelerator nerves at SA and AV nodes • norepinephrine released which increases HR and force of contraction • responsible above 100 bpm

  21. Autonomic Control of HR

  22. end diastolic volume (EDV) - volume of blood in ventricles at the end of diastole Frank-Starling Law increase in contractility increases volume pumped per beat venous return average aortic blood pressure strength of ventricular contraction Regulation of Stroke Volume

  23. venoconstriction reduces volume capacity of veins to store blood sympathetic control muscle pump respiratory pump inspiration reduces intrathoracic pressure Factors Regulating Venous Return

  24. The Skeletal Muscle Pump

  25. Components of Blood • Plasma • Liquid portion of blood • Contains ions, proteins, hormones • Cells • Red blood cells • Contain hemoglobin to carry oxygen • White blood cells • Platelets • Important in blood clotting • Hematocrit • Percent of blood composed of cells

  26. Hematocrit

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