Osmosis and Solute–Solvent Drag: Fluid Transport and Fluid Exchange in Animals and Plants

2005 ◽  
Vol 42 (3) ◽  
pp. 277-345 ◽  
Author(s):  
H. T. Hammel ◽  
Whitney M. Schlegel
Keyword(s):  
Fluid Transport ◽  
Solvent Drag ◽  
Fluid Exchange

scholarly journals Geometry of unsteady fluid transport during fluid–structure interactions

2007 ◽  
Vol 589 ◽  
pp. 125-145 ◽  
Author(s):  
ELISA FRANCO ◽  
DAVID N. PEKAREK ◽  
JIFENG PENG ◽  
JOHN O. DABIRI
Keyword(s):  
Fluid Transport ◽  
Recirculation Zone ◽  
Biological Fluid ◽  
Canonical System ◽  
Two Dimensional ◽  
Fluid Structure Interactions ◽  
Fluid Exchange ◽  
Fluid Structure ◽  
Ambient Flow ◽  
Unsteady Fluid

We describe the application of tools from dynamical systems to define and quantify the unsteady fluid transport that occurs during fluid–structure interactions and in unsteady recirculating flows. The properties of Lagrangian coherent structures (LCS) are used to enable analysis of flows with arbitrary time-dependence, thereby extending previous analytical results for steady and time-periodic flows. The LCS kinematics are used to formulate a unique, physically motivated definition for fluid exchange surfaces and transport lobes in the flow. The methods are applied to numerical simulations of two-dimensional flow past a circular cylinder at a Reynolds number of 200; and to measurements of a freely swimming organism, the Aurelia aurita jellyfish. The former flow provides a canonical system in which to compare the present geometrical analysis with classical, Eulerian (e.g. vortex shedding) perspectives of fluid–structure interactions. The latter flow is used to deduce the physical coupling that exists between mass and momentum transport during self-propulsion. In both cases, the present methods reveal a well-defined, unsteady recirculation zone that is not apparent in the corresponding velocity or vorticity fields. Transport rates between the ambient flow and the recirculation zone are computed for both flows. Comparison of fluid transport geometry for the cylinder crossflow and the self-propelled swimmer within the context of existing theory for two-dimensional lobe dynamics enables qualitative localization of flow three-dimensionality based on the planar measurements. Benefits and limitations of the implemented methods are discussed, and some potential applications for flow control, unsteady propulsion, and biological fluid dynamics are proposed.

Transcapillary Transport during Secretion by the Rabbit Submandibular Salivary Gland

1987 ◽  
Vol 66 (2) ◽  
pp. 564-568 ◽  
Author(s):  
L.H. Smaje ◽  
J. Gamble
Keyword(s):  
Blood Flow ◽  
Nerve Stimulation ◽  
Fluid Transport ◽  
Submandibular Salivary Gland ◽  
Fluid Exchange ◽  
Fluid Filtration ◽  
Parasympathetic Nerve ◽  
Capillary Recruitment

Fluid exchange in the rabbit submandibular gland has been studied with a view to improving understanding of the mechanisms underlying transcapillary transport during salivation. Using maximally vasodilated glands perfused in vitro, we found that acetylcholine had no signijicant effect on either hydraulic conductance (filtration coefficient, Lp) or reflection coefficient to albumin (σalb) of the gland microvessels. In vivo, parasympathetic nerve stimulation increased blood flow 20-fold, interstitial fluid production (total fluid efflux - saliva fTow) increased approximately 10-fold, while filtration fraction remained constant. At the same time, isogravimetric capillary pressure increased about six-fold. There are several possible explanations for these findings, and it is argued that they are likely to include capillary recruitment. Thus, during salivation, parasympathetic nerve stimulation does not lead to a change in capillary permeability as such, but rather produces a relaxation of resistance vessels and a fall in precapillary resistance, accompanied by an increase in available capillary surface area. This leads to a rise in capillary blood flow and pressure, which in turn increase fluid filtration. These changes are self-limiting due to the resulting dilution of interstitial protein and rise in interstitial pressure, but during salivation, since the secretion is pumped out of the interstitium, this fluid transport has no net effect on transcapillary gradients.

