Carbohydrate Digestion and Absorption
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Questions and Answers

What is the main site for carbohydrate digestion and absorption in the body?

The small intestine.

What enzyme breaks down starch molecules into maltose in the mouth?

Salivary amylase.

What happens to starch digestion when food enters the stomach?

Starch digestion stops.

What is the final product of starch digestion?

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

What is the role of the enzyme sucrase in carbohydrate digestion?

<p>It splits sucrose molecules into glucose and fructose molecules.</p> Signup and view all the answers

What is the primary component of oat carbohydrates?

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

What happens to lactose and sucrose molecules in the small intestine?

<p>They are broken down into glucose and fructose molecules.</p> Signup and view all the answers

What is the fate of glucose molecules 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 lactase in the breakdown of lactose from milk?

<p>Breaks down lactose into glucose and galactose molecules</p> Signup and view all the answers

What are the three types of monosaccharides absorbed by intestinal cells?

<p>Galactose, fructose, and glucose</p> Signup and view all the answers

What are fructans and galactooligosaccharides examples of?

<p>Oligosaccharides or short-chain polysaccharides</p> Signup and view all the answers

What is the function of postbiotics secreted by certain lactobacilli?

<p>Prevent the growth of harmful bacteria, viruses, and fungi in the colon</p> Signup and view all the answers

What is the primary difference between soluble and insoluble fiber?

<p>Soluble fiber is fermented by bacteria in the large intestine, while insoluble fiber is not</p> Signup and view all the answers

How much energy does a gram of fiber contribute to the human diet?

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

What are the two hormones produced by the pancreas that play key roles in regulating blood glucose levels?

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

What happens to the glucose absorbed from food in the intestinal tract?

<p>It enters the bloodstream.</p> Signup and view all the answers

What is the normal range of blood glucose level within 2 hours after eating?

<p>Between 70 mg/dl and 140 mg/dl</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 (fasting)?

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

What is the function of insulin in regulating blood glucose levels?

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

What is the function of insulin in the body?

<p>It helps lower blood glucose level by allowing glucose to enter most cells.</p> Signup and view all the answers

What is the benefit of adding oligosaccharides and probiotics to food products?

<p>Promotes the growth of beneficial gut microbes and supports overall health</p> Signup and view all the answers

What is the process called when the liver stores glucose as glycogen?

<p>Glycogen synthesis</p> Signup and view all the answers

What is the function of glucagon in the body?

<p>It promotes the breakdown of glycogen to release glucose into the bloodstream.</p> Signup and view all the answers

What is the byproduct of glucose metabolism in cells?

<p>Carbon dioxide and water</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 excess glucose in the liver when glycogen storage is at maximum capacity?

<p>It is converted into fat.</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 severe condition that can occur in people with poorly controlled type 1 diabetes?

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

What is the minimum daily intake of carbohydrates recommended to prevent ketosis?

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

Why does the body need glucose to fuel vital activities during starvation?

<p>To fuel vital activities such as breathing, transmitting nerve impulses, and pumping blood</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, weakness, and eventually death</p> Signup and view all the answers

What happens to amino acids in skeletal muscles during starvation?

<p>They are sacrificed for glucose production</p> Signup and view all the answers

What is the normal source of energy for human cells?

<p>A small proportion of energy from converting certain amino acids into glucose</p> Signup and view all the answers

What is the result of the body's altered energy metabolism during starvation?

<p>The body meets its energy needs by converting amino acids into glucose</p> Signup and view all the answers

Study Notes

Carbohydrate Digestion and Absorption

  • Cooked oatmeal, milk, and brown sugar contain carbohydrates in the form of starch, fiber, lactose, and sucrose.
  • Salivary amylase breaks down starch into maltose in the mouth, but digestion stops in the stomach due to acidic environment.
  • In the small intestine, pancreatic amylase breaks down remaining starch into maltose, which is then converted into glucose molecules by the enzyme maltase.
  • Glucose molecules are absorbed into the intestinal bloodstream and transported to the liver via the hepatic portal vein.

Sucrose and Lactose Digestion

  • Sucrose molecules are broken down into glucose and fructose molecules by the enzyme sucrase in the small intestine.
  • Lactose molecules are broken down into glucose and galactose molecules by the enzyme lactase.
  • Galactose, fructose, and glucose are absorbed by intestinal cells and transported to the liver.

Fructans and Galactooligosaccharides

  • Fructans and galactooligosaccharides are forms of carbohydrate that are poorly digested by humans but can be metabolized by beneficial gut microbes (probiotics).
  • Fructans and galactooligosaccharides support the growth of probiotics, promoting health benefits such as increased calcium absorption, reduced constipation, and protection against infections.

Fiber

  • Fiber in oats is not digested by the small intestine and enters the large intestine, where it is fermented by "friendly" bacteria.
  • Soluble fiber is broken down by bacteria, producing energy for cells, while insoluble fiber contributes to softer and easier-to-eliminate bowel movements.

Maintaining Blood Glucose Levels

  • Insulin and glucagon are hormones produced by the pancreas that regulate blood glucose levels.
  • Insulin lowers blood glucose levels by allowing glucose to enter cells, stimulating glycogen synthesis, and promoting fat and protein synthesis.
  • Glucagon raises blood glucose levels by promoting glycogen breakdown, stimulating glucose production from amino acids, and stimulating lipolysis.

Glucose for Energy

  • Cells metabolize glucose to release energy, producing carbon dioxide and water as byproducts.
  • Glucose is a primary fuel for the body's cells, especially red blood cells, brain cells, and nervous system cells.
  • When glucose is abundant, the liver stores excess glucose as glycogen or converts it into fat, which is stored in adipose cells.

Carbohydrate Requirements

  • The Recommended Dietary Allowance (RDA) for carbohydrate is 130 g/day, which is sufficient to prevent ketosis.
  • Under normal conditions, human cells obtain a small proportion of their energy needs by converting certain amino acids into glucose.

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Description

Understand how carbohydrates such as starch, fiber, lactose, and sucrose are broken down and absorbed in the digestive system. Learn about the role of salivary amylase, pancreatic amylase, and maltase in carbohydrate digestion.

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