NDT 2043 – Exam 2 Study Guide

NDT 2043 – Exam 2 Study Guide

Chapter 4 – Carbohydrates

  • Carbohydrate Categories & Food Sources

    • Monosaccharides:

    • Glucose: Found in fruits and honey.

    • Fructose: Found in fruit and high-fructose corn syrup.

    • Galactose: A component of milk sugar.

    • Disaccharides:

    • Sucrose: Commonly known as table sugar.

    • Lactose: Sugar found in milk.

    • Maltose: Present in malt, beer, and sprouted grains.

    • Polysaccharides:

    • Starch: Found in grains, potatoes, and legumes.

    • Glycogen: The storage form of carbohydrates in animals; not a food source.

    • Fiber: Found in fruits, vegetables, whole grains, and legumes.

  • Digestive Process

    • Mouth: Salivary amylase begins to break down starch into maltose.

    • Stomach: The acid environment inactivates salivary amylase.

    • Small Intestine:

    • Pancreatic amylase continues to break down starch into maltose.

    • Brush border enzymes (maltase, lactase, sucrase) further break disaccharides into monosaccharides.

    • Absorption: Monosaccharides are absorbed into the bloodstream and transported to the liver.

  • Recommended Intake (AMDR)

    • Percentage of Total Daily Calories: 45–65% should come from carbohydrates.

  • Fiber

    • Soluble Fiber:

    • Characteristics: Dissolves in water, forms a gel-like substance, slows digestion, lowers cholesterol, and regulates blood glucose levels.

    • Sources: Oats, beans, apples.

    • Insoluble Fiber:

    • Characteristics: Adds bulk to the diet, speeds up stool movement, helps prevent constipation.

    • Sources: Whole grains, vegetables, nuts.

  • Blood Glucose Regulation

    • Insulin: Produced by the pancreas, lowers blood sugar levels by facilitating glucose entry into cells.

    • Glucagon: Also produced by the pancreas, raises blood sugar levels by stimulating the breakdown of glycogen in the liver.

  • Types of Diabetes

    • Type 1 Diabetes: An autoimmune condition where no insulin is produced; requires insulin injections for control.

    • Type 2 Diabetes: Characterized by insulin resistance, often linked to obesity and lifestyle choices; can be managed through diet, medications, and insulin if necessary.

    • Gestational Diabetes: Develops during pregnancy and increases the risk of developing type 2 diabetes later in life.

  • Major Sources of Sugar in U.S. Diet

    • Common sources include sweetened beverages, desserts, candy, cereals, and processed foods.

  • Food Labels & Fiber

    • Recommendations: Look for products containing ≥ 3g of fiber per serving; ingredients should include terms like "whole grain," oats, bran, and beans.

  • Sweeteners

    • Nutritive Sweeteners: Examples include sucrose, honey, high fructose corn syrup (HFCS), and sugar alcohols.

    • Nonnutritive Sweeteners: Examples include aspartame, sucralose, stevia, and saccharin.

  • Disorders of Carbohydrate Metabolism

    • Lactose Intolerance: Difficulty digesting lactose leading to gastrointestinal discomfort.

    • Hypoglycemia: Low blood sugar levels which can cause symptoms like dizziness and weakness.

    • Diabetes Complications: Long-term conditions such as neuropathy, kidney disease, and cardiovascular disease (CVD) related to uncontrolled diabetes.

Chapter 5 – Lipids

  • Types of Lipids

    • Triglycerides: The most common type of fat in the body.

    • Phospholipids: Essential for cell membrane structure.

    • Sterols: Includes cholesterol, which is vital for hormone production and cell membrane integrity.

  • Structures of Fats

    • Saturated Fats:

    • Structure: No double bonds between carbon atoms.

    • Physical State: Solid at room temperature (e.g., butter, lard).

    • Unsaturated Fats:

    • Structure: One or more double bonds present.

    • Physical States:

      • Monounsaturated Fats: Examples include olive oil and avocados.

      • Polyunsaturated Fats: Includes omega-3 and omega-6 fatty acids.

    • Impact of Double Bonds: Create “kinks” in the fatty acid chains, which make them liquid at room temperature.

  • Food Sources of Fats

    • Saturated Fat Sources: Red meat, butter, cheese.

    • Unsaturated Fat Sources: Nuts, seeds, olive oil, canola oil.

    • Omega-3 Sources: Salmon, flaxseeds, walnuts.

    • Omega-6 Sources: Found in various vegetable oils and nuts.

    • Trans Fats: Artificially created through hydrogenation; found in partially hydrogenated oils.

  • Digestion & Absorption

    • Mouth/Stomach: Enzymes called lipases initiate the breakdown of fats.

    • Small Intestine:

    • Bile is secreted to emulsify fats making them easier to digest.

    • Pancreatic lipase breaks down triglycerides into monoglycerides and free fatty acids.

    • These products form micelles which are absorbed into cells, reassembled into triglycerides and packed into chylomicrons, then released into the lymphatic system and eventually into the bloodstream.

