Chapter 24) Metabolism and Nutrition Flashcards

1
Q

Nutrition

A
  • Nutritent) A substance in food the body uses for growth, maintenace, and repair.
  • Major Nutirents (Macronutrients)
    • Buld of ingested food
    • Carbs, Lipids and Proteins.
  • Other Nutrients (micronutrients)
    • Required in smaller ammounts
    • Vitamins and minerals
  • Water is important but not a nutrinent
  • Food Gorups) Fruits, Vegtables, Grains, Protein, Dairy
  • Essential Nutrients) nutrients that cannot be syntasized by the liver
    • Around 40 molecules
    • Non-essential nutrients viral to life as well.
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2
Q

Proteins

A
  • Complete Protiens
    • Meet all the bodys protein requirments
    • Eggs, Milk, Fish and most meats
  • Incomplete proteins
    • Nuts, Legumes, Beans, Cereals are protein rich but incomplete because they don’t contin all proteins needed for building
    • can be complete if ingested together.
  • All or None Rule) All amino acids need to be present to build a specific protein. If one is missing protein may not be built.
    • Amino Acids are not stored.
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3
Q

Vitamins

A
  • Two Types
  • Water-Soluable Vitamina
    • B complex and C are absorbed with water
    • B12 requires intrensic factor
    • Any not used are excreted from the body within one hour; issues with accumulation are rare
  • Fat-soluable Vitamins
    • A, D, E. and K absorbed with lipid digestion products
    • Sored in the body, except for vitamin K
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4
Q

Metabolism

A
  • Metabolism) Biochemical reactions inside cells involving nutrients
  • Two reactions
  • Anabolism) synthesis of large molecules from small ones
    • ex) amino acids > Proteins
  • Catabolsim) hydrolysis of complex strucures to simpler ones
    • Ex) Proteins > Amino Acids.
  • three major Stages
  1. Stage 1) Digestion and absorption in GI tract
    • moves nutrients into blood then the tissue cells
  2. Stage 2) Occurs in the Cytoplasm of Tissue Cells
    • Nutrients are build into lipids, proteins or glycogen by anabolic pathways or broken into smaller fragemnts by catabolic pathways
    • Many end up as Pyruvic acid, a metabolic intemediate
  3. Stage 3) Occurs in Mitohondria
    • Almost completely catabolic; requiures O2 and comlete breakdown of all stage 2 products.
    • Most are converted into acetal CoA > CO2, ATP
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5
Q

Cellular Respiration

A
  • Group of catabolic reacations collecively called cellular respiration
    • Glycolysis
    • Citric Acid cycle
    • Oxidative phosphorylation
  • Catabolism of fuel from food is captured in the form of ATP in cells
    • as ATP is hydrolyzed, Enymes shift high energy phosphate to other molecules (phospholrilztion)
  • Phosphorylated molecules activated to preform cellular functions
    • Goal > Trap chemical enrgy in ATP
    • Energy is also stored in glycogen and fats
    • Oxidation of Food for Fuel.
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6
Q

Carb Metabolism

A
  • oxidation of Glucose
    • CH12O6 + 6O2 > 6H20 + 6CO2 + 32ATP + Heat
  • Requires work of three pathways
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7
Q

Glycolysis

A
  • Glycolysis) “Sugar Splitting” (Glycotic pathway)
    • 10 step pathway
    • Convert glucose to two pyruvic acid
    • All steps are fully reversable except for the first (can be converted back to gluose)
    • Reaction keeps intercellular glucoce concentration low > continued glucose entry rrwuired
  • Anerobic) occurs with or without the presence of O2
  • Final Products of Glycolysis
    • 2 Pyruvic Acid (C3H4O3)
    • 2 NADH + H+
    • Net gain of 2 ATP (2 in 4 out)
  • NAD+ Must be present to acccept H+ atoms for glycolysis to continue
    • NAD+ supply limited; NADH must dontate H+ to become NADH+ and for glycolysic to continue
    • O2 Present) Occurs in midochondria in Eletron transport chain (ETC)
    • No O2 present) NADH gives H+ to pyrivic acid and it becomes Latic Acid.
  • Fate of Latic Acid
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8
Q

Role of NADH/ production of Latic Acid

A
  • NAD+ Must be present to acccept H+ atoms for glycolysis to continue
    • NAD+ supply limited; NADH must dontate H+ to become NADH+ and for glycolysic to continue
    • O2 Present) Occurs in midochondria in Eletron transport chain (ETC)
    • No O2 present) NADH gives H+ to pyrivic acid and it becomes Latic Acid.
  • Fate of Latic Acid
    • Some laves cell > liver
    • May be converted to Glucose-6-Phosphate for storage
    • May be de-phosphorlyated and release glucose to the blood.
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9
Q

Transitional Phase) Citric Acid Cycle (Krebs Cycle)

