Chapter 23, f 09

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Chapter 23, f 09

  1. 1. Human Anatomy, Second Edition McKinley & O'Loughlin Chapter 23 Lecture Outline: Vessels and Circulation 23-
  2. 2. Blood Vessels <ul><li>The heart and blood vessels form a closed-loop system. </li></ul><ul><li>Blood is continuously pumped to and from the tissues. </li></ul><ul><li>The vessels can pulsate and change shape in accordance with the body’s needs. </li></ul>23-
  3. 3. Blood Vessels <ul><li>Often share names with either the body region they traverse or the bone next to them. </li></ul><ul><li>Some are named for the structure they supply. </li></ul><ul><li>Arteries and veins that travel together sometimes share the same name. </li></ul><ul><li>The systemic circulation and pulmonary circulation work continuously and with each other. </li></ul>23-
  4. 4. Anatomy of Blood Vessels <ul><li>Arteries carry blood away from the heart to the body tissues. </li></ul><ul><li>They branch into progressively smaller vessels until they feed into the capillaries, where gas and nutrient exchange occurs. </li></ul><ul><li>From the capillaries, venules and then veins return blood to the heart. </li></ul><ul><li>Veins become progressively larger as they merge and get closer to the heart. </li></ul>23-
  5. 5. <ul><li>The aorta (d=1 inch) branches and branches into </li></ul><ul><li>Several hundred million tiny arteries and arterioles that branch into </li></ul><ul><li>10 billion capillaries (25,000 miles) that merge to form </li></ul><ul><li>Venules which merge to form </li></ul><ul><li>Veins </li></ul><ul><li>Total: 100,000 km or 60,000 miles of blood vessels! </li></ul>Extensive Blood Supply 23-
  6. 6. Anastomoses <ul><li>Site where two or more vessels merge to supply or drain the same body region is called an anastomosis . </li></ul><ul><ul><li>arterial anastomoses provide collateral circulation (most tissues supplied by more than one artery) </li></ul></ul><ul><ul><li>end arteries, if blocked, lead to necrosis of tissue beyond </li></ul></ul><ul><ul><li>functional end arteries have such small anastomoses that they function as end arteries (e.g., the heart) </li></ul></ul><ul><ul><li>veins tend to form many more anastomoses than do arteries </li></ul></ul>23-
  7. 7. Blood Vessel Tunics <ul><li>Tunica Intima, or Tunica Interna </li></ul><ul><ul><li>composed of an endothelium and a subendothelial layer </li></ul></ul><ul><li>Tunica Media </li></ul><ul><ul><li>especially important in arteries </li></ul></ul><ul><ul><li>composed of circularly arranged layers of smooth muscle cells </li></ul></ul><ul><ul><li>vasoconstriction and vasodilation </li></ul></ul><ul><li>Tunica Externa, or Tunica Adventitia </li></ul><ul><ul><li>relatively thicker in veins, but distensible </li></ul></ul><ul><ul><li>composed of an areolar connective tissue that contains elastic and collagen fibers </li></ul></ul><ul><ul><li>helps anchor the vessel to other tissues </li></ul></ul><ul><ul><li>vasa vasorum are blood vessels to the thicker blood vessels </li></ul></ul>23-
  8. 8.
  9. 9.
