Explore chapters and articles related to this topic
Human physiology, hazards and health risks
Published in Stephen Battersby, Clay's Handbook of Environmental Health, 2023
Revati Phalkey, Naima Bradley, Alec Dobney, Virginia Murray, John O’Hagan, Mutahir Ahmad, Darren Addison, Tracy Gooding, Timothy W Gant, Emma L Marczylo, Caryn L Cox
The large intestine – this mainly absorbs water so that the water content that reaches the end of the large intestine is ultimately reduced by about two-thirds. The large intestine is not essential to life. However, the bacteria present in the large intestine are important in the provision and production of vitamins, particularly those of the vitamin B group.
Gastrointestinal tract and salivary glands
Published in A Stewart Whitley, Jan Dodgeon, Angela Meadows, Jane Cullingworth, Ken Holmes, Marcus Jackson, Graham Hoadley, Randeep Kumar Kulshrestha, Clark’s Procedures in Diagnostic Imaging: A System-Based Approach, 2020
A Stewart Whitley, Jan Dodgeon, Angela Meadows, Jane Cullingworth, Ken Holmes, Marcus Jackson, Graham Hoadley, Randeep Kumar Kulshrestha
The large intestine is approximately 1.5 m long from caecum to anus, with a variable calibre from between 9 and 3 cm. It lies peripheral to the small intestine, with the more lateral structures being relatively fixed in position. From the right iliac fossa where the terminal ileum communicates via the ileo-caecal valve, the ceacum extends superiorly as the ascending colon before it turns abruptly to the left, beneath the liver, at the hepatic flexure. Crossing the abdomen, the transverse colon turns inferiorly at the splenic flexure, where it continues as the descending colon. The bowel loops to a variable degree at the sigmoid colon, passing along the posterior wall of the pelvis where it merges with the rectum at the recto-sigmoid junction. The rectum is 13 cm long and is a dilated part of the large intestine, continuous with the anal canal and anus. The large intestine displays large sacculations known as haustra that are thought to slow the passage of digested matter. The relations of the large intestine are complex and variable as the bowel traverses the different regions of the abdomen (Figs 5.52a–c).
Nanostructures for Improving the Oral Bioavailability of Herbal Medicines
Published in Bhaskar Mazumder, Subhabrata Ray, Paulami Pal, Yashwant Pathak, Nanotechnology, 2019
The colon, or the large intestine, is the final part of the GI tract. Its primary function is to absorb water and electrolytes and to store and compact feces. The colon is devoid of the villi and microvilli structure of the small intestine, however, the irregularly-folded mucosae result in a 10–15 times increase in surface area to that of a simple cylinder. A few drugs are absorbed well in this region of the GI tract and those drugs are also good candidates for formulation into oral sustained-release dosage forms. The pH of the colon may range from 6 to 6.5 in the cecum and from 7 to 7.5 in the distal part of the colon (Ashford, 2013). Due to the presence of a huge number of aerobic and anaerobic microorganisms that colonize the colon, several metabolic reactions are taking place, which may provide a good target for converting inactive conjugated drugs, such as prodrugs, into their active form. Several controlled release formulations have been developed over the years that target the metabolizing enzymes of the colonic microorganisms to affect drug release.
Theoretical investigation of double diffusion convection of six constant Jeffreys nanofluid on waves of peristaltic with induced magnetic field: a bio-nano-engineering model
Published in Waves in Random and Complex Media, 2022
Safia Akram, Maria Athar, Khalid Saeed, Alia Razia, Taseer Muhammad
Now the significant rise in the research interest of the peristaltic flows of Newtonian and non-Newtonian fluids can be attributed to its practical implications in industry and medicine. Human physiological mechanism is one of the examples of the said phenomena. Spontaneous compression and expansion of any tube or channel’s wall is called peristalsis. In human tubular structures or organs such as the gastrointestinal tract, small & large intestine, etc. fluid movement is due to peristalsis. In the movement of food emulsion along the gastrointestinal tract, waste excretion through excretory system, blood circulation in arteries, lymph transportation of lymphatic system, ovum & sperm transmission in fallopian tube & sperm ducts respectively, are all peristaltic movements. This phenomenon is used in designing medical instruments such as dialysis machines, pumping devices for medical procedures, lung heart pumps, etc. Propelling movements of worms are also involving peristalsis. Moreover, in industries pumping devices are designed on the same principle, for instance pumps to drain toxic fluids. Due to its extensive application, researchers are involved in examining the problems of peristaltic transport with non-Newtonian fluids [6–12].
Plant pharmacology: Insights into in-planta kinetic and dynamic processes of xenobiotics
Published in Critical Reviews in Environmental Science and Technology, 2022
Tomer Malchi, Sara Eyal, Henryk Czosnek, Moshe Shenker, Benny Chefetz
Absorption in human pharmacology describes the movement of a drug from its site of administration into the blood stream (Buxton & Benet, 2013). For orally administered compounds, the site of absorption is the gastrointestinal tract, composed of the mouth, pharynx, esophagus, stomach, small intestine and large intestine. The corresponding system in plants is the rhizosphere continuum; i.e. the rhizosphere (soil and water adjacent to the root), the rhizoplane (root surface area, epidermis and mucigel), and the endosphere (root cortex and endodermis) (Bakker et al., 2013; de la Fuente Cantó et al., 2020; York et al., 2016). In plant pharmacology, absorption is the compound's movement from the rhizosphere to the plant's root plasmodesmata, i.e. the cytoplasmic channels between cells providing intracellular continuity along the symplast. The plasmodesmata are analogous to gap junctions between animal cells, serving an essential role in intercellular communication (Bloemendal & Kück, 2013). Once in the symplast, compounds are able to interact with various cellular organelles, proteins and enzymes within the cytoplasm matrix (Taiz et al., 2014). Compounds may also be absorbed via direct exposure of foliage, however this is considered a less relevant route for wastewater-derived xenobiotics which are introduced via irrigation and is thus not included in further discussion in this paper.
Pharmacokinetics of α-amanitin in mice using liquid chromatography-high resolution mass spectrometry and in vitro drug–drug interaction potentials
Published in Journal of Toxicology and Environmental Health, Part A, 2021
Ria Park, Won-Gu Choi, Min Seo Lee, Yong-Yeon Cho, Joo Young Lee, Han Chang Kang, Chang Hwan Sohn, Im-Sook Song, Hye Suk Lee
To understand the most vulnerable tissue on amatoxin poisoning, excretion, and tissue distribution experiments in liver, kidneys, and large and small intestines were conducted based upon reports from humans that ingested α-amanitin displaying hepatotoxicity, renal toxicity, and final excretion into the urine (Berger and Guss 2005; Garcia et al. 2015a; Karlson-Stiber and Persson 2003). Intravenously injected α-amanitin was distributed in lung, liver, kidneys, and spleen with tissue to plasma AUC ratio of 0.2, 0.5, 1.3, and 0.6 and rapidly excreted into urine within 24 hr (Table 7 and Figure 3B). Similarly, the main excretion pathway of α-amanitin in humans was the kidneys with a excretion that occurred over 2–3 days (Karlson-Stiber and Persson 2003). However, orally exposed α-amanitin accumulated in stomach, small intestine, and large intestine. In addition, α-amanitin was distributed into lung, liver, and kidneys (Table 7). These tissue distribution results were consistent with the major intoxicated organs in humans following exposure, and therefore high levels of α-amanitin in the gastrointestinal tract, liver, and kidneys might lead to α-amanitin-induced toxicity (Garcia et al. 2015a; Karlson-Stiber and Persson 2003; Miranda et al. 2020).