PNB EXAM 1: VASCULATURE

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jam110007
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201926
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PNB EXAM 1: VASCULATURE
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2013-02-20 06:34:12
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  1. tunica interna (intima)
    • inner most layer, surrounds the lumen
    • - endothelium 
    • - subendothelial layer
  2. subendothelial layer tissue make up
    made up of loose coneective tissue and supports the endothelium in vessels larger than 1mm in diameter
  3. endothelium tissue make up
    continuation of endocardium. simple squamous epithelium
  4. Tunica media
    • middle layer; circular muscle and elastin 
    • - sympathetic vasomotor nerve fibers regulate activity; increased activity --> vasoconstriction; decreased activity --> vasodialation
  5. tunica externa
    • Outermost layer consisting of connective tissue.; collagen; vasovasorum (network of small blood vessels that serve large vessels); nerve fibers, lymphatics.
    • - collagen (connective tissue)
  6. pressure gradient is produced by what?
    contraction of heart
  7. resistance
    • opposition to flow
    • - friction between blood vessel and walls og blood vessels
  8. sources of resistance
    • - viscosity 
    • - blood vessel length
    • - blood vessel radius
  9. TPR (total peripheral resistance)
    • the sum of all resistance - due to resistance offered bu arterials
    • -
  10. TPR can affect what?
    • - mean arterial pressure 
    • - stop blood flow to certain peripheral locations and concentrate on more core organs
  11. which variables are physiologically regulated
    • - delta P
    • - r
  12. LaPlace’s Law
    The force (or tension)stretching vessel wallopen is proportional tovessel’s diameter (orradius) * BPLESS tension on walls ofvery small vessels…thusif P < CCP (closing critical pressure), (small) vessel collapses
  13. elastic artery are also called what?
    • conducting arteries 
    • - b/c they bring blood to the major regions of the body
  14. sequence of arteries
    • - elastic artery
    • - muscular artery 
    • - arterioles
  15. muscular arteries
    • - also called distributing arteries 
    • - has less elastic and proportionally more muscle in their walls 
    • - they are what lead blood to arterioles
  16. function of arteries
    • - low resistance pipes
    • - pressure reservoir (esp elastic artery)
  17. Pressure Reservoir Function of Elastic Arteries
    • • During systole, strokevolume of blood isejected, stretchingcompliant walls of elasticarteries
    • • When systole ends,stretched arterial wallsrecoil, continuing to driveblood into arteriolesduring diastole
    • – NOTE ARTERIALPRESSURE does NOT go tozero during diastole!
    • – Note VENTRICULARpressure DOES go toalmost zero during diastole!
  18. blood pressure = ?
    force / unite exerted by blood on wall of blood vessel
  19. what is normal blood pressure
    120/80
  20. pulse pressure = ?
    systolic - diastolic pressure
  21. what is mean arterial pressure
    the driving force that pushes blood around the entire systemic circuit
  22. MAP is for which system?
    systemic
  23. MPAP is for which system
    pulmonary
  24. mean arterial pressure (MAP) = ?
    diastolic pressure + 1/3 pulse pressure
  25. two major roles of arterioles
    • – Determine relative blood flows to tissues(blood flow distribution)
    • – Major factor in determining MAP (due to effect on Total Peripheral Resistance)
  26. THREE MECHANISMS regulate arteriolar radius
    • – Local Control
    • – Neural (reflex)Control
    • – Hormonal Control
  27. Local (“intrinsic”) Control of Arteriolar Radius
    • 1) Active Hyperemia: Blood flow adjusted tomeet tissue’s needs
    • 2) Flow Autoregulation
  28. Active Hyperemia: Blood flow adjusted tomeet tissue’s needs
    • Following stimuli increase blood flow(by increasing radii of arterioles, metarterioles andprecapillary sphincters):
    • – Decreased O2
    • – Increased CO2
    • – Increased [H+] / decreased pH
    • – Metabolites, including K+, ↑ osmolarity

    This mechanism is not important in MAPregulation.
  29. Flow Autoregulation
    • – Decreased blood pressure in organ => arteriolardilation in organ to restore blood flow
    • – Several factors mediate – including decreased O2and increased metabolites