  10. 10. Arteries <ul><li>Three basic types of arteries: </li></ul><ul><ul><li>elastic (conducting) arteries (2.5 cm to 1 cm) </li></ul></ul><ul><ul><ul><li>recoil to maintain blood pressure </li></ul></ul></ul><ul><ul><li>muscular (distributing) arteries (1 cm to 0.3 mm) </li></ul></ul><ul><ul><ul><li>control blood flow </li></ul></ul></ul><ul><ul><ul><li>supply groups of organs, organs, and parts of organs </li></ul></ul></ul><ul><ul><li>arterioles (0.3 mm to 10 microns - almost microscopic) </li></ul></ul><ul><ul><ul><li>artery like near artery and capillary like near capillary </li></ul></ul></ul><ul><ul><ul><li>important in regulating blood flow into capillaries and controlling blood pressure </li></ul></ul></ul><ul><ul><ul><ul><li>local factors </li></ul></ul></ul></ul><ul><ul><ul><ul><li>sympathetic division controls diameter </li></ul></ul></ul></ul><ul><ul><li>as an artery’s diameter decreases </li></ul></ul><ul><ul><ul><li>corresponding decrease in the amount of elastic fibers </li></ul></ul></ul><ul><ul><ul><li>relative increase in the amount of smooth muscle </li></ul></ul></ul>23-
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  12. 12. Capillaries <ul><li>Only the tunica intima: a basement membrane and endothelium only. There may be gaps or pores. </li></ul><ul><li>About 8-10 microns in diameter </li></ul><ul><li>Thin wall and slow flow allow gas and nutrient exchange between the blood and the body tissues to occur rapidly. </li></ul><ul><li>Smallest blood vessels, connect arterioles to venules (microcirculation). </li></ul><ul><li>The functional units of the cardiovascular system. </li></ul><ul><li>Near almost all cells </li></ul><ul><li>Distribution varies with activity </li></ul><ul><li>Direct or branching network </li></ul><ul><li>A group of capillaries (10–100) functions together and forms a capillary bed. </li></ul>23-
  13. 13.
  14. 14. The Three Basic Kinds of Capillaries <ul><li>Continuous capillaries </li></ul><ul><ul><li>the most common type </li></ul></ul><ul><ul><li>Examples: skeletal and smooth muscle, connective tissues, lungs, CNS </li></ul></ul><ul><li>Fenestrated capillaries </li></ul><ul><ul><li>many pores </li></ul></ul><ul><ul><li>Examples: kidneys, small intestinal villi, choroid plexuses, ciliary processes, endocrine glands, synovial membranes </li></ul></ul><ul><li>Sinusoids , or discontinuous capillaries </li></ul><ul><ul><li>wider, tortuous, spaces between endothelial cells </li></ul></ul><ul><ul><li>basement membrane is incomplete or absent </li></ul></ul><ul><ul><li>specialized lining cells for function of tissue </li></ul></ul><ul><ul><li>blood moves slowly through there which is good for exchanges </li></ul></ul><ul><ul><li>Examples: liver, spleen, anterior pituitary, parathyroid gland, bone marrow </li></ul></ul>23-
  15. 15.
  16. 16. Routes of Capillary Permeability <ul><li>Direct diffusion </li></ul><ul><li>Intercellular clefts </li></ul><ul><li>Pinocytic vesicles and caveolae </li></ul><ul><li>Fenestrations </li></ul>23-
  17. 17. Veins <ul><li>Walls are relatively thin and the vein lumen is larger (often collapse). </li></ul><ul><li>Systemic veins carry deoxygenated blood to the right atrium of the heart, while pulmonary veins carry oxygenated blood to the left atrium of the heart. </li></ul><ul><li>Blood pressure is substantially reduced by the time blood reaches the veins. </li></ul><ul><li>Veins function as blood reservoirs. </li></ul><ul><ul><li>Hold about 60% of the body’s blood at rest. </li></ul></ul><ul><ul><li>Major reservoirs in the abdominal organs (esp. liver and spleen) and skin </li></ul></ul><ul><ul><li>Blood can move quickly when increased muscular activity or hemorrhage </li></ul></ul>23-
  18. 18. Veins <ul><li>Most veins run with corresponding arteries </li></ul><ul><li>But, some important differences in distribution </li></ul><ul><ul><li>One systemic artery (aorta) leaves the left ventricle, but 3 veins enter the right atrium </li></ul></ul><ul><ul><li>All large and medium-sized arteries are deep for protection but many veins are superficial </li></ul></ul><ul><ul><li>Several parallel veins instead of one larger vein (may include anastomoses) </li></ul></ul><ul><ul><li>Two unusual drainage patterns </li></ul></ul><ul><ul><ul><li>Dural sinuses </li></ul></ul></ul><ul><ul><ul><li>Hepatic portal system </li></ul></ul></ul>23-
  19. 19. From Venules to Veins <ul><li>Venules merge to form veins (greater than 100 micrometers). </li></ul><ul><li>Blood pressure in veins is too low to overcome the forces of gravity, but there is a slight pressure gradient . </li></ul><ul><li>To prevent blood from pooling in the limbs, most veins contain one-way numerous valves to prevent blood backflow . </li></ul><ul><li>Many deep veins pass between skeletal muscle groups, the skeletal muscle pump . </li></ul><ul><li>Also a respiratory pump , the changes in pressure in the thoracic region from breathing help move blood back to the heart from the lower part of the body. </li></ul>23-
  20. 20. Vascular Sinus <ul><li>A vein without smooth muscle so no change in diameter </li></ul><ul><li>Examples: dural venous sinuses of brain and coronary sinus of heart </li></ul>23-
  21. 21.
