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Introduction to Anatomy and Physiology
Published in Reginald L. Campbell, Roland E. Langford, Terry L. McArthur, Fundamentals of Hazardous Materials Incidents, 2020
Reginald L. Campbell, Roland E. Langford, Terry L. McArthur
From the stomach, food passes into the upper portion of the small intestine called the duodenum, where various other enzymes break down other food constituents. The duodenum is the primary location where fatty foods are broken down into simpler compounds. The duodenum is only about 25 centimeters (10 inches) long. The next three-meter (ten-foot) portion is called the jejunum, which is very rich in enzymes that further digest the food. The remaining 4 meters (12 feet) of small intestine is called the ileum, where the food products, broken down into simpler compounds, pass to the blood through hairlike projections into the intestines. These hairlike objects are called villi (singular: villus) and are shown in Figure 2-3. They are very small, so they greatly increase the area of absorption.
General Biology of Cryptosporidium
Published in J. P. Dubey, C. A. Speer, R. Fayer, Cryptosporidiosis of Man and Animals, 2018
R. Fayer, C. A. Speer, J. P. Dubey
Although lesions can be present throughout the gastrointestinal tract, they are usually most severe in the lower jejunum and ileum.540 Mesenteric lymph nodes are sometimes swollen. Intestines appear unremarkable or hyperemic. Microscopic lesions follow a similar pattern among almost all host species infected. Cryptosporidia are found in the epithelium, usually without obvious damage to host cells except that cells may be low columnar, cuboidal, or squamous, and microvilli may be absent at the site of parasite attachment.540 At the electron microscopic level, the cytoplasm of infected cells sometimes contains mitochondria that appear swollen and vacuolated, and smaller smooth membraned vacuoles containing clear fluid may be scattered throughout the cytoplasm around the cell nucleus.98 Usually, mild to severe villous atrophy is apparent at the light microscope level. Villi appear blunt, shorter, and wider than normal and are sometimes fused with other villi.769,871 Some fused villi have desmosomal junctions between enterocytes of adjacent villi, visible with electron microscopy. Inflammatory changes are marked by cellular infiltration, usually plasma cells and neutrophils, but also macrophages and lymphocytes, into the subepithelial lamina propria.540,769 Peyer’s patches appear reactive.250 Crypts are enlarged, hyperplastic, and may contain dead cells or pink-staining gelatinous material.636
Nanotechnological Advances for Nutraceutical Delivery
Published in Rakesh K. Sindhu, Mansi Chitkara, Inderjeet Singh Sandhu, Nanotechnology, 2021
Shaveta Sharma, Puneet Sudan, Vimal Arora, Manish Goswami, Parkash Dora
Bioavailability is defined as “the rate and extent of drug that reaches in the systemic circulation.” Relative bioavailability measures the bioavailability of a formulation of a bioactive compared with its another formulation, whereas absolute bioavailability is calculated by the ratio of the area under the curve (AUC) of intravenous administration to the AUC of oral administration. Steps for orally administered nutraceuticals to reach systemic circulation are discussed as follows: Systemic circulation: Nutraceuticals that are absorbed can directly enter the systemic circulation. Polar compounds propagate into blood vessels and get into the liver through the hepatic portal vein. Hydrophobic compounds may be integrated into chylomicrons and can directly enter the systemic circulation, avoiding the first-pass hepatic metabolism [14].Solubilization: In the small intestine, nutraceuticals through food are solubilized. Nutraceuticals can be hydrophilic or hydrophobic. Hydrophilic nutraceuticals are readily dissolved in the aqueous solution in the GIT lumen. Hydrophobic nutraceuticals can get help from mixed micelle systems in the lumen fluid. The micelles are composed of endogenous bile salts and phospholipids. Food lipids can also lead to the development of micelles following digestion by lipase. Triglycerides are converted into free fatty acids, monoglycerides, and diglycerides. Phospholipids are natural amphiphilic, biocompatible molecules that can easily solubilize the nutraceuticals by micellar formation.Absorption: After solubilization, nutraceuticals are absorbed by the small intestine through various epithelial routes or mainly by the lymphatic route. The primary site for nutrient and nutraceutical absorption is the small intestine, and this happens specifically through the enterocytes (absorption epithelial cells) lining the lumen of the jejunum.
Biomechanical characterization of human small bowel wall under inflation conditions
Published in Computer Methods in Biomechanics and Biomedical Engineering, 2019
Y. Goudard, C. Masson, Y. Ammar, T. Bège
The biomechanical difference between jejunum and ileum was previously reported in rat by Dou et al. (Dou et al. 2003). It could be explained by layer anatomicalcharacteristics and physiological differences, mucosa and sub-mucosa of jejunum being more developed to allow absorption and ileum acting as a reservoir.