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Nutrition Nutrient—substance used by the body for growth, maintenance, and repair Nutrition-the study of the effects of substances in food on the body and health Malnutrition- not enough of the right nutrients Starvation-not enough food Calorie- the amount of energy needed to raise one gram of water 1 degree Celsius Use bomb calorimeter Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings Nutrition Hunger- unpleasant feeling from lack of food Satiety- the stomach being full to the point of satisfaction Takes 20 minutes to reach brain Appetite- the desire of food and the pleasure eating provides Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings Nutrition Major nutrients Carbohydrates Lipids Proteins Water Minor nutrients Vitamins Minerals Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings Five Basic Food Groups and Some of Their Major Nutrients Table 14.2 (1 of 2) Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings Five Basic Food Groups and Some of Their Major Nutrients Table 14.2 (2 of 2) Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings USDA Food Guide Pyramid Figure 14.17 Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings Energy sources Carbohydrates (CHO’s) -4 calories Proteins- 4 calories Fats- 9 calories Alcohol- 7 calories Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings Dietary Sources of Major Nutrients Carbohydrates What types of foods are carbohydrates? Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings Dietary Sources of Major Nutrients Carbohydrates Most are derived from plants Exceptions: lactose from milk and small amounts of glycogens from meats Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings Carbohydrates 4 types Monosaccharide Glucose (sugar in blood) & fructose Disaccharide Two sugars hooked together Table sugar and lactose Complex CHO’s or polysaccharides 3 or more Glycogen and starch Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings Carbohydrates Cellulose- Dietary Fiber or Roughage Body can’t break these down and digest them Reduces the rate of colorectal cancer Insoluble Does not dissolve in water Wheat, bran, whole grains, vegetables Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings Carbohydrates Soluble Dissolves in water and forms gel that picks up substances and carries it out of the body Oats, beans, barley Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings Lactose Intolerant Lack the enzyme lactase to digest lactose Symptoms: bloating, gas, cramps, diarrhea Lactaid is OTC product to help break it down Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings Diabetes Mellitus Little or no insulin produced by islet cells on pancreas Insulin is what allows glucose into the cell so it can get energy Two types of Diabetes Insulin-dependent or Juvenile Onset Non-Insulin Dependent or Adult Onset Most common Sometimes controlled by diet Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings Diabetes Mellitus Hyperglycemia High glucose level Hypoglycemia Low blood sugar Brain is starving and can lead to coma Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings Dietary Treatment of Diabetes Achieve and maintain desirable body weight Eat a balanced diet No sugars Eat 3 meals and 3 snacks a day Eat at regular times Regular pattern of exercise to regulate glucose Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings Complications of Diabetes Slow healing of cuts and bruises Kidney problems Blindness Neuropathy More risk of heart disease Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings Dietary Sources of Major Nutrients Lipids Saturated fats from animal products Unsaturated fats from nuts, seeds, and vegetable oils Cholesterol from egg yolk, meats, and milk products Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings Functions of Fat Source of stored energy Protects our organs Body insulation Part of all cell membranes (phospholipids) Needed to make hormones Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings How The Body Uses Fats Needed to digest fat soluble vitamins- A,D,E,K Provides essential nutrients Provides flavor for food Provides satiety Spares protein from use for energy Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings Structures of Fats Triglyceride- glycerol with 3 fatty acids Diglyceride- glycerol with 2 fatty acids Monoglycerol- one fatty acid Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings Saturated Vs. Unsaturated Fats Saturated Solid at room temperature Unsaturated Liquid at room temperature Stores well Becomes rancid easily Fat on meat Vegetable oil Butter Palm and coconut oil Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings Types of Fats Saturated Fats have all of the hydrogen bonds full and are not good for you Polyunsaturated fats won’t help or hurt you Monounsaturated fats will help you Artificial Fats- Olestra Can cause some digestive tract discomfort and should be used sparingly Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings Cholesterol Should be under 200 mg LDL’s – low density lipoproteins and put you at greater risk for arteriosclerosis, blood clots, heart attacks, and strokes HDL’s- high density lipoproteins and are good for you To lower LDL’s Be female Stop smoking and limit caffeine Exercise Increase Omega 3 intake and eat more