1. Blood Vessels Chapter 22

2. Introduction –Blood vessels Carry blood away from the heart - arteries Transport blood to tissues - capillaries Return blood to the heart – veins

3. Walls of Blood Vessels –3 layers Inner layer is endothelium = tunica intima Middle layer = tunica media Outer layer = tunica externa –Vasa vasorum are the vessels that supply the larger blood vessels

4. Walls of Blood Vessels

5. Arteries –Elastic arteries are the large arteries –Muscular arteries are the smaller arteries –Arterioles are very small, <0.5mm in diameter Capable of vasoconstriction and vasodilation

6. Systemic Arterial System

7. Major Arteries of the Trunk

8. Arteries of the Chest and Upper Extremity

9. Capillaries –The most important of the vessels All blood-tissue exchange occurs here –Tissue is entirely tunica intima –Three types Continuous – intact epithelial lining –Eg. Muscle & nervous tissue Fenestrated – have openings in their walls –Eg. Intestines & kidneys Sinusoids – lumen is larger; blood flow is slow –Eg. Liver, spleen, & bone marrow –Capillary beds with precapillary sphincters

10. Capillaries

11. Capillary Bed

12. Veins –Venules are very small, contain only tunica intima and tunica externa –Medium-sized veins –Large veins –Veins contain the same 3 layers as arteries Tunica media is much thinner than in arteries Tuna externa is the thickest layer –Some veins contain valves Prevent blood from flowing backwards

13. Systemic Venous System

14. Venous System of the Trunk and Upper Limb

15. Veins with Valves

16. Disorders –Varicose veins –Hypertension –Atherosclerosis

17. Atherosclerosis