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Chapter 38
Nutrition
Fundamentals of Nursing: Standards & Practices, 2E
Copyright 2002 by Delmar, a division of Thomson Learning 38-2
Physiology of Nutrition
Nutrition is the process by which the body metabolizes and utilizes nutrients.
Nutrients are classified as energy nutrients, organic nutrients, and inorganic nutrients.
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Energy nutrients release energy for maintenance of homeostasis.
Organic nutrients build and maintain body tissues and regulate body processes.
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Inorganic nutrients provide a medium for chemical reactions, transporting materials, maintaining body temperature, promoting bone formation, and conducting nerve impulses.
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Digestion• The mechanical and chemical process
that converts nutrients into a physically absorbed state is digestion.
• Mastication is the chewing, tearing, or grinding of food by the teeth into fine particles and then mixing with enzymes in saliva.
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• Deglutition is the swallowing of food.• Peristalsis is the coordinated,
rhythmic, serial contraction of the smooth muscle lining of the intestines.
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Absorption• The process by which the end products
of digestion(monosaccharides (simple sugars), amino acids, glycerol, fatty acid chains, vitamins, minerals, and water) pass through the epithelial membranes in the small and large intestines into the blood or lymph systems is known as absorption.
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• The part of the food that body enzymes cannot digest and absorb is known as dietary fiber.
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Metabolism• Metabolism is the aggregate of all
chemical reactions and process in every body cell, such as growth, generation of energy, elimination of wastes, and other bodily functions as they relate to the distribution of nutrients in the blood after digestion.
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• The breakdown of glucose by enzymes located inside the cell’s cytoplasm is known as glycolysis.
Energy• The rate of heart liberation during
chemical reactions is known as metabolic rate.
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• Calories are used to express the quantity of energy released from different foods or expended by different functional processes of the body.
• Basal metabolic rate (BMR) refers to the energy needed to maintain essential physiological functions.
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Excretion• Excretory organs are the kidneys,
sweat glands, skin, and lungs.• Digestive and metabolic waste
products are excreted through the intestines and rectum.
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Nutrients
Water• Water is the most abundant nutrient in
the body and accounts for 60% to 70% of an adult’s total body weight and 77% of an infant’s weight.
• Water and electrolytes are substances that must be acquired from the diet.
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• The body maintains a balance between the amount of fluid taken in and the amount excreted.
Vitamins• Organic compounds that are needed in
small quantities for operation of normal bodily metabolism and that cannot be manufactured in the cells of the body are vitamins.
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• Fat-soluble vitamins require the presence of fats for their absorption from the GI tract, and for cellular metabolism.
• Water-soluble vitamins require daily ingestion because they are not stored in the body.
• Review Table 38-1 Fat-Soluble and Water-Soluble Vitamins.
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Minerals• Minerals serve as catalysts in
biochemical reactions.• Minerals are classified according to
their daily requirement: macrominerals (quantities of 100mg or greater) and microminerals (trace elements, quantities less than 100 mg).
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Carbohydrates• Organic compounds composed of
carbon, hydrogen, and oxygen are known as carbohydrates.
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• Carbohydrates are classified according to the number of saccharides (sugar units). Monosaccharides (simple sugars)
include glucose, galactose, and fructose. Disaccharides (double sugars) include
sucrose, lactose, and maltose. Polysaccharides (complex sugars)
include glycogen, cellulose (fiber), and starch.
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• Glucose provides the major source of energy needed for cellular activity.
• Triglycerides and proteins are metabolized to produce energy when dietary intake is below minimum requirements.
• Three major sources of dietary carbohydrates are starches, lactose, and sucrose.
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• Insulin aids in the diffusion of glucose into the liver and muscle cells and in the synthesis of gylcogen.
• Hyperglycemia is caused by an increase in blood glucose levels.
• Hypoglycemia is caused by blood glucose levels that are below normal.
• Review Table 38-2 Normal Function and Deficiencies of Selected Nutrients.
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Proteins• Organic Compounds that contain carbon,
hydrogen, oxygen, and nitrogen atoms are known as proteins. End product of digestion are amino acids. Nonessential amino acids can be
synthesized in the cells. Essential amino acids must be ingested in
the diet because they cannot be synthesized in the body.
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• Proteins are also classified as complete or incomplete. High-biological-value proteins
(complete proteins) contain all the essential amino acids.
Low-biological-value proteins (incomplete proteins) lack one or more essential amino acids.
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• Deamination begins the process of degradation of amino acids. Gluconeogenesis, the conversion of
amino acids into glucose or glycogen. Ketogenesis, the conversion of amino
acids into keto acids or fatty acids. Nitrogen balance, the net result of intake
and loss of nitrogen that measures protein anabolism and catabolism.
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Positive nitrogen balance, the condition that exists when nitrogen intake exceeds output (protein anabolism exceeds anabolism).
Negative nitrogen balance, the condition that exists when nitrogen output exceeds intake (protein catabolism exceeds anabolism).
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Obligatory loss of proteins, the degrading of the body’s own proteins into amino acids, which are then deaminated and oxidized (occurs when a person fails to ingest adequate amounts of proteins).
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Lipids• Lipids (fats) are organic compounds
that are insoluble in water but soluble in organic solvents, such as ether and alcohol.
• Fatty acids are the basic structural unit of most lipids.
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• Saturated fatty acids form fats, glycerol esters of organic acids whose carbon atoms are joined by single bonds.
• Unsaturated fatty acids form glycerol esters of organic acids whose carbon atoms are joined by double or triple bonds.
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• Monounsaturated fatty acids are fatty acids that form esters with one double or triple bond.
• Polyunsaturated fatty acids form esters that have many carbons unbonded to hydrogen atoms.
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The most popular lipids• Triglycerides are lipid compounds
composed of three fatty acid cells attached to a glycerol molecule.
• Phospholipids are composed of one or more fatty acid molecules and one phosphoric acid radical, and usually contain a nitrogenous base.
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• Cholesterol is considered a fat and is found in whole milk and egg yolk.
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Promoting Proper Nutrition
Dietary Reference Intakes and Recommended Daily Allowances
The Food Guide Pyramid
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Weight Management
Societal ConcernsOverweight is an energy imbalance
in which more food is consumed than needed.
Underweight is when more calories are expended than consumed.
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• Anorexia nervosa (self-starvation) disrupts metabolism because of inadequate calorie intake.
• Bulimia nervosa refers to food-gorging binges followed by purging of food.
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Factors Affecting Nutrition
AgeLifestyleEthnicity, Culture, and Religious
PracticesOther Factors
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Assessment
Nutritional History• 24-Hour Recall• Food-Frequency Questionnaire• Food Record• Diet History• Review Table 38-3 on health history
related to nutrition and metabolism.
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Physical Examination• Intake and Output (I&O)• Anthropometric Measurements• Review Table 38-4 on adult physical
assessment findings: nutrient balance• Review Table 38-5 on adult growth
chart
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Diagnostic and Laboratory Data• Protein Indices• Hemoglobin Level• Total Lymphocyte Count• Nitrogen Balance• Urine Creatinine Excretion
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Nursing Diagnosis
Imbalanced Nutrition: Less Than Body Requirements
Imbalanced Nutrition: More Than Body Requirements or Risk for More Than Body Requirements
Other Nursing Diagnoses
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Outcome Identification and Planning
Planning focuses on promoting optimal nutritional care.
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Implementation
Monitoring Weight and IntakeInitiating Diet TherapyAssistance with FeedingProviding Nutrition SupportProviding Enteral Nutrition
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Review Procedure 38-1 on inserting a nasograstric or nasointestinal tube for suction and enteral feedings.
Review Procedure 38-2 on administering enteral tube feedings.
Providing Parenteral NutritionAdministering Medication through a
Feeding Tube
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Evaluation
Use current data to measure achievement of goals and outcomes.
