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Metabolism

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Title: Metabolism


1
Metabolism
  • Chapter 25 - pages 962-987

2
Linking anabolism catabolism
3
Topics in Chapter 25
  • In AP I glucose catabolism ? ATP was discussed
  • This semester in Ch 25 focus on
  • Glucose anabolism
  • Lipid metabolism
  • Protein metabolism
  • Metabolism during absorptive and post absorptive
    states
  • Heat and energy balance
  • Nutrition

4
Glucose
  • Most glucose catabolized to make ATP
  • Some used in anabolic rxns
  • To produce glycogen
  • To produce more glucose from lipid and protein
    components

5
Do not confuse these terms!
  • Glucose
  • Glycogen
  • Glucagon
  • Glycolysis
  • Glycogenolysis
  • Glycogenesis
  • Gluconeogenesis

6
Glycogenesis fig 25.11
  • Glucose storage
  • Occurs when glucose not immediately needed for
    ATP synthesis
  • _____________- stimulates hepatocytes skeletal
    muscle cells to carry out
  • From pancreatic beta cells
  • ______________ - polysaccharide, polymer of
    glucose and only stored carb in our body
  • 75 stored in skeletal muscle
  • 25 in hepatocytes

7
Glycogenolysis fig 25.11
  • Glucose release
  • Body activities require ATP ? glycogen stores in
    hepatocytes break down
  • Glucose ? blood ? cells for catabolism
  • Glucose ? ATP
  • Lactic acid (in muscle) ? glucose (in liver)
  • Phosphorylase activated by ____________ (from
    pancreatic alpha cells) ___________ (adrenal
    medulla)
  • Reversal of steps in glycogenesis

8
Glycogenesis glycogenolysis
9
Insulin pg 646-649
  • Released in response to ? blood glucose
  • Ach released from vagus nerve ? _________________
  • Certain amino acids in blood (after protein meal)
  • ________ s.i. hormone released due to glucose
    in gi tract
  • Accelerates facilitated diffusion of glucose
  • ? glycogenesis (glucose ? glycogen)
  • ? a.a uptake for ? protein synthesis
  • ? f.a. synthesis
  • Slows glycogenolysis
  • Slows gluconeogenesis

10
Fig 18.18
11
Figure 18.19
12
Glucagon
  • Stimulates ________________ in liver cells
  • Stimulates ________________
  • Glucose released into blood
  • Secretion stimulated by
  • Low blood glucose
  • ? activity of sympathetic NS (as w/exercise)
  • ? a.a in blood if blood glucose is low (after
    high protein meal)

13
Gluconeogenesis
  • Newly formed glucose
  • Non carbohydrate sources
  • Lactic acid
  • Glycerol
  • Amino acids about 60 of a.a. in body can be
    used for this
  • Stimulated by
  • _______________(glucocorticoid)
  • _______________

14
Gluconeogenesis fig 25.12
15
Glucose tolerance
  • Test bodys ability to process glucose
  • Diagnostic for hypoglycemia, __________
    __________, or malabsorption syndrome
  • Dependent upon ability of
  • Pancreas to produce release insulin
  • Cell response to insulin (membrane sensitivity)
  • Small intestine to absorb glucose
  • Liver to take up store glucose

16
Glucose tolerance (2)
  • ________ mg/100 mL blood normal, fasting
  • Load ? glucose ? within 1 hour
  • Normal followed by gradual decline
  • Abnormal glucose levels remain elevated
  • Insulin response major factor
  • See lab manual, exercise 3 for more info

17
Diabetes mellitus
  • Endocrine disorder, inability to produce (type 1)
    or use (type 2) insulin
  • 4th leading cause of death by disease in US
  • Type 1 insulin-dependent diabetes mellitus
  • ____________________ destroys pancreatic beta
    cells
  • Insulin injections required to prevent death
  • Type 2- non-insulin dependent
  • More common than type 1 ? gt90 of cases
  • Often obese gt35 yr, but, type 2 obese children
    teens ?
  • Target cells ____________ to insulin, downreg of
    receptors

18
Lipoproteins are transporters
  • __________________- lipid protein combination
  • Outer- proteins, phospholipids, cholesterol
  • Proteins help solubilize lipids in body fluids
  • Inner core- triglycerides and other lipids
  • Categorized by _________ (lipids low, proteins
    high density)
  • Chylomicrons- s.i., many dietary lipids ? adipose
  • VLDLs- very low density lipoproteins, form in
    hepatocytes, lipids? adipocytes for storage or
    muscle
  • LDLs- carry 75 of total cholesterol in blood
    which goes to
  • Cell membranes for repair, synthesis of steroid
    hormones, bile salts
  • When in excess deposit in smooth muscle of
    arteries ? fatty plaque
  • HDLs- remove excess cholesterol from cells? liver
    (elimination)