    This mechanism is not important in MAPregulation
  30. Reflex (Neural) Control of Arteriolar Radius
    • Sympathetic nervous regulation
  31. Sympathetic nervous regulation of arteriolar radius
    • - extrinsic control
    • – Increasedsympatheticstimulation => vasoconstriction
    • – Decreasedsympatheticstimulation => vasodilation
  32. what can increase TPR (total peripheral resistance)
    mass vassel constriction, which can also boost your MAP
  33. alpha 1 receptors
    blood vessel will restrict
  34. beta 2 receptors
    • do not really respond to NE but they do to EPI 
    • - they open up and relax smooth muscle
  35. Hormonal Control of Arteriolar Radius
    • Epinephrine
  36. Hormonal Control of Arteriolar Radius: Epinephrine
    Vasoconstrictorfor vessels withα1-adrenergicreceptors;vasodilator forvessels with β2-adrenergicreceptors
  37. in flight/flight mode, which mechanism over powers which?
    the extrinsic (hormonal and neural) take over the local controls
  38. Capillary wall
    thin tunica intima
  39. Types of Capillaries
    • – Continuous
    • – Fenestrated
    • – Sinusoids
  40. Capillary Beds consist of?
    • - Metarteriole
    • - True capillaries
  41. Metarteriole
    branches off the arterial and connects the arterial with its oxygenated blood with the venule with the deoxygenated blood will go - the capillaries branch off the metarteriole - also has surrounding smooth muscle where is first branches off the arterial - this muscle likewise can squeeze shut to divert blood away from capillaries- the distal region where it lacks smooth muscle is called the thoroughfare channel which connects to the venule
  42. True capillaries
    branch from the metarterioles and at the entrance of each is a precapillary sphincter which is the ultimate control of whether or not blood enters the capillaries  and thus a tissue - under local control (if it needs blood the sphincter will open. it closes when it does not need nutrients or are not burdened with wastes. closing allows the blood to flow directly into the venule)
  43. Capillary Blood Pressure
    • • 35 – 40 mm HG at beginningof capillary bed
    • • 15 – 20 mm Hg at end
  44. how do lipid soluble molecules and ions/ polar molecules diffuse through the capillaries?
    • - lipid soluble: diffuse through endothelial cell membrane
    • - ions/ polar molecules may diffuse through intercellular cleft
  45. Bulk Flow
    movement of water across capillary walls down a pressure gradient - this is important in fluid balance
  46. where does mediated transport play a role in the capillaries?
    when in the brain
  47. Failure of lymphatic system leads to what?
    edema
  48. Varicose Veins
    • Weakness / loss elasticity in venous walls
    • - Veins widen and stretch
    • – Valves don’t close => backflow of blood
  49. standing for too long can cause what?
    varicose veins
  50. veins are considered blood reservoir due to what?
    high compliance of venous walls which can accommodate large volumes of blood with realtively little increase in pressure
  51. what is a major determinant of cardiac output?
    venous pressure which determine venous return
  52. Determinants of Venous Return
    • • Total Blood Volume is one determinant of pressure(and thus venous return)
    • • Compliance, normally high, can be decreased tostiffen venous walls
    • • Valves and large lumens also crucial to venous return
  53. Two other functional adaptations ensure venous return
    • – Skeletal Muscle Pump
    • – Respiratory Pump
  54. Skeletal Muscle Pump
    • • Compression of veinsby skeletal musclecontraction raiseslocal venouspressure; thenvalves preventbackflow
    • • Blood forcedtowards heart
  55. Respiratory Pump
    • • Heart (and lungs) are inthoracic cavity
    • • Pressure in thoracic cavity is subatmospheric (negative)
  56. Inspiration (inhaling) does what to pressure
    drops pressure more,expanding lungs andcardiac chambers
  57. what are the four factor that determine venous return
    • - increase activity of sympathetic nerves to vein 
    • - increase skeletal muscle pump
    • - increase blood volume 
    • - increase inspiration movement
  58. venous return affect what?
    EDV which also affects ESV which determines stroke volume
  59. systemic blood pressures
    • • Left heart: 120/1
    • • Aorta: 120/80
    • • MAP: 93 mm Hg
  60. pulmonary blood pressures
    • • Right heart: 25/1
    • • Pulmonary artery: 25/8
    • • MPAP: 14 mm Hg

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