  • Functions of Lipids

    • Important roles include:

    • Energy storage

    • Providing insulation

    • Forming cell membranes

    • Assisting in absorption of fat-soluble vitamins

    • Serving as precursors for hormones.

  • Health Effects of Lipids

    • Lipoproteins:

    • LDL (Low-Density Lipoprotein): Often referred to as “bad” cholesterol; associated with increased risk of cardiovascular disease (CVD).

    • HDL (High-Density Lipoprotein): Known as “good” cholesterol; helps remove cholesterol from arteries.

    • Health Risks of Fats:

    • Saturated and trans fats increase the risk of developing CVD.

  • Essential Fatty Acids

    • Omega-3 Fatty Acids (linolenic acid): Known for their anti-inflammatory properties and benefits for heart health.

    • Omega-6 Fatty Acids (linoleic acid): Important for clotting and growth functions in the body.

  • Visible vs Invisible Fats

    • Visible Fats: Clearly visible fats such as cooking oils, butter, and fat present in meat.

    • Invisible Fats: Found in baked goods, dairy products, and nuts; not readily apparent.

  • Lipoproteins Overview

    • Types:

    • Chylomicrons: Carries dietary triglycerides from intestines to tissues.

    • VLDL (Very-Low-Density Lipoprotein): Transports triglycerides synthesized by the liver to tissues.

    • LDL: Delivers cholesterol to tissues throughout the body.

    • HDL: Transports cholesterol back to the liver for excretion or recycling.

  • Improving Fat Quality

    • Recommendations include replacing saturated and trans fats with unsaturated fats.

    • Incorporate sources of omega-3 fatty acids like fish, and sources of unsaturated fats such as nuts, seeds, and olive oil into the diet.

Chapter 6 – Proteins

  • Structure of Amino Acids & Bonds

    • Components of Amino Acids: Each amino acid consists of an amino group (NH2), a carboxyl group (COOH), and a unique side chain (R group).

    • Peptide Bonds: Amino acids are linked together through peptide bonds formed between the carboxyl group of one amino acid and the amino group of another.

  • DNA & Protein Synthesis

    • Process Overview:

    • DNA is transcribed into messenger RNA (mRNA) in the nucleus (transcription).

    • mRNA travels to the ribosome where it is translated into a polypeptide chain (translation); this chain then folds into a functional protein.

  • Levels of Protein Structure

    • Primary Structure: The linear sequence of amino acids in a polypeptide chain.

    • Secondary Structure: Coiling or folding of the polypeptide chain, stabilized by hydrogen bonds.

    • Tertiary Structure: The overall three-dimensional shape formed by the interaction between side chains.

    • Quaternary Structure: Structure formed when multiple polypeptide chains aggregate.

  • Protein Quality

    • Determined by the amino acid profile (essential vs. non-essential amino acids) and the digestibility of the protein source.

  • Complete vs Incomplete Proteins

    • Complete Proteins: Contain all essential amino acids (e.g., meat, eggs, soy, quinoa).

    • Incomplete Proteins: Lack one or more essential amino acids (e.g., beans, rice, nuts).

    • Complementary Proteins: Pairing of two or more incomplete proteins to make a complete protein profile (e.g., beans and rice).

  • High- vs Low-Quality Proteins

    • High-Quality Proteins: Typically found in animal sources as well as soy and quinoa.

    • Low-Quality Proteins: Generally derived from certain plant sources.

  • Deamination vs Transamination

    • Deamination: The process of removing an amino group from an amino acid or peptide.

    • Transamination: The transfer of an amino group from one amino acid to a keto acid.

  • Protein Digestion

    • Stomach: Hydrochloric acid (HCl) denatures the proteins, and pepsin breaks the proteins into peptides.

    • Small Intestine: Pancreatic enzymes continue the digestion and break down peptides into free amino acids, which are then absorbed into the bloodstream and sent to the liver.

  • Protein in the American Diet

    • Findings indicate that most individuals consume more protein than necessary.

    • An excessively high protein intake may pose risks such as kidney stress.

  • Protein Denaturation

    • Denaturation refers to the disruption of a protein's structure caused by factors like heat, acid, alcohol, or mechanical action.

  • Calculating Protein Needs

    • Recommended Dietary Allowance (RDA): General guideline set at 0.8 grams of protein per kilogram of body weight.

  • Types of Vegetarians

    • Lacto-Ovo Vegetarians: Consume dairy products and eggs.

    • Lacto Vegetarians: Consume dairy products but not eggs.

    • Ovo Vegetarians: Consume eggs but not dairy.

    • Vegans: Exclude all animal products.

    • Pescatarians: Exclude meat but include fish.

  • Nutrient Concerns for Vegetarians/Vegans

    • Potential deficiencies in Vitamin B12, iron, calcium, zinc, omega-3 fatty acids, and Vitamin D.

  • Protein-Energy Malnutrition

    • Marasmus: A severe form of malnutrition characterized by both calorie and protein deficiency leading to muscle wasting and weakness.

    • Kwashiorkor: A condition resulting from protein deficiency despite adequate caloric intake, leading to symptoms such as edema and fatty liver.