Ch. 25: Nutrition, Metabolism, and Temperature Regulation

Digestion of the Three Major Food Types (Table 24.4)

DO:

* Define nutrition, nutrients, essential nutrients, and kilocalorie.
* Describe MyPlate and its use.
* For carbohydrates, lipids, and proteins, describe their dietary sources, their uses in the body, and the daily recommended amounts of each in the diet.
* List the important vitamins and minerals for body health. Give the function and symptoms of deficiency for each.

Nutrition definition

The process by which the body obtains and uses certain components of food.

3 things chemicals are taken into the body and used for

1. to produce energy
2. for building blocks
3. to function in other chemical reactions

Why must essential nutrients be ingested?

Either because the body can’t make them at all or cannot make them in adequate amounts

6 classes of nutrients (and whether they’re required in large or small amounts)

Large:


1. Carbohydrates
2. Proteins
3. Lipids
4. Water

Small


5. Vitamins
6. Minerals

Food Guide Pyramid (diagram)

Calorie (cal)

the amount of energy it takes to heat 1 gram of H2O by 1 degree Centigrade

Kilocalorie (kcal)

1000 calories

Metabolizing 1g of protein releases how much energy?

4 kcal

Metabolizing 1g of carbohydrates releases how much energy?

4 kcal

Metabolizing 1g of fat releases how much energy?

9 kcal

Where do most carbohydrates come from?

plants

How does the body use carbohydrates?

they are broken down into monosaccharides (simple sugars) and/or converted into glucose in the liver

3 types of monosaccharides (and their chemical structure - diagram)

1. Glucose
2. Fructose
3. Galactose

2 types of disaccharides (and which two monosaccharides make combine to form them)

1. Sucrose (glucose + fructose)
2. Lactose (glucose + galactose)

2 types of polysaccharides (and which organism they are used to store energy in)

1. Glycogen (animals)
2. Starch (plants)
3. Cellulose

What is a good source of monosaccharides in our food?

starch

What is cellulose used for in plants and where does it show up in the human body?

forms plant cell walls & is the fiber (bulk) in feces

All of these carbohydrates come from plants EXCEPT:

A. fructose.

B. lactose.

C. maltose.

D. sucrose.

B. lactose.

What is 95% of lipids?

triglycerides/fats (glycerol + 3 fatty acids)

What is included in the other 5% of lipids?

cholesterol (steroids) & phospholipids

3 cholesterol molecules (and what do their structures all have in common?)

1. bile salts
2. estrogen
3. testosterone

they all have 4 rings of carbon atoms

State of unsaturated fats at room temperature

liquid (like oil)

State of saturated fats at room temperature

solid (like butter)

Where are essential fatty acids found? (5 places)

1. seeds
2. nuts
3. legumes
4. grains
5. greens

What are 2 types of essential fatty acids? (and what they come from)

1. Linoleic acid – in grains
2. α-linolenic acid – in green leaves of plants

Cholesterol

A. is manufactured in the liver.

B. is a component of the cell membrane.

C. can be modified to form steroid hormones.

D. all of these

D. all of these

How many different amino acids are there?

20

2 groups of proteins

1. Essential amino acids (9/20): obtained from the diet because the body cannot synthesize them
2. Nonessential amino acids (11/20): necessary for protein construction, but they do not have to be ingested because the body can synthesize them from the essential amino acids

Complete protein

a food that contains all 9 essential AAs

6 examples of complete proteins

1. Meat
2. Fish
3. Poultry
4. Milk
5. Cheese
6. Eggs

_ examples of incomplete proteins

1. Leafy green vegetables
2. Grains
3. Legumes

Can a combination of incomplete proteins form a complete protein?

Yes

In a healthy adult, the synthesis of AAs and break down of AAs occur at _____ in a healthy adult.

the same rate

Which element do AAs contain?

nitrogen

What does being in nitrogen balance mean?

when the N content in ingested protein = the N excreted in urine and feces

Vitamins

organic molecules in food that are needed for normal metabolism

4 types of fat-soluble vitamins

1. A
2. D
3. E
4. K

5 types of water-soluble vitamins

1. B1-3, 6, 12
2. Pantothenic acid
3. Biotin
4. Folate
5. C

Minerals

inorganic molecules needed for normal metabolic functions

What is the AMDR?

acceptable macronutrient distribution range

What is the AMDR for carbohydrates?

45-65% of daily intake of kilocalories

What is the AMDR for lipids?

20-35% of total daily kilocalories

What percentage of total daily kilocalories should be saturated fats?

10% or less

What is the AMDR for proteins?

10-35% of total kilocalories per day

What are the daily values, introduced in 2006, for daily kilocaloric intake for carbohydrates, fats, proteins, cholesterol, sodium, fiber, and vitamins?

