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Copyright © 2006 by Elsevier, Inc. The Microcirculation Figure 16-1; Guyton and Hall.

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Presentation on theme: "Copyright © 2006 by Elsevier, Inc. The Microcirculation Figure 16-1; Guyton and Hall."— Presentation transcript:

1 Copyright © 2006 by Elsevier, Inc. The Microcirculation Figure 16-1; Guyton and Hall

2 Copyright © 2006 by Elsevier, Inc. Structure of Capillary Wall Figure 16-2; Guyton and Hall

3 Copyright © 2006 by Elsevier, Inc. Interstitium and Interstitial Fluid Figure 16-4; Guyton and Hall

4 Copyright © 2006 by Elsevier, Inc. Determinants of Net Fluid Movement 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

5 Copyright © 2006 by Elsevier, Inc. Determinants of Net Fluid Movement 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

6 Copyright © 2006 by Elsevier, Inc. Plasma Proteins and Colloid Osmotic 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 Globulins Fibrinogen Total

7 Copyright © 2006 by Elsevier, Inc. Determinants of Net Fluid Movement 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

8 Copyright © 2006 by Elsevier, Inc. Forces Causing Filtration at the Arteriole End of the Capillary Forces tending to move fluid outward: Capillary pressure 30 Negative interstitial free fluid pressure3 Interstitial fluid colloid osmotic pressure8 TOTAL OUTWARD FORCE 41 Forces tending to move fluid inward: Plasma colloid osmotic pressure 28 TOTAL INWARD FORCE 28 Summation of forces: Outward 41 Inward 28 NET OUTWARD FORCE 13 mmHg

9 Copyright © 2006 by Elsevier, Inc. Forces Causing Reabsorption at the Venous End of the Capillary Forces tending to move fluid inward: Plasma colloid osmotic pressure28 TOTAL INWARD FORCE 28 Forces tending to move fluid outward: Capillary pressure10 Negative interstitial free fluid pressure 3 Interstitial fluid colloid osmotic pressure 8 TOTAL OUTWARD FORCE21 Summation of forces: Outward21 Inward28 NET INWARD FORCE7 mmHg

10 Copyright © 2006 by Elsevier, Inc. Net Starling Forces in Capillaries Mean forces tending to move fluid outward: Mean Capillary pressure17.3 Negative interstitial free fluid pressure3.0 Interstitial fluid colloid osmotic pressure8.0 TOTAL OUTWARD FORCE28.3 Mean force tending to move fluid inward: Plasma colloid osmotic pressure28.0 TOTAL INWARD FORCE28.0 Summation of mean forces: Outward28.3 Inward28.0 NET OUTWARD FORCE0.3 mmHg

11 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

12 Copyright © 2006 by Elsevier, Inc. Question Utilizing the data below, calculate the rate of net fluid movement across the capillary wall: Pressures (in mmHg) Plasma colloid osmotic = 20 Capillary hydrostatic = 20 Venous hydrostatic = 5 Arterial = 80 Interstitial hydrostatic = -5 Interstitial colloid osmotic = 5 Filtration 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)

13 Copyright © 2006 by Elsevier, Inc. Lymphatic System

14 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

15 Copyright © 2006 by Elsevier, Inc. Determinants of Lymph Flow Interstitial fluid hydrostatic pressureLymph Flow Figure 16-9; Guyton and Hall Figure 16-10; Guyton and Hall


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