Intro to Nutrition

Question 1

Identify the 3 macronutrients and their building blocks.

Answer 1

1. Carbohydrates—glucose and other sugars
2. Protein—amino acids
3. Fats—free fatty acids

Question 2

Define monosaccharides

-examples

Answer 2

• Made up of chains of simple sugars (monosaccharides; one sugar unit)
• Examples: glucose, fructose, galactose

Question 3

Define disaccharides

-examples

Answer 3

Two monosaccharides combined to form a new sugar, a disaccharide.

• Glucose + fructose = sucrose
• Galactose + glucose = Lactose
• Glucose + glucose = maltose

Question 4

Define polysaccharides

Answer 4

Made up of more than 10 monosaccharide units
•Starches = polysaccharides (many sugar units of glucose)
•Examples:
-Storage polysaccharides: glycogen (glucose) and starch (glucose polymer)
-Structural polysaccharides: cellulose (glucose) and chitin (N-acetylglucosamine)

Question 5

Given a list of foods, identify the ones that are carbohydrates.

Answer 5

• Dairy: milk, yogurt, and ice cream
• Fruit: whole fruit and fruit juice
• Grains: bread, rice, crackers, and cereal
• Legumes: beans and other plant-based proteins
• Starchy Vegetables: potatoes and corn
• Sugary Sweets: soda, candy, cookies, and other desserts

Question 6

Outline the digestion of carbs

-mechanical and chemical breakdown

Answer 6

• digestion starts in the mouth with mechanical breakdown of the food.
• Chemical digestion also begins with the secretion of saliva:
• -Saliva contains bicarbonate to help neutralize acids
• -Mucus to moisten fee and the oral cavity
• -Antibodies and lysozymes which fights oral bacteria
• -Salivary amylase is in action

Question 7

Outline the digestion of carbs

-bolus production

Answer 7

• A bolus is produced by chemical and mechanical action of the mouth on food.
• Bolus moves down esophagus to the stomach. In the stomach:
• -Hydrochloric acid denatures proteins and activates pepsin
• -Pepsin, as enzyme to digest protein
• -Gastric lipase is in action

Question 8

What is function of salivary amylase?

Answer 8

chemical digestion of starch

Question 9

What is gastric lipase?

Answer 9

an enzyme in the stomach to digest fat

Question 10

Outline the digestion of carbs

-Production and movement of chyme

Answer 10

• stomach digestive action produces “chyme” (~2 hours)
• chyme moves into the small intestines in small increments: more digestion occurs, absorption of nutrients occurs here as well

Question 11

Which organs help with digestion?

Answer 11

The pancreas, gall bladder and liver all help with digestion

Question 12

What enzymes does the pancreas produce and secrete for digestion of carbs?

Answer 12

•Amylase – digests carbohydrates
•Lipases – digests fats
•Proteases- digests proteins
*Pancreas also produces insulin and glucagon that regulate blood glucose

Question 13

What does the liver produce for digestion of carbs?

Answer 13

• Bile for emulsification of fats (stores in gallbladder)
• Receives products of digestion via the portal vein
• Releases glucose from glycogen stores

Question 14

Where do the final steps of digestion of carbs occur?

Answer 14

•Final step occurs in small intestinal enterocytes.

• Brush border of enterocytes contains enzymes in the microvilli.
• Dietary starch is digested by α-amylase produced by the pancreas: generates maltose, short oligosaccharides and limit dextrins.
• These cannot be absorbed: requires further hydrolysis.

Question 15

What happens after the carbs are absorbed from the gut into the bloodstream?

Answer 15

glucose exits the capillary, enters the interstitial space.

• glucose needs presence of insulin to enter cells of some organs (such as muscle, adipose tissue, and liver)
• other organs such as the brain, red blood cells, and the renal medulla do not require the presence of insulin to uptake glucose

Question 16

State the purpose of carbohydrates

Answer 16

• Glucose can provide energy for immediate needs shortly after a meal and long-term energy needs can be provided by storing insulin in the liver and adipose tissue.
• In presence of insulin, glucose is taken up by cells for immediate use.

