Week 6-Part 2. Skeletal muscles.

winniesmith's version from 2016-11-08 15:08

Section 1

Question Answer
How would you measure tension developmentAn electromyogram
What is a twitch A single stimulus-contraction-relaxation sequence.
What is the latent period?Period between the stimulus arriving and the muscle contracting.
What happens in the latent period?Begins at stimulation. Action potential sweeps across the sarcolemma. Ca2+ released by SR.
What is summation?Addition of 1 twitch to another.
How does summation happen?If a 2nd stimulus arrives before the relaxation phase, a second, more powerful contraction occurs
What is an incomplete tetanus?Muscle producing peak tension during rapid cycles of contraction and relaxation.
What is complete tetanus?when the rate of stimulation is increased until relaxation phase is eliminated. Contractions happen so fast there is no time for relaxation. Continuous contraction.

Section 2

Question Answer
What are the two types of muscle contraction?Isotonic and Isometric
What is isotonic contractionTension rises to a level that is maintained until relaxation occurs. Skeletal muscle shortens in length and bulges.
What is an isometric contractionTension continues to rise but the muscle does not change length. Such as pushing.
What are the 2 types of Skeletal muscle fibres?Fast fibres and Slow fibres.
Mix of both fibres.
Features of fast fibres-Contract very quickly
-Large in diameter
-Contain densely packed myofibrils -Large glycogen reserves
-Relatively few mitochondria
-Produce powerful contractions
-Fatigue rapidly
Features of slow fibres-Are slow to contract
-Small diameter
-Can continue contracting for extended periods (large O2 supply)
-More mitochondria
-High oxygen supply
-Contain myoglobin (red pigment, binds oxygen)