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EXSS 276: EXAM 2
Metabolism |
sum of all chemical reactions in the body
|
3 Macronutrients
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Protein
Glycogen
Triglycerides
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Glucose
|
6 carbon sugar
major energy source for production of ATP
|
Glycogen |
polymer of glucose
acts as stored form of glucose in liver and skeletal muscle cells
|
Glycolysis |
Glucose breakdown to produce ATP
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Gluconeogenesis
|
formation of glucose from a non-CHO precursor
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Glycogenolysis |
Breakdown of glycogen
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Glycogeneis
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synthesis of glycogen
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Glycolysis converts ___ to ____
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glucose to pyruvate
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1 molecule of glucose =
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2 molecules pyruvate
2 NADH+
2 ATP
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Glycolysis is an ___ process
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anaerobic
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Glycolysis occurs in the ___
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cytosol
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Pyruvate can be converted to ____ or ___
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Lactate or acetyl CoA
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Pyruvate converts to lactate in the ___ & the ____ pathway
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cytosol, anaerobic
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Pyruvate converts to acetyl CoA in the ____ through the ___ pathway
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mitochondrial matrix, aerobic
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Key Enzymes of Glycolysis
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Hexokinase
Phosphofructokinase (PFK)
Lactate dehydrogenase (LDH)
Pyruvate dehydrogenase (PDH)
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Hexokinase |
conversion of glucose to glucose-6-phosphate in step 1 of glycolysis
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Hexokinase is present in step ___ of ___
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1 of glycolysis
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PFK |
plays role in regulating the rate of glycolysis
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LDH
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converts pyruvate to lactate
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PDH |
converts pyruvate to Acetyl-CoA
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Things that increase glycolysis
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Increased ADP, AMP, P (increases activity of PFK)
Decrease oxygen availability, increased H+ ions (decrease ability to metabolize fats)
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Things that decrease rate of glycolysis
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increased glucose-6-phosphate (decreases activity of hexokinase)
increased ATP and citrate (decreases PFK)
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Krebs Cycle converts ____ to ___, ___ and ___
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Acetyl CoA to 1 ATP, 3 NADH+, 1 FADH & CO2
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Kerbs Cycle occurs in the ___
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Mitochondrial matrix
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Electron Transport Chain uses ___ & ____ to produce ___
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NADH & FADH from Krebs Cycle to produce ATP (and H2O)
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ETC is in the ____
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inner mitochondrial membrane
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Anaerobic/aerobic glycolysis yields ATP at a faster rate
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Anaerobic
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Net ATP yield is lower for aerobic/anaerobic glycolysis
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anaerobic |
Net ATP yield for aerobic glycolysis
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38
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___ ATP from glucose to pyruvate
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2
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___ ATP from production of NADH in cytosol
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6
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___ ATP from pyruvate to Acetyl-CoA
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6
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___ ATP from Krebs Cycle & ETC
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24
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ATP yield from anaerobic glycolysis
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2 per glucose
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Hormones that regulate carbohydrate metabolism
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Insulin
glucagon
epinephrine
growth hormone
cortisol
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__ increases glycogenesis (hormone)
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insulin |
___ increases glycogenolysis (hormone)
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epinephrine, glucagon, growth hormone
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___ decreases glycogenolysis (hormone)
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insulin |
___ increases gluconeogenesis (hormone)
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cortisol, glucagon
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___decreases gluconeogenesis (hormone)
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insulin
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____ increases glycolysis (hormone)
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epinephrine |
Beta Oxidation
|
Mitochondrial process; converts fatty acids to Acetyl Co-A
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Lipogenesis
|
lipid synthesis
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Lipolysis
|
lipid breakdown
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Lipid Metabolism: Basic Steps
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Conversion of stored triglyceride to Acetyl-CoA
Acetyl-CoA enters Krebs Cycle
NADH+ & FADH enter ETC
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Lipid metabolism is faster/slower than glycolysis
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Slower (slowest)
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Lipid metabolism produces ___ ATP
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over 100
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Lipid metabolism is a ___ process
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aerobic |
Glycerol converted to ___ or ___ depending on cell's ___ needs
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glucose or pyruvate, ATP
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Fatty acids converted to ___ & enter ____
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Acetyl CoA, Krebs Cycle
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Things that increase rate of lipid metabolism
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increased oxygen availability
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Things that decrease lipid metabolism
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increased Acetyl-CoA, NADH+
increased lactate, H+ ion produduction
|
Hormones that increase lipolysis
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catecholamines, cortisol, thyroid hormones, growth hormone, IGFs
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Hormones that decrease rate of lipolysis
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insulin
|