* Carbohydrates: 60%
* Total fats: 30% (10% saturated)
* Proteins: 10%
* Cholesterol:

Which types of vitamins are manufacturers required to list on their current nutrition labels? (4 things)

vitamin D, calcium, iron, and potassium

What are the percent daily values for nutrients related to?

energy consumption

What are the percent daily values for nutrients based on?

a 2000 kcal/day diet

How did the nutrition facts labels change in January 2021?

the original label was only required to list total sugars & the new label is required to list “includes __g added sugars”

What did the National Geographic Adventist health study in November 2005 find? (4 things)

* Adventist men live 7.3 years longer and Adventist women live 4.4 years longer than other Californians
* Not smoking, a plant-based diet, nuts several times per week, regular exercise, and normal weight increase life span by up to 10 years
* Fruits and vegetables lowered risk of heart disease and cancer
* Increasing consumption of red and white meat is associated with an increased risk of colon cancer

DO:

* Define metabolism, anabolism, and catabolism.
* Relate hydrogen atoms to energy.

Metabolism

the total of all chemical changes that occur in the body

Anabolism

a process that requires energy where small molecules are joined to form larger molecules

Catabolism

a process that releases energy where molecules are broken down into smaller molecules (starts in digestion & ends in individual cells)

What is energy from catabolism used for?

to drive anabolic reactions/processes like active transport & muscle contraction

What is energy in carbohydrates, lipids, (& proteins) used for?

to produce ATP through oxidation-reduction reactions

The energy-requiring process by which small molecules are joined to form larger molecules is

A. anabolism.

B. catabolism.

C. metabolism

D. cannibalism

A. anabolism.

How is ATP synthesized from carbohydrates, proteins, and lipids?

Carbs → glucose

Proteins → amino acids

Lipids → fatty acids

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Each of those are absorbed from the digestive tract into the blood, taken into the cells, then catabolized.

DO:

* Describe glycolysis and name its products.
* Describe the citric acid cycle and name its products.
* Explain the electron-transport chain and how ATP is produced in the process.
* Explain the difference in the number of ATP molecules produced by aerobic respiration and by lactic acid fermentation.

Anaerobic respiration (lactic acid fermentation)

the breakdown of glucose in the absence of oxygen that produces 2 ATP & 2 lactic acid (which releases a H+ and is converted to lactate)

2 phases of anaerobic respiration

1. Glycolysis
2. Lactic acid formation

Cori cycle

the process that occurs after anaerobic respiration that converts lactate to glucose when oxygen becomes available

Aerobic Respiration

the breakdown of glucose in the presence of oxygen that produces CO2, water, and 32 ATP

What is the chemical formula for aerobic respiration?

C6H12O6 (glucose) + 6 O2 (oxygen) + ADP → 6 CO2 + 6 H2O (water) + ATP

4 phases of aerobic respiration

1. Glycolysis
2. Acetyl-Co A formation
3. Citric acid cycle
4. Electron-transport chain

What are NADH and FADH and where are they produced?

molecules that carry electrons to the electron transport chain to be used to synthesize ATP produced in various stages of carbohydrate metabolism

What are the products of glycolysis? (3 things)

1. 2 pyruvic acid molecules
2. 4 total ATP, 2 net ATP (2 are consumed)
3. 2 NADH

What are the products of Acetyl-Co A formation? (2 things)

In the presence of oxygen, pyruvic acid is used to produce:


1. 2 NADH
2. 2 CO2

What are the products of the citric acid/Krebs cycle?

In one cycle:


1. 1 ATP
2. 3 NADH
3. 1 FADH2
4. 2 CO2

But the cycle runs twice, so those numbers are doubled.

What is the electron transport train?

a series of electron carriers in the inner mitochondrial membrane

Steps:


1. Electrons are transferred from NADH and FADH2 to the e- transport carriers. After the loss of the e- and the H+, the oxidized NAD+ and FAD are reused to transport additional e- from the citric acid cycle to the e- transport chain.
2. The e- pass from one e- carrier to the next through a series of oxidation-reduction reactions. Three of the e- carriers also function as proton pumps, which move the H+ from the mitochondrial matrix into the intermembrane space. Each proton pump accepts an e-, and uses some of its energy to export a H+, and passes the e- to the next e- carrier.
3. The last e- carrier in the series collects the e- and combines them with O2 and H+ to form water: 1/2 O2 + 2 H+ + 2 e- → H2O. Oxygen is the final acceptor of e- in this process.
4. The H+ released from NADH and FADH2 is moved from the intermembrane space to the matrix by active transport. As a result, the concentration of H+ in the intermembrane space exceeds that of the matrix and a H+ concentration gradient is established. The H+ cannot simply diffuse down the concentration gradient but must pass through certain channels formed by an enzyme called ATP synthase. As the H+ diffuses down the concentration gradient, energy is released that is used to produce ATP. This process is called chemiosmosis because the chemical formation of ATP is coupled to a diffusion force similar to osmosis.

