Question

In the sliding filament model, ________ stay in place and ________ are pulled toward the center of the
sarcomere.                                                                           

		Z bands, A bands
		thin filaments, thick filaments
		muscle cells, myofibrils
		fast fibers, slow fibers
		myosin filaments, actin filaments

In the sliding filament model, ________ stay in place and ________ are pulled toward the center of the
sarcomere.                                                                           

		Z bands, A bands
		thin filaments, thick filaments
		muscle cells, myofibrils
		fast fibers, slow fibers
		myosin filaments, actin filaments

In the sliding filament model, ________ stay in place and ________ are pulled toward the center of the
sarcomere.                                                                           

		Z bands, A bands
		thin filaments, thick filaments
		muscle cells, myofibrils
		fast fibers, slow fibers
		myosin filaments, actin filaments

Rapid, repeated stimulation produces a sustained muscle contraction called ________.

		tetanus
		muscle twitch
		muscle tone
		spasm
		muscle tension

Answer 1

In Sliding Filament model​​ Myosin thick filaments stay in place and Actin thin filaments move towards the centre of Sarcomere .

Explanation -Sarcomere is distance between 2 adjacent Z lines .Sarcomere is the functional unit of muscle fibres .Sarcomere is composed of alternate thick Myosin filaments and Thin Actin filaments .

At rest Mysoin head is at 45 degree orientation Myosin head which has ATP ase enzyme .Now when ATP bind with ATP ase energy released is used to change the orientation from 45 to 90 degree.

*Now when calcium is released from sarcoplasmic reticulum bind with troponin C and now Tropomysoin is released and now Actin Myosin interaction occur at 90 degree.This is cross bridge formation .Now After ATP breakdown ADP +ip left on myosin head cause the myosin to get back to 45 degree orientation and in this it contract the actin filaments towards the centre of Sarcomere .This is Sliding filament theory .

2)Rapid repetitive stimulation produces sustained muscle contraction known as Tetanus .

*When a single stimulus is applied to the nerve supplying the skeletal muscle, a sharp, momentary contraction of the muscle occurs, followed immediately by its relaxation. This response of the muscle is known as muscle twitch or, simple muscle twitch.

*Summation - Means the adding together of individual twitch contractions to increase the intensity of overall muscle contraction.
2 types a) Temporal b) Spatial

a)Temporal (frequency summation) A single motor unit, stimulated by increasing the frequency of contraction with rapidly repeated stimulation, the individual responses fuse into one continuous contraction. Such a response is called tetanus ( Tetanic contraction)