  22. 22. Blood Pressure <ul><li>Force per unit area that blood places on the inside wall of a blood vessel </li></ul><ul><li>Measured in millimeters of mercury (mm Hg) with a sphygmomanometer </li></ul><ul><li>Use brachial artery </li></ul><ul><li>Systolic pressure/diastolic pressure (less than 120/80 mm Hg is considered normal now) </li></ul><ul><li>Increased by blood volume and cardiac output, vasoconstriction, drugs (can increase or decrease) </li></ul>23-
  23. 23.
  24. 24. Hypertension: The “Silent Killer” <ul><li>Chronically elevated blood pressure, greater than 140 mm Hg systolic and/or 90 mm Hg diastolic. </li></ul><ul><li>90-95% is essential hypertension. Cause: idiopathic (unknown). </li></ul><ul><li>5-10% secondary hypertension (usually renal disease or an adrenal gland tumor) </li></ul><ul><li>Serious effects: damages blood vessel walls leading to atherosclerosis, arteriosclerosis, renal failure, stroke, heart failure </li></ul><ul><li>Treatment: weight loss, diet, exercise, no smoking, drugs (diuretics, beta-blockers, ACE inhibitors that cause vasodilation) </li></ul>23-
  25. 25. Systemic Circulation 23-
  26. 26. Branches off the Aorta <ul><li>All systemic arteries branch directly or indirectly from the aorta </li></ul><ul><li>First branching off the ascending aorta are the right and left coronary arteries </li></ul><ul><li>Branching off the aortic arch are in order: brachiocephalic trunk, l. common carotid, and l. subclavian(A, B, C ‘s) </li></ul><ul><li>The brachiocephalic trunk branches into the right common carotid and right subclavian </li></ul><ul><li>The vertebral arteries branch off the subclavians and go through the transverse foramina </li></ul><ul><li>The descending aorta is the thoracic aorta and then the abdominal aorta </li></ul>23-
  27. 27.
  28. 28. Circle of Willis (Cerebral Arterial Circle) <ul><li>An important anastomosis of arteries around the sella turcica . </li></ul><ul><li>Blood enters through two routes: the basilar artery which is formed from the vertebral arteries that branch off the subclavians and the internal carotid arteries that branch off the common carotids </li></ul><ul><li>Equalizes blood pressure in the brain and can provide collateral channels should one vessel become blocked. </li></ul>23-
  29. 29.
  30. 30.