oatmeal Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings Ketosis When the body starts using protein for energy due to lack of fat Common in athletes that try and lose too much weight Characterized by fruit oder to breath Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings Dietary Sources of Major Nutrients Proteins Complete proteins—contain all essential amino acids Most are from animal products Legumes and beans also have proteins, but are incomplete Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings Proteins Amino acids are the building blocks of proteins 9 essential amino acids that must come from diet because the body can’t make them Nonessential amino acids- body can make Complete proteins- have all essential amino acids Meat, cheese, eggs Incomplete proteins- do not have all essential amino acids Beans, corn, peanut butter Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings Proteins Complimentary Proteins Combine 2 or more incomplete proteins to make a complete protein Bread and peanut butter Recommended protein intake is .8 grams per pound of body weight Kwashiokor- enough calories, but not enough protein Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings Problems Associated With Lack of Protein Can’t make digestive enzymes Can’t make anibodies Some hormones not produced in large enough amounts, like insulin Nerve impulses not sent, apathy Hair color loss Wounds won’t heal Muscle tissue breaks down Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings Vegetarianism Why? Ethics about killing animals Religious beliefs Concern about drugs in meat Concern about cholesterol and saturated fat Expense of meat Some don’t like the taste Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings Types of Vegetarians Vegan- eat only plant foods Have the most nutritional concerns Lacto vegans- will eat dairy products Lacto-ovo-vegans- include dairy and eggs Lacto-ovo-pesco-vegans- include dairy, eggs, and fish Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings Nutritional Concerns of Vegetarian Diets B 12 Only found in animal products Must take supplements Iron Best source is red meat Calcium May need supplements or fortified foods like butter and orange juice Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings Health Advantages of Vegetarian Diets Lower body weight Lower blood cholesterol Lower rates of breast and colon cancer Better digestive health due to higher fiber diet Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings Dietary Sources of Major Nutrients Vitamins Most vitamins are used as coenzymes Found in all major food groups Needed in small quantities Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings Vitamins Fat soluble vitamins (A,D,E,K) can be stored Water soluble vitamins like vitamin C can’t be stored and must continually be supplied Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings Vitamins Folacin or Folic Acid Found in dark green leafy vegetables Deficiency causes aplastic anemia Also important in pregnant women to prevent spina bifida Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings Vitamins Vitamin C Deficiency is called scurvy Stop making collagen Weakened blood vessels Loss of hair Internal bleeding In large doses it may prevent colds Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings Vitamins Vitamin D Increases Calcium absorption Deficiency is called rickets Bones are soft and legs are bowed Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings Vitamins Have an RDA- recommended dietary allowance To preserve vitamin and mineral content Store in cool dark place eat peelings whenever possible Cook in small amounts of water and steam if possible Heat destroys many vitamins and minerals Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings Vitamins Enrichment- replace vitamins that were originally in the food, but may have been loss during processing Fortification- add vitamins and minerals that weren’t originally in the product Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings Dietary Sources of Major Nutrients Minerals Play many roles in the body Most mineral-rich foods are vegetables, legumes, milk, and some meats Many are required for nerve conduction and contraction of muscle fibers Major minerals- need in amounts greater than 100 mg a day Minor minerals- needed only in small amounts Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings Minerals Calcium Needed for bone strength, blood clotting, muscle contraction, and nerve impulse transmission Deficiency causes osteoporosis Found in dairy products and some vegetables Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings Minerals Iron Transport oxygen and carbon dioxide in hemoglobin Deficiency is called anemia Toxicity- can lead to death if overdose Found mainly in red meat If taken with vitamin C it will be absorbed better by the body Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings Minerals Iodine Helps regulate metabolism and determine rate of thyroid Deficiency can lead to a goiter Cretinism- named for the island of Crete Goiter Belt- geographic area where soil is low in iodine We now iodize salt to prevent deficiency Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings Minerals Flouride Reduces tooth decay Toxicity- rust colored stains on teeth Sources: fluoridated water, toothpaste, and