Carbohydrate Digestion and Absorption
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Questions and Answers

What is the primary site for carbohydrate digestion and absorption?

  • Mouth
  • Stomach
  • Small intestine (correct)
  • Liver
  • What happens to starch digestion when food enters the stomach?

  • Starch digestion is unaffected
  • Starch digestion stops (correct)
  • Starch digestion continues at a slower rate
  • Starch digestion accelerates
  • What breaks down the remaining polysaccharides in oat starch into maltose molecules?

  • Salivary amylase
  • Pancreatic amylase (correct)
  • Maltase
  • Sucrase
  • What is the final product of starch digestion?

    <p>Glucose molecules</p> Signup and view all the answers

    What happens to the glucose molecules after they are absorbed into the intestinal bloodstream?

    <p>They are transported to the liver via the hepatic portal vein</p> Signup and view all the answers

    What is the function of the enzyme sucrase?

    <p>To break down sucrose molecules into glucose and fructose molecules</p> Signup and view all the answers

    What is the primary component of the carbohydrates in oats?

    <p>Starch and fiber</p> Signup and view all the answers

    What is the purpose of salivary amylase?

    <p>To break down starch molecules into maltose molecules</p> Signup and view all the answers

    What enzyme breaks down lactose from milk into glucose and galactose molecules?

    <p>Lactase</p> Signup and view all the answers

    What is the primary function of the hepatic portal vein?

    <p>To transport galactose, fructose, and glucose to the liver</p> Signup and view all the answers

    What type of carbohydrates are poorly digested by humans but can be metabolized by beneficial gut microbes?

    <p>Prebiotics</p> Signup and view all the answers

    What is the primary benefit of fructans and galactooligosaccharides in the colon?

    <p>Support and promotion of the growth of probiotics</p> Signup and view all the answers

    What is the term for the 'friendly' intestinal bacteria that reside in the large intestine?

    <p>Probiotics</p> Signup and view all the answers

    What type of fiber is broken down and fermented by bacterial action in the large intestine?

    <p>Soluble fiber</p> Signup and view all the answers

    What is the estimated energy contribution of a gram of fiber to human diets?

    <p>2 kcal</p> Signup and view all the answers

    What is the normal range of blood glucose levels after sleeping overnight or not eating for several hours?

    <p>70 mg/dl to 99 mg/dl</p> Signup and view all the answers

    Which hormone plays a key role in regulating blood glucose levels by increasing glucose uptake in cells?

    <p>Insulin</p> Signup and view all the answers

    What is the term for the 'by-products' produced by the bacterial metabolism of fiber that can be used by the body for energy?

    <p>Fermentation products</p> Signup and view all the answers

    What is the recommended daily intake of carbohydrate to prevent ketosis?

    <p>130 g/day</p> Signup and view all the answers

    What is the primary source of energy for human cells under normal conditions?

    <p>Glucose from carbohydrate digestion</p> Signup and view all the answers

    During starvation, what is the primary source of glucose for the body's energy needs?

    <p>Amino acids from muscle proteins</p> Signup and view all the answers

    What happens to the glucose from the food after it is absorbed by the intestinal tract?

    <p>It is released into the bloodstream</p> Signup and view all the answers

    What is the consequence of using muscle proteins as a source of energy during starvation?

    <p>Muscle wasting and weakness</p> Signup and view all the answers

    What is the normal blood glucose level in a healthy person within 2 hours after eating?

    <p>Between 70 mg/dl and 140 mg/dl</p> Signup and view all the answers

    What is formed when the body breaks down fatty acids for energy during starvation?

    <p>Ketone bodies</p> Signup and view all the answers

    What is the effect of insulin on fat and protein metabolism?

    <p>It promotes fat and protein synthesis</p> Signup and view all the answers

    What is the primary function of insulin in the body?

    <p>To decrease blood glucose levels</p> Signup and view all the answers

    What is the role of glucagon in the body?

    <p>It promotes the breakdown of glycogen</p> Signup and view all the answers

    What is the primary fuel for the body's cells?

    <p>Glucose</p> Signup and view all the answers

    What happens to liver glucose when the blood glucose level is low?

    <p>It is released into the bloodstream</p> Signup and view all the answers

    What is the result of incomplete breakdown of fat?

    <p>Ketone bodies</p> Signup and view all the answers

    What is the condition called when ketone bodies accumulate in the blood?

    <p>Ketosis</p> Signup and view all the answers

    What is the result of excessive production of ketone bodies in uncontrolled type 1 diabetes?

    <p>Ketoacidosis</p> Signup and view all the answers

    What happens to fat in the liver when glycogen storage is at maximum capacity?

    <p>It is converted into fat</p> Signup and view all the answers

    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.

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