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CAPILLARIES

CAPILLARIES. MICROCIRCULATION AND LYMPHATIC SYSTEM. Capillaries. *Are smallest vessels with thin wall *Microscopic capillary networks are highly permeable to all water , cell nutrients and cell excreta between the tissues tissues and circulating blood

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CAPILLARIES

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  1. CAPILLARIES MICROCIRCULATION AND LYMPHATIC SYSTEM

  2. Capillaries *Are smallest vessels with thin wall *Microscopic capillary networks are highly permeable to all water , cell nutrients and cell excreta between the tissues tissues and circulating blood *Chemicals and gases diffuse across walls

  3. Functions of Capillaries *Permit diffusion of: water small solutes Lipid-soluble materials *Block: blood cells plasma proteins

  4. Capillary Function *it’s the Location of all exchange functions of cardiovascular system *Materials diffuse between blood and interstitial fluid

  5. Capillary Structure - Endothelial tube, inside thin basal lamina - No tunica media - No tunica externa *Diameter is similar to red blood cell

  6. Transport across capillary wall Endothelial cell Interstitial fluid Water-filled pore Plasma proteins generally cannot cross the capillary wall Plasma Plasma proteins Plasma membrane Lipid-soluble substances pass through the endothelial cells O2, CO2 Cytoplasm Exchangeable proteins Na+, K+, glucose, amino acids Exchangeable proteins are moved across by vesicular transport Small, water-soluble substances pass through the pores Fig. 10-16b, p. 292

  7. Capillary structureCapillary pores(Intercellular cleft)Plasmalemmal vesiclesVesicular channels

  8. Special types of (pores) in certain organs 1.Brain ,blood brain barriers tight junction 2.Liver very wide 3.GI capillaries, midway in size between muscles and liver 4. Glomerular capillaries of the kidney, Fenestrate ; small oval windows penetrate through middle of endothelial cells

  9. Capillary Networks Figure 21-5

  10. Capillaries Networks Capillary bed or capillary plexus Connect 1 arteriole and 1 venule

  11. Collaterals *Multiple arteries that contribute to 1 capillary bed *Allow circulation if 1 artery is blocked Arterial anastomosis: => fusion of 2 collateral arteries

  12. Velocity of flow (mm/sec) Anatomical distribution Total cross-sectional area (cm2) Blood flow rate (liters/min) 6,000 0.5 500 4.5 5 Aorta Arteries Arterioles Capillaries Venules Veins Venae cavae Fig. 10-14, p. 291

  13. O2 CO2 Glucose Plasma = Carrier-mediated transport Interstitial fluid Glucose + O2 CO2 + H2O + ATP Tissue cell Fig. 10-17, p. 293

  14. Capillary pressure (mm Hg) Transition point Fluid movement Inward pressure ( pP + PIF) Outward pressure (PC + pIF) Capillary length Beginning End = Reabsorption = Ultrafiltration Fig. 10-19, p. 295

  15. Pulmonary vessels 9% Systemic arteries 13% Systemic arterioles 2% Heart 7% Systemic capillaries 5% Systemic veins 64% Fig. 10-23, p. 299

  16. ARTERIAL END OF CAP FORCES OUTWARD CAP P 30+NEG IFFP 3 +IFCOP8=41 FORCES INWARD PLASMA COLLOID OSMOTIC P=28 SUMMATION OF FORCES OUTWAR 41-INWARD 28=13mmhg

  17. VENOU END OF CAP FORCES OUTWARD CAP P 10+NEG IFFP 3 +IFCOP8=21 FORCES INWARD PLASMA COLLOID OSMOTIC P=28 SUMMATION OF FORCES INWAR 28-OUTWARD 21=7mmhg

  18. STARLING EQUILIBRIUM FOR CAPILLARY PRESSURE OUTWAD FORCES MEAN CAP P=17.3 NEG IFFP=3 IFCOP=8 TOTAL=28.3mmhg INWARD FORCES PLASMA COLL OSM PRES=28mmhg RESULT(OUTWARD28.3-INWARD28=0.3

  19. LYMPHATIC CIRCULATION 1-LYMPHATIC STRUCTURE 2-FACTORS DETERMINE LYMPHATIC FLOW A.LYMPHATIC PUMP B.INTERSTIAL FLUID PRESSURE

  20. LYMPHATIC FUNCTION CONTROLL INTERSTIALFLUID 1. PROTEIN CONCENTRATION 2.VOLUME 3.PRESSURE

  21. Lymph flow1.Interstial fluid pressureA. Elevate capillary pressureB. Increase interstitial fluid colloid osmotic pressure C. Decrease plasma colloid osmotic pressureD. Increase permeability of capillaries

  22. 2. Lymph pump and valves3.External compressionA. Surrounding skeletal musclesB. Movements of parts of the bodyC. Pulsation of arteriesD. Compression of the tissues by objects outside the body

  23. 4. Lymphatic capillary pump

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