Hormones that increase lipogenesis
|
insulin |
Ketone bodies are a result of ___
|
lipid catabolism
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Ketoacidosis (acidosis)
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abnormally low blood pressure
body cannot buffer acids
sweet smell on breath
occurs in diabetics w/ insulin deficiency |
Transamination |
Amino group transferred from one molecule to anohter
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Deamination
|
Removal of amino group from molecule
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Hormones that increase protein catabolism
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cortisol
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Hormones that increase protein anabolism
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growth hormone, IGFs, thyroid hormones, insulin, estrogen, testosterone
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3 metabolic crossroads
|
glucose-6-phosphate
pyruvate
acetyl-CoA
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Positive Energy Balance
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energy intake > energy expenditure
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Energy Balance
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energy output increase > intake
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Negative Energy Balance
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output > intake (weight loss)
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Types of muscle
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Skeletal
Cardiac
Smooth
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Major functions of muscle
|
produce body movements
stabilize body positions
regulate organ volumes
movement of substances w/in body
produce heat
|
Major properties of muscle
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excitability
contractility
extensibility
elasticity
thermal
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Excitability
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ability to respond to stimuli and produce electrical signals
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contractility
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ability to shorten and generate force once excited
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Extensibility
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ability to stretch without damaging the tissue
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Elasticity
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ability to return to normal length after being stretched
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Thermal
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ability to produce heat energy
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Characteristics of Skeletal Muscles
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Attaches to bone, skin or fascia
Striated w/ light & dark bands
Voluntary control
Multi-nucleated
Many cells called fibers
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Skeletal Muscle Structure
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Fascicles
Fibers
Myofibrils
Sarcomeres
Filaments
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Connective tissue surrounding muscles
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epimysium
perimysium
endomysium
|
Epimysium
|
surrounds the whole muscle
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Perimysium
|
surrounds bundles (fascicles) of 10-100 muscle cells
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Endomysium
|
separates individual muscle cells
|
Myofibrils |
contractile elements of muscle
composed of protein filaments
|
Sarcolemma |
muscle cell membrane
|
T Tubules
|
invaginations of sarcolemma
quickly spread AP to all parts of muscle fiber
|
Sarcoplasm |
cytoplasm of muscle cell
lots of glycogen
myoglobin (binds oxygen for ATP production)
|
Sarcoplasmic Reticulum
|
tubular sacs similar to smooth ER
Stores Ca
Releases Ca to contract muscle
|
Proteins of Myofibrils
|
Contractile
Regulatory
Structural
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Contractile Protein
|
myosin and actin
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Regulatory proteins
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turn contraction on and off
troponin and tropomyosin
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Structural Proteins
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provide proper alignment, elasticity & extensibility
link myofibrils to sarcolemma
titin, myomesin, nebulin and dystropin
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Thick filaments
|
myosin |
Thin filaments
|
actin, troponin, tropomyosin
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Neuromuscular Junction
|
Region of synaptic contact between a somatic motor neuron & a skeletal muscle fiber
synaptic end bulb to motor end plate
ACh is neurotransmitter
|
Motor Unit
|
one motor neuron & all the skeletal muscle fibers it innervates
|
Motor Unit Recruitment
|
Increasing the number of active motor units
|
Not all motor units in a muscle fire at same time because..
|
delays fatigue, longer periods of contraction, smooth muscular contraction (not jerky)
|
Muscle Tone important for..
|
maintaining posture
maintaing blood pressure
|
Muscle Contraction/Relaxation Cycle
|
AP arrives at motor end plate; Release of Ca2+ from SR
Removal of troponin-tropomyosin complexes from binding sites; sliding of actin & myosin filaments to shorten sarcomeres
cessation of AP; Ca2 pumped back into SR
Toponin-tropomyosin complexes cover binding sites; sarcomeres return to resting length
|
Factors affecting force production
|
# of motor units activated
type of motor units activate
size of muscle
muscle length
joint angle
speed of action
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___ motor units activate, ___ force
|
increase, increase
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___ fast twitch motor neurons activated, ___ force
|
increase, increase
|
___ muscle fiber size, ___ force
|
increase, increase
|
___ force, ___ velocity
|
decrease, increase
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Types of Skeletal Muscle Fibers
|
Type 1: slow oxidative, slow-twitch
Type IIa: fast oxidative-glycolytic (FOG)
Type IIb: fast glycolytic, fast-twitch
|
Type 1, slow oxidative, slow twitch
|
Red in color
lots of mitochondria, myoglobin, blood vessels
produce ATP through aerobic metabolism
prolonged, sustained contractions
maintaining posture, endurance
|
Type IIa, fast oxidative-glycolytic
|
pink
fewer mitochondria, myoglobin, blood vessels
produce ATP through aerobic metabolism and anaerobic glycolysis
prolonged activities but quicker than type I
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Type IIb, fast glycolytic, fast twitch
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white
few mitochondria & blood vessels, low myoglobin content
produce ATP through anaerobic glycolysis
anaerobic movements for short duration
weight lifting, sprinting, etc.
|
Muscle Fatigue
|
inability to contract muscles
|
Contributing factors of muscle fatigue
|
protective mechanism
insufficient release of ACh
depletion of CP
decline of Ca
insufficient oxygen or glycogen
buildup of lactic acid
|
Muscle Cramps
|
painful sustained muscle contraction
myosin head doesn't completely detach from actin
insufficient ATP
electrolyte imbalance
|
Rigor Mortis
|
stiffening of muscles after death
chemical changes in muscle
No ATP; lose ability to pump Ca into SR; diffuses into sarcomere; binds w/ troponin, allows crossbridges to form
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Characteristics of Cardiac Muscle
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Involuntary
Striated
Single, centrally located nucleus
Large and numerous mitochondria to generate ATP aerobically
cells connected by intercalated discs
auto rhythmic
|
Contraction of Cardiac Muscle is ___ than skeletal
|
longer (10-15 x longer)
|
Smooth Muscle Characteristics
|
Small, involuntary cells
non-striated
single, oval-shaped, centrally located nucleus
attached to hair follicles in skin
in walls of hollow organs
|
Types of Smooth Muscle
|
Visceral
Multi-unit
|