  31. 31. Veins of the Head and Neck <ul><li>Internal jugulars </li></ul><ul><ul><li>From the sinuses </li></ul></ul><ul><ul><li>Drain the face and neck, brain </li></ul></ul><ul><ul><li>Join the subclavian, etc. </li></ul></ul><ul><li>External jugulars </li></ul><ul><ul><li>Lateral to the internal jugulars </li></ul></ul><ul><ul><li>Drain the salivary glands, facial muscles, scalp and other superficial structures </li></ul></ul><ul><ul><li>Join the subclavian, etc. </li></ul></ul><ul><ul><li>May get distended during right sided heart failure or normally with coughing or exercise </li></ul></ul><ul><li>Vertebral veins </li></ul><ul><ul><li>Drain the deep neck structures </li></ul></ul><ul><ul><li>Go through the transverse foramina into the subclavian </li></ul></ul>23-
  32. 32. Veins of the Head and Neck <ul><li>From the subclavian veins, the venous blood goes to the two brachiocephalic veins and then into the superior vena cava that drains venous blood from above the diaphragm </li></ul>23-
  33. 33.
  34. 34.
  35. 35.
  36. 36.
  37. 37. Arteries of the Thorax and Abdomen <ul><li>The descending aorta is the thoracic aorta above the diaphragm and then the abdominal aorta below the diaphragm </li></ul><ul><li>Celiac trunk off the abdominal aorta </li></ul><ul><ul><li>Common hepatic artery </li></ul></ul><ul><ul><li>Left gastric artery </li></ul></ul><ul><ul><li>Splenic artery </li></ul></ul><ul><li>Superior mesenteric </li></ul><ul><li>Inferior mesenteric </li></ul><ul><li>Common iliac arteries </li></ul><ul><ul><li>Internal iliac artery </li></ul></ul><ul><ul><li>External iliac artery becomes the femoral artery in the thigh </li></ul></ul>23-
  38. 38.
  39. 39.
  40. 40. Veins of the Thorax <ul><li>The inferior vena cava empties into the right atrium </li></ul><ul><li>Brachiocephalic veins empty into the superior vena cava </li></ul><ul><li>Azygos system of veins </li></ul>23-
  41. 41. The Azygos System <ul><li>The azygos veins collect blood from the thorax, but also may be used for a bypass for the inferior vena cava or the hepatic portal vein if they are blocked </li></ul><ul><li>They empty into the superior vena cava and brachiocephalic </li></ul>23-
  42. 42.
  43. 43.
  44. 44. Veins of the Abdomen and Pelvis <ul><li>Inferior vena cava drains the abdominal viscera and wall </li></ul><ul><ul><li>Returns blood from below the diaphragm </li></ul></ul><ul><ul><li>Widest vessel </li></ul></ul><ul><ul><li>Edema and varicose veins during pregnancy for some </li></ul></ul><ul><li>Many of the veins have the same names as the arteries </li></ul>23-
  45. 45. Hepatic Portal System <ul><li>A venous network that drains the GI tract and shunts the blood to the liver for processing and absorption of transported materials. </li></ul><ul><li>The hepatic portal vein brings deoxygenated, but nutrient rich blood to the liver. </li></ul><ul><ul><li>Needed because the GI tract absorbs digested nutrients, and these nutrients must be processed and/or stored in the liver. </li></ul></ul><ul><li>The hepatic artery brings oxygenated, but nutrient poor blood to the liver. </li></ul><ul><li>Branches of these two vessels merge and mix the two bloods in the hepatic sinusoids. </li></ul><ul><li>Blood exits the liver through hepatic veins that merge with the inferior vena cava. </li></ul><ul><li>A hepatic portal triad is a branch of the hepatic portal vein, a branch of the hepatic artery, and a bile duct. </li></ul>23-
  46. 46.
  47. 47.
  48. 48. Arteries of the Upper Extremities <ul><li>The subclavian artery becomes the </li></ul><ul><li>Axillary artery that becomes the </li></ul><ul><li>Brachial artery (blood pressure taken here) that becomes the </li></ul><ul><li>Radial and ulnar arteries that become the arteries in the hand (including anastomoses) </li></ul><ul><ul><li>The radial artery is a major artery for taking the pulse </li></ul></ul>23-
  49. 49.
  50. 50.
  51. 51.
