1. Chapter 19: Functions of the Blood Vessels Chapter 19: Functions of the Blood Vessels

2. Copyright © 2007 by Saunders, an imprint of Elsevier Inc. All rights reserved. 2 The Blood Vessels Deliver Functions of blood vessels: 1.Act as a delivery system 2.Regulate blood pressure 3.Engage in the exchange of nutrients and waste between the capillaries and cells 4.Redistribute blood in response to changing body needs 5.Help regulate body temperature Functions of blood vessels: 1.Act as a delivery system 2.Regulate blood pressure 3.Engage in the exchange of nutrients and waste between the capillaries and cells 4.Redistribute blood in response to changing body needs 5.Help regulate body temperature

3. Copyright © 2007 by Saunders, an imprint of Elsevier Inc. All rights reserved. 3 The Blood Vessels Deliver (cont’d.) “5 Cool Ps” of occlusive arterial disease: –Pain –Pulselessness –Pallor –Paresthesia –Paralysis –Coolness “5 Cool Ps” of occlusive arterial disease: –Pain –Pulselessness –Pallor –Paresthesia –Paralysis –Coolness

4. Copyright © 2007 by Saunders, an imprint of Elsevier Inc. All rights reserved. 4 Blood Vessels Regulate Blood Pressure Blood pressure: force of blood presses against the walls of the blood vessels Systolic pressure: pressure in the arteries at the peak of ventricular contraction Diastolic pressure: pressure in the large arteries when the ventricles of the heart are relaxing Pulse pressure: difference between systolic and diastolic pressure Blood pressure: force of blood presses against the walls of the blood vessels Systolic pressure: pressure in the arteries at the peak of ventricular contraction Diastolic pressure: pressure in the large arteries when the ventricles of the heart are relaxing Pulse pressure: difference between systolic and diastolic pressure

5. Copyright © 2007 by Saunders, an imprint of Elsevier Inc. All rights reserved. 5 Blood Vessels Regulate Blood Pressure (cont’d.) Normal range: 100 to 140 mm Hg (systolic) and 60 to 90 mm Hg (diastolic) for adult males Hypertension: chronic elevation of blood pressure Korotkoff sounds: caused by blood flow through an artery Normal range: 100 to 140 mm Hg (systolic) and 60 to 90 mm Hg (diastolic) for adult males Hypertension: chronic elevation of blood pressure Korotkoff sounds: caused by blood flow through an artery

6. Copyright © 2007 by Saunders, an imprint of Elsevier Inc. All rights reserved. 6 Blood Vessels Regulate Blood Pressure (cont’d.)

7. Copyright © 2007 by Saunders, an imprint of Elsevier Inc. All rights reserved. 7 Blood Vessels Regulate Blood Pressure (cont’d.)

8. Copyright © 2007 by Saunders, an imprint of Elsevier Inc. All rights reserved. 8 Blood Vessels Regulate Blood Pressure (cont’d.) Skeletal muscle pump.

9. Copyright © 2007 by Saunders, an imprint of Elsevier Inc. All rights reserved. 9 Blood Vessels Regulate Blood Pressure (cont’d.) Respiratory pump: effect of respiratory activity on venous blood flow Venoconstriction: constriction of the veins pushes additional blood out of the veins toward the heart Respiratory pump: effect of respiratory activity on venous blood flow Venoconstriction: constriction of the veins pushes additional blood out of the veins toward the heart

10. Copyright © 2007 by Saunders, an imprint of Elsevier Inc. All rights reserved. 10 Blood Vessels Regulate Blood Pressure (cont’d.) Relationship between pressure and force.

11. Copyright © 2007 by Saunders, an imprint of Elsevier Inc. All rights reserved. 11 Blood Vessels Regulate Blood Pressure (cont’d.) Vasodilation: muscles relax and the openings of the arterioles increase; resistance decreases in the blood vessels Vasoconstriction: muscles contract and the openings of the arterioles become smaller; resistance increases in the blood vessels Vasodilation: muscles relax and the openings of the arterioles increase; resistance decreases in the blood vessels Vasoconstriction: muscles contract and the openings of the arterioles become smaller; resistance increases in the blood vessels

12. Copyright © 2007 by Saunders, an imprint of Elsevier Inc. All rights reserved. 12 Blood Vessels Regulate Blood Pressure (cont’d.)

