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1 Chapter 25 Metabolism Functions of food Functions of food source of energy source of energy essential nutrients essential nutrients stored for future.

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Presentation on theme: "1 Chapter 25 Metabolism Functions of food Functions of food source of energy source of energy essential nutrients essential nutrients stored for future."— Presentation transcript:

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2 1 Chapter 25 Metabolism Functions of food Functions of food source of energy source of energy essential nutrients essential nutrients stored for future use stored for future use Metabolism is all the chemical reactions of the body Metabolism is all the chemical reactions of the body some reactions produce the energy stored in ATP that other reactions consume some reactions produce the energy stored in ATP that other reactions consume all molecules will eventually be broken down and recycled or excreted from the body all molecules will eventually be broken down and recycled or excreted from the body

3 2 Catabolism and Anabolism Catabolic reactions breakdown complex organic compounds Catabolic reactions breakdown complex organic compounds providing energy (exergonic) providing energy (exergonic) glycolysis, Krebs cycle and electron transport glycolysis, Krebs cycle and electron transport Anabolic reactions synthesize complex molecules from small molecules Anabolic reactions synthesize complex molecules from small molecules requiring energy (endergonic) requiring energy (endergonic) Exchange of energy requires use of ATP (adenosine triphosphate) molecule. Exchange of energy requires use of ATP (adenosine triphosphate) molecule.

4 3 ATP Molecule & Energy Each cell has about 1 billion ATP molecules that last for less than one minute Over half of the energy released from ATP is converted to heat

5 4 Energy Transfer Energy is found in the bonds between atoms Energy is found in the bonds between atoms Oxidation is a decrease in the energy content of a molecule Oxidation is a decrease in the energy content of a molecule Reduction is the increase in the energy content of a molecule Reduction is the increase in the energy content of a molecule Oxidation-reduction reactions are always coupled within the body Oxidation-reduction reactions are always coupled within the body whenever a substance is oxidized, another is almost simultaneously reduced. whenever a substance is oxidized, another is almost simultaneously reduced.

6 5 Mechanisms of ATP Generation Phosphorylation is Phosphorylation is bond attaching 3rd phosphate group contains stored energy bond attaching 3rd phosphate group contains stored energy Mechanisms of phosphorylation Mechanisms of phosphorylation within animals within animals substrate-level phosphorylation in cytosol substrate-level phosphorylation in cytosol oxidative phosphorylation in mitochondria oxidative phosphorylation in mitochondria in chlorophyll-containing plants or bacteria in chlorophyll-containing plants or bacteria photophosphorylation. photophosphorylation.

7 6 Phosphorylation in Animal Cells In cytoplasm (1) In mitochondria (2, 3 & 4)

8 7 Carbohydrate Metabolism--In Review In GI tract In GI tract polysaccharides broken down into simple sugars polysaccharides broken down into simple sugars absorption of simple sugars (glucose, fructose & galactose) absorption of simple sugars (glucose, fructose & galactose) In liver In liver fructose & galactose transformed into glucose fructose & galactose transformed into glucose storage of glycogen (also in muscle) storage of glycogen (also in muscle) In body cells --functions of glucose In body cells --functions of glucose oxidized to produce energy oxidized to produce energy conversion into something else conversion into something else storage energy as triglyceride in fat storage energy as triglyceride in fat

9 8 Fate of Glucose ATP production during cell respiration ATP production during cell respiration uses glucose preferentially uses glucose preferentially Converted to one of several amino acids in many different cells throughout the body Converted to one of several amino acids in many different cells throughout the body Glycogenesis Glycogenesis hundreds of glucose molecules combined to form glycogen for storage in liver & skeletal muscles hundreds of glucose molecules combined to form glycogen for storage in liver & skeletal muscles Lipogenesis (triglyceride synthesis) Lipogenesis (triglyceride synthesis) converted to glycerol & fatty acids within liver & sent to fat cells converted to glycerol & fatty acids within liver & sent to fat cells

10 9 Glucose Movement into Cells In GI tract and kidney tubules, Na+/glucose symporters Most other cells, GluT facilitated diffusion transporters move glucose into cells insulin increases number of GluT transporters in the membrane of most cells in liver & brain, always lots of GluT transporters Glucose 6-phosphate forms immediately inside cell (requires ATP) thus, glucose hidden in cell Concentration gradient favorable for more glucose to enter