  52. 52. Veins of the Upper Extremities <ul><li>Superficial and deep have valves </li></ul><ul><li>Superficial are larger and often visible </li></ul><ul><li>Lots of anastomoses </li></ul><ul><li>Deep often accompany arteries and have the same names </li></ul><ul><li>Most deep veins are paired </li></ul>23-
  53. 53. Veins of the Upper Extremities <ul><li>Superficial </li></ul><ul><ul><li>Cephalics </li></ul></ul><ul><ul><li>Basilar </li></ul></ul><ul><ul><li>Median antebrachials </li></ul></ul><ul><ul><li>Median cubital veins are used often for blood samples and injections </li></ul></ul><ul><li>Deep run with the arteries (note the same names) </li></ul><ul><ul><li>Radials </li></ul></ul><ul><ul><li>Ulnars </li></ul></ul><ul><ul><li>Brachials </li></ul></ul><ul><ul><li>Axillaries </li></ul></ul><ul><ul><li>Subclavians </li></ul></ul>23-
  54. 54.
  55. 55. Arteries of the Lower Limb <ul><li>External iliac artery becomes the femoral artery in the thigh then the </li></ul><ul><li>Popliteal artery that becomes the </li></ul><ul><li>Anterior tibial artery, posterior tibial artery, and fibular artery, etc. </li></ul><ul><li>Anterior tibial artery becomes the doralis pedis artery (important for assessing circulation in the lower limbs) </li></ul>23-
  56. 56.
  57. 57. Veins of the Lower Extremities <ul><li>Superficial </li></ul><ul><ul><li>Great saphenous </li></ul></ul><ul><ul><ul><li>Longest vein - used often for bypasses (mammary arteries used for short bypasses also) </li></ul></ul></ul><ul><ul><ul><li>Anterior to the medial malleolus so it is useful for prolonged IVs </li></ul></ul></ul><ul><ul><ul><li>Subject to varicosities </li></ul></ul></ul><ul><ul><li>Small saphenous </li></ul></ul><ul><li>Deep </li></ul><ul><ul><li>Same names as arteries usually </li></ul></ul><ul><ul><li>Examples: anterior and posterior tibial, politeal, femoral </li></ul></ul><ul><li>Many anastomoses between the superficial and between the superficial and the deep </li></ul>23-
  58. 58.
  59. 59.
  60. 60. Palpating the Pulse <ul><li>Temporal artery </li></ul><ul><li>Facial artery </li></ul><ul><li>Common carotid artery </li></ul><ul><li>Brachial artery </li></ul><ul><li>Radial artery </li></ul><ul><li>Femoral artery </li></ul><ul><li>Popliteal artery </li></ul><ul><li>Posterior tibial artery </li></ul><ul><li>Dorsalis pedis artery </li></ul><ul><li>Above are also pressure points to prevent bleeding </li></ul>23-
  61. 61. Varicose Veins <ul><li>Incompetent valves </li></ul><ul><li>Causes: heredity, mechanical factors, aging </li></ul><ul><li>Especially common in surface veins of leg </li></ul><ul><li>Treatment: rest, elevation, stockings, sclerosing chemicals, surgery </li></ul><ul><li>Hemorrhoids: varicose veins in anorectal region </li></ul><ul><li>Mild form: spider veins </li></ul><ul><li>Possible consequences </li></ul><ul><ul><li>Edema </li></ul></ul><ul><ul><li>Blood clots, phlebitis, gangrene </li></ul></ul>23-
  62. 62. Deep Vein Thrombosis (DVT) <ul><li>Thrombus </li></ul><ul><li>Common site: calf (sural) region, also femoral region </li></ul><ul><li>Occurs in heart disease, inactivity, immobilization (“economy class syndrome”), pregnancy </li></ul><ul><li>Symptoms: fever, tenderness and redness, severe pain and swelling, rapid heartbeat </li></ul><ul><li>Severe complication: pulmonary embolism </li></ul><ul><li>Treatment: anticoagulants </li></ul>23-
  63. 63. <ul><li>Progressive disease of the elastic and muscular arteries. Characterized by atheroma (or atheromatous plaque) leading to thickening of the tunica intima and narrowing of the lumen. </li></ul><ul><li>Not well understood, most accepted is response-to-injury hypothesis. Infection, trauma, hypertension. </li></ul><ul><li>Risk factors: hypercholesterolemia, being male, age, smoking, and hypertension. </li></ul><ul><li>Treatment options: angioplasty, coronary bypass surgery </li></ul><ul><li>Prevention: healthy diet, drugs for high cholesterol, not smoking, monitoring and treating hypertension. </li></ul>Atherosclerosis 23-
  64. 64. Pulmonary Circulation <ul><li>Responsible for carrying deoxygenated blood from the right side of the heart to the lungs, and then returning the newly oxygenated blood to the left side of the heart. </li></ul>23-
  65. 65.