mouthwash Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings Water Body is 70-75% water Functions of Water Place for chemical reactions Maintain acid/base balance Nutrient and waste transport Regulation of temperature Lubrication and shock absorbancy Hard water contains high levels of calcium, magnesium, and iron Soft water- minerals replaced with salt Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings Nutrition and the Cancer Patient Many cancer patients lose weight Loss of appetite High energy demands of tumor Nutrition and maintaining weight is very important Those who have not lost weight live twice as long Chemotherapy is more effective if weight can be maintained Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings Diet and Prevention of Cancer Reduce fat to 30% or less to reduce risk of breast and colon cancer Increase fiber Increase vitamin A and C Reduce processed meats Salt-cured, pickled and smoked meats Reduce alcohol Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings Metabolism Chemical reactions necessary to maintain life Catabolism—substances are broken down to simpler substances; energy is released Anabolism—larger molecules are built from smaller ones Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings Carbohydrate Metabolism Carbohydrates are the body’s preferred source to produce cellular energy (ATP) Glucose (blood sugar) is the major breakdown product and fuel to make ATP Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings Cellular Respiration Oxygen-using events take place within the cell to create ATP from ADP Carbon leaves cells as carbon dioxide (CO2) Hydrogen atoms are combined with oxygen to form water Energy produced by these reactions adds a phosphorus to ADP to produce ATP ATP can be broken down to release energy for cellular use Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings Carbohydrate Metabolism Figure 14.18 Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings Metabolic Pathways Involved in Cellular Respiration Glycolysis—energizes a glucose molecule so it can be split into two pyruvic acid molecules and yield ATP Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings Cellular Respiration Chemical energy (high-energy electrons) CO2 CO2 Glycolysis Glucose Cytosol of cell Pyruvic acid Mitochondrion Chemical energy Krebs cycle Electron transport chain and oxidative phosphorylation H2O Mitochondrial cristae Via oxidative phosphorylation ATP ATP ATP Figure 14.19 Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings Cellular Respiration Chemical energy (high-energy electrons) Mitochondrion Glycolysis Glucose Cytosol of cell Pyruvic acid Mitochondrial cristae ATP Figure 14.19, step 1 Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings Cellular Respiration Chemical energy (high-energy electrons) CO2 CO2 Glycolysis Glucose Cytosol of cell ATP Pyruvic acid Mitochondrion Chemical energy Krebs cycle Mitochondrial cristae ATP Figure 14.19, step 2 Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings Cellular Respiration Chemical energy (high-energy electrons) CO2 CO2 Glycolysis Glucose Cytosol of cell Pyruvic acid Mitochondrion Chemical energy Krebs cycle Electron transport chain and oxidative phosphorylation H2O Mitochondrial cristae Via oxidative phosphorylation ATP ATP ATP Figure 14.19, step 3 Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings Metabolic Pathways Involved in Cellular Respiration Krebs cycle Produces virtually all the carbon dioxide and water resulting from cell respiration Yields a small amount of ATP Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings Cellular Respiration Chemical energy (high-energy electrons) CO2 CO2 Glycolysis Glucose Cytosol of cell Pyruvic acid Mitochondrion Chemical energy Krebs cycle Electron transport chain and oxidative phosphorylation H2O Mitochondrial cristae Via oxidative phosphorylation ATP ATP ATP Figure 14.19 Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings Metabolic Pathways Involved in Cellular Respiration Electron transport chain Hydrogen atoms removed during glycolysis and the Krebs cycle are delivered to protein carriers Hydrogen is split into hydrogen ions and electrons in the mitochondria Electrons give off energy in a series of steps to enable the production of ATP Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings Cellular Respiration Chemical energy (high-energy electrons) CO2 CO2 Glycolysis Glucose Cytosol of cell Pyruvic acid Mitochondrion Chemical energy Krebs cycle Electron transport chain and oxidative phosphorylation H2O Mitochondrial cristae Via oxidative phosphorylation ATP ATP ATP Figure 14.19 Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings Metabolic Pathways Involved in Cellular Respiration Figure 14.20a Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings Metabolism of Carbohydrates Hyperglycemia—excessively high levels of glucose in the blood Excess glucose is stored in body cells as glycogen If blood glucose levels are still too high, excesses are converted to fat Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings Metabolism of Carbohydrates Figure 14.21a Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings Metabolism of Carbohydrates Hypoglycemia—low levels of glucose in the blood Liver breaks down stored glycogen and releases glucose into the