1. Copyright © 2013, 2010 by Saunders, an imprint of Elsevier Inc. Chapter 43 Review of Hemodynamics

2. 2Copyright © 2013, 2010 by Saunders, an imprint of Elsevier Inc. 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 Pulmonary circulation and systemic circulation  Regulation of cardiac output  Regulation of arterial pressure (AP)

3. 3Copyright © 2013, 2010 by Saunders, an imprint of Elsevier Inc. Overview of the Circulatory System  Components of the circulatory system  Arteries  Arterioles  Capillaries  Venules  Veins

4. 4Copyright © 2013, 2010 by Saunders, an imprint of Elsevier Inc. 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. 5Copyright © 2013, 2010 by Saunders, an imprint of Elsevier Inc. Fig. 43–1. Distribution of blood in the circulatory system.

6. 6Copyright © 2013, 2010 by Saunders, an imprint of Elsevier Inc. Fig. 43–2. Forces that promote and impede flow of blood.

7. 7Copyright © 2013, 2010 by Saunders, an imprint of Elsevier Inc. Fig. 43–3. Distribution of pressure within the systemic circulation.

8. 8Copyright © 2013, 2010 by Saunders, an imprint of Elsevier Inc. 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 Controlled by the autonomic nervous system  Stroke volume Myocardial contractility Myocardial contractility Cardiac afterload Cardiac afterload Cardiac preload Cardiac preload  Preload End-diastolic volume or end-diastolic pressure End-diastolic volume or end-diastolic pressure  Afterload Arterial pressure the left ventricle must overcome to eject blood Arterial pressure the left ventricle must overcome to eject blood

9. 9Copyright © 2013, 2010 by Saunders, an imprint of Elsevier Inc. 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 Systemic filling pressure Auxiliary muscle pumps Auxiliary muscle pumps Resistance to flow between peripheral vessels and the right atrium Resistance to flow between peripheral vessels and the right atrium Right atrial pressure Right atrial pressure  Starling’s law and maintenance of systemic- pulmonary balance

10. 10Copyright © 2013, 2010 by Saunders, an imprint of Elsevier Inc. Fig. 43–4. Venous valves and the auxiliary venous “pump.”

11. 11Copyright © 2013, 2010 by Saunders, an imprint of Elsevier Inc. Fig. 43–5. The Starling relationship between myocardial fiber length and contractile force.

12. 12Copyright © 2013, 2010 by Saunders, an imprint of Elsevier Inc. Fig. 43–6. Systemic-pulmonary imbalance that develops when the output of the left and right ventricles is not identical.

13. 13Copyright © 2013, 2010 by Saunders, an imprint of Elsevier Inc. Regulation of Arterial Pressure  Overview of control system  AP = Peripheral resistance × Cardiac output  Arterial pressure is regulated by: Autonomic nervous system (ANS) Autonomic nervous system (ANS) Renin-angiotensin system Renin-angiotensin system Kidneys Kidneys

14. 14Copyright © 2013, 2010 by Saunders, an imprint of Elsevier Inc. 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. 15Copyright © 2013, 2010 by Saunders, an imprint of Elsevier Inc. Regulation of Arterial Pressure  Renin-angiotensin-aldosterone system  Constriction of arterioles and veins (angiotensin II)  Retention of water by the kidney (aldosterone)

16. 16Copyright © 2013, 2010 by Saunders, an imprint of Elsevier Inc. 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) Atrial natriuretic peptide (ANP) B (brain)-natriuretic peptide (BNP) B (brain)-natriuretic peptide (BNP) C-natriuretic peptide (CNP) C-natriuretic peptide (CNP)