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The Microcirculation. Figure 16-1; Guyton and Hall. Structure of Capillary Wall. Figure 16-2; Guyton and Hall. Interstitium and Interstitial Fluid. Figure 16-4; Guyton and Hall. Determinants of Net Fluid Movement across Capillaries. - PowerPoint PPT Presentation
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Copyright © 2006 by Elsevier, Inc.
The Microcirculation
Figure 16-1; Guyton and Hall
Copyright © 2006 by Elsevier, Inc.
Structure of Capillary Wall
Figure 16-2; Guyton and Hall
Copyright © 2006 by Elsevier, Inc.
Interstitium and Interstitial Fluid
Figure 16-4; Guyton and Hall
Copyright © 2006 by Elsevier, Inc.
Determinants of Net FluidMovement across Capillaries
• Capillary hydrostatic pressure (Pc)-tends to force fluid outward through the capillary membrane.
• Interstitial fluid pressure (Pif)- opposes filtration when value is positive.
Figure 16-5; Guyton and Hall
Copyright © 2006 by Elsevier, Inc.
Determinants of Net FluidMovement across Capillaries
• Plasma colloid osmotic pressure ( c)- opposes filtration causing osmosis of water inward through the membrane
• Interstitial fluid colloid pressure ( if) promotes filtration by causing osmosis of fluid outward through the membrane
NP = Pc - c - Pif + if
Figure 16-5; Guyton and Hall
Copyright © 2006 by Elsevier, Inc.
Plasma Proteins and ColloidOsmotic Pressure
• 75% of the total colloid osmotic pressure of plasma results from the presence of albumin and 25% is due to globulins.
gm/dl p(mmHg)
Albumin 4.5 21.8Globulins 2.5 6.0Fibrinogen 0.3 0.2
Total 7.3 28.0
Copyright © 2006 by Elsevier, Inc.
Determinants of Net FluidMovement Across Capillaries
• Filtration rate = net filtration pressure (NFP) multiplied by the filtration coefficient
• Filtration coefficient (Kf) is a product of surface area times the hydraulic conductivity of membrane
Figure 16-5; Guyton and Hall
Copyright © 2006 by Elsevier, Inc.
Forces Causing Filtration at theArteriole End of the Capillary
Forces tending to move fluid outward:Capillary pressure 30
Negative interstitial free fluid pressure 3 Interstitial fluid colloid osmotic pressure 8TOTAL OUTWARD FORCE 41
Forces tending to move fluid inward: Plasma colloid osmotic pressure 28TOTAL INWARD FORCE 28
Summation of forces:Outward 41Inward 28
NET OUTWARD FORCE 13
mmHg
Copyright © 2006 by Elsevier, Inc.
Forces Causing Reabsorption at the Venous End of the Capillary
Forces tending to move fluid inward: Plasma colloid osmotic pressure 28TOTAL INWARD FORCE 28Forces tending to move fluid outward:
Capillary pressure 10 Negative interstitial free fluid pressure 3 Interstitial fluid colloid osmotic pressure 8TOTAL OUTWARD FORCE 21
Summation of forces:Outward 21Inward 28
NET INWARD FORCE 7
mmHg
Copyright © 2006 by Elsevier, Inc.
Net Starling Forces in Capillaries
Mean forces tending to move fluid outward:Mean Capillary pressure 17.3Negative interstitial free fluid pressure 3.0
Interstitial fluid colloid osmotic pressure 8.0TOTAL OUTWARD FORCE 28.3
Mean force tending to move fluid inward: Plasma colloid osmotic pressure 28.0TOTAL INWARD FORCE 28.0
Summation of mean forces:Outward 28.3Inward 28.0
NET OUTWARD FORCE 0.3
mmHg
Copyright © 2006 by Elsevier, Inc.
Net Starling Forces in Capillaries
• Net filtration pressure of .3 mmHg which causes a net filtration rate of 2ml/min for entire body.
Figure opener; Guyton and Hall
Copyright © 2006 by Elsevier, Inc.
QuestionUtilizing the data below, calculate the rate of net fluidmovement across the capillary wall:Pressures (in mmHg)Plasma colloid osmotic = 20Capillary hydrostatic = 20 Venous hydrostatic = 5Arterial = 80Interstitial hydrostatic = -5Interstitial colloid osmotic = 5Filtration coefficient = 10 ml/min/mmHg
a. 0 ml/min d. 100 ml/min (Reabsorption)b. 10 ml/min (Filtration) e. 10 ml/min (Reabsorption)c. 100 ml/min (Filtration)
Copyright © 2006 by Elsevier, Inc.
Lymphatic System
Copyright © 2006 by Elsevier, Inc.
Determinants of Lymph Flow
• The degree of activity of the lymphatic pump
- smooth muscle filaments in lymph vessel cause them to contract
- external compression also contributes to lymphatic pumping
Figure 16-11; Guyton and Hall
Copyright © 2006 by Elsevier, Inc.
Determinants of Lymph Flow
Interstitial fluid hydrostatic pressure Lymph Flow
Figure 16-9; Guyton and Hall
Figure 16-10; Guyton and Hall