19
Lipoprotein figure 25.13
20
Pathways of lipid metabolism
21
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22
Metabolic regulation depend on
  • Chemical environment in cell
  • ATP level
  • Oxygen
  • Nervous system
  • Endocrine system
  • Some functions of metabolism depend on- time
    since last meal

23
Absorptive state figure 25.17
  • Ingested ______________________ necessary for 2
    main events of this state
  • Oxidation of glucose for ATP production
  • Storage of excess food molecules occurring (for
    later use between meals)
  • Hepatocytes, adipocytes, skeletal muscle
  • ? 4 hours for complete absorption
  • _____________ dominates during this state

24
Reactions (absorptive state) figure 25.17
  • 50 glucose absorbed from meal ? _________
  • Most glu that enters liver (10) ? ___________
  • Some f.a. triglycerides syn in liver
  • Some stay in liver
  • Most ? VLDLs to carry lipids to adipose
  • Adipocytes uptake glu (40)? _____________
  • Most dietary lipids ? adipose tissue
  • Chylomicrons, VLDLs, or synthesized
  • Many a.a.? liver? Krebs- ATP, or syn glu fa
  • Some a.a. ? hepatocytes synthesize proteins
  • a.a not taken up in hepatocytes ? body cells
  • synthesis of proteins, hormones, or enzymes

25
Absorptive state
26
Regulation of metabolism- absorptive
  • GIP ? blood glu ( some aa)?______________
  • Insulin (see table 25.3)
  • ? enzymes of anabolism syn to storage molecules
  • ? enzymes of catabolism
  • Promotes glucose a.a ? ____________________
  • Stim. phosphoyrlation of glu - hepatocytes?G6P
  • Stim. G6P ? glycogen in liver muscle
  • Enhances _____________________(liver adipose)
  • Stim. protein syn throughout body

27
Postabsorptive state figure 25.18
  • ________ of nutrients from GI tract ________
  • Bodily energy needs being met by fuel already
    created
  • If no snacks, times ? 4 hours spent in
    postabsorptive state (late morning, late
    afternoon, most night)
  • __________________ involved in regulation
  • Glucose production glucose conservation

28
Postabsorptive glucose production
  • ATP dominant fuel in ______ (fa cant cross bbb)
  • RBC get ATP from glycolysis - lack mitochondria
  • Rxns that _____________________ in this state
  • Breakdown of liver glycogen
  • Lipolysis
  • Gluconeogenesis using lactic acid
  • Gluconeogenesis using amino acids

29
Postabsorptive glucose conservation
  • Reactions to _______________ in this state
  • Oxidation of fatty acids
  • Oxidation of lactic acids (in cardiac muscle)
  • Oxidation of amino acids (in hepatocytes)
  • Oxidation of ketone bodies
  • Can be used by heart, kidneys, other tissue ?
    ATP
  • breakdown of muscle glycogen
  • Glycogen ? G6P (glycolysis) ? ATP

30
Postabsorptive state
31
Regulation of metabolism postabsorb
  • Hormones
  • ______________ hormones
  • Glucagon- ? gluconeogenesis glycogenolysis
  • See table 25.4 for summary
  • Sympathetic NS
  • Glucose sensitive neurons activate release of NT
    norepinephrine
  • Adrenal medulla releases
  • Epinephrine stimulates glycogen breakdown
  • Norepinephrine both NE E stimulate lipolysis

32
Metabolism- fasting starvation
  • ___________- w/out food several hours few days
  • Glycogen stores depleted within hours
  • Protein catabolism gt anabolism, aa? gluconeo
  • _______________- weeks or months of food
    deprivation or inadequate intake
  • Triglyceride proteins stores- last several
    weeks
  • Amt of adipose tissue determines survival time
  • During both
  • Nervous tissue RBC use glucose ? ATP
  • ? ketone bodies in hepatocytes ? plasma ? bbb
  • ? glu needed for ATP syn, ? need for gluconeo, ?
    catabolism of muscle proteins

33
Heat and energy
  • Heat- form of energy
  • Measured by temperature
  • Expressed in units- calories
  • calorie (cal) amt of heat to ? temp of 1g of
    water 1C
  • cal is small ? use kilocalories (kcal) or Calorie
    (Cal)
  • Core body temp 37C, shell 1-6C less
  • Too high ? denatures body proteins
  • Too low ? cause cardiac arrhythmias (? death)

34
Heat production
  • ________________
  • Hormonesthyroid, testosterone, insulin, hGH
  • _________________ NE E
  • Body temp - ? body temp ? ? biochem rxns
  • Ingestion of food energy cost of digestion
  • ________ child gt elderly (? during growing)
  • Others gender (males gt females, exception-
    pregnancy ?), climate, sleep, malnutrition

