Question

What is a hypothesis for the effects of stimulus intensity on frog skeletal muscle?

What is a hypothesis for stretch and stimulus frequency on the frog skeletal muscle response?

What is a hypothesis for fatigue on frog skeletal muscle?

Answer 1

Frogs are species with niches,an important part which can live in both aquatic and terrestrial ecosystems. Of the three types of muscles type,frogs mainly use skeletal muscles , which helps in jumping and swimmimg.

Many scientists have done experiments in their lab and came to the folowing hypothesis.

All the above factors( stimulus,frequency and fatigue) will enhance the muscle contraction in frogs.The muscle regulation takesplace through spatial(number of motor neuron is increased) and temporal(frequency of action potential is changed)recruitment and this study will help us to understand the muscle contraction in humans.The process by which the myosin binds to the actin filaments is called as the cross -bridge cycle.

Hypothesis 1) If the stimulus intensity that is,electrical stimulus in frogs muscle is varied there results an increase in stimulation amplitude for muscle contraction.In experiments conducted by researchers using a single stimulus(stimulus applied using electrodes), the voltage of the stimulus is varied from 0 to 2 volts and the force for muscle contraction is recorded. Forces are measured using a force transducer.

Hypothesis 2) If frequency of stimulation is increased at constant voltage, there results in an increase in the force generated by the muscle untill a point where it change. Reserchers used the voltage obtained in the experiment 1, for effect of stimulus intensity and increased the frequency from 0.5 to 30 Hz and hence the force increased upto the point where there changes takesplace.

Hypothesis 3) Muscle fatigue is defined as the decrease in ability of a muscle to generate force.It is due to the reduction in force production by individual cross-bridges.Many of the properties of muscles change during fatigue which includes action potential,ions concentration,and other metabolic processes.

A contribution was made by Hill and Kupalov in 1929 that an isolated frog muscle which was stimulated by in Nitrogen gas fatigued rapidly and accumulated lactic acid. The interesting result was that if the muscle was transferred to a Nitrogen saturated solution, it recovered the product lactic acid which get diffused out of the muscle .This shows that lactic acid could cause fatigue.