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Advances in Physiology Education Jun 2017Since the discovery of the composition and structure of the mammalian cell membrane, biologists have had a clearer understanding of how substances enter and exit the...
Since the discovery of the composition and structure of the mammalian cell membrane, biologists have had a clearer understanding of how substances enter and exit the cell's interior. The selectively permeable nature of the cell membrane allows the movement of some solutes and prevents the movement of others. This has important consequences for cell volume and the integrity of the cell and, as a result, is of utmost clinical importance, for example in the administration of isotonic intravenous infusions. The concepts of osmolarity and tonicity are often confused by students as impermeant isosmotic solutes such as NaCl are also isotonic; however, isosmotic solutes such as urea are actually hypotonic due to the permeant nature of the membrane. By placing red blood cells in solutions of differing osmolarities and tonicities, this experiment demonstrates the effects of osmosis and the resultant changes in cell volume. Using hemoglobin standard solutions, where known concentrations of hemoglobin are produced, the proportion of hemolysis and the effect of this on resultant hematocrit can be estimated. No change in cell volume occurs in isotonic NaCl, and, by placing blood cells in hypotonic NaCl, incomplete hemolysis occurs. By changing the bathing solution to either distilled water or isosmotic urea, complete hemolysis occurs due to their hypotonic effects. With the use of animal blood in this practical, students gain useful experience in handling tissue fluids and calculating dilutions and can appreciate the science behind clinical scenarios.
Topics: Animals; Erythrocytes; Hemolysis; Osmosis; Physiology; Sodium Chloride; Students; Urea
PubMed: 28526694
DOI: 10.1152/advan.00083.2016 -
Quarterly Reviews of Biophysics Feb 1979
Review
Topics: Hydrostatic Pressure; Mathematics; Osmosis; Permeability; Rheology; Solutions; Viscosity
PubMed: 386410
DOI: 10.1017/s0033583500002602 -
Advances in Physiology Education Dec 2018Understanding osmolarity and tonicity is one of the more challenging endeavors undertaken by students of the natural sciences. We asked students who completed a course...
Understanding osmolarity and tonicity is one of the more challenging endeavors undertaken by students of the natural sciences. We asked students who completed a course in animal physiology to submit an essay explaining what they found most perplexing about this subject, and what in-class activities proved most useful to them. Students had difficulty distinguishing osmolarity from tonicity and determining tonicity based on the solution's composition. The most useful activities were questions requiring simultaneous consideration of both osmolarity and tonicity. Problems that require calculating osmotic concentration and the volumes of body fluid compartments after administration or loss of various solutions emphasize the significance of osmolarity and tonicity in the context of systemic homeostasis and clinical medicine. We hope that our approach to teaching osmolarity and tonicity will prove useful to physiology lecturers who are looking for new ways of introducing this complicated topic to their health professions students.
Topics: Animals; Cell Size; Humans; Learning; Osmolar Concentration; Osmosis; Physiology; Students, Health Occupations; Teaching
PubMed: 30303411
DOI: 10.1152/advan.00094.2018 -
Chemical Reviews Apr 2022Evaporation, pervaporation, and forward osmosis are processes leading to a mass transfer of solvent across an interface: gas/liquid for evaporation and solid/liquid... (Review)
Review
Evaporation, pervaporation, and forward osmosis are processes leading to a mass transfer of solvent across an interface: gas/liquid for evaporation and solid/liquid (membrane) for pervaporation and osmosis. This Review provides comprehensive insight into the use of these processes at the microfluidic scales for applications ranging from passive pumping to the screening of phase diagrams and micromaterials engineering. Indeed, for a fixed interface relative to the microfluidic chip, these processes passively induce flows driven only by gradients of chemical potential. As a consequence, these passive-transport phenomena lead to an accumulation of solutes that cannot cross the interface and thus concentrate solutions in the microfluidic chip up to high concentration regimes, possibly up to solidification. The purpose of this Review is to provide a unified description of these processes and associated microfluidic applications to highlight the differences and similarities between these three passive-transport phenomena.
Topics: Biological Transport; Microfluidics; Osmosis; Solutions; Solvents
PubMed: 34882390
DOI: 10.1021/acs.chemrev.1c00459 -
Academic Psychiatry : the Journal of... Aug 2021
Topics: Humans; Osmosis
PubMed: 33860470
DOI: 10.1007/s40596-021-01450-x -
JASA Express Letters Aug 2021Electro-osmosis (EO) is a non-traditional pumping and transduction mechanism with the ability to project acoustic energy in fluids. This investigation experimentally...
Electro-osmosis (EO) is a non-traditional pumping and transduction mechanism with the ability to project acoustic energy in fluids. This investigation experimentally validates the influence of zeta potential, a well-studied physical characteristic used for quantifying the efficacy of an EO pump, on generation of sound pressure level. Acoustic signals of discrete frequencies were observed from 130 Hz to over 150 kHz. EO-type projectors are an attractive technology in that it does not contain moving parts, can be fabricated using a variety of materials, is intrinsically resilient to effects of hydrostatic pressure, and may be designed on the micro-electromechanical system scale.
Topics: Acoustics; Osmosis
PubMed: 36154251
DOI: 10.1121/10.0005763 -
Biochemical and Biophysical Research... Oct 1989
Topics: Biological Transport; Gravitation; Osmosis
PubMed: 2803306
DOI: 10.1016/0006-291x(89)91725-7 -
The American Journal of Physiology Jul 1978We present a tutorial on the mechanisms of and connections among osmosis, diffusion, and convection. For simplicity, we consider only two-component nonelectrolyte...
We present a tutorial on the mechanisms of and connections among osmosis, diffusion, and convection. For simplicity, we consider only two-component nonelectrolyte solutions under isothermal conditions. Further, we confine our attention to laminar convection with application to the case of flow through narrow channels, as might occur in membranes containing pores or slits. The application of equilibrium and near-equilibrium thermodynamics to flow processes is just like considerations of mechanics with friction, or hydrodynamics. The description of flow processes of more than two atomistic components, either solutions or suspensions, is identical in the dilute limit to the description we give, except possibly when the curvature of the flow field (at the velocity profile) is significant. Flow fields, therefore, naturally divide into three regimes: 1) "one-dimensional" flow fields, e.g., solutions or suspensions in extended regions, whose velocity profile is macroscopically flat (compared to the atomistic curvature); 2) flow fields with significant curvature, e.g., Poiseuille or turbulent fields; and 3) high curvature fields, e.g., narrow flow channels.
Topics: Biophysical Phenomena; Biophysics; Diffusion; Mathematics; Osmosis; Thermodynamics
PubMed: 677337
DOI: 10.1152/ajpregu.1978.235.1.R3 -
Odontologisk Tidskrift 1953
Topics: Diffusion; Humans; Osmosis; Permeability; Solutions; Tooth
PubMed: 13099792
DOI: No ID Found -
Physiological Research 2000A mathematical description is presented of osmotic flows across both ideally semipermeable membranes and membranes permeable not only for the solvent but also for the... (Review)
Review
A mathematical description is presented of osmotic flows across both ideally semipermeable membranes and membranes permeable not only for the solvent but also for the solute. The principles of thermodynamics of irreversible processes used for the description are given and illustrated on the example of electroosmosis. Modern ideas about the physical basis of osmotic pressure on porous membranes are discussed and an experiment is described that models the processes of osmosis on a macroscopic level.
Topics: Membranes; Models, Biological; Osmosis; Osmotic Pressure; Permeability; Thermodynamics
PubMed: 10984083
DOI: No ID Found