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Metabolismeotot dan tulang[Blok 7: Lokomosi]
Rifana Cholidah
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Muscle
a place of many metabolic activities
Three types of muscle: skeletal, cardiac, smooth
The main function: to turn chemical energy intomechanical energy through the breaking down
of ATP Changes in muscle metabolism during prolonged
activities: metabolic rate, relative rate of utilizationof glucose and fatty acids as fuel
Main function as locomotion and heat production,
also to provide protein reserves forgluconeogenesis during fasting
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Structure of muscle Contains light (l-band;
isotropic) band anddark (A-band;anisotropic) band
Center of the I-band:darker Z-line
Center of A-band:lighter H-zone with thecentral M-line
Sarcomere: From Z to Z-line
M-line
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Continued..
I-band (thin, actin filaments, extendingfrom Z-line)
A-band (thick, myosin filaments,
extending from M-line)Darker straining regions of the A-band: the
region of overlap of actin and myosin
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Mucle energy metabolism
Based on ATPase activity and the source ofATP synthesis: anaerobic and aerobic
Mucle types related to muscle function
Striated (skeletal) muscle is divided into:
1. Fast-glycolytic muscle:
White in appearance
Low blood flow Low mitochondrial density
Decreased myoglobin content
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2. Fast glycolytic fibers:
o
Increased glycogen storeo Lower fat content
o Depends on glycogen and anaerobicglycolysis for short burst contraction
o Not capable of sustaining long contractionscompared to slow-oxidative fibers
3. Slow-oxidative fibers:
o Well perfused with blood
o Rich in mitochondia and myoglobin
o Ability in sustaining low-intensity contractionfor long periods
o Slow muscle uses fatty acid oxidation for ATPproduction
o The characteristic of cardiac muscle insimilar with slow-oxidative skeletal muscle
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Muscle contraction
Membrane ion fluxCalcium release and re-uptake
ATP hydrolysis and synthesis:
Maintenance of ion gradients
Restoration of intracellular Ca levels Actual process of muscle shortening
o Muscle shortening: sarcomere dependson the interaction of filamentous protein,
actin (thin) „n myosin (thick filaments) o Myosin head has ATPase activity
hydrolyzes ATP
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Continued…
Thick filaments is made up from myosinprotein
Thin filaments:
Mainly actin
Tropomyosin and troponin family Muscle contraction (shortening)=
ATP is available
Calcium is present
ATP availability depends on:
Synthesis from ADP by the creatinephosphate
Production from aerobic „nanaerobic metabolism
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: actin: troponin
: tropomyosin
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Energy supplies
1. Short-duration, high intensity contraction: Depends on ATP stores
an additional reserve of the high-energystorage compound (creatine-P) ATPrapidly during the 1st minute as
glycogenolysis is activated During the first stages of exercise:
Muscle glycogenolysis
Followed by both anaerobic and aerobicglycogenolysis as the major source ofenergy
Calcium entry into muscle to formulateCa2+ --calmodilum complex activates
phosphorylase kinase
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2. Low intensity, long duration contractions
Availability and utilization of O2 as thelimitation for sustaining continuous PA
Low intensity of PA, O2 is readily available
Aerobic oxidation of lipid is the main source
of ATP synthesis Art the higher work intensities O2 can
become limiting the work rate of the
muscle decreases
Adaptation to regular vigorous PA involves
increasing muscle mass and oxygenation
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During the first 15-30 minutes of exercise,there is a gradual shift glycogenolysis and
aerobic glycolysis to aerobic metabolism offatty acids
In many cases, the glycogen reserves inmuscle are sufficient to support the energyneeds of muscle during exercise for about 1
hour
Exercise continues epinephrine activateshepatic gluconeogenesis to provide anexogenous source of glucose for muscle
Lipids gradually become the main source ofenergy in muscle during long-term exercise
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3. Long-term muscle performance
Ex: marathon runner
Glycogen is the storage form of glucose in skeletalmuscle
For the sufficient availability of ATP, a continuingbasal level of glycogen and CHO metabolism inmuscle is required
CHO metabolism is important as a source ofpyruvate
Increasing the availability of circulating glucosefrom gluconeogenesis or CHO ingestion
Increased the utilization of fatty acids
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Bone
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Fungsi tulang
Memberikan rangka tubuh
Melindungi organ-organ vital
Pergerakan
Menjaga keseimbangan elektrolit danasam-basa
Produksi sel darah
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Struktur tulang
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Bone Metabolism
The factors
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A. Hormonal
Vitamin D
Parathyroidhormone
Estrogen
Thyroid hormone
Insulin
B. Nutrisi
Calcium (Ca)
Phosporus(P)
Magnesium
Zinc
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Lifestyle Factor Physical activity
Smoking:
Menopause yang lebih awal Penurunan BMD
Alcohol consumption:
Meningkatkan osteoporotic fracture
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Calcium
Salah satu mineral yang penting untuk tulang
1200gram pada org dewasa (1-2% BW)
Metabolisme Ca Vit D, calcitonin, & PTH
Bersama dg P, Ca membentuk “insoluble salt”(hydroxyapatite) tulang dan gigi
Kedua mineral ini sangat penting utk bone strength rigiditas dan struktur
Keseimbangan Ca dan P
Ketersediaan Ca:
Dietary Ca
Absorpsi Ca Absorpsi t.u di usus halus, sebagian kecil di colon
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Phoshorus
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Penting untuk mineralisasi tulang
Kurangnya P dapat menyebabkan
gangguan mineralisasi tulang
80% dari total body P terdapat dijaingan
tulang dan gigi
85% P ditemukan dalam bentuk kristal
hydroxyapatite
P homeostasis sangat dipengaruhi oleh bone
formation
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Summary
ATP produced in muscle is important tomaintenance ion gradient, restoration of Ca leveland the contractile process
Fast glycolytic muscle: depends on glycogen and
anaerobic glycolysis for short, high intensity ofmuscle activity
Slow oxidative muscle: anaerobic tissue , uses fatas the main source
During the initial phases, depends on
glycogenolysis and glycolysis, then graduallyconverts to fat metabolism for long-term energyproduction
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Thanks
Any questions
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