Solute Translocations
Lelio G. Colombetti in Biological Transport of Radiotracers, 2020
The consequences of placing an impermeable solute on only one side of a semipermeable membrane extend beyond those described above. Water will move from the side without added solute (where the chemical activity of water is high) to the side containing the impermeable molecule (where the activity of water is low). In a completely open system, this process — called osmosis — results in dilution of the solute. In a system where the solute-containing compartment is closed, the process results in a pressure in the closed compartment. The osmotic pressure is defined practically as the pressure on the compartment containing the impermeable molecule required to prevent the flow of water. It is the semipermeable nature of biological membranes which results in the osmotic activity of cells. As the osmotic pressure depends on the concentration of the dissolved solute (and not on its chemical nature), the pressure can be maintained or modified by molecules as diverse as proteins, amino acids, and inorganic ions.
Introduction: Background Material
Nassir H. Sabah in Neuromuscular Fundamentals, 2020
It should be noted that when an ionic substance dissociates into ions in solution, each ion would count as a particle as far as osmotic pressure is concerned, at least at the low concentrations normally encountered in biological systems. The contribution to osmotic pressure can be defined in terms of osmoles, where an osmole is a mole of an osmotically active particle. Thus, one osmole equals one mole multiplied by n×o, where n is the number of particles resulting from dissociation of one molecule of solute and o is the osmotic coefficient, which, in the simplest case, accounts for any incomplete dissociation of the solute as well as the interaction between dissociated particles. For a dilute solution of NaCl, for example, one osmole is usually considered to be two moles, since NaCl ideally dissociates into two osmotically active particles, Na+ and Cl−, each of which contributes to osmosis like a mole of sugar which does not dissociate in solution into more particles.
Potassium and calcium
Shaun Phillips in Fatigue in Sport and Exercise, 2015
Potassium plays crucial roles in body function. First, K+, along with another electrolyte, sodium (Na+), helps to regulate intra- and extracellular water content. Water molecules do not have an electrical charge, and cells cannot move water from intra to extracellular locations directly. However, the components of water, hydrogen and oxygen, do have an electrical charge (hydrogen has a positive charge, and oxygen a negative charge). These charges are attracted to the electrical charges of K+ and Na+ ions, meaning that electrolytes ‘attract’ water molecules to them. If a cell membrane is permeable to water, then water will move across the membrane to the side with the highest concentration of electrolytes, as this is the side that is exerting the greatest ‘pull’ on the water molecules. This movement of water will continue until the electrolyte concentration on both sides of the cell membrane is equal. The force required to move water across a membrane is called the osmotic pressure. It is in this way that cells regulate body water content.
Pharmaceutical implants: classification, limitations and therapeutic applications
Published in Pharmaceutical Development and Technology, 2020
Zahra Mohtashami, Zahra Esmaili, Molood Alsadat Vakilinezhad, Ehsan Seyedjafari, Hamid Akbari Javar
Implants could also be classified based on the drug release controlling mechanisms. These systems could be categorized as diffusion-controlled, chemically controlled, swelling controlled, osmotically controlled, magnetically controlled, etc. Every system has its unique characteristics. Zero-order released could be achieved in either reservoir or matrix type diffusion-controlled systems where the polymer layer and diffusional distance would consider as rate-limiting factors respectively. In chemically controlled systems, bioerosion of polymer is responsible for drug releasing rate. The zero-order kinetic would achieve where the surface area remains constant over time. In osmotically controlled systems, osmotic pressure is a driving force of drug release through the semipermeable membrane of the delivery system. So on.
Comparing membrane and spacer biofouling by Gram-negative Pseudomonas aeruginosa and Gram-positive Anoxybacillus sp. in forward osmosis
Published in Biofouling, 2019
Anne Bogler, Douglas Rice, Francois Perreault, Edo Bar-Zeev
The combination of global water scarcity and more stringent regulations for environmental protection has prompted scientists to investigate new technologies for the sustainable production of fresh water (McGinnis and Elimelech 2008; Bogler et al. 2017). Forward osmosis (FO) is a developing membrane technology that uses an osmotic pressure gradient between the two sides of an asymmetric membrane to draw pure water out of contaminated water. FO has potential applications for advanced wastewater treatment and reuse since the separation is done at low hydraulic pressure, which reduces system complexity (Coday et al. 2014; Lutchmiah et al. 2014; Shaffer et al. 2015). However, like all membrane-based technologies, the efficiency of FO processes is hindered by fouling (Valladares Linares, Bucs, et al. 2014; Kwan et al. 2015; She et al. 2016).
Copolymer Micelle-administered Melatonin Ameliorates Hyperosmolarity-induced Ocular Surface Damage through Regulating PINK1-mediated Mitophagy
Published in Current Eye Research, 2022
Jing Xu, Peng Chen, Guangfen Zhao, Susu Wei, Qiqi Li, Chuanlong Guo, Qilong Cao, Xianggen Wu, Guohu Di
HCECs were cultured in DMEM/F12 medium (DF12, Hyclone, Logan, UT, USA) including 10% fetal bovine serum (FBS, ExCell Bio, Shanghai, China), 1% streptomycin and penicillin (Solarbio) with 5% CO2 at 37 °C. Cells were subjected to hyperosmotic exposure by the addition of 70-mM sodium chloride (NaCl) to achieve hypertonic stress (450 mOsM, HS), as our previous description.33 The osmolarity was assessed by an osmotic pressure gauge (Tianhe analytical instrument Co., Ltd. Tianjin, China). Mel was dissolved in dimethyl sulfoxide (DMSO) and diluted to a ratio of 1:1000. Five groups were created: control group (312 mOsM), con + Mel (10 µM) group, HS + vehicle (PVCL–PVA–PEG micelles solution) group, HS + Mel (10 µM) group, and HS + Mel-Mic (10 µM) group. After treatment for 24 h, HCECs were collected for flow cytometry (FCM) assay or lysed in radioimmunoprecipitation assay (RIPA) for western blotting.
Related Knowledge Centers
- Solution
- Semipermeable Membrane
- Osmosis
- Van 'T Hoff Factor
- Colligative Properties
- Pitzer Equations
- Osmoregulation
- Homeostasis
- Tissue
- Cell