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Chapter 43

Chapter 43. Review of Hemodynamics. Review of Hemodynamics. Overview of the circulatory system Delivery of oxygen, nutrients, hormones, electrolytes, and other essentials to the cells Removal of carbon dioxide, metabolic wastes, and other detritus from cells Two major divisions

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Chapter 43

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  1. Chapter 43 Review of Hemodynamics

  2. Review of Hemodynamics • Overview of the circulatory system • Delivery of oxygen, nutrients, hormones, electrolytes, and other essentials to the cells • Removal of carbon dioxide, metabolic wastes, and other detritus from cells • Two major divisions • Pulmonary circulation and systemic circulation • Regulation of cardiac output • Regulation of arterial pressure (AP)

  3. Overview of the Circulatory System • Components of the circulatory system • Arteries • Arterioles • Capillaries • Venules • Veins

  4. Overview of the Circulatory System • Distribution of blood • 9% in the pulmonary circulation • 7% in the heart • 84% in the systemic circulation • What makes blood flow? • Force that drives flow is greater than resistance • How does blood get back to the heart?

  5. Fig. 43–1. Distribution of blood in the circulatory system.

  6. Fig. 43–2. Forces that promote and impede flow of blood.

  7. Fig. 43–3. Distribution of pressure within the systemic circulation.

  8. Regulation of Cardiac Output • Determinants of cardiac output • Average adult, 5 L/min • Cardiac output = Heart rate × Stroke volume • Heart rate • Controlled by the autonomic nervous system • Stroke volume • Myocardial contractility • Cardiac afterload • Cardiac preload • Preload • End-diastolic volume or end-diastolic pressure • Afterload • Arterial pressure the left ventricle must overcome to eject blood

  9. Regulation of Cardiac Output • Control of stroke volume by venous return • Starling’s law of the heart • Factors that determine venous return • Systemic filling pressure • Auxiliary muscle pumps • Resistance to flow between peripheral vessels and the right atrium • Right atrial pressure • Starling’s law and maintenance of systemic-pulmonary balance

  10. Fig. 43–4. Venous valves and the auxiliary venous “pump.”

  11. Fig. 43–5. The Starling relationship between myocardial fiber length and contractile force.

  12. Fig. 43–6. Systemic-pulmonary imbalance that develops when the output of the left and right ventricles is not identical.

  13. Regulation of Arterial Pressure • Overview of control system • AP = Peripheral resistance × Cardiac output • Arterial pressure is regulated by: • Autonomic nervous system (ANS) • Renin-angiotensin system • Kidneys

  14. Regulation of Arterial Pressure • Steady-state control by the ANS • Regulates AP by adjusting cardiac output (CO) and peripheral resistance • Rapid control by the ANS: the baroreceptor reflex • Constriction of nearly all arterioles • Constriction of veins • Acceleration of heart rate

  15. Regulation of Arterial Pressure • Renin-angiotensin-aldosterone system • Constriction of arterioles and veins (angiotensin II) • Retention of water by the kidney (aldosterone)

  16. Regulation of Arterial Pressure • Renal retention of water • Postural hypotension (orthostatic hypotension) • Natriuretic peptides • Protect the cardiovascular system in the event of volume overload • Three principal members • Atrial natriuretic peptide (ANP) • B (brain)-natriuretic peptide (BNP) • C-natriuretic peptide (CNP)

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