Author/Editor     Blinc, Aleš
Title     Izmenjava snovi in tekočin
Translated title     Exchange of matter and fluid
Type     članek
Source     Med Razgl
Vol. and No.     Letnik 35, št. Suppl 2
Publication year     1996
Volume     str. 23-9
Language     slo
Abstract     The exchange of matter and fluid between blood and tissues mainly takes place through the capillary wall. Blood flows into capillaries by convective flow, an efficient transport mechanism across large distances. In capillaries, filtration and absorption of fluids take place due to the interaction of the hydrostatic and colloid osmotic pressures in the plasma and interstitium. Under stationary conditions, slightly more fluid is filtered than absorbed and the remainder returns with lymph flow. The mechanism of filtration and absorption is important for the regulation of the volume of interstitial fluid and less so for the transport of dissolved substances from blood to tissues. The exchange of dissolved substances between blood and tissues takes place mainly by diffusion flow which is very efficient over distances up to a few tens of micrometers, but decreases exponentially with distance due to a reduction of concentration gradient. Macromolecules pass the capillary wall in cytoplasmic vesicles and by filtration through large pores.
Summary     Izmenjava snovi in tekočin med krvjo in tkivi poteka v največji meri preko kapilarne stene. Kri priteka v kapilare v konvekcijskim tokom, ki je učinkovit mehanizem transporta na velike razdalje. V kapilarah poteka filtracija in absorpcija tekočin zaradi delovanja hidrostatskega in koloidno osmotskega tlaka v plazmi in intersticiju. V ravnovesnih pogojih se filtrira nekoliko več tekočine, kot se je reabsorbira, razlika pa se vrne v kri z limfnim tokom. Mehanizem filtracije in absorpcije je pomemben za uravnavanje prostornine intersticijske tekočine, manj pa za transport topljencev iz krvi v tkiva. Izmenjava topljencev med krvjo in tkivi poteka v glavnem z difuzijskim tokom, ki je zelo učinkovit na razdaljah do nekaj desetin mikrometrov, vendar eksponentno upada z razdaljo zaradi zmanjševanja koncentracijskega gradienta. Makromolekule prehajajo preko kapilarne stene v citoplazemsnkih veziklih in s filtracijo skozi velike pore.
Descriptors     BIOLOGICAL TRANSPORT
ENDOTHELIUM, VASCULAR
CAPILLARY PERMEABILITY
DIFFUSION
FILTRATION
ABSORPTION