11 10 Glucose Catabolism Cellular respiration Cellular respiration 4 steps are involved 4 steps are involved glucose + O2 produces H2O + energy + CO2 glucose + O2 produces H2O + energy + CO2 Anaerobic respiration Anaerobic respiration called glycolysis (1) called glycolysis (1) formation of acetyl CoA (2) is transitional step to Krebs cycle formation of acetyl CoA (2) is transitional step to Krebs cycle Aerobic respiration Aerobic respiration Krebs cycle (3) and electron transport chain (4) Krebs cycle (3) and electron transport chain (4)

12 11 Glycolysis of Glucose & Fate of Pyruvic Acid Breakdown of six-carbon glucose molecule into 2 three- carbon molecules of pyruvic acid Breakdown of six-carbon glucose molecule into 2 three- carbon molecules of pyruvic acid 10 step process occurring in cell cytosol 10 step process occurring in cell cytosol produces 4 molecules of ATP after input of 2 ATP produces 4 molecules of ATP after input of 2 ATP utilizes 2 NAD+ molecules as hydrogen acceptors utilizes 2 NAD+ molecules as hydrogen acceptors If O2 shortage in a cell If O2 shortage in a cell pyruvic acid is reduced to lactic acid so that NAD+ will be still available for further glycolysis pyruvic acid is reduced to lactic acid so that NAD+ will be still available for further glycolysis rapidly diffuses out of cell to blood rapidly diffuses out of cell to blood liver cells remove it from blood & convert it back to pyruvic acid liver cells remove it from blood & convert it back to pyruvic acid

13 12 Formation of Acetyl Coenzyme A Formation of Acetyl Coenzyme A Pyruvic acid enters the mitochondria with help of transporter protein Pyruvic acid enters the mitochondria with help of transporter protein Decarboxylation Decarboxylation pyruvate dehydrogenase converts 3 carbon pyruvic acid to 2 carbon fragment (CO2 produced) pyruvate dehydrogenase converts 3 carbon pyruvic acid to 2 carbon fragment (CO2 produced) pyruvic acid was oxidized so that NAD+ becomes NADH pyruvic acid was oxidized so that NAD+ becomes NADH 2 carbon fragment (acetyl group) is attached to Coenzyme A to form Acetyl coenzyme A which enter Krebs cycle 2 carbon fragment (acetyl group) is attached to Coenzyme A to form Acetyl coenzyme A which enter Krebs cycle coenzyme A is derived from pantothenic acid (B vitamin). coenzyme A is derived from pantothenic acid (B vitamin).

14 13 Krebs Cycle (Citric Acid Cycle) Series of oxidation- reduction & decarboxylation reactions occurring in matrix of mitochondria It finishes the same as it starts (4C) acetyl CoA (2C) enters at top & combines with a 4C compound 2 decarboxylation reactions peel 2 carbons off again when CO2 is formed

15 14 Krebs Cycle Krebs Cycle Energy stored in bonds is released step by step to form several reduced coenzymes (NADH & FADH2) that store the energy Energy stored in bonds is released step by step to form several reduced coenzymes (NADH & FADH2) that store the energy In summary: each Acetyl CoA molecule that enters the Krebs cycle produces In summary: each Acetyl CoA molecule that enters the Krebs cycle produces 2 molecules of C02 2 molecules of C02 one reason O2 is needed one reason O2 is needed 3 molecules of NADH + H+ 3 molecules of NADH + H+ one molecule of ATP one molecule of ATP one molecule of FADH 2 one molecule of FADH 2 Remember, each glucose produced 2 acetyl CoA molecules Remember, each glucose produced 2 acetyl CoA molecules

16 15 The Electron Transport Chain Series of integral membrane proteins in the inner mitochondrial membrane capable of oxidation/reduction Each electron carrier is reduced as it picks up electrons and is oxidized as it gives up electrons Small amounts of energy released in small steps Energy used to form ATP by chemiosmosis

17 16 Chemiosmosis Small amounts of energy released as substances are passed along inner membrane Energy used to pump H+ ions from matrix into space between inner & outer membrane High concentration of H+ is maintained outside of inner membrane ATP synthesis occurs as H+ diffuses through a special H+ channel in inner membrane