  66. 66.
  67. 67.
  68. 68. Differences from the Systemic Circulation <ul><li>Only postnatal arteries carrying O 2 poor blood and veins carrying O 2 rich blood </li></ul><ul><li>Shorter distance </li></ul><ul><li>Arteries are more like systemic veins: </li></ul><ul><ul><li>Larger diameter, thinner, less elastic tissue </li></ul></ul><ul><ul><li>Less resistance and, therefore, less pressure needed </li></ul></ul><ul><li>Less hydrostatic pressure (B.P.) decreases risk of edema </li></ul><ul><li>Vessels constrict when O 2 low so blood goes to where O 2 can be picked up (in tissues vessels dilate when O 2 is low to bring more oxygenated blood to the O 2 poor tissues) </li></ul>23-
  69. 69. Fetal Circulation <ul><li>Oxygenated blood from the placenta enters through the umbilical vein. </li></ul><ul><li>Blood is shunted away from the liver and to the inferior vena cava through the ductus venosus and oxygenated blood mixes with deoxygenated blood. </li></ul><ul><li>Blood empties into the right atrium. </li></ul><ul><li>Most of the blood is shunted to the left atrium via the foramen ovale. </li></ul><ul><li>Blood flows into the left ventricle and out the aorta. </li></ul><ul><li>A small amount of blood enters the right ventricle and pulmonary trunk, but much of this blood is shunted to the aorta through ductus arteriosus . </li></ul><ul><li>Blood travels to the rest of the body, and the deoxygenated blood returns to the placenta through umbilical arteries. </li></ul>23-
  70. 70.
  71. 71. <ul><li>If ductus arteriosus fails to close, then blood from the aorta can enter the pulmonary system </li></ul><ul><li>Over several years, results in pulmonary hypertension and failure of the right ventricle </li></ul><ul><li>Treat first with prostaglandin-inhibiting medication. If not successful, then surgery. </li></ul>Patent Ductus Arteriosis 23-
  72. 72. <ul><li>Aneurysm = a localized, abnormal dilation of a blood vessel </li></ul><ul><li>Aorta especially prone between the renal arteries and the bifurcation of the common iliac arteries </li></ul><ul><li>Often a consequence of atherosclerosis </li></ul><ul><li>Enlarges and may rupture </li></ul><ul><li>Severe medical emergency </li></ul><ul><li>May replace with an artificial vascular prosthesis or reinforce with a stent </li></ul>Abdominal Aortic Aneurysm 23-
  73. 73. Aging and the Cardiovascular System <ul><li>Heart and blood vessels become less resilient. </li></ul><ul><li>Elastic arteries are less able to withstand the forces from the pulsating blood. </li></ul><ul><li>Systolic blood pressure may increase with age. </li></ul><ul><li>Apt to develop an aneurysm, whereby part of the arterial wall thins and balloons out. </li></ul><ul><li>Wall is more prone to rupture, which can cause massive bleeding and death. </li></ul><ul><li>Incidence and severity of atherosclerosis increases. </li></ul>23-

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