Lymphatics and the Lung: 413

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Lymphatics and the Lung 4/13

• This will be on test 3
• Capillary Exchange pg 761- 763
• Lymphatics pg 800-803
• What is edema and how is it different from
  inflammation?
• What are the mechanisms affecting fluid transport
  across a capillary?
• How do the lymphatics prevent excessive
  interstitial fluid accumulation?

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What causes fluids to become inappropriately
sequestered (accumulated) in tissues?

• Sequestration Causes Pleural Effusion/Edema
  (cold to touch)
• 1) Increased Capillary Permeability Congestiv
  e heart failure, renal failure, old age
• 2) Loss of Plasma Oncotic Pressure Hypoprotei
  nemia, Liver Failure, Radiation
• 3) Obstructive Lymphatic Drainage Changing
  capillary fluid dynamics
• Contrast with inflammation increased tissue
  fluid that is warm to the touch and reddish in
  appearance (increased blood flow)!
• Why is edema so much more commonly observed in
  the lower extremities?
• Why do you give huge intraperitoneal injections
  of isotonic glucose/saline following severe
  dehydration?

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Predictions of fluid movement out of (swelling)
or into (reduced swelling) capillaries are based
on opposing forces of hydrostatic pressure (blood
pressure) and colloid osmotic pressure (protein
solvent drag).

• Pressures inside the capillary?
• Protein effects are called colloid (mmHg)
  
• Hydrostatic effects (mmHg)-
• Pressures around the outside of the capillary?
• Protein effects are called colloid-
• Hydrostatic effects-
• Net Filtration Pressure
• valuefluid goes into interstitiumFiltration
  tissue swells
• - valuefluid goes into capillaryReabsorptions
  welling disappears
• Why do fluids tend to exit capillaries at
  beginning??
• Why do fluids tend to enter capillaries at the
  end??
• Remember that interstitial fluids contain
  relatively little soluble protein and are under a
  slight vacuum created by fluid movement into the
  lymphatic system.

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HOW DO LYMPHATICS DRAIN TISSUES OF EXCESS
INTERSTITIAL FLUID (REDUCE EDEMA/INFLAMMATION)?

• Lymphatics Low to VERY-VERY-Low Pressure
  Drainage with valves to prevent backflow.
• Anatomy of Lymphatic System Explains quite a
  lot.LyCapillariesgtLyNodesgtLyVesselsgtLyDuctsgt
  Subclavian Vein gtVenaCava Ultimate drainage into
  venous system
• Lymph contents fatty acids, lipoproteins,
  lymphocytes, and a VERY LOW PROTEIN CONTENT!
• Tissue Swelling HotInflammation vs. ColdEdema
• Blockage of lymph vessels ? Edema
• Vasodilation of arterioles ? Inflammation

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1) Lymph fluids are pulled/pushed into the
right subclavian vein, 2) Lymph fluids carried
away from the gut may contain toxins (WBC in
nodes clean it a bit), and 3) If a node is
blocked, interstitial fluids back up causing
fluid to accumulate.
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Why are the lymphatics important for the
diagnosis of diease?

• 1) Why do they look for swollen axillary lymph
  nodes if they find a bump on your breast exam.
• 2) Why do they palpate your submandibular lymph
  nodes if you have a sore throat?
• 3) Why did the Elephant Man have swollen legs?
• 4) Why do tissues like the lung and intestine
  have tremendous numbers of lymphatic vessels?
• 5) Why does the surgeon often remove lymph nodes
  when a cancer is removed?
• 6) Why are you more likely to develop edema if
  the lymph nodes are removed?

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WHY IS CAPILLARY FLUID TRANSPORT TO/FROM THE
INTERSTITIUM DETERMINED PARTLY BY THE ANATOMICAL
FEATURES OF THE CAPILLARY?

• 4 Routes of Capillary Exchange at Endothelial
  Wall 1 Intracellular clefts (filtration) 2
  Fenestrata or pores (filtration) 3 Pinocytosis
  (transcytosis) 4 Diffusion through plasma
  membrane
• Where are Important Endothelial
  Barriers? brain, birth, drugs, disease,
  toxicity
• Importance for portal circulation for blood
  cleaning and hormone transport into blood?
• PROTEIN Solvent Drag and Spheres of Hydration
  Ionized molecules carry water via H-bonds

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What normally happens in a normal capillary under
normal conditions? Why do some tissues
accumulate fluid (inflammation, edema or
glomerular filtrate)? How do we promote the
reduction of interstitial fluids in a sprained
ankle? Please look at Figure 20.17 and the text
that supports this on pages 770 and 771. The
section on Lymphatics (pages 808-812) will also
help you understand the concepts of capillary
filtration and interstitial fluid reabsorption.
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What happens in the glomerulus? What is the
net at the start and end of a glomerular
capillary if blood hydrostatic is 70 mmHg at
arteriolar end, 50 mmHg at the distal end, and
blood colloid osmotic pressure is 28 mmHg and
colloid osmotic pressure in the glomerular
capsule is 0 mmHg (filtrate)? What process
predominates Filtration or Reabsorption?(Do Math)
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NORMAL CONDITIONS--What is net at the start and
end of a normal capillary if blood hydrostatic is
35 mmHg at arteriolar end, 15 mmHg at distal end,
and blood colloid osmotic pressure is 25 mmHg and
colloid osmotic pressure in the interstitium is 1
mmHg? (Do The Math)What process predominates
Arteriolar End of Capillary Filtration or
reabsorption? What process predominates Venous
End of Capillary Filtration or reabsorption?
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TRICKY What if you sprained your ankle? It
would swell up, but WHY????? Why because
immune system causes the endothelium to become
quite permeable to Plasma Protein (pores enlarge)
and water moves from blood into the interstitium!
Why is the swelling WORSE if you stand on the
ankle and reduced if you ELEVATE the ankle above
the level of your heart? What is net at the
start and end of your capillaries if Blood
hydrostatic is 37 mmHg at arteriolar end, 17 mmHg
at distal end, interstitial hydrostatic is 1
mmHg. Blood colloid osmotic pressure is 28 mmHg
(at start) and 20 mmHg at the end of the
capillary (protein left the blood so number not
the same), therefore colloid osmotic pressure is
now high (10 mmHg). What process predominates
Filtration or Reabsorption?