35
Metabolic Rate
  • Overall rate at which metabolic rxns use energy
  • _________________- body quiet, resting fasting
  • BMR- measure amt of oxygen used per kilocalorie
    of food metabolized
  • 1L ____________ to oxidize mix of carbs, proteins
    fats ? 4.8 Cal of energy released
  • BMR 1200-1800 Cal/day in adults
  • Added calories needed 500 small relatively
    inactive person ? 3000 for a person training for
    the Olympics
  • Accounts for 60 of energy expenditure

36
Thyroid hormones metabolism
  • TRH (hypothalamus) ? TSH (pituitary)? release
    thyroid hormones
  • ___________________ in skin hypothalamus sense
    temp ? ? TRH release
  • Thyroid hormones released in bloodstream
  • Slowly ? _____________ by stimulating cell resp.
  • Cells use more O2 ? body temp ?
  • 1C rise in core temp ? biochemical rxns by 10
  • Part of negative feedback loop (fig 25.19)

37
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38
Vitaminsfat vs. water soluble, table 25.6
  • Vitamins organic nutrients- small amt to
    maintain growth metab
  • Do not provide energy, function as coenzymes
  • Most must be ingested, cannot be synthesized
  • _______________ vitamins- absorbed w/dietary
    lipids in chylomicrons, need lipids to be
    absorbed adequate quantities
  • Can be stored in cells (esp. hepatocytes)
  • Vitamins A, D, E, K -- see table for functions
  • Water soluble vitamins- dissolved in bodily
    fluids
  • Excess quantities excreted in urine
  • Several B vitamins, vitamin C see table
  • C, E and beta-carotene-________________________

39
Vitamin Source Function
A, fat soluble Carotene (veg), liver, milk General health of epi cells, antiox.
B complex, fat Whole grain, egg, pork, nuts, liver yeast metabolism, Ach synthesis, steroid hormones
C, water Citrus, tomatoes, green vegetables Protein syn, Ab, collagen form, antioxidant
D, fat Fish-liver oil, egg yolk, fortified milk Absorb Ca P, works w/PTH
K, fat Intes bacteria, spinach, cauli, cabbage, liver Synthesis of several clotting factors by liver
40
Importance of minerals table 25.5
  • Minerals inorganic elements occur naturally in
    earths crust
  • 4 of total body mass, heavily conc in
    _____________
  • Body generally uses ion form
  • Na distribution of water, bicarbonate buffer,
    AP
  • K generation conduction of AP
  • Ca form bones teeth, clotting, nerve muscle
    activity, endo exocytosis, cell chromosome
    motility, glycogen metab, rel NT hormones
  • Fe component of Hb cytochromes in ETC
  • P form bones teeth, blood buffer system,
    nerve muscle activity, energy transfer (ATP),
    part of DNA, RNA
  • I req by thyroid to make hormones, reg
    metabolic rate

41
Nutrition figure 25.20
  • Nutrients- chemical substances in food body cells
    use (growth, maintenance, repair)
  • Water, carbs, lipids, proteins, minerals,
    vitamins
  • Dietary Reference Intake (DRI)- or Recommended
    Daily Allowance (RDA)
  • http//fnic.nal.usda.gov/nal_display/index.php?inf
    o_center4tax_level2tax_subject256topic_id13
    42placement_default0
  • Proteins listed as macronutrients on website

42
Amino acids
  • Building blocks for structural functional cmpds
    in the body (enzymes, membrane carriers,
    hormones)
  • _______________amino acid or ________________amino
    acid that which cannot be synthesized by the
    body and must be acquired through dietary intake
  • Histidine, isoleucine, leucine, lysine,
    methionine, phenylalanine, theronine, tryptophan
    valine
  • Nonessential amino acid can be made by human
    body

43
Protein types and sources
  • _____________ proteins the 9 indispensible a.a.
    are found in animal sources meat, fish,
    poultry, eggs, milk, cheese and yogurt
  • Incomplete proteins- sources that lack 1 of the 9
    indispensible a.a., are found in plants, legumes,
    seeds, grains, nuts, vegetables
  • Complementary protein combinations- those that
    give all the indispensible a.a. by combining
    incomplete with complete protein sources

44
DRI establishment see www.nap.edu
  • Are developed from recommended daily allowance
    adequate intake
  • Increases from infancy thru childhood to
    adulthood- RDA for males females up to the
    age of 13 34 g/day
  • RDA levels off
  • age 19-30 males 56g/d
  • Age 14-18 females 46g/d
  • Males have higher RDA than females
  • Pregnancy double amt of 9-13 yr old girl
    (71g/d)
  • Lactation same as pregnancy

45
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