1. 13 - 1 Chapter 13 The Cardiovascular System: Blood Vessels

2. 13-1: Blood Vessels  Blood flow from heart: arteries arterioles capillaries venules veins arteries  arterioles  capillaries  venules  veins Structure of Vessel Walls  Three layers:  Tunica intima  Tunica intima—innermost layer  Tunica media  Tunica media—middle layer, thickest  Tunica externa  Tunica externa—covers outside of vessel 13 - 2

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4.  Vasoconstriction lumen vasodilation  Vasoconstriction decreases lumen size, vasodilation increases lumen size Arteries & Arterioles  Elastic arteries  Elastic arteries—large vessels (aorta, pulmonary arteries, major arteries)  Muscular arteries  Muscular arteries—distribute blood to muscles & internal organs  Arterioles have smallest lumen 13 - 4

5. Capillaries  Have thin walls to allow rapid gas exchange from blood to tissues capillary bed  Form interconnected network of capillaries in a capillary bed 13 - 5

6. Veins & Venules  Venules  Venules—smallest veins  Medium-sized veins  Medium-sized veins—similar to muscular arteries valves  Contain valves to prevent backflow of blood  Large veins  Large veins—largest veins (vena cavae) 13 - 6

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9. 13-1 Checkpoint 1.List the 5 types of blood vessels. 2.A cross section of a vessel shows a small, thin-walled vessel with very little muscle tissue in the tunica media. Which type of vessels are these? 3.Why are valves found in veins, but not in arteries? 13 - 9

10. 13-2: Pressure & Resistance Factors Affecting Blood Flow pressure increases  When pressure increases, blood flow increases  Blood flows from high pressure to low pressureResistance resistance decreases  When resistance increases, blood flow decreases  Resistance opposes movement of blood 13 - 10

11.  Vascular resistance  Vascular resistance—largest component of resistance  Friction between blood & blood vessels creates resistance  Viscosity  Viscosity—resistance to flow  Low viscosity flows faster than high viscosity  Turbulence  Turbulence—irregular internal surfaces slows blood flow & increases resistance 13 - 11

12. Cardiovascular Pressures Blood Pressure (Arterial Pressure)  Systolic pressure  Systolic pressure—peak BP during ventricular contraction  Diastolic pressure  Diastolic pressure—minimum BP during ventricular relaxation  Pulse  Pulse is wave of blood through an artery 13 - 12

13. Alterations in BP  Hypotension  Hypotension—systolic BP below 100  Caused by blood loss or variations in body size, fitness level  Hypertension  Hypertension—sustained BP of 140/90  Caused by diet, obesity, age, race, heredity, stress, smoking, kidney disorders 13 - 13

15. Capillary Pressures  Capillary pressure  Capillary pressure—pushes against capillary walls for:  Distribution of nutrients, hormones, gases  Moving proteins & lipids  Flushing toxins  Movement of materials across capillary walls occurs through diffusion, filtration, or osmosis 13 - 15

16. Venous Pressure  Venous pressures are low  Venous blood must flow against gravity to return to heart  Muscular compression  Muscular compression—skeletal muscles contract to push venous blood  Respiratory pump  Respiratory pump—breathing assists in venous fill 13 - 16

17. 13-2 Checkpoint 1.In a healthy individual, where is blood pressure greater: at the aorta or at the vena cava? Explain. 2.While standing in the hot sun, Sally begins to feel light-headed & then faints. Explain what happened. 13 - 17

18. 13-3: Cardiovascular Regulation Autoregulation of Blood Flow  Vasodilators vasoconstrictors  Vasodilators dilate capillaries; vasoconstrictors constrict capillaries Neural Control of BP & Blood Flow  Vasomotor center in medulla oblongata controls diameters of arterioles  Venoconstriction  Venoconstriction—constricts veins 13 - 18

19. Baroreceptor Reflexes  Baroreceptors monitor stretch in organs & vessels  Increased BP = decreased cardiac output, vasodilation  Decreased BP = increased cardiac output, vasoconstriction 13 - 19

20. 13-3 Checkpoint 1.Describe the actions of vasodilators and vasoconstrictors. 2.How does vasodilation decrease an elevated blood pressure? 13 - 20

21. 13-4: Stressors Exercise & the Cardiovascular System  Vasodilation increases blood flow  Venous return increases  Cardiac output rises due to increased venous return 13 - 21

22. Cardiovascular Response to Bleeding  Short-term responses  BP elevated by increasing heart rate & vasoconstriction  Long-term response:  Increased fluid retention  Erythropoietin stimulates more RBC production 13 - 22

23. 13-4 Checkpoint 1.Why does blood pressure increase during exercise? 2.Name the immediate and long-term problems related to the cardiovascular response to bleeding. 13 - 23

24. 13-5: Cardiovascular Circuits  Pulmonary circuit  Pulmonary circuit— arteries & veins that transport blood between heart & lungs  Systemic circuit  Systemic circuit— arteries & veins that distribute blood between heart & body 13 - 24

25.  Patterns of blood vessels  Arteries & veins on L & R sides usually identical in location  Single vessel may undergo several name changes  Tissues & organs perfused by several arteries & veins 13 - 25

26. 13-5 Checkpoint 1.Identify the two circuits of the cardiovascular system. 2.Identify the three general functional patterns of the body’s blood vessels. 13 - 26

27. 13-6: Pulmonary Circuit Vessels pulmonary trunk  Blood enters pulmonary trunk & moves to lungs  Releases CO 2, picks up O 2, returns to heart  Pulmonary arteries  Pulmonary arteries carry deoxygenated blood to lungs  Pulmonary arterioles alveoli  Pulmonary arterioles provide blood to lung’s alveoli for gas exchange  Pulmonary veins  Pulmonary veins carry oxygenated blood to heart 13 - 27

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29. 13-6 Checkpoint 1.Name the blood vessels that enter & exit the lungs, and indicate the oxygen content of the blood in each. 2.Trace the path of a drop of blood through the lungs, beginning at the right ventricles and ending in the left atrium. 13 - 29

30. 13-7: Systemic Circuit Vessels Ascending Aorta  Ascending aorta becomes aortic arch & descending aorta Arteries of the Aortic Arch  Supply blood to head, neck, shoulders, & upper limbs  Carotid, subclavian, axillary, brachial, radial/ulnar 13 - 30

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32. Descending Aorta  Supplies blood to vertebral column, organs, lower limbs  Thoracic, abdominal, iliac, femoral, tibial/fibular 13 - 32

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35. Systemic Veins  Arteries & veins often run side-by-side & have similar names Superior Vena Cava  Receives blood from head, neck, upper limbs, shoulders, & chest  Jugular, radial/ulnar, brachial, axillary, brachiocephalic 13 - 35

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37. Inferior Vena Cava  Collects blood from organs below diaphragm  Tibial/fibular, femoral, iliac, hepatic portal system 13 - 37

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40. 13-7 Checkpoint 1.A blockage in which major artery would interfere with blood flow to the left arm? 2.Grace is in an automobile accident, and her descending aorta is ruptured. Which organs will be affected most directly by this injury? 3.How do the jugular veins differ from the carotid arteries? How are they similar? 13 - 40