Nutrition 1165 Final

Glycolysis

(also called anaerobic metabolism) Metabolic reactions in the cytosol of the cell that split glucose into 2 three-carbon pyruvate molecules, yielding two ATP molecules

How does protein quality compare between animal and plant sources?

*Animal sources of protein* - B vitamins and minerals such as iron, zinc and calcium; Low in fiber and can be high in saturated fat, cholesterol *Plant sources of protein* - a good source of B vitamins, iron, zinc, and calcium, but in less absorbable (less bioavailable) forms

How does the distribution of body fat affect the risks of excess body fat?

*Visceral fat* - android obesity Greater health risk Easier to mobilize Floods liver and increases blood lipids *Subcutaneous fat* - gynoid obesity Less of a health risk Harder to mobilize

What are the different categories of the DRI's?

1. *Bone* (Calcium, phosphorus, magnesium, vitamin D and fluoride) 2. *Water-soluble vitamins* (B Vitamins and choline) 3. *Antioxidants* ( Vitamin C, Vitamin e, selenium and β-carotene) 4. *Micronutrients* (Vitamin A, Vitamin K, iron, other trace minerals) 5. *Energy and macronutrients* 6. *Electrolytes and water*

Describe 2 methods for determining body composition

1. BIA:Resistance to painless, low energy electrical current Lean tissue more conductive Affected by hydration status 2. DXA : Dual-energy X-ray absorptiometry (DXA) Two X-ray energies used to determine fat, bone, and lean mass Can assess visceral fat

What are the components that make up total energy expenditure?

1. Basal metabolism 2. Physical activity 3. Thermic effect of food (TEF) 4. Adaptive thermogenesis

What are the six classes of nutrients?

1. Carbohydrates 2. Lipids 3. Proteins 4. Water 5. Vitamins 6. Minerals

Which types of DRI standards can be used as a goal for individual intake?

1. Estimated Energy Requirements (EERs) 2. Acceptable Macronutrient Distribution Ranges (AMDRS)

What is glycogen and where is it stored?

A carbohydrate made of many glucose molecules linked together in a highly branched structure. It is the storage form of carbohydrate in animals. It is stored in the liver.

Insulin

A hormone secreted by the pancreas that allows the uptake of glucose by muscle and adipose tissue and has other metabolic effects such as stimulating protein and fat synthesis and the synthesis of glycogen in liver and muscle.

Glucagon

A hormone secreted by the pancreas that stimulates the breakdown of liver glycogen and the synthesis of glucose to increase blood sugar.

What is an essential nutrient?

A nutrient that must be provided in the diet because the body either cannot make it or cannot make it in sufficient quantities to satisfy its needs.

What is an essential amino acid?

An amino acid that cannot be synthesized by the human body in sufficient amounts to meet needs and therefore must be included in the diet

What contributes the most to TEE in a sedentary person?

Basal metabolism

What components of digestive secretions are critical for fat absorption?

Bile and Pancreatic Lipase

What is the function of bile in fat digestion and absorption?

Bile emulsifies fat so that it is broken up into smaller molecules in order to be absorbed

Which nutrients are energy-yielding?

Carbohydrates, Fats & Proteins

Describe the general structure of a protein. How do they differ from other macronutrients?

Constructed of one or more folded, chain-like strands. Contain at least carbon, hydrogen, oxygen, and nitrogen

What is diabetes and what symptom is it best characterized/diagnosed by?

Diabetes is a disease caused by insufficient insulin production and/or decreased sensitivity of cells to insulin. It results in elevated blood glucose levels.

Explain short-term mechanisms that can drive you to eat a meal and one that makes you stop eating when you have eaten enough at a meal.

Drive to eat: hunger and appetite Don't eat: satiation and satiety - feeling of fullness and satisfaction Hypothalamus - region of brain that regulates satiety and energy expenditure

What type of DRI standard can be used to evaluate the adequacy of nutrient intake in a population?

Estimated Average Requirement

Under what dietary conditions are our glycogen stores depleted/used?

Exercising

How are bonds between monosaccharides formed? Broken?

Formed by condensation, broken by hydrolysis

Which groups of people are the DRIs intended for?

Healthy people

How do HDLs differ from LDLs?

High levels of HDL in blood help to prevent cholesterol from depositing in artery walls High levels of LDL-cholesterol in blood increases risk for heart disease

Where does energy production from nutrients occur in our cells?

In the mitochondria

What is the difference between cholesterol and plant sterols? Where are they found in foods? How do they affect our blood cholesterol?

Instead of fatty acids there are multiple chemical rings in cholesterol More than 90% of cholesterol in body is found in cell membranes Diets high in cholesterol may increase blood cholesterol

Compare the roles of insulin and glucagon in regulating blood glucose.

Insulin - lowers blood sugar Glucagon - increases blood sugar

What is the main function of glucose in the body?

It's the primary form of carbohydrate used to provide energy for the body

what enzymes are important for fat digestion?

