Muscle Ageing W4 Flashcards
What is the equation for power?
Power= Force x Velocity
Where does strength loss occur primarily when decreased with age?
Lower body
What gender has greater age-related declines in velocity?
Women
What happens with age?
Lose muscle strength with age
Greater loss in lower limbs
Muscle power decreases
Fall likelihood increases
What has a greater loss with age- muscle strength or muscle loss?
Muscle strength
What happens to motor units with age?
They decrease in number
What does a loss of motor units do?
Causes muscle fibres to become denervated
Causes muscle atrophy
Causes muscle fibre loss
How does the size of motor units effect their efficiency?
Motor units become less efficient
What can atrophying fibres be reinnervated by?
Remaining MUs
How does denervation and collateral re-innervation alter muscle characteristics?
Increases co-expression of myosin isoforms
Increases force output
Decreases velocity of contraction and hence power
How does denervation and collateral re-innervate muscle fibres?
Increases size of motor units
Preserves some muscle mass
How does changes to the excitation-coupling alter muscle function?
Decreases Ca2+ release from SR
How does changes to the sarcoplasmic reticulum alter muscle function?
Decreases Ca2+ uptake
How does changes to showing of the myosin molecule alter function?
Decreases intrinsic speed of shortening
How does changes to reduced acto-myosin cross bridges alter function?
Decreases force output per muscle fibre
