Exam II

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Author:
sarawoods116
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107246
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Exam II
Updated:
2011-10-09 09:43:37
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Blood Vessels
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Chapter 21
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  1. What are the 3 types of blood vessels?
    • veins
    • arteries
    • vaso vasorum
  2. Veins
    Carry blood to the heart from the tissues
  3. Arteries
    Carry blood away from the heart towards the tissues
  4. List the 3 tunics in veins and arteries
    • Tunica interna
    • Tunica media
    • Tunica external (adventitia)
  5. Tunica interna (tunica intima)
    • endothelium-lines the lumen (simple squamous e. with direct contact with the blood)
    • areolar connective tissue-underlying the endothelium
    • contains a small amt of smooth muscle
    • internal elastic membrane-indicator of boundary between t. interna and t. media
  6. Tunica media
    Composed of varying amounts of elastic fibers, circularly arranged smooth muscle, and thickness varies on pressue
  7. Tunica external (tunica adventitia)
    • Composed primarily of loose connective tissue (contains collagen and elastic fibers)
    • Scattered smooth muscle
    • In larger arteries a well organized layer of elastic fibers (external elastic membrane)
  8. Capillaries
    • Smallest blood vessel carrying blood away from the heart
    • Range from 4-12 micormeters in diameter
    • Always connect arterioles to venules
    • Permit the exchange of nutrients, waste, and gases between blood tissue cells and interstitial fluid
    • Lack elastic fibers
    • Form extensive networks inside a tissue
    • Wall of capillary is composed only of an endothelium
  9. Sinusoids
    • Special capillaries
    • Wider diameter lumen
    • More highly coiled
    • Always connect arterioles to venules
    • Found in specific locations including liver, spleen, adenphypophysis, and parathyroid gland
    • Largely lined with phagocytic cells instead of endothelium
  10. Major properties of arteries
    • Elasticity: stretches from large volume of blood and recoils to original size when blood is gone
    • Contractility: due to circulary arranged smooth muscle fibers-narrows the opening of lumen "vasoconstriction"-smooth muscle relases-lumen opens "vasodilation"
  11. 2 types of collateral circulation
    • Non-anastamosing circulation
    • Anastamosing circulation
  12. Non-anastamosing circulation (independent routes)
    • No connections between 2 arteries supplying the tissue
    • Exanterior and posterior interventricular arteries
    • both supply blood to right and left ventricle but are not connected to each other
  13. Anastamosing circulaton
    • The 2 arteries are connected often near distal ends (ex. Circle of Willis)
    • Common around joints
    • Very common to vital organs
    • Anastomoses help to equalize the pressure and distribution of blood
  14. Veins
    • Have the same 3 coats as arteries
    • The blood has lost considerable pressure by the time it reaches the veins
    • Still capible of moderate distention and recoil allowing them to adapt to minor changes in blood volume and pressure
  15. What are the advantages of having low pressure in veins?
    • "Driving force" of blood pressure in the lower limbs is barely enough to overcome the pull of gravity
    • Structurally veins conain a series of "one-way valves" to insure blood flow to the heart
    • Weak valves can lead to extensive problems over time
  16. One way valves
    • Offer little or no resistance to flow toward the heart
    • Easily close against any flow away from the heart
  17. Problems that occur from having weak valves
    • Allows blood to be pulled down by gravity and pooled in extremity (edema)
    • Repetitive pooling of blood stretched out the wall of the vein (vericose vein)
    • Can be a progressive problen-valve under weakened valve becomes weakened also
    • stretched flabby vein allows more fluid to leak out of vein and causes edema of the surronding tissues
    • Variscosities are common in superficial vessels of the leg and superficial vessels of the anal canal
  18. Fetal circulation
    • Fetus digestive, urinary, and respiratory systems are not functioning
    • Fetus depends upon the maternal blood supply to provide the functions of those systems
    • accomplished by exchange occuring in the placenta (responsible for the exhange of nutrients, wastes, and gases between maternal and retal blood---ocurs by typical process--difussion, osmosis, active transport, not by mixing blood, and passive exchange across the placenta)
  19. Portal circulation
    • Blood passes through 2 capillary beds before returning to the heart
    • Blood in the hepatic portal vein is rich in material absorbed in digestive organs
    • Liver processes the blood before it goes into general circulation
  20. How does the liver process blood in portal circulation?
    • Monitor and regulate blood nutrient levels (high after a meal and low before a meal)
    • Modify some nutrients to a more cell usable form
    • Detoxify harmful materials that are absorbed
    • Microbes are removed by phagocytosis "Kupffer cells"
    • Receives only low O2 blood---not good for liver
  21. What are the extra structures in fetal circulation that allow most blood to bypass the lungs?
    • Foramen ovale: a calve (flap of tissue) in the opening of the inferior vena cava that directs blood through the foramen ovale (bypass the right ventricle)
    • Ductus arteriousus: short vessle that connects the pulmonary trunk with the aorta-when the right ventricle ejects blood most of it passes throught the ductus arteriousus directly to the aorta
  22. What are the special fetal structures that are no longer needed at birth?
    • Umbilical vein: closes and atrophies to become the round ligament
    • Ductus venosus: closes and atrophies to become the ligamentum venosum
    • Placenta: passes down the birth canal as after birth
    • Foramen ovale: normally closes, atrophies, and becomes the fossa ovalis
    • Ductus arteriosis-normally closes, atrophies, and becomes the ligamentum arteriosum
  23. What facters determine blood pressure?
    • Flow: volume of blood delivered to a vessel per minute
    • Resistance: any mechanism that inhibits te movement (flow) of blood
  24. Flow
    • Cardiac is the principal determinant of flow and therefore the principle determinant of blood pressure
    • Cardiac output is determined by 2 factors:stroke volume (force of ventrical contraction) and heart rate (reflexes, and, etc.)
  25. Resistance
    • Viscosity of the blood-increasing blood viscosity increases resistance and therefore blood pressure (same with decreasing)
    • 2 common ways to increase blood viscosity- increase plasma protein levels of albumin and increase the number of eryrthrocytes polycythemia
    • Peripheral resistance offered by altering the lumen diameter of blood vessels
    • Elasticty of vessel
    • Length of vessel
  26. Pressure gradient
    • Aorta: 100mmHg
    • Arteries (small and large): 100mmHg-40mmHg
    • Arteroles: 40mmHg-25mmHg
    • Capillaries: 25mmHg-12mmHg
    • Venules: 12mmHg-5mmHg
    • Veins: 10mmHg-5mmHg
    • Vena cava: 2mmHg

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