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UA / Human Development / HDFS 101 / Why do our body need sugar?

Why do our body need sugar?

Why do our body need sugar?


School: University of Alabama - Tuscaloosa
Department: Human Development
Course: Intro Human Nutrition
Professor: Libo tan
Term: Summer 2015
Cost: 50
Name: NHM 101- EXAM 2 Study Guide
Description: A comprehensive, complete study guide for Exam 2! Detailed explanations, images and processes are included!
Uploaded: 10/03/2015
9 Pages 53 Views 4 Unlocks

Willie Colvin (Rating: )

NHM 101- Exam 1 Study Guide 

Why do our body need sugar?


**what are they? ???? Macronutrient

????Contain C, H, and O atoms, usually with a H:O atom ratio of 2:1.

????The name (hydrates of carbon) comes from an early observation that heating these compounds  produced water and a black residue of carbon.

1. Dietary carbohydrates and sources

o Starch: grain products

o Fiber: legumes, vegetables, and fruits

o Sugars: natural sugars (milk, fruits), added sugars

i. Major Functions:

1. Provide energy through their oxidation in the body: energy-producing. 2. Serve as a storage form of energy (i.e. glycogen)

3. Supply carbon atoms for biosynthesis of other organic molecules

What are the most common complex carbohydrates?

4. Act as structural components.  

2. Classification of carbohydrates

a. Simple carbohydrates:

i. Monosaccharides- single sugars

1. Glucose, fructose, galactose

ii. Disaccharides- pairs of monosaccharides

1. Maltose, sucrose, lactose

b. Complex carbohydrates:

i. Oligosaccharides- 3-10 monosaccharides

ii. Polysaccharides- long chain of monosaccharides

1. Glycogen, starch, fiber

• Glucose is the energy source for all cells.

• Maltose: glucose + glucose; Sucrose: glucose + fructose; Lactose: glucose +  galactose

• Starch: storage form of glucose/energy in plants; Glycogen: storage form of  glucose/energy in animals (liver and muscle)

What causes lactose intolerance?

We also discuss several other topics like How is populism depicted in movies?

• Fiber: cannot be digested. Why? ????—Bonds between fibers monosaccharides  cannot be broken down by digestive enzymes 

3. Carbohydrate digestion

• Begins in the mouth

• Functions of :

o pancreatic amylase- Digest (most) starch to maltose

o maltase- digest maltose into glucose

o lactase- digest lactose to glucose and galactose Don't forget about the age old question of What do implementation provisions that statute to do?

o sucrase- digest sucrose to glucose and fructose

• Digestion products: glucose, fructose, galactose

4. Causes of lactose intolerance We also discuss several other topics like What's a commerce clause?

a. —Lactase declines with age: only about 30% of adults have enough lactase b. —Lactase deficiency: Intestinal villi are damaged by disease, medications, prolonged  diarrhea

5. Glucose in the body

• Glycogen formation: excess glucose in the body is stored as glycogen in the liver  and muscles

• glycogen breakdown: When blood glucose falls, liver break down glycogen and  release glucose into the blood, which becomes available to supply energy to  tissues; Muscle break down their glycogen to use by themselves.

• Gluconeogenesis: the making of new glucose from body protein when adequate  dietary carbohydrates do not exist.

• Blood glucose homeostasis: regulation by insulin and glucagon

o Insulin: Blood glucose rises ???? insulin released ???? moves glucose from  blood into cells ????blood glucose returns to normal  

o Glucagon: Blood glucose falls between meals ????glucagon released  

signals liver to breakdown glycogen stores???? blood glucose returns to  


• Diabetesv: blood glucose remains above normal after a meal due to inadequate or  ineffective insulin We also discuss several other topics like What makes emails asynchronous?

o Type 1 Diabetes

✂ Pancreas does not produce any or enough insulin 

✂ Typically diagnosed in childhood

o Type 2 Diabetes

✂ Cells do not respond to insulin 

✂ Typically occurs due to obesity

6. Identify added sugars on the ingredient label.

a. •Corn syrup solids

b. •Dextrose

c. •Fructose

d. •High fructose corn syrup

e. •Honey

f. •Lactose

g. •Malt Syrup

h. •Nectars

i. •Raw sugar

j. •Sucrose

7. Health effects and Recommended intake

a. Sugar in excess can be detrimental.

b. Obesity and Chronic Disease

i. Americans who drink sugar-sweetened beverages have a higher energy intake 1. Weigh more with high intake of added sugar

ii. Increased risk of diabetes, inflammation, hypertension, heart disease

c. Nutrient Deficiencies

i. Foods and beverages containing lots of added sugars deliver very few  essential nutrients or fiber.

d. Dental Caries

**Reduce intake of kcal from added sugars

-According to the DRIs, sugar should make up no more than 25% of your kcal

• AMDR for carbohydrates= 45-65% Don't forget about the age old question of Define dual federalism.

