It is very important to accept the truth that consuming extra calories does not mean your metabolism will burn those extra calories; in fact eating extra calories beyond what your natural metabolism can process will result in weight gain as those extra calories are stored. This article was published by Michigan State University Extension. Understanding your metabolism. Did you find this article useful? Please tell us why Submit. Mindful Eating Lunch and Learn After they enter the cells, other enzymes act to speed up or regulate the chemical reactions involved with "metabolizing" these compounds.
During these processes, the energy from these compounds can be released for use by the body or stored in body tissues, especially the liver, muscles, and body fat. Anabolism pronounced: uh-NAB-uh-liz-um , or constructive metabolism, is all about building and storing. It supports the growth of new cells, the maintenance of body tissues, and the storage of energy for future use. In anabolism, small molecules change into larger, more complex molecules of carbohydrates, protein, and fat.
Catabolism pronounced: kuh-TAB-uh-liz-um , or destructive metabolism, is the process that produces the energy needed for all activity in the cells. Cells break down large molecules mostly carbs and fats to release energy. This provides fuel for anabolism, heats the body, and enables the muscles to contract and the body to move.
As complex chemical units break down into more simple substances, the body releases the waste products through the skin, kidneys, lungs, and intestines. Several hormones of the endocrine system help control the rate and direction of metabolism. Thyroxine, a hormone made and released by the thyroid gland, plays a key role in determining how fast or slow the chemical reactions of metabolism go in a person's body.
When the acidified food passes from the stomach to the duodenum, it is neutralized by copious amounts of sodium bicarbonate that is contained in the pancreatic juice, the bile, and the secretions of gland tissue embedded in the mucous membranes of the duodenum itself.
Accordingly, the pH optima of the pancreatic enzymes are in the neutral to slightly alkaline range. Among its many other functions, the liver also serves as an exocrine gland. In the bile concentrate, solutes may exceed their solubility limit and start to precipitate or crystallize within the bile bladder, forming gallstones.
This occurs most commonly with cholesterol and bilirubin, both of which are excreted with the bile see chapters 11 and 17 , respectively. Like the pancreatic juice, the bile is also rich in sodium bicarbonate and contributes to the neutralization of the acidified stomach content as it enters the duodenum. Unlike the pancreatic juice, however, the bile does not contain digestive enzymes. Disruption of bile secretion will therefore cause deficient digestion of fat only, but not of proteins or carbohydrates.
The greater share of the bile acids is taken up again in the lowermost section of the small intestine, that is, the terminal ileum. Via the portal vein, they return to the liver, where they are extracted and again secreted. The small intestine comprises, from top to bottom, the duodenum, the jejunum, and the ileum. Small substrate molecules produced by the digestive enzymes within the gut are taken up by active transport across the mucous membrane of the small intestine.
The capacity for substrate uptake is obviously related to the surface area. Accordingly, the mucous membrane is highly folded so as to maximize the surface available for substrate uptake. This slide illustrates how surface maximization is realized at all hierarchical levels of tissue and cell structure. The inner surface of the small intestine has circular folds, which in turn are covered by villi. The individual epithelial cells that cover the villi are, on their luminal surfaces, covered by microvilli.
The blood that perfuses the villi of the intestinal mucosa red arrow and carries away the absorbed nutrients is drained toward the liver via the portal vein see slide 1. These microscopic pictures of the mucous membrane illustrate the villi and microvilli in the small intestine.
The left panel shows a low-power view of a section across a circular fold, which is covered by a dense mane of villi. The right panel shows an electron-microscopic image of microvilli atop an individual epithelial cell. In combination, the circular folds, villi, and microvilli amplify the surface from approximately 0. As an example of foodstuff processing in the small intestine, let us take a quick look at the digestion of starch.
The constituents of starch are amylose and amylopectin. In the small intestine, amylose and amylopectin are broken down by pancreatic amylase. The two disaccharides are cleaved to glucose by maltase and isomaltase, respectively. These enzymes are anchored to the surfaces of the epithelial cells of the intestinal mucosa.
The same epithelial cells then take up glucose by active transport see next slide. After digestion, the metabolites have to be taken up by the epithelial cells at the inner surface of the small intestine. In most cases, nutrients are taken up by active transport , which can transport solutes energetically uphill, that is, against their concentration gradients. Active transport thus enables the quantitative uptake of the nutrients.
In the case of glucose, active transport is driven by the simultaneous uptake of two sodium ions per molecule of glucose. This coupling is effected by the SGLT1 transporter. Sodium secreted as bicarbonate is plentiful in the gut lumen, while its concentration is low inside the cells.
An additional driving force is the membrane potential: the cytosol is electrically negative relative to the extracellular space. The uphill transport of glucose is therefore driven by the simultaneous downhill movement of sodium.
Similar transporters exist for other sugars, e. On the basolateral side of the intestinal epithelia—that is, the side that faces the surrounding tissue, not the gut lumen—glucose is released into the extracellular space, from where it can freely diffuse into the bloodstream to reach the liver. The export from the epithelial cells is mediated by GLUT transporters.
These operate by passive transport, also known as facilitated diffusion see slide 3. Understanding how your metabolism is functioning is key to a whole range of preventative health care measures.
Our 3 month management program is designed to provide you with individual nutrition and activity solutions, to improve your metabolism to achieve your weight loss and health goals. Why Metabolism Matters The definition of metabolism is the set of complex biochemical processes which exist inside all living organisms, in order to maintain life. Get in touch today.
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