Muscle Structure And Functiom Flashcards
What are the 3 key biochemical characteristics of muscle fibres
1.oxidative capacity
2.types of myosin isoform expressed
3.abundance of contractile protein within the fibre
45-55% of type 1 fibres are where
In arm and leg muscles
What does muscle contraction speed depend on
Depends on the rate of cross bridge cycling, which depends on myosin ATPase isoform
Maximal power output=
Force times shortening velocity
What is oxidative capacity
Number of capillaries, mitochondria and amount of myoglobin
What is gel electrophoresis
Identify myosin isoforms specific to different fibre types
Describe a muscle twitch
1.after stimulation there’s a short latent period exist-corresponds to depolarisation of muscle fibre
2. Contraction calcium released from SR
3.relaxation reuptake of calcium into SR
Speed of shortening is greater in fast fibres:
SR releases calcium at a faster rate
Higher ATPase activity
Motor neurons supplying larger faster motor units have:
1.larger cell bodies
2.large diameter axons
3.greater number of axon branches
4.sparse afferent innervation
5.more complex and extensive motor end plate of neuromuscular junction
What is the henneman size principal
Progressive recruitment of units, force increases in a step wise manner
Slow motor units have:
Easily excitable motor neurons
Fast motor units have:
Higher threshold motor neurons, harder to excite
Muscle force power relationship:
At any given velocity of movement, the peak power generated is greater in a muscle twitch with a higher percent of fast twitch muscle fibres
Muscle force velocity relationship:
At any absolute force exerted by the muscle, the speed of movement is greater in muscles w higher fast twitch fibres.
Maximum velocity of shortening is greater at the lowest force for both slow and fast fibres
