3. Carbohydrates

Question 1

How are carbohydrates created and what is their role?

Answer 1

Provide important health benefits (especially fiber-rich foods) and essential nutrients.

Generally constitute 45%-65% of our daily calorie intake.

Main fuel source for many cells.

Glycogen: a carbohydrate made of multiple glucose molecules.
- highly branched structure, storage form of glucose in humans

Question 2

What are monosaccharides?

Answer 2

Simple carbohydrates containing one sugar unit.

1. Glucose: major monosaccharide in body; form digestion of starches and sucrose; source of fuel for cells
2. Fructose: component of disaccharide sucrose; converted into glucose in the liver; excess may form fat
3. Galactose: bonded to glucose in lactose; converted to glucose in the liver

Question 3

What are disaccharides?

Answer 3

Formed by bonding of two monosaccharides.

1. Sucrose (glucose + fructose)
2. Lactose (galactose + glucose)
3. Maltose (glucose + glucose) - alcohol

Question 4

What are polysaccharides?

Answer 4

Complex carbohydrates containing many glucose units, from 10 to 1000 more.

1. Starch: storage form of carbohydrate in plants.
2. Glycogen: storage form of carbohydrate in humans and animals.
3. Fiber: cannot be digested by humans.

Question 5

What are some food sources of carbohydrates?

Answer 5

• Soda
• Energy drink
• M&Ms
• Fruits
• Vegetables
• Dairy
• Grains
• Proteins

Question 6

How are carbohydrates digested and absorbed?

Answer 6

1. Mouth/salivary glands: Some starch is broken down to maltose by salivary amylase. Mechanism digestion includes breaking down food into smaller pieces by chewing.
2. Liver /Gallbladder: glucose, fructose, and galactose absorbed from the small intestine travel through the blood to the liver via the portal vein.
3. Stomach: salivary amylase is inactivated by strong acid in the stomach. No carb digestion occurs in the stomach.
4. Pancreas: enzymes (pancreatic amylase) secreted by the pancreas break down starch into maltose in the small intestine.
5. Small intestine: enzymes in the wall of the small intestine break down the disaccharides sucrose, lactose, and maltose into monosaccharides glucose, fructose, and galactose.
6. Large intestine/rectum: soluble fiber is fermented into various acids and gases by bacteria in the large intestine. Insoluble fiber escapes digestion and is excreted in the feces, but little other dietary carbs remain.

Question 7

Define diverticula, diverticulosis, and diverticulitis.

Answer 7

Diverticula: pouches protrude through exterior wall of the large intestine.

Diverticulosis: condition of having many diverticula in the large intestine.

Diverticulitis: inflammation of diverticula caused by acids produced by bacterial metabolism inside diverticula.

Question 8

What is the RDA for carbohydrates?

Answer 8

130 grams per day for adults

Question 9

What are the guidelines for carbohydrate intake?

Answer 9

45% - 65% of daily calorie intake

Question 10

What does maltase do?

Answer 10

Breaks down maltose to two glucose

Question 11

What does sucrase do?

Answer 11

Breaks down sucrose to glucose and fructose

Question 12

What does lactase do?

Answer 12

Breaks down lactose to glucose and galactose.