1. NOTES: BLOOD VESSELS – Arteries and Veins (UNIT 6 part 2)

2. Blood vessels form
a closed circuit of
tubes that carry
blood from the
heart to body cells
and back again.
*composed of arteries, arterioles, capillaries, venules, & veins

3. Blood Vessels
3 kinds of blood vessels: Arteries, veins, and capillaries
Arteries- any vessel that carries blood away from the heart
Adapted to carry blood away under high pressure
Small arteries are called arterioles
Arteries are also mainly distributors which carry blood to the arterioles
Veins- any vessel that carries blood to the heart
Small veins are called venules
Veins are both collectors and reservoir vessels by returning blood to the heart and accommodating varying amounts of blood

4. 3. Capillaries- microscopic vessels that carry blood from arterioles to venules
smallest diameter blood vessel (1 blood cell)
Although the smallest type of vessel, these are the most important because they are the primary exchange vessels of the cardiovascular system
capillary wall = a single layer of cells; forms a semipermeable membrane
There are so many capillaries that it if they were joined end to end they would stretch 62,000 miles

5. Capillary in muscle tissue

6. CAPILLARIES
● tissues that use more energy/oxygen have the most capillaries (i.e. muscle tissue, nerve tissue)
● tissues that use less energy/oxygen have the fewest capillaries (i.e. epidermis, cartilage, tendons)

7. Exchanges in Capillaries:
● blood in capillaries drops off their nutrients and oxygen in exchange for metabolic wastes (CO2, etc.)
● large molecules (e.g. plasma proteins) remain in the blood
● most materials move across the capillary wall by DIFFUSION

9. General Vessel Structure
Outer Layer: Tunica adventitia
“Coat that comes first”
Made of strong, flexible fibrous connective tissue that helps hold vessels open and prevents the tearing of vessel walls during movement
Middle Layer: Tunica Media
“Middle coat”
Made of elastic connective tissue and smooth muscle that permit changes in blood vessel diameter
Thicker in arteries than veins

10. LUMEN!
tunica=
cloak

11. Innermost Layer: Tunica Intima
“Innermost coat”
Made up of endothelium that forms a completely smooth lining
Also forms valves in veins

14. *When smooth muscles in the tunica media contract, artery diameter decreases:
VASOCONSTRICTION
*When smooth muscles
relax, artery diameter
increases:
VASODILATION

15. Circulatory Route VEINS ARTERIES -carry blood to the -carry blood away
heart
-largest vein = Vena Cava
ARTERIES
-carry blood away
from heart
-largest artery = AORTA
ARTERIOLES
VENULES
CAPILLARIES
-walls are only
1 cell thick

16. Pulmonary Circuit
Systemic Circuit

17. ARTERIAL SYSTEM Major Arteries exiting the heart:
● PULMONARY ARTERIES (from heart to lungs)
● AORTA (from heart to body)

18. AORTA: ● the aorta is the largest artery (diameter)
● the aorta can be divided into the:
*ASCENDING AORTA (as it emerges from the heart)
*AORTIC ARCH
*DESCENDING AORTA

19. Principal branches of the ASCENDING AORTA & AORTIC ARCH:
● the major branches are the:
*CORONARY ARTERIES (branch off from the base of the ascending aorta to supply myocardial cells)
*BRACHIOCEPHALIC (branch of the aortic arch)
*LEFT COMMON CAROTID (branch of the aortic arch)
*LEFT SUBCLAVIAN (branch of the aortic arch)

20. Arteries to the Neck, Head, and Brain
● the brachiocephalic artery branches into the:
R COMMON CAROTID and R SUBCLAVIAN

22. Arteries to the Shoulder and Arm
● the subclavian artery becomes the:
*AXILLARY ARTERY (wall of chest) – which becomes the:
*BRACHIAL ARTERY (upper arm) – which branches into the:
*ULNAR ARTERY (parallels the ulna) & the
*RADIAL ARTERY (parallels the radius)

24. **as the radial artery nears the wrist, it approaches the surface and provides a convenient vessel for taking the “pulse” (RADIAL PULSE)  # beats per minute

25. Principal branches of the DESCENDING AORTA:
● the descending aorta gives rise to the:
*THORACIC AORTA and
*ABDOMINAL AORTA
● the abdominal aorta gives rise to the:
*R and L RENAL arteries (go to the kidneys)
*MESENTERIC arteries (go to intestines)
*R and L COMMON ILIAC arteries (supplies blood to pelvis & legs)

28. Arteries to the Pelvis and Legs
● each common iliac artery divides into an:
Internal iliac artery
External iliac artery (main
blood supply to lower limbs)

29. Int. iliac

30. Arteries to the Legs ● the external iliac artery becomes the:
*FEMORAL ARTERY – which becomes the:
*POPLITEAL ARTERY (knee joint)
● the popliteal artery divides
into the:
*ANTERIOR and
POSTERIOR TIBIAL
ARTERIES

32. VENOUS SYSTEM Characteristics of Venous Pathways:
veins return blood to the heart
many veins are hard to follow/identify because they connect in irregular pathways
 the larger veins typically parallel the arteries (and have the same names as their arterial counterparts)
(ex: renal vein parallels the renal artery; femoral vein parallels the femoral artery, ulnar artery/ulnar vein, etc.)

34. Major Veins entering the heart:
● PULMONARY VEINS (oxygenated blood from lungs to heart)
● SUPERIOR VENA CAVA (from head and arms)
● INFERIOR VENA CAVA (from torso & legs; both drain into the R atrium)

35. Veins from the Brain/Head:
● JUGULAR VEINS: bringing deoxygenated blood from the head and face back towards the heart (R atrium) ultimately through the SUPERIOR VENA CAVA

36. COOL!!!!!

37. Some Veins from the Abdominal Cavity:
● RENAL VEINS: deoxygenated & filtered blood leaving the kidneys
● HEPATIC VEINS: deoxygenated blood leaving the liver; also contains digestion products
● both carry blood to the INFERIOR VENA CAVA

38. The longest vein is found in the leg:
**GREAT SAPHENOUS VEIN: runs upward along the medial side of the leg and thigh; penetrates deep into the thigh and joins with the femoral vein
 Can be removed & used for heart bypass surgeries

39. Great Saphenous
Vein