18 17 Steps in Electron Transport Carriers of electron transport chain are clustered into 3 complexes that each act as proton pump (expel H+) Mobile shuttles pass electrons between complexes Last complex passes its electrons (2H+) to a half of O2 molecule to form a water molecule (H2O)

19 18 Proton Motive Force & Chemiosmosis Buildup of H+ outside the inner membrane creates + charge electrochemical gradient potential energy is called proton motive force ATP synthase enzyme within H+ channel uses proton motive force to synthesize ATP from ADP and P

20 19 Summary of Cellular Respiration Glucose + O2 is broken down into CO2 + H2O + energy used to form 36 to 38 ATPs 2 ATP are formed during glycolysis 2 ATP are formed by phosphorylation during Krebs cycle electron transfers in transport chain generate 32 or 34 ATPs from one glucose molecule Summary in Table 25.1 Points to remember ATP must be transported out of mitochondria in exchange for ADP uses up some of proton motive force Oxygen is required or many of these steps can not occur

21 20 Carbohydrate Loading Long-term athletic events (marathons) can exhaust glycogen stored in liver and skeletal muscles Long-term athletic events (marathons) can exhaust glycogen stored in liver and skeletal muscles Eating large amounts of complex carbohydrates (pasta & potatoes) for 3 days before a marathon maximizes glycogen available for ATP production Eating large amounts of complex carbohydrates (pasta & potatoes) for 3 days before a marathon maximizes glycogen available for ATP production Useful for athletic events lasting for more than an hour Useful for athletic events lasting for more than an hour

22 21 Glycogenesis & Glycogenolysis Glycogenesis glucose storage as glycogen 4 steps to glycogen formation in liver or skeletal muscle stimulated by insulin Glycogenolysis glucose release not a simple reversal of steps enzyme phosphorylase splits off a glucose molecule by phosphorylation to form glucose 1-phosphate enzyme only in hepatocytes so muscle can’t release glucose enzyme activated by glucagon (pancreas) & epinephrine (adrenal)

23 22 Gluconeogenesis Liver glycogen runs low if fasting, starving or not eating carbohydrates forcing formation from other substances lactic acid, glycerol & certain amino acids (60% of available) Stimulated by cortisol (adrenal) & glucagon (pancreas) cortisol stimulates breakdown of proteins freeing amino acids thyroid mobilizes triglycerides from adipose tissue

24 23 Transport of Lipids by Lipoproteins Most lipids are nonpolar and must be combined with protein to be tranported in blood Most lipids are nonpolar and must be combined with protein to be tranported in blood Lipoproteins are spheres containing hundreds of molecules Lipoproteins are spheres containing hundreds of molecules outer shell polar proteins (apoproteins) & phospholipids outer shell polar proteins (apoproteins) & phospholipids inner core of triglyceride & cholesterol esters inner core of triglyceride & cholesterol esters Lipoprotein categorized by function & density Lipoprotein categorized by function & density 4 major classes of lipoproteins 4 major classes of lipoproteins chylomicrons, very low-density, low-density & high-density lipoproteins chylomicrons, very low-density, low-density & high-density lipoproteins

25 24 Classes of Lipoproteins Chylomicrons (2 % protein) Chylomicrons (2 % protein) form in intestinal epithelial cells to transport dietary fat form in intestinal epithelial cells to transport dietary fat apo C-2 activates enzyme that releases the fatty acids from the chylomicron for absorption by adipose & muscle cells apo C-2 activates enzyme that releases the fatty acids from the chylomicron for absorption by adipose & muscle cells liver processes what is left liver processes what is left VLDLs (10% protein) VLDLs (10% protein) transport triglycerides formed in liver to fat cells transport triglycerides formed in liver to fat cells LDLs (25% protein) --- “bad cholesterol” LDLs (25% protein) --- “bad cholesterol” carry 75% of blood cholesterol to body cells carry 75% of blood cholesterol to body cells apo B100 is docking protein for receptor-mediated endocytosis of the LDL into a body cell apo B100 is docking protein for receptor-mediated endocytosis of the LDL into a body cell if cells have insufficient receptors, remains in blood and more likely to deposit cholesterol in artery walls (plaque) if cells have insufficient receptors, remains in blood and more likely to deposit cholesterol in artery walls (plaque) HDLs (40% protein) --- “good cholesterol” HDLs (40% protein) --- “good cholesterol” carry cholesterol from cells to liver for elimination carry cholesterol from cells to liver for elimination

