Lab Activity 25Blood Vessels & CirculationPortland Community CollegeBI 2322Artery and VeinHistology• Walls have 3 layers:• Tunica intima• Tunica media• Tunica externa3Tunica 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 intima4Tunica Media• Is the middle layer• Contains concentric sheets of smooth muscle in loose connective tissue• Binds to inner and outer layers5Tunica 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 cells6Arteries 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 lumen7Martinipg. 7118VeinArtery9Arteries• 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.10Elastic 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 arteries11n = smooth muscle cellTA = tunica adventitia TI = tunica intimaTM = tunica mediael = elastic fibersend = endothelial cellsAorta12Muscular Arteries• Also called distribution arteries, are medium-sized (most arteries)• Tunica media has many muscle cells• Examples:• External carotid arteries• Brachial arteries• Femoral arteries13Muscular Arteries14Arterioles• The smallest branches of arteries• Feed into capillaries• Have little or no tunica externa• Have thin or incomplete tunica media15Arterioleendend = endothelial cell nucleusn = smooth muscle nucleusrbc = red blood cells16Capillaries• 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• Sinusoids17Continuous 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 proteins18Continuous Capillary19Continuous CapillariesSimple squamous epitheliumRBCBasal lamina20Fenestrated 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 tract21Fenestrated Capillary22FenestratedCapillaryFenestrations23Sinusoids• Modified, extremely leaky, fenestrated capillaries • Found in locales where large stuff needs to exit/enter the bloodstream.• Liver• Spleen• Bone marrow• Endocrine organs24Sinusoid25Hepatic Sinusoid26Veins• 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 capillaries27Veins• 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 cava28Venous Valve in Medium Veinad = adipose tissueTA = tunica adventitiaTM = tunica mediav = valve29Large Vein30Vasa Vasorum• “Vessels of Vessels”• Small arteries and veins in the walls of large arteries and veins• Supply cells of tunica media and tunica externaAortaVasa Vasorum31Ascending AortaAortic ArchRight Coronary A.Left Coronary A.32AorticArchExternal carotidInternal CarotidR. VertebralCommon CarotidBrachiocephalic TrunkR. Axillary a.R.Subclavian a. L.Subclavian a.33Brachiocephalic TrunkLeft Common CarotidL..SubclavianR.SubclavianRight Common CarotidVertebral34External carotidInternal CarotidVertebralCircle of Willis35Axillary ArteryR. Axillary a.Brachial a.Radial a. Ulnar a.3637Circle of WillisR. VertebralL. VertebralBasilarInternal Carotid (cut)Anterior cerebralAnterior communicatingMiddle cerebralPosterior cerebralPosterior communicating38Middle cerebralPosterior cerebralAnterior cerebralInternal Carotid39AbdominalAortaCeliac TrunkSuperior MesentericGonadalRenal A.Inferior MesentericCommon IliacExternal IliacInternal Iliac40Renal a. SpleenSplenic a.41Abdominal AortaCeliac TrunkCommon HepaticLeft GastricSplenicInferior MesentericSuperior Mesenteric4243ThighExternal IliacFemoralDeep FemoralAnterior Posterior44LowerLegFemoralPoplitealAnterior tibialPosterior tibialFibularDorsalis PedisFibular4546Petrosal sinusSuperior Sagittal sinusTransverse SinusStraight sinus47Superior Sagittal sinusPetrosal sinusStraight sinusCavernous sinusTransverse sinusSigmoid sinusVertebral VeinInternal JugularExternal JugularSubclavian veinBrachiocephalicRightLeftSuperior Vena Cava48AzygosHemiazygosBrachiocephalicRight Left Subclavian veinAxillary veinCephalic veinBrachial veinBasilic vein49Axillary vein Cephalic veinBasilic veinBrachial veinMedian Cubital veinRadial veinUlnar veinBasilic veinCephalic vein5051Hepatic veinsRenal veinInferior Vena CavaCommon iliac veinExternal iliac veinInternal iliac vein5253FemoralDeep FemoralGreat SaphenousSmall SaphenousSmall SaphenousPoplitealPosterior TibialFibularAnterior Tibial54Anterior TibialSmall SaphenousGreat SaphenousPoplitealSmall SaphenousFemoralAnterior TibialPosterior TibialFibular5556Inferior Vena CavaHepatic veinsHepatic Portal veinInferior MesentericSuperior MesentericSplenic vein57The