MMB [019] Muscle Function in Health and Diseases Flashcards
…..are low motor neurons
Alpha fibers
True or false ?
A single motor neuron can innervate both types of muscle fibers
FALSE :
-Each motor neuron innervates only one kind of muscle fibers
- either (slow oxidative = red muscle fibers) or (fast glycolytic = white muscle fibers)
Concentric isotonic Contraction ?
Muscle shortens As lifting a load
Eccentric isotonic Contraction ?
-Muscle lengthens while contracting
-contractile activity resists stretch = lengthening contraction
AS lowering a load to the ground
Which type of isotonic Contractions is Most likely to cause muscle injury ?
Eccentric isotonic (lengthening)
Def Muscle Fatigue
It is the temporary decrease in muscle force of contraction due to previous contractile activity
The onset of muscle fatigue depends on ?
—1) Duration & intensity of contractile activity
— 2) Type of muscle fiber, some muscle fibers resists fatigue
Types of muscle fatigue ?
—A) Muscular fatigue
— B) Neuromuscular fatigue
—C) Central psychological fatigue
Explain Muscular fatigue
—Depletion of energy stores inside the muscle (glycogen)
— lactic acid accumulation with ↑ intracellular acidity inhibition of the key enzymes in energy pathways
Why lactic acid accumulation in muscles further complicate energy manifestation ?
↑ intracellular acidity inhibits the key enzymes in energy pathways
Explain Neuromuscular fatigue :
— It is due to depletion of Acetyl choline (Ach) stores at the motor end plate as the rate of Ach release is more than its rate of synthesis
—It occurs during fast-powerful activities
When does Neuromuscular fatigue accur ?
It occurs during fast-powerful activities
Explain Central psychological fatigue
—Occurs when CNS no longer adequately activates the motor neurons supplying the working muscles
‘Athlete’s performance is not only dependent on the physical state of his muscles, but also, upon the will to win “ability to overcome psychological fatigue’
A special type of muscle fibers ?
—There is another type of skeletal muscle fibers called fast oxidative (type IIa)
—It has combined features from both fiber types and rare in human
Which muscle fiber type is of larger diameter ?
White muscle fibers typII
2 types of changes can be induced by training in muscle fibres:
•Changes in their vascular supply & ATP synthesis capacity
•Changes in their diameter (CSA)