Question 17

State the purpose of proteins

Answer 17

Provide the body with material for building blood cells, body tissue, hormones, muscle, and other structural elements and are also burned to produce energy.

• Repair and maintenance of body tissue and growth in children.
• Energy—can be stored as fat or converted to glucose for energy needs
• Hormones and enzyme synthesis
• Transport and storage of molecules (hemoglobin, ferritin)
• Antibodies

Question 18

State the purpose of fat

Answer 18

Used to provide and store energy in the body, insulate body tissues, cushion internal organs, transport fat-soluble vitamins, and as integral parts of cell membranes, brain, hormones, hair, and skin.

Question 19

Identify the organs that store glucose.

Answer 19

1. Liver - stored as glycogen
2. Muscle - stored as glycogen, used for quick energy needs
3. Adipose tissue - unlimited

Question 20

Identify the purpose of glycogen.

Answer 20

• In the presence of Insulin, extra glucose is taken up by the liver and stored as glycogen.
• Muscles can also store glucose as glycogen and use it for quick energy needs.

Question 21

Identify the relative impact of carbohydrates, protein, and fats on blood glucose over time.

Answer 21

Percentage of nutrients changes to blood glucose:
• Carbohydrate: up to 100%
• Protein: 50%
• Fat: < 10%

Question 22

State number of kilocalories in 1 gram of carbohydrates, protein, and fats.

Answer 22

• Carbohydrates - 4kcal/g
• Protein - 4 kcal/g
• Fat - 9 kcal/g

Question 23

Identify the percent of macronutrients in a normal healthy diet.
-carbohydrates

Answer 23

45- 65% of total calories

Question 24

Identify the percent of macronutrients in a normal healthy diet.
-proteins

Answer 24

Intake for an adult should be about 0.8 gm/kg of body weight or about 20% of caloric intake.

Question 25

Identify the percent of macronutrients in a normal healthy diet.
-fats

Answer 25

• < 30% of total calories
• Limit saturated fats to < 10% of total calories (raises LDL)
• Increase amount of monounsaturated fats (increases HDL) and polyunsaturated fats

Question 26

State the effect of insulin on carbohydrates

Answer 26

• in presence of insulin, glucose is taken up by cells for immediate use.
• in the presence of Insulin, extra glucose is taken up by the liver and stored as glycogen.
• muscles can also store glucose as glycogen and use it for quick energy needs.
• liver and muscle glycogen stores are limited and can be quickly consumed if demand is great.
• adipose tissue is unlimited and can store glucose for future use.
• insulin promotes the conversion of glucose into fat.

Question 27

State the effect of insulin on proteins

Answer 27

• Amino acids can also stimulate the pancreas to secrete insulin.
• Insulin stimulates the uptake of glucose and amino acids by the muscle cells. It promotes protein synthesis by increasing amino acid transport and stimulating ribosomal protein synthesis.
• Insulin also promotes glycogen synthesis to replace glycogen storage used during muscle activity.
• Insulin accomplishes this by increasing glucose uptake, enhancing glycogen synthase activity, and inhibiting glycogen phosphorylase.
• Muscle stores about 500 to 600 grams of glycogen.
• Muscle lacks the enzyme glucose-6-phosphatase, so it does not contribute to blood glucose.

Question 28

State the effect of insulin on fats

Answer 28

• Most fats are used for energy or stored for later use with the help of insulin.
• When other fuels are in short supply, such as during a prolonged fast, the level of insulin in the blood falls.
• The reduced level of circulating insulin promotes the removal of fat from the storage depots and helps its entry into the circulation.
• It may then be used by muscle and other organs.
• Insulin stimulates glucose and fatty acid uptake leading to lipogenesis (triglyceride production and storage) and inhibits lipolysis.
• Insulin accomplishes these effects by inducing production of lipoprotein lipase in adipose tissue, increasing glucose uptake to produce alpha-glycerol phosphate, and inhibition of intracellular lipase to decrease lipolysis.