blood Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings Fat Metabolism Handled mostly by the liver Uses some fats to make ATP Synthesizes lipoproteins, thromboplastin, and cholesterol Releases breakdown products to the blood Body cells remove fat and cholesterol to build membranes and steroid hormones Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings Use of Fats for ATP Synthesis Fats must first be broken down to acetic acid Within mitochondria, acetic acid is completely oxidized to produce water, carbon dioxide, and ATP Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings ATP Formation Figure 14.21d Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings Fat Metabolism Acidosis (ketoacidosis) results from incomplete fat oxidation in which acetoacetic acid and acetone accumulate in the blood Breath has a fruity odor Common with “No carbohydrate” diets Uncontrolled diabetes mellitus Starvation Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings Fat Metabolism Figure 14.21b Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings Protein Metabolism Proteins are conserved by body cells because they are used for most cellular structures Ingested proteins are broken down to amino acids Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings Protein Metabolism Cells remove amino acids to build proteins Synthesized proteins are actively transported across cell membranes Amino acids are used to make ATP only when proteins are overabundant or there is a shortage of other sources Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings Production of ATP from Protein Amine groups are removed from proteins as ammonia The rest of the protein molecule enters the Krebs cycle in mitochondria The liver converts harmful ammonia to urea which can be eliminated in urine Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings Protein Metabolism Figure 14.21c Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings Role of the Liver in Metabolism Several roles in digestion Manufactures bile Detoxifies drugs and alcohol Degrades hormones Produces cholesterol, blood proteins (albumin and clotting proteins) Plays a central role in metabolism Can regenerate if part of it is damaged or removed Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings Metabolic Functions of the Liver Glycogenesis—“glycogen formation” Glucose molecules are converted to glycogen Glycogen molecules are stored in the liver Glycogenolysis—“glucose splitting” Glucose is released from the liver after conversion from glycogen Gluconeogenesis—“formation of new sugar” Glucose is produced from fats and proteins Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings Metabolic Functions of the Liver Figure 14.22 Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings Metabolic Functions of the Liver Fats and fatty acids are picked up by the liver Some are oxidized to provide energy for liver cells The rest are broken down into simpler compounds and released into the blood Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings Cholesterol Metabolism Cholesterol is not used to make ATP Functions of cholesterol Serves as a structural basis of steroid hormones and vitamin D Is a major building block of plasma membranes Most cholesterol is produced in the liver (85%) and is not from diet (15%) Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings Cholesterol Transport Cholesterol and fatty acids cannot freely circulate in the bloodstream They are transported by lipoproteins (lipid-protein complexes) Low-density lipoproteins (LDLs) transport to body cells Rated “bad lipoproteins” since they can lead to artherosclerosis High-density lipoproteins (HDLs) transport from body cells to the liver Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings Body Energy Balance Energy intake = total energy output (heat + work + energy storage) Energy intake is liberated during food oxidation Energy output Heat is usually about 60% Storage energy is in the form of fat or glycogen Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings Regulation of Food Intake Body weight is usually relatively stable Energy intake and output remain about equal Mechanisms that may regulate food intake Levels of nutrients in the blood Hormones Body temperature Psychological factors Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings Metabolic Rate and Body Heat Production Basic metabolic rate (BMR)—amount of heat produced by the body per unit of time at rest Average BMR is about 60 to 72 kcal/hour Kilocalorie (kcal) is the unit of measure for the energy value of foods and the amount of energy used by the body 3,500 calories equals one pound Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings Metabolic Rate and Body Heat Production Factors that influence BMR Surface area—a small body usually has a higher BMR Gender—males tend to have higher BMRs Age—children and adolescents have higher BMRs The amount of thyroxine produced is the most important control factor More thyroxine means a higher metabolic rate Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings Factors Determining BMR Table 14.3 Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings Total Metabolic Rate (TMR) Total amount of kilocalories the body must consume to fuel ongoing activities TMR increases with an increase in body activity TMR must equal calories consumed