1. Blood Vessels

2. Types of Blood Vessels Artery – carries blood away from the heart Artery – carries blood away from the heart Vein – A vessel that carries blood towards the heart Vein – A vessel that carries blood towards the heart Capillaries – microscopic vessels that carry blood from small arteries to small viens Capillaries – microscopic vessels that carry blood from small arteries to small viens

3. The Pathway of Blood ArteryArterioleCappillaryVenuoleVein

4. Blood Vessel Structure Tunica Intima (endothelium) Tunica Intima (endothelium) Tunica Media (smooth muscle; elastic connective tissue) Tunica Media (smooth muscle; elastic connective tissue) Tunica Adventitia (fibrous type of vessel connective tissue) Tunica Adventitia (fibrous type of vessel connective tissue)

6. Arteries Tunica Intima – Smooth lining Tunica Intima – Smooth lining Tunica Media – Allows constriction and dilation of vessels; thicker than in veins; muscle innervated by autonomic fibers Tunica Media – Allows constriction and dilation of vessels; thicker than in veins; muscle innervated by autonomic fibers Tunica Adventitia – Provides flexible support that resists collapse or injury; thicker than in veins; thinner than tunica media Tunica Adventitia – Provides flexible support that resists collapse or injury; thicker than in veins; thinner than tunica media

7. Veins Tunica Intima – Smooth lining with semi-lunar valves to ensure one way blood flow Tunica Intima – Smooth lining with semi-lunar valves to ensure one way blood flow Tunica Media – Allows constriction and dilation of vessels; thinner than in arteries; muscle innervated by autonomic fibers Tunica Media – Allows constriction and dilation of vessels; thinner than in arteries; muscle innervated by autonomic fibers Tunica Adventitia – Provides flexible support that resists collapse or injury; thinner than in arteries; thicker than tunica media Tunica Adventitia – Provides flexible support that resists collapse or injury; thinner than in arteries; thicker than tunica media

8. Cappillaries Tunica Intima – Makes up the entire wall of the capillary; thinness permits transport across vessel wall Tunica Intima – Makes up the entire wall of the capillary; thinness permits transport across vessel wall Tunica Media – Absent Tunica Media – Absent Tunica Adventitia – Absent Tunica Adventitia – Absent

9. Micrograph of Blood Vessel Structure This light micrograph of a cross section of tissue contains an artery (left) and a vein (right). Note the prominence of the smooth muscle (tunica media) in the artery compared to the vein

10. Function of Capillaries Most important vessels functionally Most important vessels functionally Very tiny (on average, only 1mm long) Very tiny (on average, only 1mm long) According to one estimate, 1 cubic cm of muscle tissue contains more than 100,000 capillaries According to one estimate, 1 cubic cm of muscle tissue contains more than 100,000 capillaries Primary exchange vessels Primary exchange vessels The small size and large number ensures slow blood flow The small size and large number ensures slow blood flow

11. Microcirculation

12. Function of Arteries Arteries serve mainly as “distributors,” carrying blood to the arterioles, which then carry blood to the capillaries Arteries serve mainly as “distributors,” carrying blood to the arterioles, which then carry blood to the capillaries Arterioles are important in maintaining normal blood pressure and circulation (resistance vessels) Arterioles are important in maintaining normal blood pressure and circulation (resistance vessels) Precapillary sphincters function as valves regulating blood flow into the capillaries Precapillary sphincters function as valves regulating blood flow into the capillaries

13. Function of Veins Function both as collectors and reservoir vessels (ability to hold blood) Function both as collectors and reservoir vessels (ability to hold blood) Capacitance -- Great ability to strech, therefore, they can hold large amounts of blood with almost no change in blood pressure Capacitance -- Great ability to strech, therefore, they can hold large amounts of blood with almost no change in blood pressure Valves maintain the one way flow of blood Valves maintain the one way flow of blood

14. The reservoir function of veins Pooled blood is moved toward the heart as valves are forced open by pressure from volume of blood from below. Closure of valves prevents backflow. Pooled blood is moved toward the heart as valves are forced open by pressure from volume of blood from below. Closure of valves prevents backflow.

15. Circulatory Routes Systemic Circulation – blood is pumped from the left side of the heart to all the tissues of the body Systemic Circulation – blood is pumped from the left side of the heart to all the tissues of the body Pulmonary Circulation – blood is pumped from the right side of the heart to the gas exchange tissues of the lungs Pulmonary Circulation – blood is pumped from the right side of the heart to the gas exchange tissues of the lungs

16. Blood Flow Through the Circulatory System

17. Main Arteries of the Body

18. The Aorta

19. Arteries of the Head and Neck

20. Arteries at the Base of the Brain

21. Major Arteries of the Upper Extremity

22. Major Arteries of the Loser Extremity

23. General Principles About Veins Veins branch into vessels of increasing size Veins branch into vessels of increasing size Vessels vary considerable in size and location from person to person Vessels vary considerable in size and location from person to person Veins found deep in the body are called deep veins and those found near the surface are called superficial veins Veins found deep in the body are called deep veins and those found near the surface are called superficial veins

24. Major Veins of the Body

25. Major Veins of the Head and Neck

26. Major Veins of the Upper Extremity

27. Principal Veins of the Thorax

28. Inferior Vena Cava and its Abdominopelvic Tributaries

30. Disorders of the Cardiovascular System

31. Mitral Valve Prolapse

32. Coronary Bypass

33. Partial Blockage of Artery in Atherosclerosis

34. Balloon Angioplasty

35. Varicose Veins