the first organ to receive monosaccharides after absorption is what organ
Affiliate 4. Carbohydrates
Digestion and Absorption of Carbohydrates
From the Mouth to the Stomach
The mechanical and chemical digestion of carbohydrates begins in the oral fissure. Chewing, also known equally mastication, crumbles the carbohydrate foods into smaller and smaller pieces. The salivary glands in the oral crenel secrete saliva that coats the nutrient particles. Saliva contains the enzyme, salivary amylase. This enzyme breaks the bonds between the monomeric sugar units of disaccharides, oligosaccharides, and starches. The salivary amylase breaks downwards amylose and amylopectin into smaller bondage of glucose, called dextrins and maltose. The increased concentration of maltose in the oral cavity that results from the mechanical and chemic breakdown of starches in whole grains is what enhances their sweetness. Only well-nigh five percent of starches are broken downwardly in the oral cavity. (This is a good thing as more glucose in the mouth would pb to more than tooth decay.) When carbohydrates reach the stomach no further chemical breakdown occurs considering the amylase enzyme does not role in the acidic conditions of the tum. But mechanical breakup is ongoing—the strong peristaltic contractions of the stomach mix the carbohydrates into the more compatible mixture of chyme.
Figure iv.half dozen Salivary Glands in the Mouth
From the Stomach to the Small Intestine
The chyme is gradually expelled into the upper part of the small intestine. Upon entry of the chyme into the small intestine, the pancreas releases pancreatic juice through a duct. This pancreatic juice contains the enzyme, pancreatic amylase, which starts again the breakdown of dextrins into shorter and shorter carbohydrate chains. Additionally, enzymes are secreted past the abdominal cells that line the villi. These enzymes, known collectively as disaccharidase, are sucrase, maltase, and lactase. Sucrase breaks sucrose into glucose and fructose molecules. Maltase breaks the bond between the two glucose units of maltose, and lactase breaks the bond between galactose and glucose. One time carbohydrates are chemically broken down into single carbohydrate units they are and so transported into the inside of intestinal cells.
When people do not have enough of the enzyme lactase, lactose is non sufficiently cleaved down resulting in a status chosen lactose intolerance. The undigested lactose moves to the large intestine where bacteria are able to digest it. The bacterial digestion of lactose produces gases leading to symptoms of diarrhea, bloating, and abdominal cramps. Lactose intolerance normally occurs in adults and is associated with race. The National Digestive Diseases Information Immigration House states that African Americans, Hispanic Americans, American Indians, and Asian Americans have much college incidences of lactose intolerance while those of northern European descent have the least.[1] Nigh people with lactose intolerance can tolerate some amount of dairy products in their diet. The severity of the symptoms depends on how much lactose is consumed and the caste of lactase deficiency.
Assimilation: Going to the Blood Stream
The cells in the modest intestine have membranes that contain many ship proteins in order to get the monosaccharides and other nutrients into the blood where they tin can be distributed to the rest of the body. The starting time organ to receive glucose, fructose, and galactose is the liver. The liver takes them up and converts galactose to glucose, breaks fructose into fifty-fifty smaller carbon-containing units, and either stores glucose as glycogen or exports information technology back to the blood. How much glucose the liver exports to the blood is nether hormonal control and you will soon discover that fifty-fifty the glucose itself regulates its concentrations in the blood.
Figure iv.7 Saccharide Digestion
Maintaining Blood Glucose Levels: The Pancreas and Liver
Glucose levels in the blood are tightly controlled, equally having either too much or too picayune glucose in the blood can have health consequences. Glucose regulates its levels in the blood via a process chosen negative feedback. An everyday example of negative feedback is in your oven because it contains a thermostat. When yous set up the temperature to cook a succulent homemade noodle casserole at 375°F the thermostat senses the temperature and sends an electrical signal to turn the elements on and rut up the oven. When the temperature reaches 375°F the thermostat senses the temperature and sends a point to turn the element off. Similarly, your body senses blood glucose levels and maintains the glucose "temperature" in the target range. The glucose thermostat is located within the cells of the pancreas. After eating a meal containing carbohydrates glucose levels rise in the blood.
Insulin-secreting cells in the pancreas sense the increase in blood glucose and release the hormone, insulin, into the blood. Insulin sends a signal to the body's cells to remove glucose from the blood by transporting it into different organ cells effectually the body and using it to make free energy. In the case of muscle tissue and the liver, insulin sends the biological bulletin to store glucose away as glycogen. The presence of insulin in the blood signifies to the torso that glucose is available for fuel. Every bit glucose is transported into the cells around the torso, the blood glucose levels decrease. Insulin has an opposing hormone called glucagon. Glucagon-secreting cells in the pancreas sense the driblet in glucose and, in response, release glucagon into the blood. Glucagon communicates to the cells in the body to end using all the glucose. More specifically, it signals the liver to break down glycogen and release the stored glucose into the blood, so that glucose levels stay inside the target range and all cells get the needed fuel to office properly.
