6. Types of striated muscles, energy source of muscle functioning, oxygen debt Flashcards

1
Q

Muscle tissue is constructed from different fibres:

A

fast twitch fibre,
slow twitch fibres
intermediate types as well

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2
Q

fast twist fibre

A

capable of powerful contraction and can cover energy needs by means of anaerobic glycolysis: These are „white”, or phasic muscles.

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3
Q

slow twist fibre

A

capable of more sustained work, and gaining energy only from glucose oxidation. Other names are „red”, or tonic muscle fibres.

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4
Q

intermediate types as well.

A

Fibre types are usually intermixed in most of the muscles: the relative percentage of these distinct fibre types determine the type to which a muscle belongs.

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5
Q

muscle type: ATPase type:

A

The basic difference is found in the speed of the ATPase activity

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6
Q

muscle type: SR pump:

A

The activity of the ATPase must be quickly followed by the removal of calcium: this process can also determine the speed of the calcium signal and that of the muscle twitch.

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7
Q

muscle type: Junction/fibra:

A

myoneural junction in phasic fibres provides a 1:1 fibre:nerve connection ratio. A motor nerve fibre splits in many branches 25:1 fibre:nerve ratio is normal.

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8
Q

muscle types: T-system:

A

the development of a T-tubule system can obviously increase contractile speed.

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9
Q

muscle type: Muscle AP/neural AP:

A

Red muscles do not require frequent AP discharges to contract: rare AP signals are also able to cause almost continous contraction.

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10
Q

muscle type: Contraction time:

A

The fastest phasic fibres (e.g. in ocular muscles) are able to contract totally within a few milliseconds.

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11
Q

muscle type: Metabolism:

A

By definition, it is the type of metabolism what separates muscle fibre types.

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12
Q

Muscle type: Fatigue:

A

Since red muscle is capable to produce energy continously by oxidative processes, and since lack of oxygen does not normally occur, red muscles practically are not exhaustible.

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13
Q

muscle type: Fibre length:

A

The longer the fibres are in a muscle, the more efficient becomes the mechanical movement.

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14
Q

energy source of muscle functioning

A

ATP
creation-phospahte
anaerobic glycolysis
oxidative phosphorilation

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15
Q

ATP

A

Both contraction + relaxation need ATP! ATP concentration of Myocyte :5 mmol/l
o covers the O2 need for 2-3 sec only

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16
Q

Creatin-phosphate

A

Provides energy reserve for short term, intensive contraction
o Concentration of Myocyte CRP :20 mmol/l

17
Q

Anaerobic glycolysis

A

Energy source can be:
▪ glycogen(for fast movement;glycogenolysis)
▪ glucose(energy source of prolonged, long term contraction!!). o If more ATP is used than produced, it leads to oxygen debt

18
Q

Oxidative phosphorilation

A

o Energy source of very-long term muscle activity (Red-muscles)
o Pyruvate is transformed to AcCoA