exam 2
Q: What are the two main types of carbohydrates?
A:
Simple carbohydrates (sugars): monosaccharides (glucose, fructose, galactose) and disaccharides (sucrose, lactose, maltose).
Complex carbohydrates: polysaccharides (starch, glycogen, fiber).
Q: How do their structures differ?
A: Simple carbs have 1–2 sugar units; complex carbs are long chains of sugar units linked together.
Q: Give food examples of each:
A:
Simple: fruit, honey, table sugar, milk.
Complex: grains, legumes, potatoes, vegetables.
Q: What are the 3 main polysaccharides and their roles?
A:
Starch: storage form of glucose in plants (grains, roots).
Glycogen: storage form of glucose in animals; stored in liver & muscle.
Fiber: structural part of plants; not digested by human enzymes.
Q: What are the two types of fiber and how do they differ?
A:
Soluble fiber: dissolves in water, forms gels, slows digestion, helps lower blood cholesterol and glucose (found in oats, apples, beans).
Insoluble fiber: does not dissolve in water, adds bulk to stool, speeds passage through the colon (found in whole grains, vegetables, bran).
Q: Health benefits of fiber?
A: Improves digestion, lowers cholesterol, controls blood glucose, promotes fullness, reduces constipation, lowers risk of heart disease, diabetes, colon cancer.
Q: Where does carbohydrate digestion begin?
A: In the mouth with salivary amylase breaking starch into maltose.
Q: What happens in the small intestine?
A:
Pancreatic amylase breaks starch into maltose.
Maltase, sucrase, lactase (from intestinal cells) break disaccharides into monosaccharides (glucose, fructose, galactose).
Q: Final product of carbohydrate digestion?
A: Monosaccharides (mainly glucose).
Q: How are they absorbed and transported?
A: Absorbed by intestinal cells → travel through the bloodstream → liver (via portal vein) → converted to glucose → distributed to body cells for energy or storage.
Q: What happens to fiber in digestion?
A: Mostly passes undigested to the large intestine where it’s fermented by gut bacteria, producing short-chain fatty acids and gas.
Q: What hormones regulate blood glucose?
A:
Insulin (from pancreas β-cells): lowers blood glucose by helping cells absorb glucose.
Glucagon (from pancreas α-cells): raises blood glucose by signaling liver to release stored glycogen as glucose.
Q: Describe Type 1 Diabetes.
A:
Pancreas does not produce insulin.
Autoimmune destruction of β-cells.
Usually develops in youth.
Treated with insulin injections and careful diet.
Q: Describe Type 2 Diabetes.
A:
Body cells become resistant to insulin.
Pancreas may still make insulin but not enough.
Linked to obesity, poor diet, inactivity, genetics.
Managed with diet, exercise, sometimes medication.
Q: Factors that lower Type 2 Diabetes risk?
A: Healthy weight, balanced diet, physical activity, limiting added sugars, not smoking.
Q: Long-term complications of poorly managed diabetes?
A: Heart disease, nerve damage, kidney failure, blindness, poor wound healing.
Q: What is hyperglycemia?
A: High blood glucose; occurs when insulin is insufficient or ineffective.
Q: What is hypoglycemia?
A: Low blood glucose; occurs from too much insulin, skipping meals, or excessive exercise.
Treatment: Eat or drink a fast-absorbing carb (juice, glucose tablets).
Q: Health risks of too much sugar?
A: Weight gain, tooth decay, increased triglycerides, insulin resistance, higher risk of diabetes and heart disease.
Q: Health benefits of high-fiber diets?
A: Reduced risk of heart disease, type 2 diabetes, constipation, colon cancer; helps with weight management.
Q: Whole grains vs. refined grains?
A:
Whole grains: contain bran, germ, and endosperm (fiber & nutrients intact).
Refined grains: only endosperm (fiber, vitamins, and minerals removed).
Examples: Whole wheat, oats, quinoa, brown rice.
Q: Dietary recommendations for carbs and grains?
A:
Carbs: 45–65% of total daily calories.
Whole grains: at least half your daily grains should be whole.
Q: What factors affect the chemistry and characteristics of fatty acids?
A:
Carbon chain length (short, medium, long).
Type of bond between carbons (single or double bonds).
These determine whether a fat is solid or liquid at room temperature and how it affects health.
Q: What are the three main types of fatty acids?
