vessels ch 21.txt

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vessels ch 21.txt
2011-02-24 01:52:02


vessels ch 21
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  1. types of vessels and fxn
    • 1. arteries: carry blood away from the heart
    • 2. arterioles: very abundant, become metarterioles prior to cap
    • 3. capillaries: site of exchange
    • 4. venues: thinner walls than arterioles
    • 5. veins: carry blood TO the heart
  2. Arteries
    • Elastic Arteries: fxn as a pressure reservoir, LARGEST in diameter, but THIN walls
    • Muscular Arteries: THICK walls, capable of large vasodilation & vasoconstriction
  3. Anastomoses
    Union of the branches of 2 or more arteries supplying same area
  4. Capillaries
    • Smallest blood vessels
    • fxn to exchange b/w blood & interstitial fluid
    • LACK tunica media & externa
  5. 3 types of Capillaries
    • Continuous: endothelial cell membrane
    • Fenestrated: have pores
    • Sinusoids: wider & QUICKEST AT EXCHANGE
  6. Portal vein
    blood passes thru 2nd capillary bed
  7. Veins
    same 3 layers as in arteries BUT NOT designed to withstand HIGH pressure (thinner walls)
  8. 3 layers or tunics
    • Tunica interna (intima)
    • Tunica media
    • Tunica externa
  9. Tunica interna
    • inner lining in direct contact w/blood
    • endothelium continuous with heart lining
  10. Tunica media
    • muscular & connective tissue
    • smooth muscle regulates diameter
  11. Tunica externa
    • Elastic & Collagen fibers
    • anchors vessels to surrounding tissue
  12. Location of largest portion of blood
    in SYSTEMIC veins & venules
  13. Venoconstriction
    the reduction of volume of blood in vein reservoirs to allow more blood to flow where needed
  14. Capillary EXCHANGE
    • 3 methods of movement b/w blood & interstitial fluid
    • 1. Diffusion: substances move down the conc. gradient to body cells
    • 2. Transcytosis: pinocytosis (imp for lipid insoluble molecules as its the only way for them to cross)
    • 3. Bulk flow: passive process, salt & ions move together
  15. blood brain barrier
    tight junctions which LIMIT diffusion
  16. Sterling's Law
    as much is reabsorbed as is filtered
  17. Cardiac OUtput
    CO = Heart RATE (HR) X Stroke Volume (SV)
  18. Blood Pressure
    how much blood is leaving the heart
  19. Vascular Resistance
    • Opposition of blood flow due to FRICTION b/w blood & walls of vessels
    • Depends on
    • size of lumen
    • blood viscosity
    • vessel length
  20. If high blood viscosity
    • This means HIGH resistance which can result in closing of blood flow
    • this leads to stroke & hemorrhaging
  21. Skeletal muscle pump
    • 2 mechanisms
    • 1. skeletal muscle pump - pumps in 1 direction due to valves
    • 2. respitory pump: due to presure change in thoracic & abdominal
  22. Velocity of blood
    SLOWEST in capillaries
  23. CIRCULATION time
    Takes 1 min @ REST for 1 drop of blood to flow from RA back to the RA
  24. Cardiovascular Center (CV)
    • in medulla oblongata
    • regulates heart rate (HR) & stroke volume (SV)
    • Neurons REGULATE heart RATE (not rhythm, which is done by SA an AV node)
  25. 3 types of Sensory Receptors
    • Proprioceptors: monitor joint and muscle movement during physical activity
    • Baroreceptors: monitor PRESSURE changes & stretch blood vessels
    • Chemoreceptors: monitor concentration of chem in blood
  26. Hormonal Regulation OF BP
    • Renin system: released when blood vol or flow DECREASES. RAISES BP by vasoconstriction & bringing ALDOSTERONE
    • Epi & NorEpi: Released to INCREASE cardiac output by increasing rate & force of CONTRACTIONS
    • ADH(Antidiuretic hormone): INCREASES BP