26 25 Blood Cholesterol Sources of cholesterol in the body Sources of cholesterol in the body food (eggs, dairy, organ meats, meat) food (eggs, dairy, organ meats, meat) synthesized by the liver synthesized by the liver All fatty foods still raise blood cholesterol All fatty foods still raise blood cholesterol liver uses them to create cholesterol liver uses them to create cholesterol stimulate reuptake of cholesterol containing bile normally lost in the feces stimulate reuptake of cholesterol containing bile normally lost in the feces Desirable readings for adults Desirable readings for adults total cholesterol under 200 mg/dL; triglycerides mg/dL total cholesterol under 200 mg/dL; triglycerides mg/dL LDL under 130 mg/dL; HDL over 40 mg/dL LDL under 130 mg/dL; HDL over 40 mg/dL cholesterol/HDL ratio above 4 is undesirable risk cholesterol/HDL ratio above 4 is undesirable risk Raising HDL & lowering cholesterol can be accomplished by exercise, diet & drugs Raising HDL & lowering cholesterol can be accomplished by exercise, diet & drugs

27 26 Fate of Lipids Oxidized to produce ATP Oxidized to produce ATP Excess stored in adipose tissue or liver Excess stored in adipose tissue or liver Synthesize structural or important molecules Synthesize structural or important molecules phospholipids of plasma membranes phospholipids of plasma membranes lipoproteins that transport cholesterol lipoproteins that transport cholesterol thromboplastin for blood clotting thromboplastin for blood clotting myelin sheaths to speed up nerve conduction myelin sheaths to speed up nerve conduction cholesterol used to synthesize bile salts and steroid hormones. cholesterol used to synthesize bile salts and steroid hormones.

28 27 Lipid Anabolism: Lipogenesis Synthesis of lipids by liver cells = lipogenesis Synthesis of lipids by liver cells = lipogenesis from amino acids from amino acids converted to acetyl CoA & then to triglycerides converted to acetyl CoA & then to triglycerides from glucose from glucose from glyceraldehyde 3-phosphate to triglycerides from glyceraldehyde 3-phosphate to triglycerides Stimulated by insulin when eat excess calories Stimulated by insulin when eat excess calories

29 28 Ketosis Blood ketone levels are usually very low Blood ketone levels are usually very low many tissues use ketone for ATP production many tissues use ketone for ATP production Fasting, starving or high fat meal with few carbohydrates results in excessive beta oxidation & ketone production Fasting, starving or high fat meal with few carbohydrates results in excessive beta oxidation & ketone production acidosis (ketoacidosis) is abnormally low blood pH acidosis (ketoacidosis) is abnormally low blood pH sweet smell of ketone body acetone on breath sweet smell of ketone body acetone on breath occurs in diabetic since triglycerides are used for ATP production instead of glucose & insulin inhibits lipolysis occurs in diabetic since triglycerides are used for ATP production instead of glucose & insulin inhibits lipolysis

30 29 Fate of Proteins Proteins are broken down into amino acids Proteins are broken down into amino acids transported to the liver transported to the liver Usage Usage oxidized to produce ATP oxidized to produce ATP used to synthesize new proteins used to synthesize new proteins enzymes, hemoglobin, antibodies, hormones, fibrinogen, actin, myosin, collagen, elastin & keratin enzymes, hemoglobin, antibodies, hormones, fibrinogen, actin, myosin, collagen, elastin & keratin excess converted into glucose or triglycerides excess converted into glucose or triglycerides no storage is possible no storage is possible Absorption into body cells is stimulated by insulinlike growth factors (IGFs) & insulin Absorption into body cells is stimulated by insulinlike growth factors (IGFs) & insulin

31 30 Protein Catabolism Breakdown of protein into amino acids Breakdown of protein into amino acids Liver cells convert amino acids into substances that can enter the Krebs cycle Liver cells convert amino acids into substances that can enter the Krebs cycle deamination removes the amino group (NH2) deamination removes the amino group (NH2) converts it to ammonia (NH3) & then urea converts it to ammonia (NH3) & then urea urea excreted in the urine urea excreted in the urine Converted substances enter the Krebs cycle to produce ATP Converted substances enter the Krebs cycle to produce ATP