A
  • Occurs in Mitochondrial Matrix
  • Fueled by pyruvic acid from glycolysis and fatty acids from fat breakdown.
  • Transitional Phase
    • Occurs between glycolysis and Citric Acid Cycle
    • Converts Pyruvic Acid to Acetyl CoA (Coenzyme A)
    • Forms Molecule of CO2 and NADH
  • Products of Each Turn of The Citric Acid Cycle
    • 1 glucose > 2 Pyruvic acid > 2 turns of Krebs cycle
    • Final Producets) 6NADH, 2FADH2, 4CO2, 2ATP,
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10
Q

Electron Transport Chain and Oxidative Phosphorlation

A
  • None of the reactions in the citric acid cycle use oxygen diretly
  • ELectron Transport Chain) Carries out final catabolic reactions in mitochondrial membrane
    • Reduced coenzymes produced in citric acid cycle are the substrates for the electron transfer chain
    • Pathways are coupleled and aerobic (oxygen required)_
  • Overview
    • NADH + H+ and FADH2 (From glycolysis and Krebs Cycle) deliver H+ atoms
    • H+ combines with O2 to form water
    • Energy releases harnessed > Turned into ATP via Oxidative Phosphorlization
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11
Q

Summary of ATP prodution

A
  • Complete Oxifation of 1 Glucose
    • Glycolysis + Krebs Cycle + Electron Transport Produces Co2, H20, and 32 molecules of ATP.
    • Net result is about 30 ATP because of energy required to move NADH+ H+
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12
Q
A
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13
Q

Glycogenesis, Glycogenolysis, and Glucogenesis

A
  • Glycolysis) Converts Glucose to Pyruvic Acid.
  • Glycogenisis) Polymerizes glucose to form glycogen
    • Liver and Skeletal mucles
  • Glycogenolysis) Hydrolyzes glycogen to glucose monomers
    • hepatocytes and some kindey and intestinal cells
  • Gluconeogenisis) Forms glucose from noncarb precursors
    • Formed in liver from glycerol and amino acids when blood glucose drops
    • Protects agains hypoglycemia.
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14
Q

Lipid Metabolism

A
  • Greater Energy yield from glucose or proteins catabolism
  • Chylomicrons) products of fat digestion transported in the lymph
    • Hydrolyzed by endothelial enxymes into Fatty Acids and GLycerol
  • Only Triglycerides are oxidixed for energy
  • Two building blocks oxidized seperatly
  1. Glycerol Pathway
    • Glycerol > Glyceraldhyde-3Phosphate (same as glycolysis)
    • Enters the Krebs Cycle
    • Yeilds about 1/2 the ATP of glucose (15 ATP per glycerol)
  2. Fatty Acid Pathway
    • Pathway in which fatty acids are broken.
    • Turns fatty acids into Acytel CoA
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15
Q

Lypogenisis

A
  • Diatary Glycerol and Fatty Acids not needed for energy > Stored as Triglerecided
  • Tryglyceride Synthesis (Lipogenesis)
    • Occurs when cellular ATP and glucose levels are high
  • Glucose easily converted to fat because acetyl CoA
    • Is intermediate in glucose catabolism
    • Starting point for Fatty Acid Synthesis
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16
Q

Lypolysis

A
  • Stored Fat broken > Glycerol and Fatty Acids for Fuel
    • Done by liver, cardiac muscle, and resting skeletal muscle
  • Converted to Glucose if Carbs Deficent
    • Ability of acetyl CoA to enter citric acid cycle depends on ammount of intermdiate carbohydrayes if glucose is deficent
    • Intermediates are conveted to glucose to feed brain and stop aceytal CoA
  • Ketogenesis) Excess Acetyl CoA is converted to ketone bodies (ketones) which are relesed into the blood
  • Ketosis) accumulation of ketones in blood
17
Q

Protein Metabolism

A
  • Proteins have a limited life span and must be broken down and replaced before they detiorate
  • Amino acids recyleled into a new protein or diffrent compound
  • Protein not stored in the body
    • Excess amino acids are oxidized for energy or converted to fat for storage
  • Amino Acids form most anabolic nutrients
    • Form all proteins and bulk of macromolecules
  • Hormonally Controlled (Growth Hormone, Thyroxine, Sex hormones)
  • Requires complete Set for Protein Syntesis
    • “All or Nothing”
    • Essential amino acids reuqired in diet, nonessential acids can be synthesized in the liver
18
Q

Catabolic-Anabolic Steady State of the Body

A
  • Blood Concentrations of Energy sources equalized between
    • absorbptive state or fed state
    • postabsorptive or fasting state.
  • Absorptiive state laste about four hours after eating begins
    • absorption of nutrients
  • Postabsorbatie State) GI tract is empty and body reserves are broken down to supply energy.
19
Q

