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Microcirculation and Lymphatic System- Jaime

  1. Arterioles
    Highly muscular

    Can change diameter

    Resistance
  2. Metarterioles
    terminal arterioles

    don't have muscular coat

    smooth muscle fibers that encircle the vessel at various points.
  3. 1. Capillary

    2. Precapillary sphincter
    Where exchange takes place

    Capillary originates from metarteriole smooth muscle that encircles the capillary

    2. Precapillary sphincter- can open or close the capillary
  4. Venules
    Larger than arterioles

    Weaker muscular coat

    Can contract (low pressure inside)
  5. Function of pores in Capillary membrane
    small pathways that connect the interior of the capillary with the exterior.
  6. Intracellular cleft of capillary membrane
    Thin slit curving channel that lies at the bottom of the figure between endothelial cells.

    Interrupted by protein attachments

    Uniform spacing smaller than the diameter of albumin

    Water molecules can diffuse with ease
  7. Pores of capillaries in Blood Brain Barrier
    Tight junctions that only allow extremely small molecules through
  8. Pores of capillaries in Liver
    Clefts between capillary endothelial cells are wide so that almost all dissolved substances of plasma including plasma proteins can come through.
  9. Vasomotion
    Blood flow through the capillaries

    Does not flow continuously,

    Intermittently on and off every few seconds or minutes

    Intermittent contraction of metarterioles and precapillary sphincters. (This causes blood to flow. )
  10. The most important factor leading to degree of opening and closing of metarterioles and precapillary sphincters in vasomotion is?
    Oxygen in the tissues
  11. Regulation of Vasomotion

    TEST ???
    • 1. Concentration of O2 in tissues
    • 2. When tissue use of oxygen is high the intermittent flow in the capillaries occurs more frequently, for a longer duration.
    • 3. Leads to  increased oxygen and nutrients to the tissues.
  12. Most important means of transportation through the plasma and interstitial fluid? 

    Or capillary membrane?
    Diffusion

    • Results from thermal motion of water molecules and dissolved substances in the fluid.
  13. What substances can diffuse directly through the cell membranes of the capillary endothelium
    Lipid  soluble substances

    • Can diffuse directly through cell membrane
  14. Amount of free fluid in interstitium
    Less than 1%

    Unless edema is present, number is much higher
  15. Hydrostatic Pressure in capillaries does what?
    forces fluid and dissolved substances through capillary pores into the interstitial fluid.
  16. Osmotic pressure in the capillaries is caused by what?
    Plasma protein exert osmotic pressure and this  tends to cause fluid movement by osmosis from the interstitial fluid into the blood.

    Osmotic pressure that is exerted normally prevents loss of fluid volume from the blood into the interstitial spaces
  17. Four primary forces that determine whether the fluid will move in or out of the blood.

    Starling Forces
    capillary hydrostatic pressure= Pc
    interstitial hydrostatic pressure= Pi
    plasma colloid osmotic pressure=TTp
    interstitial fluid osmotic pressure=TTif
    1. Capillary pressure- force fluid outward

    2. Interstitial pressure- force fluid inward through capillary membrane, inward if positive, outward if negative.

    3. Plasma colloid osmotic pressure- cause osmosis of fluid inward

    4. Interstitial fluid colloid osmotic pressure- causes osmosis of fluid outward.
  18. Starling equation
    Jv=(Pc-Pi)-(TTp-TTi)

    • Jv= free movement
    • Pc=capillary hydrostatic pressure
    • Pi= interstitial hydrostatic pressure
    • TTp= plasma osmotic pressure
    • TTi= interstitial osmotic pressure
  19. Under normal conditions what is net filtration pressure?
    Positive
  20. Interstitial pressure in loose subcutaneous tissue is generally________?
    slightly negative

    generally slightly less than sub atmospheric pressure
  21. Plasma Oncotic Pressure (called this to differentiate from osmosis that occurs in the cell) 
    aka Plasma colloid osmotic pressure
    What causes it?
    Normal values
    • Proteins molecules in plasma and interstitial fluid that do not readily pass through semipermeable membrane and capillary pores are responsible for causing oncotic pressure.
    • Causes pressure on both sides of capillary membrane.
    • This causes osmosis to occur through capillary membrane
    • 28 mmHg for normal human plasma
    • 19 from dissolved protein
    • 9 from Donnan effect
    • 80% albumin, 20% globulin, 0.2% fibrinogen
  22. Value of  plasma oncotic pressure aka plasma colloid osmotic  pressure in normal human plasma

    How much is dissolved protein?

    Broken down into percentage
    28 mmHg

    • 19 mm from dissolved protein
    • 8 from Donnan effect.

    • 80% albumin fraction
    • 20% globulins
    • 0.2% fibrinogen
  23. Interstitial osmotic pressure
    aka interstitial fluid colloid osmotic pressure

    Average protein concentration ____?
    Pressure______?
    Small amount of protein leaks through pores into interstitial spaces. ( some pores allow this)

    Average protein concentration is only 40% of plasma

    Pressure =8 mmhg
  24. Exchange of fluid through capillary membrane.

    Average capillary pressure at the arterial ends of capillaries is __________ than at venous ends.

    Difference causes___________?
    Average capillary pressure at the arterial ends of capillaries is 15-25 mmHg greater than at venous ends.

    Difference causes fluid to filter out of the capillaries at their arterial ends but at their venous ends fluid is reabsorbed.
  25. Total outward force at arterial end
    41 mmHg
  26. Arterial end of capillary moves fluid ______?
    out

    Favor filtration
  27. Venous end of capillary moves fluid _______?
    In

    Favors reabsorption
  28. Total inward force at venous end?
    28 mmHg
  29. Lymphatics

    Essential to life
    Accessory route which fluid can flow from interstitial spaces into the blood

    • Essential function is to return protein to blood, without this we would die within 24 hours.
  30. Lymph vessels from lower body empty into___?
    The thoracic duct- which empties into the blood venous system at the juncture of the left internal jugular vein and left subclavian vein.
  31. Lymph from left side of head, arm, and chest enter _______ prior to emptying into veins?
    Thoracic duct
  32. Lymph from right neck and head and arm and part of thorax enter_______ and empties into _____ and _____ and ________?
    right lymph duct and empties into the blood venous system and the right subclavian and internal jugular veins.
  33. 1/10th of fluid enters the lymphatic capillaries instead of traveling to veins.
    Total quantity of lymph ______?

    Protein can enter the lymph ______?
    2-3 liters per day

    Proteins can enter lymph system unimpeded.
  34. Protein concentration of the interstitial fluid is about ______, and protein concentration of lymph is _______?
    2 g/dl

    about the same

    Just know they are the same
Author
jaime.davenport
ID
239787
Card Set
Microcirculation and Lymphatic System- Jaime
Description
Midterm Fall 2013 Renal
Updated

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