to maintain homeostasis and maintain a constant weight Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings Body Temperature Regulation Most energy is released as foods are oxidized Most energy escapes as heat Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings Body Temperature Regulation The body has a narrow range of homeostatic temperature Must remain between 35.6°C to 37.8°C (96°F to 100°F) The body’s thermostat is in the hypothalamus Initiates heat-loss or heat-promoting mechanisms Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings Body Temperature Regulation Heat-promoting mechanisms Vasoconstriction of blood vessels Blood is rerouted to deeper, more vital body organs Shivering—contraction of muscles produces heat Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings Body Temperature Regulation Heat-loss mechanisms Heat loss from the skin via radiation and evaporation Skin blood vessels and capillaries are flushed with warm blood Evaporation of perspiration cools the skin Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings Mechanisms of Body Temperature Regulation Skin blood vessels dilate: Capillaries become flushed with warm blood; heat radiates from skin surface Sweat glands activated: Secrete perspiration, which is vaporized by body heat, helping to cool the body Activates heat-loss center in hypothalamus Body temperature decreases: Blood temperature declines and hypothalamus heat-loss center “shuts off” Blood warmer than hypothalamic set point Stimulus: Increased body temperature (e.g., when exercising or the climate is hot) Homeostasis = normal body temperature (35.6°C–37.8°C) Stimulus: Decreased body temperature (e.g., due to cold environmental temperatures) Blood cooler than hypothalamic set point Body temperature increases: Blood temperature rises and hypothalamus heat-promoting center “shuts off” Skin blood vessels constrict: Blood is diverted from skin capillaries and withdrawn to deeper tissues; minimizes overall heat loss from skin surface Activates heatpromoting center in hypothalamus Skeletal muscles activated when more heat must be generated; shivering begins Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings Figure 14.23 Mechanisms of Body Temperature Regulation Stimulus: Increased body temperature (e.g., when exercising or the climate is hot) Homeostasis = normal body temperature (35.6°C–37.8°C) Figure 14.23, step 1 Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings Mechanisms of Body Temperature Regulation Activates heat-loss center in hypothalamus Blood warmer than hypothalamic set point Stimulus: Increased body temperature (e.g., when exercising or the climate is hot) Homeostasis = normal body temperature (35.6°C–37.8°C) Figure 14.23, step 2 Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings Mechanisms of Body Temperature Regulation Skin blood vessels dilate: Capillaries become flushed with warm blood; heat radiates from skin surface Activates heat-loss center in hypothalamus Blood warmer than hypothalamic set point Stimulus: Increased body temperature (e.g., when exercising or the climate is hot) Homeostasis = normal body temperature (35.6°C–37.8°C) Figure 14.23, step 3 Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings Mechanisms of Body Temperature Regulation Skin blood vessels dilate: Capillaries become flushed with warm blood; heat radiates from skin surface Activates heat-loss center in hypothalamus Sweat glands activated: Secrete perspiration, which is vaporized by body heat, helping to cool the body Blood warmer than hypothalamic set point Stimulus: Increased body temperature (e.g., when exercising or the climate is hot) Homeostasis = normal body temperature (35.6°C–37.8°C) Figure 14.23, step 4 Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings Mechanisms of Body Temperature Regulation Skin blood vessels dilate: Capillaries become flushed with warm blood; heat radiates from skin surface Activates heat-loss center in hypothalamus Sweat glands activated: Secrete perspiration, which is vaporized by body heat, helping to cool the body Body temperature decreases: Blood temperature declines and hypothalamus heat-loss center “shuts off” Blood warmer than hypothalamic set point Stimulus: Increased body temperature (e.g., when exercising or the climate is hot) Homeostasis = normal body temperature (35.6°C–37.8°C) Figure 14.23, step 5 Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings Mechanisms of Body Temperature Regulation Skin blood vessels dilate: Capillaries become flushed with warm blood; heat radiates from skin surface Activates heat-loss center in hypothalamus Sweat glands activated: Secrete perspiration, which is vaporized by body heat, helping to cool the body Body temperature decreases: Blood temperature declines and hypothalamus heat-loss center “shuts off” Blood warmer than hypothalamic set point Stimulus: Increased body temperature (e.g., when exercising or the climate is hot) Homeostasis = normal body temperature (35.6°C–37.8°C) Figure 14.23, step 6 Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings Mechanisms of Body Temperature Regulation Homeostasis = normal body temperature (35.6°C–37.8°C) Stimulus: Decreased body temperature (e.g., due to cold environmental temperatures) Figure 14.23, step 7 Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings Mechanisms of Body Temperature Regulation Homeostasis = normal body temperature (35.6°C–37.8°C) Stimulus: Decreased body temperature (e.g., due to cold environmental temperatures) Blood cooler than hypothalamic set point Activates heatpromoting center in hypothalamus Figure 14.23, step 8 Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings Mechanisms of Body Temperature Regulation Homeostasis = normal body temperature (35.6°C–37.8°C) Stimulus: Decreased body temperature (e.g., due to cold environmental temperatures) Blood cooler than hypothalamic set point Activates heatpromoting center in hypothalamus Skeletal muscles activated when more heat must be generated; shivering begins Figure 14.23, step 9 Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings Mechanisms of Body Temperature Regulation Homeostasis = normal body temperature (35.6°C–37.8°C) Stimulus: Decreased body temperature (e.g., due to cold environmental temperatures) Blood cooler than hypothalamic set point Skin blood vessels constrict: Blood is diverted from skin capillaries and withdrawn to deeper tissues; minimizes overall heat loss from skin surface Activates heatpromoting center in hypothalamus Skeletal muscles activated when more heat must be generated; shivering begins Figure 14.23, step 10 Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings Mechanisms of Body Temperature Regulation Homeostasis = normal body temperature (35.6°C–37.8°C) Stimulus: Decreased body temperature (e.g., due to cold environmental temperatures) Blood cooler than hypothalamic set point Body temperature increases: Blood temperature rises and hypothalamus heat-promoting center “shuts off” Skin blood vessels constrict: Blood is diverted from skin capillaries and withdrawn to deeper tissues; minimizes overall heat loss from skin surface Activates heatpromoting center in hypothalamus Skeletal muscles activated when more heat must be generated; shivering begins Figure 14.23, step 11 Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings Mechanisms of Body Temperature Regulation Homeostasis = normal body temperature (35.6°C–37.8°C) Stimulus: Decreased body temperature (e.g., due to cold environmental temperatures) Blood cooler than hypothalamic set point Body temperature increases: Blood temperature rises and hypothalamus heat-promoting center “shuts off” Skin blood vessels constrict: Blood is diverted from skin capillaries and withdrawn to deeper tissues; minimizes overall heat loss from skin surface Activates heatpromoting center in hypothalamus Skeletal muscles activated when more heat must be generated; shivering begins Figure 14.23, step 12 Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings Mechanisms of Body Temperature Regulation Skin blood vessels dilate: Capillaries become flushed with warm blood; heat radiates from skin surface Sweat glands activated: Secrete perspiration, which is vaporized by body heat, helping to cool the body Activates heat-loss center in hypothalamus Body temperature decreases: Blood temperature declines and hypothalamus heat-loss center “shuts off” Blood warmer than hypothalamic set point Stimulus: Increased body temperature (e.g., when exercising or the climate is hot) Homeostasis = normal body temperature (35.6°C–37.8°C) Stimulus: Decreased body temperature (e.g., due to cold environmental temperatures) Blood cooler than hypothalamic set point Body temperature increases: Blood temperature rises and hypothalamus heat-promoting center “shuts off” Skin blood vessels constrict: Blood is diverted from skin capillaries and withdrawn to deeper tissues; minimizes overall heat loss from skin surface Activates heatpromoting center in hypothalamus Skeletal muscles activated when more heat must be generated; shivering begins Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings Figure 14.23, step 13 Body Temperature Regulation Fever—controlled hyperthermia Results from infection, cancer, allergic reactions, CNS injuries If the body thermostat is set too high, body proteins may be denatured and permanent brain damage may occur Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings Developmental Aspects of the Digestive System The alimentary canal is a continuous tube by the fifth week of development Digestive glands bud from the mucosa of the alimentary tube The developing fetus receives all nutrients through the placenta In newborns, feeding must be frequent, peristalsis is inefficient, and vomiting is common Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings Developmental Aspects of the Digestive System Newborn reflexes Rooting reflex helps the infant find the nipple Sucking reflex helps the infant hold on to the nipple and swallow Teething begins around age six months Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings Developmental Aspects of the Digestive System Problems of the digestive system Gastroenteritis—inflammation of the gastrointestinal tract Appendicitis—inflammation of the appendix Metabolism decreases with old age Middle-age digestive problems Ulcers Gallbladder problems Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings Developmental Aspects of the Digestive System Activity of the digestive tract in old age Fewer digestive juices Peristalsis slows Diverticulosis and cancer are more common Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings