M2 L12 Flashcards
(13 cards)
1
Q
what are the key differences between skeletal muscle fibre types?
A
- type of myosin produced
- oxidative vs glycolytic
- type of serca pump
2
Q
Type I fibres
A
- slow myosin ATPase
- many mitochondria, many oxidative enzymes, rich blood supply
- thin circumference
- slow SERCA
- pinker
3
Q
type IIA fibres
A
- fast myosin ATPase
- mix of oxidative and glycolytic
- intermediate speed/fatigue
4
Q
type IIB
A
glycolytic fibres
- fast myosin ATPase
- few mitochondria, few oxidative enzymes, few capillaries
- fast SERCA
5
Q
what are the effects of strength training
A
- more actin and my son -> increased fibre diameter
- more cross-bridges -> more force
6
Q
what are the effects of endurance training?
A
- increased oxidative capacity -> increased ability for sustained activity
- more mitochondria (more enzymes)
- more capillaries, more myoglobin
- increased muscle stores of lipids
- increased ability to use lipids directly from blood
7
Q
factors that affect fibre distribution
A
- motor unit firing rate
- disease
- genetics
- space flight (less slow fibres)
- aging (less fast fibres)
8
Q
motor units
A
- all muscles in one unit are the same type (slow or fast)
- amount of fibres per unit varies
- all fibres in unit activate at once
9
Q
what regulates muscle force
A
recruitment and summation
10
Q
recruitment
A
- number of fibres active at once (determined by number of neurons active)
- small units recruited first, then largest
- smaller units more tonically active
- fine graded control of small forces
11
Q
summation
A
- higher stimulus frequency
- changes force produced by one motor unit
- SERCA cannot clear calcium between twitches
12
Q
which type of muscle contraction is most likely to cause injury?
A
lengthening
13
Q
what is length tension relationship?
A
there is an optimal overlap of thick and thin filaments
- too short and not enough cross bridges
- too much and everything is cramped
