Biomaterial Database

Model experiments on the effect of bifurcations on capillary blood flow and oxygen transport. 1979

P Gaehtgens, and A Pries, and K H Albrecht

O2-delivery by a single capillary is a function of the flow rate and the fraction of flow made up of red blood cells. Capillary flow rate in turn depends upon flow resistance which is determined by the fraction of capillary volume occupied by red blood cells. Experiments were carried out to study the relationship between these parameters in an in vitro model consisting of glass capillaries (I.D. 3.3--11.0 micrometer) branching from a large bore feeding channel which was perfused at variable flow rates with suspensions of human red cells with different hematocrits. Capillary flow rates ranged from 0--10(-4) mm3s-1. The results indicate that the red cell flow fraction increases with increasing capillary flow rate and with decreasing feeding vessel flow rate. Capillary volume fraction occupied by red cells similarly depends on these two parameters, but is consistently lower than the red cell flow fraction. Capillary flow resistance increases with flow rate due to increasing volume fraction of cells. If the results obtained with the model system are applicable to in vivo capillaries it must be concluded that O2-delivery by a single capillary is not linearly related to flow rate but increases more than proportionately with flow rate. Due to alteration of resistance with flow rate another type of "autoregulation" of capillary flow is proposed which tends to keep flow rate constant despite changes of driving pressure.

UI	MeSH Term	Description	Entries
D008954	Models, Biological	Theoretical representations that simulate the behavior or activity of biological processes or diseases. For disease models in living animals, DISEASE MODELS, ANIMAL is available. Biological models include the use of mathematical equations, computers, and other electronic equipment.	Biological Model,Biological Models,Model, Biological,Models, Biologic,Biologic Model,Biologic Models,Model, Biologic
D010100	Oxygen	An element with atomic symbol O, atomic number 8, and atomic weight [15.99903; 15.99977]. It is the most abundant element on earth and essential for respiration.	Dioxygen,Oxygen-16,Oxygen 16
D001783	Blood Flow Velocity	A value equal to the total volume flow divided by the cross-sectional area of the vascular bed.	Blood Flow Velocities,Flow Velocities, Blood,Flow Velocity, Blood,Velocities, Blood Flow,Velocity, Blood Flow
D002196	Capillaries	The minute vessels that connect arterioles and venules.	Capillary Beds,Sinusoidal Beds,Sinusoids,Bed, Sinusoidal,Beds, Sinusoidal,Capillary,Capillary Bed,Sinusoid,Sinusoidal Bed
D005898	Glass	Hard, amorphous, brittle, inorganic, usually transparent, polymerous silicate of basic oxides, usually potassium or sodium. It is used in the form of hard sheets, vessels, tubing, fibers, ceramics, beads, etc.
D006400	Hematocrit	The volume of packed RED BLOOD CELLS in a blood specimen. The volume is measured by centrifugation in a tube with graduated markings, or with automated blood cell counters. It is an indicator of erythrocyte status in disease. For example, ANEMIA shows a low value; POLYCYTHEMIA, a high value.	Erythrocyte Volume, Packed,Packed Red-Cell Volume,Erythrocyte Volumes, Packed,Hematocrits,Packed Erythrocyte Volume,Packed Erythrocyte Volumes,Packed Red Cell Volume,Packed Red-Cell Volumes,Red-Cell Volume, Packed,Red-Cell Volumes, Packed,Volume, Packed Erythrocyte,Volume, Packed Red-Cell,Volumes, Packed Erythrocyte,Volumes, Packed Red-Cell
D006706	Homeostasis	The processes whereby the internal environment of an organism tends to remain balanced and stable.	Autoregulation
D006801	Humans	Members of the species Homo sapiens.	Homo sapiens,Man (Taxonomy),Human,Man, Modern,Modern Man
D012212	Rheology	The study of the deformation and flow of matter, usually liquids or fluids, and of the plastic flow of solids. The concept covers consistency, dilatancy, liquefaction, resistance to flow, shearing, thixotrophy, and VISCOSITY.	Flowmetry,Velocimetry,Velocimetries
D014655	Vascular Resistance	The force that opposes the flow of BLOOD through a vascular bed. It is equal to the difference in BLOOD PRESSURE across the vascular bed divided by the CARDIAC OUTPUT.	Peripheral Resistance,Total Peripheral Resistance,Pulmonary Vascular Resistance,Systemic Vascular Resistance,Peripheral Resistance, Total,Resistance, Peripheral,Resistance, Pulmonary Vascular,Resistance, Systemic Vascular,Resistance, Total Peripheral,Resistance, Vascular,Vascular Resistance, Pulmonary,Vascular Resistance, Systemic