A review of mixing and propulsion of chyme in the small intestine: fresh insights from new methods
Gespeichert in:
Verfasser / Beitragende:
[R. Lentle, C. de Loubens]
Ort, Verlag, Jahr:
2015
Enthalten in:
Journal of Comparative Physiology B, 185/4(2015-05-01), 369-387
Format:
Artikel (online)
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| 024 | 7 | 0 | |a 10.1007/s00360-015-0889-5 |2 doi |
| 035 | |a (NATIONALLICENCE)springer-10.1007/s00360-015-0889-5 | ||
| 245 | 0 | 2 | |a A review of mixing and propulsion of chyme in the small intestine: fresh insights from new methods |h [Elektronische Daten] |c [R. Lentle, C. de Loubens] |
| 520 | 3 | |a The small intestine is a convoluted flexible tube of inconstant form and capacity through which chyme is propelled and mixed by varying patterns of contraction. These inconstancies have prevented quantitative comparisons of the manner in which contractile activity engenders mixing of contained chyme. Recent quantitative work based on spatiotemporal mapping of intestinal contractions, macro- and micro-rheology, particle image velocimetry and real-time modelling has provided new insights into this process. Evidence indicates that the speeds and patterns of the various types of small intestinal contraction are insufficient to secure optimal mixing and enzymatic digestion over a minimal length of intestine. Hence particulate substrates and soluble nutrients become dispersed along the length of the lumen. Mixing within the lumen is not turbulent but results from localised folding and kneading of the contents by contractions but is augmented by the inconstant spatial disposition of the contractions and their component contractile processes. The latter include inconstancies in the sites of commencement and the directions of propagation of contraction in component groups of smooth muscle cells and in the coordination of the radial and circular components of smooth muscle contraction. Evidence suggests there is ongoing augmentation of mixing at the periphery of the lumen, during both the post-prandial and inter-meal periods, to promote flow around and between adjacent villi. This results largely from folding of the relatively inelastic mucosa during repeated radial and longitudinal muscular contraction, causing chyme to be displaced by periodic crowding and separation of the tips of the relatively rigid villi. Further, micro-rheological studies indicate that such peripheral mixing may extend to the apices of enterocytes owing to discontinuities in the mobile mucus layer that covers the ileal mucosa. | |
| 540 | |a Springer-Verlag Berlin Heidelberg, 2015 | ||
| 690 | 7 | |a Small intestine |2 nationallicence | |
| 690 | 7 | |a Luminal mixing |2 nationallicence | |
| 690 | 7 | |a Stochastic vortices |2 nationallicence | |
| 690 | 7 | |a Real-time modelling |2 nationallicence | |
| 690 | 7 | |a Annealing of mucins : Process of union of individual masses of mucin secreted from individual goblet cells by inter-diffusion of their respective carbohydrate side chains |2 nationallicence | |
| 690 | 7 | |a Apical crowding of villi : Gathering together of the tips of villi in the region between adjacent mucosal microfolds that leads to expulsion of fluid from the spaces between the tips |2 nationallicence | |
| 690 | 7 | |a Continuously stirred tank reactor (CSTR) : A theoretical ideal chemical reactor that runs at a steady rate with continuous flow of reactants and product with complete, i.e. perfect mixing, so that the concentration of reactants is uniform within |2 nationallicence | |
| 690 | 7 | |a Mucosal microfolds : Inwardly projecting folds of mucosa that develop spontaneously as a result of relative differences in the mechanical properties and in the axial lengths of the mucosal and muscular components of the small intestine |2 nationallicence | |
| 690 | 7 | |a Newtonian fluid : A fluid in which the shear rates that develop during flow are always proportional to the shear stress applied, so that viscosity remains constant |2 nationallicence | |