Aerobic respiration overview (diagram)

How much ATP is produced from 1 glucose molecule?

2+2+25+3 = 32

* Glycolysis → 2 ATP
* Citric Acid cycle → 2 ATP
* Electron transport train (via 10 NADH: 2.5 ATP/1 NADH) → 25 ATP
* Electron transport train (via 2 FADH: 1.5 ATP/1 FADH) → 3 ATP

In what areas of the body does the amount of ATP differ? (5 things)

Less (30 ATP):


1. skeletal muscle
2. brain tissue

More (>32):


1. liver
2. kidney
3. heart

Besides ATP, the end products of aerobic respiration are

A. lactic acid and pyruvic acid.

B. lactic acid and citric acid.

C. carbon dioxide and water.

D. carbon dioxide, lactic acid, and water.

C. carbon dioxide and water.

At the end of aerobic respiration, all six carbon atoms from the glucose molecule are

A. found in carbonic acid molecules.

B. found in carbon dioxide molecules.

C. found in NADH molecules.

D. still present in glucose.

B. found in carbon dioxide molecules.

DO:

* Describe the basic steps involved in using lipids as an energy source.

How are lipids primarily stored?

as triglycerides in adipose tissue

How are lipids metabolized?

1. Adipose triglycerides are broken down and released as free fatty acids, which are taken up by cells and broken down by beta-oxidation into acetyl-CoA.
2. Acetyl-CoA can enter the citric acid cycle as ATP or be converted to ketone bodies (usually the large amounts of unused Acetyle-CoA in the liver) or travel to tissues as ATP.

In the process of beta-oxidation, two carbon atoms are removed from the end of a(n) __________ to form __________ .

A. amino acid, fatty acids

B. acetyl-CoA, fatty acids

C. fatty acid, amino acids

D. fatty acid, acetyl-CoA

D. fatty acid, acetyl-CoA

DO:

* Describe the basic steps involved in using proteins as an energy source.

Amino acid metabolism

1. Once absorbed, amino acids are quickly taken up by cells, especially in the liver.
2. Amino acids are either used to synthesize proteins or as a source of energy.
3. Amino acids not stored in body (unlike lipids and glucose) and can enter carbohydrate metabolism at many points.

3 ways the body can synthesize non-essential amino acids

1. Transamination
2. Oxidative deamination
3. Conversion of ammonia to urea

Transamination conversions

amino acid → a-ketoglutaric acid → a-keto acid → glutamic acid

Oxidative deamination conversions

glutamic acid → NAD+ → NADH → a-ketoglutaric acid → ammonia (toxic)

Conversion of ammonia to urea conversions

ammonia (toxic) + carbon dioxide → urea + water

Where does the conversion of ammonia to urea take place?

the liver

3 (8 detailed) ways to maintain homeostasis

1. keep glucose levels normal to make ATP
2. 3 ways to maintain ATP (metabolic rate)
3. 4 ways heat is exchanged to produce heat balance

DO:

* Define glycogenesis, lipogenesis, glycogenolysis, and gluconeogenesis.

Interconversion of nutrient molecules

Absorptive state


1. Glycogenesis: excess glucose is used to form glycogen
2. Lipogenesis: when glycogen stores filled, glucose and amino acids turn into lipids

Postabsorptive state


1. Glycogenolysis: the breakdown of glycogen into glucose (in the liver)
2. Gluconeogenesis: the formation of glucose from amino acids and/or glycerol.

The process by which amino acids and glycerol can be converted to glucose is called

A. beta-oxidation.

B. gluconeogenesis.

C. glycogenesis.

D. glycogenolysis.

B. gluconeogenesis.

Absorptive metabolic state

the period immediately after eating where nutrients are absorbed through the intestinal wall into the circulatory and lymphatic systems (occurs about 4 hours after each meal)

Postabsorptive metabolic state

the period that occurs after the absorptive state is done (usually late in morning, afternoon, or night) where blood glucose levels are maintained by the conversion of other molecules to glucose

What is the first source of blood glucose in the postaborptive state?

glycogen from the liver

Why is it important to maintain blood glucose levels during the postabsorptive state?

The brain relies almost entirely on ______ for energy production

A. sucrose

B. glucose

C. fatty acids

D. protein

B. glucose

Name three sources for this glucose (in the post absorptive state)

* Glycogen
* Amino Acids (from Proteins)
* Glycerol (From Triglycerides)

DO:

* Differentiate between the absorptive and postabsorptive metabolic states.
* Define metabolic rate and describe the three major uses of metabolic energy in the body.

Metabolic rate

the total amount of energy produced and used by the body per unit of time