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Questions and Answers
What is the primary site for carbohydrate digestion and absorption?
What happens to starch digestion when food enters the stomach?
What breaks down the remaining polysaccharides in oat starch into maltose molecules?
What is the final product of starch digestion?
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What happens to the glucose molecules after they are absorbed into the intestinal bloodstream?
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What is the function of the enzyme sucrase?
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What is the primary component of the carbohydrates in oats?
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What is the purpose of salivary amylase?
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What enzyme breaks down lactose from milk into glucose and galactose molecules?
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What is the primary function of the hepatic portal vein?
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What type of carbohydrates are poorly digested by humans but can be metabolized by beneficial gut microbes?
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What is the primary benefit of fructans and galactooligosaccharides in the colon?
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What is the term for the 'friendly' intestinal bacteria that reside in the large intestine?
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What type of fiber is broken down and fermented by bacterial action in the large intestine?
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What is the estimated energy contribution of a gram of fiber to human diets?
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What is the normal range of blood glucose levels after sleeping overnight or not eating for several hours?
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Which hormone plays a key role in regulating blood glucose levels by increasing glucose uptake in cells?
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What is the term for the 'by-products' produced by the bacterial metabolism of fiber that can be used by the body for energy?
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What is the recommended daily intake of carbohydrate to prevent ketosis?
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What is the primary source of energy for human cells under normal conditions?
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During starvation, what is the primary source of glucose for the body's energy needs?
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What happens to the glucose from the food after it is absorbed by the intestinal tract?
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What is the consequence of using muscle proteins as a source of energy during starvation?
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What is the normal blood glucose level in a healthy person within 2 hours after eating?
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What is formed when the body breaks down fatty acids for energy during starvation?
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What is the effect of insulin on fat and protein metabolism?
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What is the primary function of insulin in the body?
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What is the role of glucagon in the body?
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What is the primary fuel for the body's cells?
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What happens to liver glucose when the blood glucose level is low?
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What is the result of incomplete breakdown of fat?
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What is the condition called when ketone bodies accumulate in the blood?
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What is the result of excessive production of ketone bodies in uncontrolled type 1 diabetes?
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What happens to fat in the liver when glycogen storage is at maximum capacity?
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Study Notes
Carbohydrate Digestion and Absorption
- Carbohydrates in oats are primarily starch and fiber, while milk and brown sugar add lactose and sucrose.
- Salivary amylase in the mouth breaks down oat starch into maltose, but stops functioning in the acidic stomach environment.
- Starch digestion resumes in the small intestine, where pancreatic amylase breaks down polysaccharides into maltose molecules.
- Maltase then converts maltose into glucose molecules, which are absorbed into the bloodstream and transported to the liver via the hepatic portal vein.
Sugar Digestion
- Sucrose in brown sugar is broken down into glucose and fructose molecules by the small intestinal enzyme sucrase.
- Lactose in milk is broken down into glucose and galactose molecules by the enzyme lactase.
- Intestinal cells absorb galactose, fructose, and glucose, which are then transported to the liver via the hepatic portal vein.
- The liver converts fructose and galactose into glucose.
Fiber Digestion
- Fiber is not digested by the small intestine and enters the large intestine.
- Soluble fiber is fermented by "friendly" bacteria in the large intestine, producing energy.
- Insoluble fiber does not break down completely and contributes to softer and easier-to-eliminate bowel movements.
- The body can use by-products produced by bacterial metabolism of fiber for energy, adding 2 kcal to human diets per gram of fiber.
Maintaining Blood Glucose Levels
- Insulin and glucagon are key hormones that regulate blood glucose levels.
- Insulin helps lower blood glucose levels by allowing glucose to enter cells, stimulating liver to store glucose as glycogen, and promoting fat and protein synthesis.
- Glucagon opposes insulin's effects, promoting the breakdown of glycogen, releasing glucose into the bloodstream, and stimulating liver and kidney cells to produce glucose from amino acids.
Glucose for Energy
- Cells metabolize glucose to release energy stored in the molecule's chemical bonds.
- Glucose is a primary fuel for the body's cells, particularly red blood cells, brain, and other nervous system cells.
- Cells use oxygen to release energy from glucose, producing carbon dioxide and water.
- When blood glucose levels are low, the liver releases glucose into the bloodstream for cells to burn for energy.
- When blood glucose levels are normal, excess glucose is stored as glycogen, and when glycogen storage is at maximum capacity, excess glucose is converted into fat.
Ketone Bodies
- Ketone bodies are chemicals produced by the incomplete breakdown of fat.
- Muscle and brain cells can use ketone bodies for energy.
- Ketosis occurs when ketone bodies accumulate in the blood, often due to fasting, starvation, or very low-carbohydrate diets.
- In cases of poorly controlled type 1 diabetes, excessive ketone production can lead to ketoacidosis.
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Description
This quiz covers the digestion and absorption of carbohydrates, including the regulation of blood glucose and what happens when cells lack glucose for energy.
