skeletal muscle: contraction, tension, and fibre types (lecture 9)

Question 1

what is the order of the cross bridge cycle processes

Answer 1

attached state, released state, cocked state, cross bridged state, power stroke state

Question 2

how are myofilaments constructed?

Answer 2

actin (thin filaments) maintain sturcture around each individual myosin (thick) filament with space between the myosin heads and the actin when muscle is relaxed, and through the aid of calcium the myosin head energise and slide the myofilament in a contraction

Question 3

what is a muscle fibres plasma membrane called?

Answer 3

the sarcolemma

Question 4

define the process of recruitment

Answer 4

the activation of more fibres to generate more force

Question 5

outline the frequency of stimulation

Answer 5

a single action potential will result in a contraction pulse, short period of tension called a twitch,
many action potentials fired in a rapid sequence results in a sustained period of tension and a longer contraction (summation),
eventually tetanus will occur where the muscle reach their maximum capacity and plateau

Question 6

explain length tension relationship

Answer 6

muscles have an optimal length where it will be strongest, and maximise force for a contraction. yet if initially shorter or longer than optimal then the result is either not enough cross bridges created, or no space left to contract

Question 7

what is the difference between fast fibres and slow fibres?

Answer 7

fast fibres fatigue quicker but maintain a larger fibre diameter with less capillary and mitochondria supply.
in comparison to the steady force, slow muscle fibres that contain a much larger capillary and mitochondria supply to withstand fatigue longer.
which both allow the fibres to reach their peak tension fast or slowly (relative).