32 31 Protein Anabolism Production of new proteins by formation of peptide bonds between amino acids Production of new proteins by formation of peptide bonds between amino acids 10 essential amino acids are ones we must eat because we can not synthesize them 10 essential amino acids are ones we must eat because we can not synthesize them nonessential amino acids can be synthesized by transamination (transfer of an amino group to a substance to create an amino acid) nonessential amino acids can be synthesized by transamination (transfer of an amino group to a substance to create an amino acid) Occurs on ribosomes in almost every cell Occurs on ribosomes in almost every cell Stimulated by insulinlike growth factor, thyroid hormone, insulin, estrogen & testosterone Stimulated by insulinlike growth factor, thyroid hormone, insulin, estrogen & testosterone Large amounts of protein in the diet do not cause the growth of muscle, only weight-bearing exercise Large amounts of protein in the diet do not cause the growth of muscle, only weight-bearing exercise

33 32 Phenylketonuria (PKU) Genetic error of protein metabolism that produces elevated blood levels of amino acid phenylalanine Genetic error of protein metabolism that produces elevated blood levels of amino acid phenylalanine causes vomiting, seizures & mental retardation causes vomiting, seizures & mental retardation normally converted by an enzyme into tyrosine which can enter the krebs cycle normally converted by an enzyme into tyrosine which can enter the krebs cycle Screening of newborns prevents retardation Screening of newborns prevents retardation spend their life with a diet restricting phenylalanine spend their life with a diet restricting phenylalanine restrict Nutrasweet which contains phenylalanine restrict Nutrasweet which contains phenylalanine

34 33 Metabolic Adaptations Absorptive state Absorptive state nutrients entering the bloodstream nutrients entering the bloodstream glucose readily available for ATP production glucose readily available for ATP production 4 hours for absorption of each meal so absorptive state lasts for 12 hours/day 4 hours for absorption of each meal so absorptive state lasts for 12 hours/day Postabsorptive state Postabsorptive state absorption of nutrients from GI tract is complete absorption of nutrients from GI tract is complete body must meet its needs without outside nutrients body must meet its needs without outside nutrients late morning, late afternoon & most of the evening late morning, late afternoon & most of the evening assuming no snacks, lasts about 12 hours/day assuming no snacks, lasts about 12 hours/day more cells use ketone bodies for ATP production more cells use ketone bodies for ATP production maintaining a steady blood glucose level is critical maintaining a steady blood glucose level is critical

35 34 Metabolism During Fasting & Starvation Fasting means going without food for hours/days Fasting means going without food for hours/days Starvation means weeks or months Starvation means weeks or months can survive 2 months or more if drink enough water can survive 2 months or more if drink enough water amount of adipose tissue is determining factor amount of adipose tissue is determining factor Nutritional needs Nutritional needs nervous tissue & RBC need glucose so amino acids will be broken down for gluconeogenesis nervous tissue & RBC need glucose so amino acids will be broken down for gluconeogenesis blood glucose stabilizes at 65 mg/100 mL blood glucose stabilizes at 65 mg/100 mL lipolysis releases glycerol used in gluconeogenesis lipolysis releases glycerol used in gluconeogenesis increase in formation of ketone bodies by liver cells due to catabolism of fatty acids increase in formation of ketone bodies by liver cells due to catabolism of fatty acids by 40 days, ketones supply 2/3’s of brains fuel for ATP by 40 days, ketones supply 2/3’s of brains fuel for ATP

36 35 Absorption of Alcohol Absorption begins in the stomach but is absorbed more quickly in the small intestine Absorption begins in the stomach but is absorbed more quickly in the small intestine fat rich foods keep the alcohol from leaving the stomach and prevent a rapid rise in blood alcohol fat rich foods keep the alcohol from leaving the stomach and prevent a rapid rise in blood alcohol a gastric mucosa enzyme breaks down some of the alcohol to acetaldehyde a gastric mucosa enzyme breaks down some of the alcohol to acetaldehyde Females develop higher blood alcohols Females develop higher blood alcohols have a smaller blood volume have a smaller blood volume have less gastric alcohol dehydrogenase activity have less gastric alcohol dehydrogenase activity

