Memmler’s The Human Body in Health and Disease 11th edition Chapter 20 Metabolism, Nutrition and Body Temperature Memmler’s The Human Body in Health and Disease 11th edition

Metabolism *Remember: All of the life-sustaining reaction that occur within the body systems (energy is generated and used) Two categories Catabolism Breakdown complex compounds into simpler compounds (digestion) Anabolism Building simple compounds into needed substances (building of bones)

Cellular Respiration Energy released from nutrients in a series of reactions Occurs in mitochondria Anaerobic and aerobic phases

The Anaerobic Phase The Aerobic Phase Occurs in mitochondria Occurs in cytoplasm Yields 2 ATP molecules per glucose molecule Product is pyruvic acid The Aerobic Phase Occurs in mitochondria Yields 34-36 ATP molecules per glucose molecule Product is carbon dioxide and water

Metabolic Rate Rate at which energy is released from nutrients in cells Decreases with age Measured in kilocalories (kcal) We need to maintain this to continue the basic life functions (homeostasis)

The Use of Nutrients for Energy Glucose is main source of energy Reserves stored in liver and muscle cells as glycogen We get this mainly from carbohydrates Other energy sources Glycerol and Fatty acids (from fat digestion) Amino Acids (from protein digestion) * Before proteins can be used for energy, they must have nitrogen removed from them. The removal is done in the liver and the kidneys excrete them.

Anabolism (nutrients built this way) Reactions catalyzed by enzymes! There are 20 amino acids (Building blocks of protein) Nonessential amino acids - 11 can be synthesized in body Essential amino acids Nine of 20 must be eaten Essential fatty acids Linoleic acid and linolenic acid (obtained in diet)

Minerals and Vitamins Minerals are chemical elements (some are parts of vitamins) Body structure pg. 437-438 – Table 20-3 Fluid balance and Table 20-4 Muscle contraction Nerve impulse conduction Blood clotting Vitamins are complex substances (parts of enzymes) Water soluble – must be taken in Fat soluble – kept in reserve in fatty tissue Antioxidants Stabilize free radicals (unstable molecules that lead to aging and disease)

Nutritional Guidelines Percentage of calories in daily diet Carbohydrate: 55 – 50% Fat: 30% or less Protein: 15 – 20%

Carbohydrates - Diet should be mainly complex, naturally occurring (- grains, legumes, potatoes) Normal blood glucose range 85 to 125 mg/dL Glycemic effect measures how rapidly food raises blood glucose level, stimulates release of insulin (very important in teaching diabetics) - grains, legumes, potatoes, fruit

Fats Saturated Most are from animal sources Solid at room temperature Associated with heart disease and cancer) (should make up less than 10% of fat intake) Unsaturated Derived from plants Liquid at room temperature

Proteins Not stored in body (should be taken in all the time) Most animal proteins supply all essential amino acids Most vegetable proteins lack one or more essential amino acids (so, vegans need to combine foods)

Vitamin and Mineral Supplements Supplements are controversial Some populations may benefit Some vitamins cause toxic effects when taken in excess (- This is important for your patient teaching)

Alcohol Not a nutrient Interferes with metabolism and contributes to a variety of disorders Should be consumed in moderation Advise pregnant women against alcohol consumption

Nutritional Disorders - Diet related disorders result from: Excess of nutrients Shortage of nutrients - Issues now that are important to know: Weight control Food allergies (teach patients about common allergens)

Food Allergies Allergens can be food or food additives Allergic reactions involve Skin Respiratory tract Gastrointestinal tract Reactions can develop anytime and can be fatal

Malnutrition - Can occur from missing nutrients or too much of wrong Foods If any vital nutrient is missing from the diet, malnutrition will occur Watch for in elderly population (important for healing process)

Overweight and Obesity Causes are complex Incidence is increasing Shortens life span Measured by body mass index (BMI) Overweight is BMI of 25 – 30 Obese is BMI greater than 30

Underweight Low reserves of energy Reproductive disturbances Nutritional deficiencies BMI less than 18.5

Nutrition and Aging Nutritional deficiencies may develop Medications may interfere with appetite and absorption

Body Temperature Heat is byproduct of chemical activities in body tissues Regulatory devices keep body temperature constant within narrow limits Homeostasis !!

Heat Production Amount of heat produced by organs affected by Exercise Hormone production Food intake Age

Heat Loss More than 80% of heat loss occurs through skin Conduction Radiation Convection Evaporation 15-20% heat loss through respiration and elimination Heat loss prevention Clothing Fat layer under skin *** children lose heat more rapidly

Temperature Regulation Body has internal mechanisms for regulating temperature - hypothalamus

The Role of the Hypothalamus Regulation of Heat loss (protective mechanism) Constrict skin blood vessels Shiver Increase cell metabolism Overheating Stimulate sweat glands Dilate skin blood vessels Muscle relaxation

Age Factors Newborns and elderly Reduced ability to produce heat Reduced ability to regulate overheating

Normal Body Temperature Normal range is 36.3ºC to 37.6ºC (97.8ºF to 100.8ºF) Varies with time of day Varies by body part : - axilla is lower than oral & rectal is higher than oral

Fever Higher than normal body temperature (febrile – with fever) Causes Infection Malignancies Brain injuries Toxic reactions Vaccine reactions Central nervous system diseases Drugs that reduce fever are antipyretics Febrile seizures – most occur due to a sudden spike in temperature; can be CNS related

Responses to Excessive Heat Heat cramps Localized muscle cramping Heat exhaustion Heat retention and fluid loss Heat stroke Medical emergency that can be fatal

Responses to Excessive Cold Hypothermia Excessively low body temperature Used in some types of surgery Frostbite Can cause permanent local tissue damage Likely areas are face, ears, extremities

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