✁ Example: Michael eats 2500 kcalories a day and 300 grams of  

carbohydrates. Is he consuming enough carbohydrates according to the  

Acceptable Macronutrient Distribution Range for carbohydrates?

✁ Answer: 300 g * 4 kcal/g = 1200 kcal; 1200/2500= 0.48 = 48% (Yes) • Recommended intake of fiber for men and women

✁ Men: 35 g or more

✁ Women: 25 g or more


1. Amino acids

• Protein is made of amino acids.

• Basic structure of amino acids

o —Central carbon atom If you want to learn more check out What is an impact of tourism?

o —Hydrogen atom

o —Acid group (COOH)

o —Amino Group (NH2)

o Side group varies with different amino acids.

• Essential amino acids: the body cannot synthesize

o Histidine, Isoleucine, leucine, Lysine, Methionine, Phenylalanine, Threonine,  Tryptophan, Valine

2. Structure of proteins

• Amino acids are linked by peptide bonds.

• Dipeptide

o — Two amino acids bonded together

• Tripeptide

o —Three amino acids bonded together

• Polypeptide

o —Multiple amino acids bonded together

• Most proteins contain a few dozen to hundreds of amino acids

• Four levels of protein structures

• Primary Structure – Amino acid sequence

o The 20 amino acids can be linked together in a variety of sequences

• Secondary Structure – Polypeptide Shapes

o Sections of polypeptide chain twists into specific shapes, for example, a helix

• Tertiary structure – Polypeptide tangles

o Long polypeptide chain twists and folds into a complex, tangled shape

• Quaternary Structure – Multiple polypeptide interactions

• Denaturation:

o Protein uncoil and lose their shapes due to heat, agitation, acid

o Lose their ability to function

o Ex. Hardening of an egg when it is cooked

3. Protein digestion

• Digestion products: amino acids, tripeptides, dipeptides

• Location • Enzyme • Source of  

enzyme • Function

• Stomach • Pepsin • Stomach cells • Break protein into smaller polypeptides

• Proteases • Pancreas • Break polypeptide into tri- and di-peptides

• Small  


• Peptidase

• Outer membrane  of small intestine  cells

• Break most tri- and dipeptides into amino acids

• End products: amino acids, di- and tripeptides

4. Functions of proteins

a. Structural  

i. Building blocks of muscles, blood, and skin

ii. Major structural component of all cells

b. Catalysis (Enzymes)

i. Ex. digestive enzymes

c. Regulation (Hormones)

i. Messenger molecules that elicit response to restore normal conditions

ii. Some hormones are proteins

Ex. Insulin and glucagon  

5. Protein metabolism

• Excess amino acids from dietary protein intake can NOT be stored in the body; they  can be converted to body fats.

6. High quality proteins vs. low quality proteins

a. High quality proteins: animal proteins, soy protein

b. Low quality proteins: plant proteins  

7. Recommended intake

• AMDR: 10-35% of calories from protein

• Translates into 50-175g protein

• RDA: 0.8 grams/kilogram of body weight for adults

• Pound to kilogram conversion is 2.2

• Divide weight in pounds by 2.2 to get kilograms.

Example: Joe weighs 180 lbs. Based on the RDA for protein, how many grams of protein  should he consume each day? (Divide body weight in pounds by 2.2 to get body weight  in kilograms). Answer: 180 lbs/2.2 = 81.8kg; 81.8 kg * 0.8g/kg = 65g


1. Lipids are a group of compounds that are insoluble in water.

2. Fatty acids: A chain of carbon and hydrogen atoms with an acid group (COOH) at the end  • saturated fatty acids: No double bonds between carbon atoms

• monounsaturated: one double bond

• polyunsaturated fatty acids: two or more double bonds

• The omega number of an unsaturated fatty acid based on its chemical structure. (closest double bond to methyl group)

• Essential fatty acids: the body cannot synthesize:

o linoleic acid: Omega-6; veg. oils, meats

o linolenic acid: Omega- 3, dark green vegetables, veg. oils, flaxseed

3. Triglycerides

• Composed of three fatty acids attached to one glycerol

• Fats (saturated fats):solid triglycerides; from animals other than fish

• Oils (unsaturated fats): liquid triglycerides; from plants or fish  

• Fats and oils differ in their fatty acid components.

o Oils: a high proportion of unsaturated fatty acids, which have lower melting  points

o Fats: mostly saturated fatty acids.