Absorbative State

A
  • Anabolism exceeds Catabolism
    • Nutrients are beins stored
  • Carbohydrates) mostly GLucose
    • glucose converted to glycogen or fat in liver
    • Synthesized fat/ proteins relesed to blood as very low density lypoproteins
  • Tryglucerides) Lipoprotein lipase catalyzes lipids od chylomicrons in mucle and fat tissue
    • Most glycerol/fattyacids are converted to triglycerides for storage
    • Triglycerides used by adipose tissue, liver, and muscle as primary energy soruce.
  • Amino Acids) Excess Amino Acids deaminated and used for ATP synthesis or stored as fat in liver
    • most used in protein synthesis.
  • Hormonal Control) Primarily controlled by Insulin; Emhnces
    • Diffucion of glucose into cells
    • Glucose Oxidation for Energy
    • Glycogen and Triglyceride formation
    • Active transport of amino acids into tissue cells
    • Protein Synthesis
    • Inhibits Glucose release from Liver / Gluconeogenesis.
20
Q

Postabsorbative State

A
  • Maintains Blood glucose between meals
    • Makes glucose avaible to the blood
    • Promotes use of fats for energy (saves glucose for organs that need it._
  • Where does postabsortavive blood glucose come from?
    • Glycogenolysis in liver and skeletal muscle
    • Lipolysis in adipose tissue and liver
    • Catabolism of celllar protein when glycogen and fat are nearly exhauseted.
  • Hormonal Control) triggerd by reduced insulin release as blood glucose drops
    • Glucogen) tells liver and adipose to promote glycogenolysis gluconeogenesis.
    • Lypolysis in adipose tissue
  • Amino Acids raise both insulin and glucogen
    • done to make sure there are propper glucose levels.
21
Q

Metabolic Role of the Liver

A
  • Hepatocytes
    • about 500 metabolic funtions
    • Process nearly every class of nutrient
    • Play major role in regulating choleterol levels
    • Stores vitamens and minerals
    • Metabolize alchol, drugs, hormones and bilirubin
  • Cholesterol
    • Structural basis of bole salts, steroid hormones and vitamin D
    • Major component of plasma membranes
    • 15 % of blood cholesterol is injested; rest is made in liver
22
Q

Cholesterol Tranport) Lipoproteins

A
  • Lipoportieins
    • transport cholesterol and triglycerides in the blood
    • Regulate lipid entry/exit at target cells
    • contain triglycerides, phospolipids, cholesterol and protein
    • higher density of lipids > lower density overall
    • higher density of protein > higher density
  • Types of Transport lipoproteins
    • HDLs (high density) highest protein content
      • Transport excess cholesterol from peripheral tissue to liver and become part of bile
      • provide cholesterol to steroid producing organs.
    • LDLs (low density) Cholesterol-rich
      • tranposr chilesterol to pheripheral tissues for membranes, srorage, or gomone synthsis
    • VLDLs (Very low density) mostly triglycerides
      • Transport triglycerides from liver to peripheral tissues
    • Chylomicrons) Lowest denstiy
23
Q

Recomended Cholesterol Levels

A
  • Total cholesterol = 200mg/dl or less
    • Greater leves linked to atherosclerosis
  • High HDL though to protect against heart desiess
  • High LDL) Cholesterol deposits in vessels
24
Q

Trans Fats

A
  • Healty oils with added H+; forced to be solid
  • Worse effect on chlolesteol levels than saturated fats
    • Increase LDL’s and reduce HDL’s
      *
25
Q

Obesity

A
  • Body Mass Index) formula for determining obesity based on height and weight
    • Wt (lb) x 705/(height in inches)2
    • Considered overweight if BMI 25-30
    • Obese if greater than 30
26
Q

Metabolic Rate and Heat Production

A
  • Metabolic Rate) Total heat produced by chemical reactions / mechanical work of the body
  • Basal Metabolic Rate (BMR)
    • reflects energy body needs to perform its essential activties
    • Influenced by body surface area, age, gender, temp, stress, thyroxine
    • Decresed with age; higher in males
    • Increases with stress or temp
  • Total Metabolic Rate (TMR)
    • Rate of kilocalorie consumption needed to fuel all activities
    • Increases with actvitie and food ingestion
27
Q

Regulation Of Body Temp

A
  • Reflects balance between heat procution and loss
  • At rest liver, heart, brain, kindeys and endocrine organs generate the most heat
  • during activity skeletam mucle heat increases dramtically
  • 96.6
    • Increased temp denatures proteins and supresses nuerons
  • Insensible Heat Loss) acompanies water loss
    • 10% of heat production
  • Sensible heat loss) due to body tempratue rising
28
Q

Heat-Promoting Mechanisms

A
  • Constiction of cutaniois blood vessels
  • Shivering
  • Increased Metabolic Rate
    • epinepherine and norepinephiren
    • chemical thermogenisis (nonshiveing)
  • Enhanced thyroxine release (infant)
  • Behavioral modification
    • more clothes
    • drinking hot
    • Changing posture
    • Increasing activity
29
Q

Heat Loss mechanisms

A
  • Dilation of Cutaneous blood vessels
  • Enhnanced sweating
  • Voluntaty measures
    • moving inside
    • wearing light clothes
      *