Question

You are walking on campus one day and out of nowhere a moose charges you. What type of muscle fibers will you primarily use to run away? What energy sources in your muscles will you use? Why? [3 pts for identifying muscle fiber twitch type, 3 pts for identifying energy sources, 4 pts for reasoning; 10 points]

Answer 1

Muscle fibre : Fast twitch muscles fibres ( White muscles)

Energy sources:

a)In the fast twitch muscles , there is large amount of  glycogen and in these muscles since they are fast twitch muscles a sudden stroke of energy is required.Here,the energy for these muscles are derived from the aneorobic respiration where the glycolytic breakdown of glycogen takes place as depicted as:

In the presence of glycolytic enzymes , glycolytic breakdown of glycogen to lactic acid takes place and ATP (Adenosine triphosphate)is produced from ADP.

Glycogen $\rightarrow$ Lactic acid.

b) Energy is also derived from the creatinine phosphate which provides an inorganic phosphate to adenosine diphosphate (ADP) tp form ATP, which serves as an energy molecule in the process of anerobic pathway.

Reasoning:

When a moose charges, there is an immediate need to run which is a phasic activity and needs sudden action.In this process,there needs to be a fast and rapid movement of the muscles of the legs and hands.In such a condition,where oxygen supply to these muscles are not adequately present ,fast contraction is possible only by the fast twitch fibres because they are presented with larger amounts of glycogen and fewer myogblin and blood supply capillaries such that it can effectively function in case of fast running , or a fast twitch which is facilitated by the anerobic breakdown of the stored glycogen.This process aids in the generation of energy at a shorter span compared to the anerobic process. Thus altogether effectively favors a flight mode which is facilitated by these muscle fibres.