Stauber Skeletal Muscle
Terms
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- (An)aerobic pathways in the different fibers
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Anaerobic -Glucose to lactic acid. Well developed in Type II muscles (Type IIb/X)
Aerobic - Oxid. phosphorylation. Cardiac and Type I muscles. Unlimited capacity for ATP production
- 3 impt. feature of contractile process
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1) hydrolysis of ATP
2) Hydrolysis of ATP linked to muscle shortening and tension development
3) 1 and 2 controlled by Ca. Depolarization -> release of Ca from SR; remobal -> relaxation
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3components of muscle contraction.
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1) Isometric energy (hold load)
2) Energy to perform work (move load)
3) Energy for rate of moving. (velocity) [more X-bridgeport; Inc load=Dec. velocity]
- 4 major proteins in sarcomere
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Actin
Myosin
Tropomyosin
Troponin complex
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Muscle strength.
Force is a function of ___.
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1) (AP) Frequency.
2) Motor unit recruitment
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After load; what is it?
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Additional resistance not directly related to the load.
- Biological properties of Actin
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Activates myosin ATPase; physical-chemical change
- Biological properties of myosin
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-ATPase activity found in myosin glob. heads. (Hydrolysis of ATP)
-Tail region - aggregates. Filamentous, coiled-coiled.
-Form the thick filaments
- Head perpendicular to filament; forms X-bridge.
- Ca trigger pathway
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Triggered by coupling MAP down T-tubule, releasing Ca from lateral cisternae.
The longitudinal SR transports Ca back into storage for relaxation.
Diffusion distance: from SR to Troponin C
- Compared to the number of troponin molecules, how much Ca is release in skeletal muscles?
- Enough to bing all the troponin, given enough time.
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Eccentric muscle actions;
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Can absorbs energy.
- Energy hierarchy
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-ATP (money) - always present in cell.
-Creatine Phosphate (ATM machine) Major storage of high-energy phosphates. Rephosphorylate ATP. Enough for about 30 secs.
-glycogen
-Respiration
-Fat cells
- Fancy names for T-tublue and calcium release channel.
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DHR: dihydropyridine receptor
RyR1: ryanodine receptor
- Force-velocity relationship
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Inc load=Dec. velocity b/c of X-bridges.
For Type I and Type II; Type II move same load 4x faster. (power)
- Functional implication of myosin
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-Isoforms have different ATPase activity
-Low ATPase activity = slow rate of muscle shortening, and vice versa.
- Ismetric contraction
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Total tension - Passive tension = Active tension
- Look at rigor cycle
- Look at rigor cycle
- Muscle fibers anatomy.
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Multinucleated.
Adaptable in diameter.
- Myofibril anatomy.
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Composed of actin and myosin.
Arranged into sarcomere.
Z line
A band
H zone
I band
- Organization w/in sarcomere of actin
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-backbone of thin filaments in sarcomere
[-7 per half-turn of polymer]
- Sarcolemma anatomy.
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Surround muscle fibers.
T-tuble - nutrients diffusion area. Invagination in S.
- Sarcoplasm anatomy.
- The cytoplasm not related to contractile process. Ex: glycogen, ribosomes, mitochondria.
- Sarcoplasmic reticulum anatomy.
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Specialized ER for Ca storage and release.
Lateral cisternae - stores and releases Ca. (More in Type II). 2 + 1 T-tublue = 1 triad.
Longiitudinal tubule.
- Skeletal muscles consume energy in ___.
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Resting (maintain homeostasis); contraction and work; recovery (Ca transport)
- Tell me about the release of Ca from the SR.
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In inc. Ca; binds to troponin C
RyR1 opens; Ca goes down gradient out of cell to Troponin.
- Tropomyosin organization
- In groove b/w 2 actin helixes.
- Troponin complex biological characteristics
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Troponin I - interacts w/ inhibitor protein
Troponin T - binds to tropobyosin
Troponin C - binds to Ca (makes tropomyosin move away from binding sites on actin)
- Type I fibers
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Slow twitch
Oxidative
More mitochondria
Red
- Type II (a and b/X) fibers
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Fast twitch fibers.
IIa - fast twitch, oxidative
IIb/X - fast twitch, glycolytic
White
- What are 4 physiological functions of skeletal muscle?
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-Thermogenesis
-Protein storage
-Psychological
-Biochemical (can absorb energy)
- What's SERCA? What's it do?
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Sarco(endo)plasmic reticulum Ca-ATPase
a Ca pump, uses ATP hydrolysis
2 Ca ion for 1 ATP
SERCA 1 (higher uptake rates; Type II)
SERCA 2a (Type I muscles)