A:
Saturated fatty acids – no double bonds; solid at room temp (e.g., butter, meat fat).
Monounsaturated fatty acids (MUFA) – one double bond; liquid at room temp (e.g., olive oil, avocado).
Polyunsaturated fatty acids (PUFA) – two or more double bonds; liquid (e.g., nuts, seeds, fish oils).
Q: What are cis and trans bonds?
A:
Cis: hydrogens on the same side of the double bond — bends chain, natural form, healthier.
Trans: hydrogens on opposite sides — straightens chain, acts like saturated fat, unhealthy.
Q: What are trans fatty acids and how are they formed?
A: Artificially made during hydrogenation (adding hydrogen to unsaturated fats to make them solid).
Effects: Raise LDL (“bad” cholesterol), lower HDL (“good” cholesterol), increase heart disease risk.
Sources: Margarine, fried foods, baked goods.
Q: What are essential fatty acids (EFAs)?
A:
Omega-3 (alpha-linolenic acid) and Omega-6 (linoleic acid) — must be obtained from food.
Found in fish, flaxseed, walnuts (omega-3); vegetable oils, nuts (omega-6).
Support heart and brain health, reduce inflammation, help with cell membrane structure.
Q: What are the three classes of lipids?
A:
Triglycerides (most common in food and body).
Phospholipids.
Sterols (including cholesterol).
Q: What are triglycerides made of and what are their functions?
A: 1 glycerol + 3 fatty acids.
Functions: Main form of stored energy, insulation, protection, energy source.
Q: What are phospholipids and what do they do?
A: Made of glycerol, 2 fatty acids, and a phosphate group.
Functions: Form cell membranes; act as emulsifiers (e.g., lecithin in egg yolks).
Q: How are sterols different?
A: Have a ring structure (not chain-like).
Cholesterol is a sterol used to make hormones, bile, and vitamin D.
Q: Where is cholesterol made and found?
A: Made by the liver and found in animal products (meat, eggs, dairy).
Q: How do plant sterols affect health?
A: They block cholesterol absorption in the intestine, helping lower blood cholesterol levels.
Q: Where does fat digestion begin?
A: Slightly in the mouth (lingual lipase) and stomach (gastric lipase), but mainly in the small intestine.
Q: What helps emulsify fat in the small intestine?
A: Bile, produced by the liver and stored in the gallbladder, breaks large fat globules into smaller droplets.
Q: What enzymes break down fats?
A: Pancreatic lipase – breaks triglycerides into monoglycerides, glycerol, and fatty acids.
Q: What are the final products of lipid digestion?
A: Glycerol, monoglycerides, and free fatty acids.
Q: How are lipids absorbed and transported?
A:
Small lipids (short-chain) → directly into bloodstream.
Large lipids (long-chain, cholesterol) → packaged into chylomicrons → enter lymphatic system → bloodstream.
Q: What happens inside the intestinal cell?
A: Lipids are reassembled into triglycerides and combined with proteins to form lipoproteins for transport.
Q: What are the four main types of lipoproteins?
A:
Chylomicrons: Carry dietary fat from intestines → body tissues.
VLDL (Very Low-Density Lipoprotein): Deliver triglycerides made in liver → tissues.
LDL (Low-Density Lipoprotein): Deliver cholesterol → body cells (bad when in excess).
HDL (High-Density Lipoprotein): Carry cholesterol from body → liver for removal (protective).
Q: Why is LDL considered “bad”?
A: High LDL deposits cholesterol in arteries → plaque buildup → atherosclerosis.
Q: Why is HDL considered “good”?
A: It removes excess cholesterol from the bloodstream and carries it to the liver for excretion.
Q: What is the #1 cause of death in U.S. men and women?
A: Cardiovascular disease (CVD).
Q: What leads to atherosclerosis (artery plaque buildup)?
A: High LDL, high blood pressure, smoking, diabetes, inflammation, and high saturated/trans fat intake.
Q: What are major risk factors for CVD?
A: High LDL, low HDL, high blood pressure, smoking, obesity, inactivity, diabetes, family history, diet high in trans/saturated fat.
Q: How can you lower LDL or raise HDL?
A:
Lower saturated & trans fat intake.
Increase fiber and omega-3 fats.
Exercise regularly.
Maintain healthy weight.
Quit smoking.
Q: How do trans fats affect heart disease risk?