Components of Glucose Transport in the Host–Parasite System, Hymenolepis diminuta (Cestoda) and the Rat Intestine

1974 ◽  
Vol 52 (2) ◽  
pp. 183-197 ◽  
Author(s):  
R. B. Podesta ◽  
D. F. Mettrick
Keyword(s):  
Glucose Transport ◽  
Fluid Transport ◽  
Glucose Absorption ◽  
Hymenolepis Diminuta ◽  
Hydrogen Ion ◽  
Ion Concentration ◽  
Solvent Drag ◽  
Rat Intestine ◽  
Hydrogen Ion Concentration

Glucose and fluid transport by the rat intestine and by the tapeworm Hymenolepis diminuta has been studied in vivo, using closed loops of the entire small intestine. The effect of pH, glucose concentration, and the presence of sodium on solute and solvent absorption has been determined in both host and parasite. The effect of the worms on intestinal absorption by the rat has also been evaluated. Three components of the glucose transport system, namely active transport, diffusion, and solvent drag, were determined by means of a model transport equation.Saturation kinetics for glucose absorption did not occur and the absence of sodium in the luminal fluid, while not affecting glucose absorption, markedly reduced fluid absorption by both the intestine and the worms. Lowering the pH of luminal fluids significantly reduced glucose transport by the intestine but increased absorption of fluid and glucose by H. diminuta. Irrespective of pH, fluid and glucose absorption were significantly reduced in the parasitized intestine.Active transport of glucose by normal or parasitized intestine and by H. diminuta was unaffected by the concentration of glucose in the lumen, or by changes in pH. The solvent drag and diffusion components of glucose transport were reduced by increasing the hydrogen ion concentration in uninfected and parasitized intestines. The solvent drag component of glucose absorption by the tapeworms was increased with increasing hydrogen ion concentration.The results are discussed in terms of the current hypotheses on the mechanism of glucose transport, sodium dependency, and the effect of hydrogen ions on transport mechanisms.

Effects of amiloride on the endolymphatic sac

1989 ◽  
Vol 103 (5) ◽  
pp. 466-470 ◽  
Author(s):  
M. Takumida ◽  
D. Bagger-Sjöbäck
Keyword(s):  
Epithelial Cells ◽  
Ion Exchange ◽  
Fluid Transport ◽  
Endolymphatic Hydrops ◽  
Endolymphatic Sac ◽  
Intercellular Spaces ◽  
Exchange System ◽  
Fluid Exchange ◽  
Apical Portion ◽  
Lateral Intercellular Spaces

AbstractThe effect of amiloride on the murine endolymphatic sac was investigated. The amiloride caused collapse of the lateral intercellular spaces in the endolymphatic sac epithelium and a subsequent mild endolymphatic hydrops. These changes indicated a decreased absorption of endolymph in the endolymphatic sac. Amiloride is known to inhibit the transcellular fluid transport without inducing any changes in the paracellular fluid transport. It is therefore suggested that amiloride specially inhibits the fluid and ion exchange in the apical portion of the epithelial cells resulting a decrease in transcellular fluid transport across the endolymphatic sac epithelium. The transcellular fluid transport seems to be one of the main mechanisms in the endolymphatic sac fluid exchange system.

scholarly journals The Glymphatic System (En)during Inflammation

2021 ◽  
Vol 22 (14) ◽  
pp. 7491
Author(s):  
Frida Lind-Holm Mogensen ◽  
Christine Delle ◽  
Maiken Nedergaard
Keyword(s):  
Fluid Transport ◽  
Neurological Diseases ◽  
Lymphatic Vessels ◽  
Perivascular Spaces ◽  
Fluid Exchange ◽  
Glymphatic System ◽  
The Central Nervous System ◽  
The Brain ◽  
Privileged Site ◽  
Vascular Compartment

