Exercise 21

1. Exercise 21 Blood Vessels & Circulation Portland Community College BI 232

2. Blood vessels • Arteries transport blood away from the heart. • Deliver blood to capillary beds where gas and nutrient exchange occurs. • Veins transport blood toward the heart.

3. Martinipg. 711

4. Artery and VeinHistology • Walls have 3 layers: • Tunica intima • Tunica media • Tunica externa

5. Tunica Intima • Is the innermost layer near the lumen • Includes: • The endothelial lining • Connective tissue layer • Internal Elastic Membrane: In arteries, is a thick layer of elastic fibers in the outer margin of the tunica intima

6. Tunica Media • Is the middle layer • Contains concentric sheets of smooth muscle in loose connective tissue • Binds to inner and outer layers

7. Tunica Externa (aka: Tunica Adventitia) • Is outer layer • Contains connective tissue sheath • Anchors vessel to adjacent tissues • In arteries: • Contain collagen • Elastic fibers • In veins: • Contain elastic fibers • Smooth muscle cells

8. Arteries • Carry blood away from the heart. • Pulmonary arteries: The pulmonary trunk and its branches; leave the right ventricle of the heart and contain deoxygenated blood. • Systemic arteries: The aorta and its branches; leave the left ventricle of the heart and contain oxygenated blood.

9. Elastic Arteries • Also called conducting arteries, these are the largest arteries • Tunica media has many elastic fibers and few muscle cells • Elasticity evens out pulse force • Examples: • Pulmonary trunk • Aorta • Common carotid arteries • Subclavian arteries • Common iliac arteries

10. Aorta n = smooth muscle cell TA = tunica adventitia el = elastic fibers end = endothelial cells TI = tunica intimaTM = tunica media

11. Muscular Arteries • Also called distribution arteries, are medium-sized (most arteries) • Tunica media has many muscle cells • Examples: • External carotid arteries • Brachial arteries • Femoral arteries

12. Muscular Arteries

13. Arterioles • The smallest branches of arteries • Feed into capillaries • Have little or no tunica externa • Have thin or incomplete tunica media

14. Arteriole end = endothelial cell nucleusn = smooth muscle nucleusrbc = red blood cells end = endothelial cell nucleusn = smooth muscle nucleusrbc = red blood cells

15. Veins • Carry blood to the heart • Are larger in diameter than arteries • Have thinner walls • Contain valves • Folds of tunica intima that prevent blood from flowing backward • Venules: The smallest veins that carry blood away from the capillaries

16. Veins • Medium-sized veins: • Thin tunica media and few smooth muscle cells • Tunica externa with longitudinal bundles of elastic fibers • Large veins: • Have all 3 tunica layers • Thick tunica externa • Thin tunica media • Example: Inferior and Superior vena cava

17. Venous Valve in Medium Vein ad = adipose tissueTA = tunica adventitiaTM = tunica mediav = valve

18. Large Vein

19. Arteries Vs. Veins • Arteries and veins run side-by-side • Arteries have thicker walls and higher blood pressure • Collapsed artery has small, round lumen • Vein has a large, flat lumen

20. Vein Artery

21. Capillaries • The smallest vessels • Structure: Simple squamous epithelium tube • Lumen side has a thin basal lamina • No tunica media, No tunica externa • Location of exchange between blood and interstitial fluid. • Gasses and chemicals diffuse across their walls • Types: • Continuous • Fenestrated • Sinusoids

22. Continuous Capillaries • Have complete endothelial lining (most common type of capillary) • Permit diffusion of: • Water • Small solutes • Lipid-soluble materials • Prevent diffusion of: • Blood cells • Plasma proteins

23. Continuous Capillary

24. Continuous Capillaries Simple squamous epithelium RBC Basal lamina

25. Fenestrated Capillaries • Have pores in endothelial lining • Permit rapid exchange of water and larger solutes between plasma and interstitial fluid • Are found in: • Choroid plexus • Endocrine organs • Kidneys • Intestinal tract

26. Fenestrated Capillary

27. FenestratedCapillary Fenestrations

28. Sinusoids • Modified, extremely leaky, fenestrated capillaries • Found in locales where large stuff needs to exit/enter the bloodstream. • Liver • Spleen • Bone marrow • Endocrine organs

29. Sinusoid

30. Hepatic Sinusoid

31. Vasa Vasorum • “Vessels of Vessels” • Small arteries and veins in the walls of large arteries and veins • Supply cells of tunica media and tunica externa Vasa Vasorum Aorta

32. Activity 21.1 • View prepared slides of arteries and veins • Be able to ID layers under the microscope.

33. Aortic Arch Left Coronary A. Ascending Aorta Right Coronary A.

34. AorticArch Internal Carotid External carotid Common Carotid R. Vertebral R. Axillary a. R.Subclavian a. L.Subclavian a. Brachiocephalic Trunk

35. Right Common Carotid R.Subclavian Vertebral L..Subclavian Brachiocephalic Trunk Left Common Carotid

36. Circle of Willis Internal Carotid Vertebral External carotid

37. Axillary Artery R. Axillary a. Brachial a. Radial a. Ulnar a.

39. Circle of Willis Anterior communicating Anterior cerebral Internal Carotid (cut) Middle cerebral Posterior communicating Posterior cerebral Basilar L. Vertebral R. Vertebral

40. Anterior cerebral Internal Carotid Middle cerebral Posterior cerebral

41. AbdominalAorta Celiac Trunk Superior Mesenteric Renal A. Gonadal Inferior Mesenteric Common Iliac External Iliac Internal Iliac

42. Spleen Splenic a. Renal a.

43. Celiac Trunk Abdominal Aorta Common Hepatic Left Gastric Splenic Superior Mesenteric Inferior Mesenteric

45. Thigh Anterior Posterior External Iliac Femoral Deep Femoral

46. LowerLeg Femoral Popliteal Fibular Anterior tibial Fibular Posterior tibial Dorsalis Pedis

48. Superior Sagittal sinus Petrosal sinus Transverse Sinus Straight sinus

49. Petrosal sinus Cavernous sinus Superior Sagittal sinus Straight sinus Transverse sinus Internal Jugular Sigmoid sinus Brachiocephalic Right Left Vertebral Vein External Jugular Superior Vena Cava Subclavian vein

50. Brachiocephalic Right Left Subclavian vein Axillary vein Cephalic vein Brachial vein Basilic vein Hemiazygos Azygos