13. Copyright © 2007 by Saunders, an imprint of Elsevier Inc. All rights reserved. 13 Blood Vessels Regulate Blood Pressure (cont’d.) Blood pressure = cardiac output × vascular resistance Cardiac output: amount of blood pumped by the heart each minute Vasopressors: substances that cause vasoconstriction and elevate blood pressure Blood pressure = cardiac output × vascular resistance Cardiac output: amount of blood pumped by the heart each minute Vasopressors: substances that cause vasoconstriction and elevate blood pressure

14. Copyright © 2007 by Saunders, an imprint of Elsevier Inc. All rights reserved. 14 Blood Vessels Regulate Blood Pressure (cont’d.) Rapidly acting mechanisms for blood pressure regulation: –Baroreceptor reflex –Sympathetic nervous system stimulation –Parasympathetic nervous system stimulation Rapidly acting mechanisms for blood pressure regulation: –Baroreceptor reflex –Sympathetic nervous system stimulation –Parasympathetic nervous system stimulation

15. Copyright © 2007 by Saunders, an imprint of Elsevier Inc. All rights reserved. 15 Blood Vessels Regulate Blood Pressure (cont’d.) Baroreceptor reflex structures: receptors, sensory nerves, medulla oblongata, and motor nerves Baroreceptors: pressure receptors located in the walls of the aortic arch and carotid sinus Baroreceptor reflex structures: receptors, sensory nerves, medulla oblongata, and motor nerves Baroreceptors: pressure receptors located in the walls of the aortic arch and carotid sinus

16. Copyright © 2007 by Saunders, an imprint of Elsevier Inc. All rights reserved. 16 Blood Vessels Regulate Blood Pressure (cont’d.) Slower-acting mechanisms for blood pressure regulation: –Renin-angiotensin-aldosterone mechanism –Antidiuretic hormone (ADH) –Atrial natriuretic peptide (ANP) –Brain natriuretic peptide (BNP) Slower-acting mechanisms for blood pressure regulation: –Renin-angiotensin-aldosterone mechanism –Antidiuretic hormone (ADH) –Atrial natriuretic peptide (ANP) –Brain natriuretic peptide (BNP)

17. Copyright © 2007 by Saunders, an imprint of Elsevier Inc. All rights reserved. 17 Blood Vessels Act as Exchange Vessels

18. Copyright © 2007 by Saunders, an imprint of Elsevier Inc. All rights reserved. 18 Blood Vessels Act as Exchange Vessels (cont’d.) Capillaries as exchange vessels: –Thin capillary walls –Millions of capillaries –Slow velocity of blood flow Capillaries as exchange vessels: –Thin capillary walls –Millions of capillaries –Slow velocity of blood flow

19. Copyright © 2007 by Saunders, an imprint of Elsevier Inc. All rights reserved. 19 Blood Vessels Act as Exchange Vessels (cont’d.)

20. Copyright © 2007 by Saunders, an imprint of Elsevier Inc. All rights reserved. 20 Blood Vessels Act as Exchange Vessels (cont’d.) Capillary exchange processes: –Diffusion: substance moves downhill from an area of high concentration to an area of low concentration –Filtration-osmosis: outward and inward movement of water and dissolved substances Capillary exchange processes: –Diffusion: substance moves downhill from an area of high concentration to an area of low concentration –Filtration-osmosis: outward and inward movement of water and dissolved substances

21. Copyright © 2007 by Saunders, an imprint of Elsevier Inc. All rights reserved. 21 Blood Vessels Distribute Blood Flow Distribution of blood flow at rest and exercise.

22. Copyright © 2007 by Saunders, an imprint of Elsevier Inc. All rights reserved. 22 Blood Vessels Distribute Blood Flow (cont’d.) Distribution of blood flow: –Vasodilation –Vasoconstriction Distribution of blood flow: –Vasodilation –Vasoconstriction

23. Copyright © 2007 by Saunders, an imprint of Elsevier Inc. All rights reserved. 23 Blood Vessels Regulate Body Temperature Role of blood vessels: –Dissipate heat –Conserve heat Role of blood vessels: –Dissipate heat –Conserve heat