37 36 Metabolic Rate Rate at which metabolic reactions use energy Rate at which metabolic reactions use energy energy used to produce heat or ATP energy used to produce heat or ATP Basal Metabolic Rate (BMR) Basal Metabolic Rate (BMR) measurements made under specific conditions measurements made under specific conditions quiet, resting and fasting condition quiet, resting and fasting condition Basal Temperature maintained at 98.6 degrees Basal Temperature maintained at 98.6 degrees shell temperature is usually 1 to 6 degrees lower shell temperature is usually 1 to 6 degrees lower

38 37 Heat Production Factors that affect metabolic rate and thus the production of body heat Factors that affect metabolic rate and thus the production of body heat exercise increases metabolic rate as much as 15 times exercise increases metabolic rate as much as 15 times hormones regulate basal metabolic rate hormones regulate basal metabolic rate thyroid, insulin, growth hormone & testosterone increase BMR thyroid, insulin, growth hormone & testosterone increase BMR sympathetic nervous system’s release of epinephrine & norepinephrine increases BMR sympathetic nervous system’s release of epinephrine & norepinephrine increases BMR higher body temperature raises BMR higher body temperature raises BMR ingestion of food raises BMR 10-20% ingestion of food raises BMR 10-20% children’s BMR is double that of an elderly person children’s BMR is double that of an elderly person

39 38 Mechanisms of Heat Transfer Temperature homeostasis requires mechanisms of transferring heat from the body to the environment Temperature homeostasis requires mechanisms of transferring heat from the body to the environment conduction is heat exchange requiring direct contact with an object conduction is heat exchange requiring direct contact with an object convection is heat transfer by movement of gas or liquid over body convection is heat transfer by movement of gas or liquid over body radiation is transfer of heat in form of infrared rays from body radiation is transfer of heat in form of infrared rays from body evaporation is heat loss due to conversion of liquid to a vapor (insensible water loss) evaporation is heat loss due to conversion of liquid to a vapor (insensible water loss)

40 39 Hypothalamic Thermostat Preoptic area in anterior hypothalamus Preoptic area in anterior hypothalamus receives impulses from thermoreceptors receives impulses from thermoreceptors generates impulses at a higher frequency when blood temperature increases generates impulses at a higher frequency when blood temperature increases impulses propagate to other parts of hypothalamus impulses propagate to other parts of hypothalamus heat-losing center heat-losing center heat-promoting center heat-promoting center Set in motion responses that either lower or raise body temperature Set in motion responses that either lower or raise body temperature

41 40 Thermoregulation Declining body temperature Declining body temperature thermoreceptors signal hypothalamus to produce TRH thermoreceptors signal hypothalamus to produce TRH TRH causes anterior pituitary to produce TSH resulting in TRH causes anterior pituitary to produce TSH resulting in vasoconstriction in skin vasoconstriction in skin adrenal medulla stimulates cell metabolic rate adrenal medulla stimulates cell metabolic rate shivering shivering release of more thyroid hormone raises BMR release of more thyroid hormone raises BMR Increases in body temperature Increases in body temperature sweating & vasodilation sweating & vasodilation

42 41 Hypothermia Lowering of core body temperature to 35°C (95°F) Lowering of core body temperature to 35°C (95°F) Causes Causes immersion in icy water (cold stress) immersion in icy water (cold stress) metabolic diseases (hypoglycemia, adrenal insufficiency or hypothyroidism) metabolic diseases (hypoglycemia, adrenal insufficiency or hypothyroidism) drugs (alcohol, antidepressants, or sedatives) drugs (alcohol, antidepressants, or sedatives) burns and malnutrition burns and malnutrition Symptoms that occur as body temperature drops Symptoms that occur as body temperature drops shivering, confusion, vasoconstriction, muscle rigidity, bradycardia, acidosis, hypoventilation, coma & death shivering, confusion, vasoconstriction, muscle rigidity, bradycardia, acidosis, hypoventilation, coma & death

43 42 Regulation of Food Intake Hypothalamus regulates food intake Hypothalamus regulates food intake feeding (hunger) center feeding (hunger) center satiety center satiety center Stimuli that decrease appetite Stimuli that decrease appetite glucagon, cholecystokinin, epinephrine, glucose & leptin glucagon, cholecystokinin, epinephrine, glucose & leptin stretching of the stomach and duodenum stretching of the stomach and duodenum Signals that increase appetite Signals that increase appetite growth releasing hormone, opioids, glucocorticoids, insulin, progesterone & somatostatin growth releasing hormone, opioids, glucocorticoids, insulin, progesterone & somatostatin