Figure four.8 The Regulation of Glucose
Leftover Carbohydrates: The Big Intestine
Almost all of the carbohydrates, except for dietary fiber and resistant starches, are efficiently digested and absorbed into the body. Some of the remaining indigestible carbohydrates are broken downwardly by enzymes released past bacteria in the large intestine. The products of bacterial digestion of these slow-releasing carbohydrates are short-concatenation fatty acids and some gases. The curt-chain fatty acids are either used by the bacteria to make energy and abound, are eliminated in the carrion, or are absorbed into cells of the colon, with a small amount being transported to the liver. Colonic cells use the short-chain fatty acids to back up some of their functions. The liver can also metabolize the short-chain fatty acids into cellular energy. The yield of free energy from dietary cobweb is about ii kilocalories per gram for humans, simply is highly dependent upon the fiber blazon, with soluble fibers and resistant starches yielding more than energy than insoluble fibers. Since dietary fiber is digested much less in the gastrointestinal tract than other saccharide types (simple sugars, many starches) the rising in blood glucose subsequently eating them is less, and slower. These physiological attributes of high-fiber foods (i.east. whole grains) are linked to a decrease in weight gain and reduced risk of chronic diseases, such as Type 2 diabetes and cardiovascular disease.
Figure four.9 Overview of Carbohydrate Digestion
A Carbohydrate Banquet
You are at a your grandma's house for family unit dinner and you only consumed kalua pig, white rice, sweet potatoes, mac salad, chicken long rice and a hot sweet bread roll dripping with butter. Less than an hour later yous meridian it off with a slice of haupia pie and so lie down on the couch to lookout TV. The "hormone of plenty," insulin, answers the food telephone call. Insulin sends out the physiological message that glucose is abundant in the claret, so that cells can absorb information technology and either utilize it or store it. The upshot of this hormone bulletin is maximization of glycogen stores and all the excess glucose, protein, and lipids are stored as fat.
A typical American Thanksgiving meal contains many foods that are dumbo in carbohydrates, with the majority of those being simple sugars and starches. These types of carbohydrate foods are rapidly digested and captivated. Blood glucose levels rise quickly causing a spike in insulin levels. Contrastingly, foods containing loftier amounts of cobweb are like time-release capsules of saccharide. A measurement of the effects of a carbohydrate-containing nutrient on claret-glucose levels is chosen the glycemic response.
Glycemic Alphabetize
The glycemic responses of various foods take been measured and and then ranked in comparison to a reference food, usually a slice of white bread or just straight glucose, to create a numeric value called the glycemic index (GI). Foods that have a low GI practice not raise blood-glucose levels neither as much nor as fast as foods that take a higher GI. A nutrition of depression-GI foods has been shown in epidemiological and clinical trial studies to increase weight loss and reduce the risk of obesity, Blazon two diabetes, and cardiovascular disease.[two]
Tabular array 4.1 The Glycemic Index: Foods In Comparing To Glucose
| Foods | GI Value |
| Depression GI Foods (< 55) | |
| Apple, raw | 36 |
| Orange, raw | 43 |
| Banana, raw | 51 |
| Mango, raw | 51 |
| Carrots, boiled | 39 |
| Taro, boiled | 53 |
| Corn tortilla | 46 |
| Spaghetti (whole wheat) | 37 |
| Baked beans | 48 |
| Soy milk | 34 |
| Skim milk | 37 |
| Whole milk | 39 |
| Yogurt, fruit | 41 |
| Yogurt, plain | 14 |
| Icecream | 51 |
| Medium GI Foods (56–69) | |
| Pineapple, raw | 59 |
| Cantaloupe | 65 |
| Mashed potatoes | 70 |
| Whole-wheat bread | 69 |
| Brownish rice | 55 |
| Cheese pizza | 60 |
| Sweetness white potato, boiled | 63 |
| Macaroni and cheese | 64 |
| Popcorn | 65 |
| High GI Foods (70 and higher) | |
| Banana (over-ripe) | 82 |
| Corn fries | 72 |
| Pretzels | 83 |
| White bread | lxx |
| White rice | 72 |
| Bagel | 72 |
| Rice milk | 86 |
| Cheerios | 74 |
| Raisin Bran | 73 |
| Fruit roll-up | 99 |
| Gatorade | 78 |
For the Glycemic Index on different foods, visit http://world wide web.mendosa.com/gilists.htm.
The type of carbohydrate within a nutrient affects the GI along with its fat and fiber content. Increased fat and cobweb in foods increases the fourth dimension required for digestion and delays the rate of gastric emptying into the small-scale intestine which, ultimately reduces the GI. Processing and cooking also affects a food'south GI by increasing their digestibility. Advancements in the technologies of food processing and the high consumer need for user-friendly, precooked foods in the United states of america has created foods that are digested and absorbed more speedily, independent of the fiber content. Mod breakfast cereals, breads, pastas, and many prepared foods accept a high GI. In contrast, about raw foods have a lower GI. (However, the more ripened a fruit or vegetable is, the higher its GI.)
The GI can be used every bit a guide for choosing healthier carbohydrate choices but has some limitations. The offset is GI does not take into account the amount of carbohydrates in a portion of food, only the blazon of carbohydrate. Some other is that combining low- and loftier-GI foods changes the GI for the meal. Also, some food-dense foods have higher GIs than less nutritious food. (For example, oatmeal has a higher GI than chocolate because the fat content of chocolate is higher.) Lastly, meats and fats practice non have a GI since they do non contain carbohydrates.
More Resources
Visit this online database to detect the glycemic indices of foods. Foods are listed past category and also by depression, medium, or high glycemic index.
http://www.gilisting.com/
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Source: http://pressbooks-dev.oer.hawaii.edu/humannutrition/chapter/digestion-and-absorption-of-carbohydrates/#:~:text=The%20cells%20in%20the%20small,and%20galactose%20is%20the%20liver.
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