The glymphatic system is a fluid-transport system that accesses all regions of the brain. It facilitates the exchange of cerebrospinal fluid and interstitial fluid and clears waste from the metabolically active brain. Astrocytic endfeet and their dense expression of the aquaporin-4 water channels promote fluid exchange between the perivascular spaces and the neuropil. Cerebrospinal and interstitial fluids are together transported back to the vascular compartment by meningeal and cervical lymphatic vessels. Multiple lines of work show that neurological diseases in general impair glymphatic fluid transport. Insofar as the glymphatic system plays a pseudo-lymphatic role in the central nervous system, it is poised to play a role in neuroinflammation. In this review, we discuss how the association of the glymphatic system with the meningeal lymphatic vessel calls for a renewal of established concepts on the CNS as an immune-privileged site. We also discuss potential approaches to target the glymphatic system to combat neuroinflammation.

“Quasi industre giardiniero”

2016 ◽  
Vol 33 (4) ◽  
pp. 522-568
Author(s):  
Cory M. Gavito
Keyword(s):  
Complex Nature ◽  
Editorial Process ◽  
Fluid Exchange ◽  
Oral Transmission ◽  
Musical Practices

Among the roughly 150 Italian songbooks published between 1610 and 1665 with the guitar tablature known as alfabeto, about thirteen are anthologies. These anthologies often advertise the role of a compiler who has gathered together music by diverse authors. The extent to which compilers also functioned as authors and editors is not well understood. This essay considers the case of Giovanni Stefani, a compiler who, in the preface to his Scherzi amorosi of 1622, describes the anthology as a collection of his choosing that contains “varie compositioni de Virtuosi della prima classe” (various compositions of first-class virtuosos). Intriguingly, none of the settings Stefani prints (in both this alfabeto anthology and two others) include attributions. Since the 1880s, scholars have been preoccupied with matters of transmission and attribution, unearthing a network of textual and musical concordances. This article expands the nexus of Stefani’s songs and their concordant sources, revealing an array of examples that range from identical copies to “partial” concordances that take over motives, phrases, refrains, or harmonic schemes. These examples indicate that in preparing his anthologies, Stefani mined a corpus of existing prints and manuscripts while also relying heavily on oral transmission. The complex nature of Stefani’s approach, taken together with his complete avoidance of composer attributions, points toward an editorial process shaped by a fluid exchange between oral and written musical practices.

scholarly journals Research on a Piezoelectric Pump with Flexible Valves

2021 ◽  
Vol 11 (7) ◽  
pp. 2909
Author(s):  
Weiqing Huang ◽  
Liyi Lai ◽  
Zhenlin Chen ◽  
Xiaosheng Chen ◽  
Zhi Huang ◽  
...  
Keyword(s):  
Flow Rate ◽  
Fluid Transport ◽  
Smooth Transition ◽  
Driving Voltage ◽  
Piezoelectric Pump ◽  
Venous Valve ◽  
Output Pressure ◽  
Small Flow ◽  
Working Principle ◽  
Opening And Closing

Imitating the structure of the venous valve and its characteristics of passive opening and closing with changes in heart pressure, a piezoelectric pump with flexible valves (PPFV) was designed. Firstly, the structure and the working principle of the PPFV were introduced. Then, the flexible valve, the main functional component of the pump, was analyzed theoretically. Finally, an experimental prototype was manufactured and its performance was tested. The research proves that the PPFV can achieve a smooth transition between valved and valveless by only changing the driving signal of the piezoelectric (PZT) vibrator. The results demonstrate that when the driving voltage is 100 V and the frequency is 25 Hz, the experimental flow rate of the PPFV is about 119.61 mL/min, and the output pressure is about 6.16 kPa. This kind of pump can realize the reciprocal conversion of a large flow rate, high output pressure, and a small flow rate, low output pressure under the electronic control signal. Therefore, it can be utilized for fluid transport and pressure transmission at both the macro-level and the micro-level, which belongs to the macro–micro combined component.

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