• Partial hydrogenation of vegetable oils

o double bonds are saturated to single bonds by adding hydrogen molecules o Food processing hydrogenation makes vegetable oils more solid by converting  double bonds to single bonds, e.g., margarine, shortening.

o Prolongs shelf life of food products

o Improves texture of foods

o During food processing hydrogenation, most fats are partially hydrogenated o The remaining double bonds change their configuration from cis to trans. o Partial hydrogenation can produce trans-fatty acids/fats.

o Most trans-fats in our diet are from partially hydrogenated vegetable oils.

4. Phospholipids and sterols

• Phospholipids are the major constituents of cell membranes

• Most common sterol: cholesterol

• Sterols cannot provide energy

5. Triglycerides digestion

• Cholecystokinin (CCK) signals the gallbladder to release bile into small intestine to  emulsify fat

• Bile acts as an emulsifier so the enzymes can act on the fat

• Pancreatic lipases hydrolyze triglycerides into monoglycerides and fatty acids.

6. Lipid transport: lipoproteins

• Vehicles for transporting lipids in blood stream

• Chylomicrons: Deliver dietary lipids (mostly triglycerides) from SI to the rest of the  body

• VLDL: Deliver lipids synthesized in the liver (mostly triglycerides) to other tissues • LDL: Deliver lipids synthesized in the liver (mostly triglycerides) to other tissues • HDL: Picks up cholesterol from tissues and return it to liver for disposal • Health implications of LDL and HDL

i. A high level of LDL can deposit a high level of cholesterol into the endothelia  cells of the arteries ???? plaque, a thick and hard deposit that can clog arteries  (atherosclerosis).  

1. If a clot blocks a narrowed artery, blood flow is stopped and heart  

attack or stroke can result.  

ii. §HDL can clear deposited cholesterol in arteries; HDL lowers the risk of heart  disease.

7. Health effects and recommendations

• Saturated fats & trans fats: increase CVD risk; should decrease intake

• MUFAs & PUFAs: decrease CVD risk; should increase intake, especially w-3 FAs.

• Dietary Guidelines 2010

• —AMDR for fat—20-35% calories from fat

• —Dietary Cholesterol: <300 mg per day

• —Egg yolks—up to 1 per day

• —SFA: <10% of calories

• —Replace with PUFAs and MUFAs

• —TFA: little or no

• Adequate Intake (AI)

• —5-10% of calories from linoleic acid

• —0.6-1.2% of calories from linolenic acid

Energy metabolism

1. Metabolism: The sum total of all the chemical reactions occurring in the body  2. Anabolism: Building up of body compounds, require energy

3. Catabolism: break down of body compounds, releases energy

4. ATP

• Most of the energy released from macronutrients breakdown is captured in ATP. • The linking intermediate between energy-yielding and energy-requiring chemical  reactions in the body.

• an energy reservoir

• a high energy compound

5. Process of carbohydrate, protein, and fat metabolism in the body.  

a. Carbs????Glucose

b. Proteins???? Amino acids

c. Fats???? Glycerol+Fatty acids

• All three macronutrients can be broken down to Acetyl CoA and enter the TCA  cycle.

• CO2 and H+ are produced from the TCA cycle.

• Electron transport chain: final pathway of energy metabolism; water is formed  from oxygen and H+ and ATP is synthesized.

• Anaerobic oxidation of glucose: glucose ???? pyruvate ???? lactate

• During prolonged fasting/starvation, acetyl CoA produced from fat breakdown is  converted to ketone bodies for fuel.

6. Energy metabolism during feasting and fasting.  

a. Feasting: Extra glucose

i. Stored as glycogen (limited capacity)

ii. After glycogen capacity is filled, still extra glucose is converted to body  fats.

iii. Extra fats

1. Stored as body fats (unlimited capacity)

iv. Extra amino acids

1. NO capacity to store extra amino acids

2. Extra amino acids can be converted to body fats 

v. Excessive energy intake, no matter in which form of macronutrients, can  lead to weight gain.

b. Fasting:

i. Short-term fasting (1 day)

1. Breakdown of glycogen to release glucose for energy

ii. Fasting for 2-5 days

1. Breakdown of body fats for energy

iii. Breakdown of lean tissues (protein) to release amino acids, which are  converted to glucose

1. gluconeogenesis 

iv. Long-term fasting (weeks or longer)

1. Breakdown of body fats 

2. Acetyl CoA converted to ketone bodies 

3. Breakdown of lean tissues 

v. Metabolic Rate DECREASES

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