The cell and tissues
Peate Ian, Dutton Helen in Acute Nursing Care, 2020
Before considering the basic structure of the cell, it is important to consider its physiological environment. All human cells contain an aqueous fluid (intracellular fluid), known as cytosol. Apart from the organelles, this fluid contains substances such as proteins, other nutrient molecules, metabolic products and also a range of chemicals known as electrolytes. Outside the cells, there is the extracellular fluid, which is composed of the interstitial fluid and the circulating fluid; the latter consists of blood in the vascular system and the lymph in the lymphatic vessels. The extracellular fluid has a similar composition to the intracellular fluid. However, there are important differences in the composition of these fluids, particularly in the type and quantity of electrolytes and in the distribution of protein molecules, as well as the dissolved gases. The intracellular and extracellular environments are separated by the cell membrane, which is selectively permeable; it is able to control the movement of electrolytes and other molecules across it. This characteristic will be discussed later in the chapter. The correct balance and movement of these chemicals between the intracellular and extracellular environments is vital to the maintenance of normal function and therefore health (Marieb and Hoehn 2019). A disruption of this balance is one of the factors that can cause homoeostatic imbalance and potentially lead to a medical emergency (Kumar and Clarke 2017).
The cell and tissues
Ian Peate, Helen Dutton in Acute Nursing Care, 2014
Before considering the basic structure of the cell it is important to consider the physiological environment of the cell. All human cells contain an aqueous fluid (intra-cellular fluid) identified as cytosol. Apart from the organelles, this fluid contains substances such as protein, other nutrient molecules, metabolic products and also a range of chemicals known as electrolytes. Outside the cells there is the extracellular fluid, which is composed of the interstitial fluid just mentioned and the circulating fluid; this is composed of blood in the vascular system and the lymph found in the lymphatic vessels. The extracellular fluid has a similar composition to the intracellular fluid. However, there are important differences in the composition of these fluids, particularly in the type and quantity of electrolytes and in the distribution of protein molecules.
Fungi and Water
Chuong Pham-Huy, Bruno Pham Huy in Food and Lifestyle in Health and Disease, 2022
Every cell in the body contains fluid. When cells lose their fluid, they quickly shrink and die. On the other hand, when cells take in too much fluid, they swell and burst apart (170). About two-thirds of the body’s fluid is held within the walls of cells and is therefore called intracellular fluid. The remaining third of the body’s fluid is referred to as extracellular fluid because it flows outside of the cells (170). There are two types of extracellular fluid: interstitial fluid and intravascular fluid. Interstitial fluid flows between the cells that make up a particular tissue or organ, such as muscle fibers or the liver (170). Intravascular fluid is the water in the bloodstream and lymph. Plasma is specifically the extracellular fluid portion of blood that transports blood cells within the body’s arteries, veins, and capillaries (170).
Antibiotic exposure at the site of infection: principles and assessment of tissue penetration
Published in Expert Review of Clinical Pharmacology, 2019
Nynke G. L. Jager, Reinier M. van Hest, Jeffrey Lipman, Jason A. Roberts, Menino O. Cotta
Interstitial fluid surrounds the tissue cells and is the main component of extracellular fluid in the human body [7]. Antibiotic concentrations within the interstitial fluid of a tissue can be measured using microdialysis. This technique consists of the insertion of a microdialysis probe into the tissue or organ of interest. The probe is continuously flushed with a tissue-compatible perfusion fluid and has a semipermeable membrane that allows substance uptake by passive diffusion. Since only low-molecular-weight substances are diffusible through the membrane, this technique only allows the sampling of unbound concentrations of small molecules present in the interstitial fluid [33]. The major advantages of microdialysis over tissue biopsies are (i) its capacity for continuous sampling within a time period, such as an antibiotic dosing interval, in the same individual and the same area with minimal tissue perturbation, allowing it to be potentially utilized in almost every human tissue and (ii) in the case of extracellular infections, which account for the majority of bacterial infections, the measurement of antibiotic concentrations at the site of interest.
Comparative studies on the potential use of 177Lu-based radiopharmaceuticals for the palliative therapy of bone metastases
Published in International Journal of Radiation Biology, 2020
Hesham M. H. Zakaly, Mostafa Y. A. Mostafa, Darya Deryabina, Michael Zhukovsky
In Figure 5, the models for 153Sm-EDTMP and 177Lu-EDTMP are visualized using the data provided in Table 2. However, the values of the excretion coefficients for mice were experimentally obtained for 177Lu-EDTMP (Chakraborty, Das, Sarma, et al. 2008). These data can be used as a first approximation for humans. This technique is quite common when evaluating the effectiveness of drugs before conducting preclinical studies (Chakraborty, Das, Sarma, et al. 2008). Figure 6 shows the biokinetic model of the 177Lu-EDTMP preparation, based on transformed data for the human body. All the liquid in the human body can be divided into intracellular and extracellular types. Extracellular fluid is approximately 33% of total body fluid. Intracellular fluid is the fluid circulating between cells and plasma in the bloodstream (Insel and Turner 2007).
Evaluation of brain targeting in rats of Salvianolic acid B nasal delivery by the microdialysis technique
Published in Xenobiotica, 2018
Suiling Zhang, Yajun Shi, Lizhi Tang, Jing Wang, Dongyan Guo, Mei Wang, Xiaofei Zhang
From Table 1, it can be seen that the value of recoveries seems quite low. There are some reasons for this. The tissue structure is the main limiting factor of drug absorption. In in vivo, the material diffusion is mainly through the cell gap, which leads to prolong the extension of diffusion path and slows down the speed. The extracellular fluid contains glycoprotein and other macromolecules and they have gel properties and high viscosity, which may interact with membrane materials. These factors can slow the drug diffusion rate and block the drug recovery. Therefore, the recovery rate is generally low in vivo. Ward et al. (2003) compared the ability of propylene glycol and encapsin to increase the recovery rate of SB-265123 (a lipophilic high protein compound) in vivo and in vitro. The result showed that the recovery rate of 20% propylene glycol was 75–80%. Sun & Stenken (2003) used different membrane materials to improve the recovery rate of prostaglandin B2, leukotriene B4 and C4 in the lipophobic compounds, the recovery rate was also seen to improve. However, the addition of the recovery form will change the physiological characteristics of the tissue, so it need to be more rigorous to use.
Related Knowledge Centers
- Body Fluid
- Body Water
- Cell Biology
- Lymph
- Multicellular Organism
- Cell
- Fluid Compartments
- Blood
- Circulatory System
- Blood Plasma