44 43 Guidelines for Healthy Eating Nutrients include water, carbohydrates, lipids, proteins, vitamins and minerals Nutrients include water, carbohydrates, lipids, proteins, vitamins and minerals Caloric intake Caloric intake women 1600 Calories/day is needed women 1600 Calories/day is needed active women and most men 2200 Calories active women and most men 2200 Calories teenage boys and active men 2800 calories teenage boys and active men 2800 calories Food guide pyramid developed by U.S. Department of Agriculture Food guide pyramid developed by U.S. Department of Agriculture indicates number of servings of each food group to eat each day indicates number of servings of each food group to eat each day

45 44 Food Guide Pyramid

46 45Minerals Inorganic substances = 4% body weight Inorganic substances = 4% body weight Functions Functions calcium & phosphorus form part of the matrix of bone calcium & phosphorus form part of the matrix of bone help regulate enzymatic reactions help regulate enzymatic reactions calcium, iron, magnesium & manganese calcium, iron, magnesium & manganese magnesium is catalyst for conversion of ADP to ATP magnesium is catalyst for conversion of ADP to ATP form buffer systems form buffer systems regulate osmosis of water regulate osmosis of water generation of nerve impulses generation of nerve impulses

47 46 Vitamins Organic nutrients needed in very small amounts Organic nutrients needed in very small amounts serve as coenzymes serve as coenzymes Most cannot be synthesized by the body Most cannot be synthesized by the body Fat-soluble vitamins Fat-soluble vitamins absorbed with dietary fats by the small intestine absorbed with dietary fats by the small intestine stored in liver and include vitamins A, D, E, and K stored in liver and include vitamins A, D, E, and K Water-soluble vitamins are absorbed along with water in the Gl tract Water-soluble vitamins are absorbed along with water in the Gl tract body does not store---excess excreted in urine body does not store---excess excreted in urine includes the B vitamins and vitamin C includes the B vitamins and vitamin C

48 47 Antioxidant Vitamins C, E and beta-carotene (a provitamin) C, E and beta-carotene (a provitamin) Inactivate oxygen free radicals Inactivate oxygen free radicals highly reactive particles that carry an unpaired electron highly reactive particles that carry an unpaired electron damage cell membranes, DNA, and contribute to atherosclerotic plaques damage cell membranes, DNA, and contribute to atherosclerotic plaques arise naturally or from environmental hazards such as tobacco or radiation arise naturally or from environmental hazards such as tobacco or radiation Protect against cancer, aging, cataract formation, and atherosclerotic plaque Protect against cancer, aging, cataract formation, and atherosclerotic plaque

49 48 Vitamin and Mineral Supplements Eat a balanced diet rather than taking supplements Eat a balanced diet rather than taking supplements Exceptions Exceptions iron for women with heavy menstrual bleeding iron for women with heavy menstrual bleeding iron & calcium for pregnant or nursing women iron & calcium for pregnant or nursing women folic acid if trying to become pregnant folic acid if trying to become pregnant reduce risk of fetal neural tube defects reduce risk of fetal neural tube defects calcium for all adults calcium for all adults B12 for strict vegetarians B12 for strict vegetarians antioxidants C and E recommended by some antioxidants C and E recommended by some

50 49 Fever Abnormally high body temperature Abnormally high body temperature toxins from bacterial or viral infection = pyrogens toxins from bacterial or viral infection = pyrogens heart attacks or tumors heart attacks or tumors tissue destruction by x-rays, surgery, or trauma tissue destruction by x-rays, surgery, or trauma reactions to vaccines reactions to vaccines Beneficial in fighting infection & increasing rate of tissue repair during the course of a disease Beneficial in fighting infection & increasing rate of tissue repair during the course of a disease Complications--dehydration, acidosis, & brain damage. Complications--dehydration, acidosis, & brain damage.

51 50 Obesity Body weight more than 20% above desirable standard Body weight more than 20% above desirable standard Risk factor in many diseases Risk factor in many diseases cardiovascular disease, hypertension, pulmonary disease, cardiovascular disease, hypertension, pulmonary disease, non-insulin dependent diabetes mellitus non-insulin dependent diabetes mellitus arthritis, certain cancers (breast, uterus, and colon), arthritis, certain cancers (breast, uterus, and colon), varicose veins, and gallbladder disease. varicose veins, and gallbladder disease.


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