Lipase converts triglycerides into both fatty acids and glycerol. Amylase converts carbohydrates into simple sugars. Elastases degrades the protein elastin. Trypsin converts proteins to amino acids. Chymotrypsin converts proteins to amino acids. Nucleases convert nucleic acids to nucleotides and nucleosides. Phospholipase converts phospholipids into fatty acids.

Where do chylomicrons come from and what is their function?

Lipoprotein particles that consist of triglycerides, phospholipids, cholesterol, and proteins. They transport dietary lipids from the intestines to other locations in the body. Chylomicrons are produced in the small intestine, found in the blood and lymphatic fluid where they serve to transport fat from its port of entry in the intestine to the liver and to adipose (fat) tissue.

Describe what happens during the process of glycolysis

Metabolic reaction in the cytosol of the cell that split glucose into tow 3-carbon pyruvate molecules, yielding 2 ATP molecules.

Aerobic Metabolism

Metabolism in the presence of oxygen, which can completely break down glucose to yield carbon dioxide, water, and as many as 38 ATP molecules

What distinguishes a saturated fat from a monounsaturated fat? From a polyunsaturated fat? From a trans fat?

Monounsaturated - one carbon double bond - MUFA Polyunsaturated - 2 or more carbon double bonds - PUFA Trans fat - hydrogen atoms on the opposite side of the double bond

How are fat-soluble nutrients absorbed and transported throughout the body?

Most Fat-soluble nutrients are absorbed and transported through the lymphatic system

Describe the process of fat digestion and absorption

Most digestion of lipids takes place in small intestine In the stomach, lingual lipase and gastric lipase aid in the digestion of lipids In the small intestine, lipids need to be emulsified. Bile is released into the small intestine from the liver and gallbladder. Bile emulsifies lipids into small droplets in order to increase surface area so that enzymes may breakdown the lipids. Pancreatic lipase then breaks down triglycerides. Lipids are absorbed through simple diffusion.

What pathway produces the most ATP?

Oxidative Phosphorylation: 28 ATP Glycolysis: 2 ATP Krebs Cycle: 2 ATP Fermentation: 2 ATP

What is protein complementation and when is it important?

Protein complementation - combines foods with different limiting AA

What are the differences between refined flour and unrefined flour?

Refined flour contains mostly carbohydrates that it is enriched with

What are the different fibers and how do we classify them? How do they affect our cardiovascular health and gastrointestinal health?

Soluble & Insoluble fiber are defined by whether they can dissolve or absorb water. Soluble fiber can absorb and dissolve water while insoluble fiber cannot dissolve in water. Fiber draws water into the intestines and thus dilutes intestinal contents and increases volume as well as slowing the absorption of glucose.

What is the basic unit of carbohydrate?

Sugar (monosaccharides)

What is the thermic effect of food?

The energy required for the digestion of food and the absorption, metabolism, and storage of nutrients. It is equal to approximately 10% of daily energy intake.

What is a limiting amino acid and how does it affect protein synthesis?

The essential amino acid that is available in the lowest concentration in relation to the body's needs. It limits protein synthesis.

When blood sugar drops, how do we increase it to maintain normal levels? What processes are important?

The pancreas secretes glucagon, glucagon signals liver cells to break down glycogen into glucose, which is released into the bloodstream Glycolysis & aerobic metabolism

Where do most digestion and absorption occur?

The small intestine (95% of digestion)

How does the structure of the intestine aid absorption?

The small intestine has increased surface area because of 3 different structures: circular folds, villi, and microvilli

Gluconeogenesis

The synthesis of glucose from simple noncarbohydrate molecules. Amino acids from protein are the primary source of carbons for glucose synthesis.

Which DRI standard can help you determine if a supplement contains a toxic level of a nutrient?

Tolerable Upper Intake Levels (ULs)

How do the different fatty acids/fats affect our heart disease risk? How do they affect our LDL and HDL levels?

Trans fat - increase blood LDL, reduce HDL, increase inflammation and blood clotting Saturated fat - increase blood LDL and inflammation

What is the predominant lipid in our body and food?

Triglyceride - consists of 3 fatty acids attached to a glycerol molecule

VLDL, HDL, and LDL

VLDL transports lipids out of the liver and delivers them to body cells High levels of HDL in blood help to prevent cholesterol from depositing in artery walls LDL - primary cholesterol delivery system to cells

Under what dietary conditions do we increase our glycogen stores?

When consuming foods. Diabetes is attributed to increased glycogen in the liver

How is fat broken down for energy in our body? What metabolic processes are involved?

When fats are used as an energy source, they are broken down in cellular mitochondria through a process called beta-oxidation.

What products of digestion are transported by the lymphatic system?

fat-soluble nutrients

List two foods that are sources of monounsaturated fatty acids, two that are sources of omega-3 fatty acids, and two that that are sources of cholesterol.

monounsaturated fatty acids: olive oil, canola oil omega-3 fatty acids: flaxseed oil, walnuts cholesterol: butter, red meat

What products of digestion are absorbed and then transported via the hepatic portal circulation?

water-soluble nutrients