A: They raise LDL and lower HDL → increase plaque buildup and heart disease risk.
Q: Dietary fat recommendations?
A:
Total fat: 20–35% of total calories.
Saturated fat: <10% of total calories.
Trans fat: as little as possible.
Q: What atoms make up amino acids?
A: Carbon (C), hydrogen (H), oxygen (O), and nitrogen (N).
Q: What makes amino acids unique compared to carbs and fats?
A: Proteins contain nitrogen, while carbs and fats do not.
Q: How many amino acids are essential for adults?
A: 9 essential amino acids (must come from food).
11 nonessential amino acids can be made by the body.
Q: What are proteins made of?
A: Long chains of amino acids joined by peptide bonds (polypeptides).
Q: What type of reaction forms peptide bonds?
A: Condensation (water is released).
Hydrolysis breaks bonds (water is added).
Q: What are the four levels of protein structure?
A:
Primary: Amino acid sequence.
Secondary: Coils/folds (α-helix, β-sheet).
Tertiary: 3D shape due to side chain interactions.
Quaternary: Two or more polypeptide chains joined together (e.g., hemoglobin).
Q: What is denaturation?
A: The unfolding of proteins, losing structure and function.
Caused by: Heat, acid, alcohol, heavy metals (e.g., cooking eggs).
Q: List major functions of proteins in the body:**
A:
Structural: Build muscle, skin, hair (collagen, keratin).
Enzymes: Speed up chemical reactions.
Hormones: Regulate body processes (insulin).
Immune system: Make antibodies.
Transport: Carry substances (hemoglobin, lipoproteins).
Fluid balance: Maintain proper water distribution.
Acid-base balance: Act as buffers to stabilize pH.
Energy: Used for energy when carbs/fats are low.
Q: Where does protein digestion begin?
A: In the stomach.
Q: What has to happen first before digestion starts?
A: Denaturation by stomach acid (HCl) unfolds proteins.
Q: What enzymes digest protein?
A:
Pepsin (stomach): Breaks large proteins into smaller peptides.
Trypsin & chymotrypsin (pancreas → small intestine): Split peptides into smaller chains.
Peptidases (intestinal enzymes): Split dipeptides and tripeptides into single amino acids.
Q: What hormones aid protein digestion?
A:
Gastrin: Triggers HCl and pepsin release in stomach.
Secretin & CCK: Stimulate pancreatic enzyme release into small intestine.
Q: What are the final products of protein digestion?
A: Individual amino acids (plus some di- and tripeptides).
Q: How are amino acids absorbed and transported?
A: Absorbed into intestinal cells (enterocytes) → travel via bloodstream → liver → distributed to body cells.
Q: What are the main fates of amino acids once absorbed?
A:
Build body proteins (enzymes, hormones, collagen, transporters, antibodies).
Used for energy or glucose if needed.
Converted to fat if intake exceeds need.
Q: How does the body excrete nitrogen?
A:
Deamination: Nitrogen removed from amino acid.
Forms ammonia (NH₃) → converted to urea in the liver.
Urea enters bloodstream → filtered by kidneys → excreted in urine.
Q: What % of daily calories should come from protein?
A: 10–35% of total calories per day.
Q: What’s the difference between high- and low-quality proteins?
A:
High-quality: Contain all 9 essential amino acids (animal foods, soy, quinoa).
Low-quality: Missing or low in one or more essential amino acids (plant sources).
Q: What are complementary proteins?
A: Two or more incomplete plant proteins combined to make a complete one.
Examples: Rice + beans, peanut butter + whole-grain bread.
Q: Basics of vegetarian/vegan diets:**
A:
Vegetarian: Avoid meat, may include dairy or eggs.
Vegan: Avoid all animal products.
Important nutrients: Protein, B12, iron, zinc, calcium, omega-3.
Q: What is PEM (Protein-Energy Malnutrition)?
A: Deficiency of protein and/or calories.
Conditions:
Marasmus: Severe calorie and protein deficiency → wasting.
Kwashiorkor: Protein deficiency → swelling (edema), fatty liver.
Q: Risks of too much protein?
A: Dehydration, kidney strain, calcium loss, heart disease (if high in animal fat sources).
summary for proteins
Protein: 10–35% total kcal/day
9 essential amino acids
Digestion starts: Stomach
Final product: Amino acids
Nitrogen excreted as: Urea