Nutrition Chapter 24 Flashcards

Nutrients Overview

• Essential nutrients must be obtained through diet; the body cannot synthesize them.
• Nonessential nutrients can be made by the body from other nutrients.

Macronutrients vs Micronutrients

• Macronutrients are required in large amounts and provide energy: includes carbohydrates, proteins, fats, and water.
• Micronutrients are needed in small amounts: includes vitamins and minerals, crucial for detoxification and disease prevention.

Energy Content of Macronutrients

• Carbohydrates provide 4 calories/gram.
• Proteins provide 4 calories/gram.
• Fats provide 9 calories/gram.

Carbohydrates

• Glucose is the primary carbohydrate utilized for ATP production.
• Glycogen is the storage form of glucose; excess glucose converts to fat when glycogen stores are full.

Sweeteners and Absorption

• Fructose and galactose are converted to energy after absorption; glucose requires sodium ions for transport.

Lipids

• Essential for energy, absorption of fat-soluble vitamins, and structural components of membranes.
• Major storage form of fat is triglyceride, made of glycerol and three fatty acids.
• Saturated fats: solid at room temperature, no double bonds.
• Unsaturated fats: liquid at room temperature, contains double bonds.

Lipoproteins

• Chylomicrons transport dietary fats from intestines.
• Very low-density lipoproteins (VLDL) transport triglycerides from the liver.
• Low-density lipoproteins (LDL) deliver cholesterol to tissues.
• High-density lipoproteins (HDL) carry excess cholesterol back to the liver.

Cholesterol

• Required for bile salts, steroid hormones, and vitamin D, and is a component of cell membranes.
• 85% of blood cholesterol is synthesized by the liver, only 15% comes from diet.
• Dietary saturated fats increase cholesterol synthesis; unsaturated fats aid in cholesterol excretion.

Amino Acids and Proteins

• Essential amino acids cannot be synthesized by the body and must be included in the diet.
• Complete proteins contain all essential amino acids; sources include eggs, milk, fish, and most meats.

Protein Energy Utilization

• Amino acids are either used to build proteins or converted to glucose or fat for energy.
• Protein is used as an energy source primarily under starvation conditions.

Nitrogen Balance

• Positive nitrogen balance occurs when protein retention exceeds breakdown, typical in growth or recovery.
• Negative nitrogen balance indicates higher protein breakdown than synthesis, common during stress or inadequate intake.

Vitamins

• Fat-soluble vitamins (A, D, E, K) are absorbed with lipids; excess can lead to toxicity.
• Water-soluble vitamins are easily excreted; toxicity is rare.
• Important for energy metabolism—vitamins B3 (NAD) and B2 (FAD) are crucial coenzymes.

Minerals

• Comprise 4% of body weight, add strength to structures, and function as ions in cells and blood.

Metabolic Stages

• Stage One: Digestion in the gastrointestinal tract and nutrient absorption.
• Stage Two: Anabolism occurs, building macromolecules from nutrients.
• Stage Three: Oxidation in mitochondria produces ATP, water, and carbon dioxide.

Cellular Respiration

• A series of metabolic processes converting energy from nutrients into ATP.

Redox and Oxidation Reactions

• Redox reactions involve electron transfer; oxidants gain electrons, reductants lose them.
• Oxidation involves gain of oxygen or loss of hydrogen.