| 690 | 7 | |a Phasic contraction : Concerted or coordinated short-lived contraction of groups of smooth muscle following neural or myogenic stimulation, e.g. peristalsis |2 nationallicence | |
| 690 | 7 | |a Pseudoplasticity : The property of a non-Newtonian fluid in which its apparent viscosity decreases with increase in shear rate |2 nationallicence | |
| 690 | 7 | |a Reynolds number : The ratio of the inertial forces within a moving fluid (that generally cause motion to continue) to viscous forces (that can be viewed as frictional and generally cause motion to slow). For flow within a simple tube Reynolds numbers of less than 2,300 are considered to describe a condition in which viscous forces predominate so that flow is laminar, i.e. occurs in an orderly fashion that can be viewed as a series of concentric tubes within the pipe. Conversely, Reynolds numbers >2,300 describe a condition in which inertial forces predominate so that flow in elements of the liquid become unstable and turbulent |2 nationallicence | |
| 690 | 7 | |a Rheometry : Techniques that determine the relationship between the forces that stress materials, or mixtures of materials, and the elastic and fluid deformations that they produce |2 nationallicence | |
| 690 | 7 | |a Shear : Deformation induced in a material when its layers are shifted laterally in relation to each other |2 nationallicence | |
| 690 | 7 | |a Shear rate : In a fluid is given by the rate of change in velocity (velocity gradient) with which one fluid layer passes over an adjacent layer |2 nationallicence | |
| 690 | 7 | |a Strain : Degree of deformation by stretch or compression. Generally determined as a percentage increase or decrease of original length |2 nationallicence | |
| 690 | 7 | |a Strain rate : The rate at which a component is deformed by stretching (positive strain rate) or compression for example during contraction (negative strain rate) |2 nationallicence | |
| 690 | 7 | |a Stress : Force per unit area either parallel or perpendicular to the area to which it is applied |2 nationallicence | |
| 690 | 7 | |a Tonic contraction : Longer lasting contraction resulting from sustained contraction of groups of component smooth muscle cells, chiefly through inhibition of actin-myosin ATPase, that generates ongoing tension (tone) within the wall of the structure in which it operates |2 nationallicence | |
| 690 | 7 | |a Turbulent mixing : A condition in which widespread mixing results from the ongoing appearance of unsteady vortices and areas of folding and kneading on many length scales that interact with one another other |2 nationallicence | |
| 690 | 7 | |a Viscosity : The ratio of the force that is applied to a liquid to the longitudinal movement of the fluid, i.e. shear, that it generates |2 nationallicence | |
| 690 | 7 | |a Viscoelasticity : Time-dependent property of materials that exhibit the characteristics of solid behaviour, i.e. elasticity and of liquid flow, i.e. viscosity when undergoing deformation. The elastic component of digesta is thought to result from interaction of the contained particles |2 nationallicence | |
| 700 | 1 | |a Lentle |D R. |u Institute of Food, Nutrition and Human Health, Massey University, Private Bag 11222, Palmerston North, New Zealand |4 aut | |
| 700 | 1 | |a de Loubens |D C. |u UMR 782 Génie et Microbiologie des Procédés Alimentaires, INRA, AgroParisTech, CBAI, 78850, Thiverval-Grignon, France |4 aut | |
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| 950 | |B NATIONALLICENCE |P 700 |E 1- |a Lentle |D R. |u Institute of Food, Nutrition and Human Health, Massey University, Private Bag 11222, Palmerston North, New Zealand |4 aut | ||
| 950 | |B NATIONALLICENCE |P 700 |E 1- |a de Loubens |D C. |u UMR 782 Génie et Microbiologie des Procédés Alimentaires, INRA, AgroParisTech, CBAI, 78850, Thiverval-Grignon, France |4 aut | ||
| 950 | |B NATIONALLICENCE |P 773 |E 0- |t Journal of Comparative Physiology B |d Springer Berlin Heidelberg |g 185/4(2015-05-01), 369-387 |x 0174-1578 |q 185:4<369 |1 2015 |2 185 |o 360 | ||