Muscular System 2 Lab Worksheet

What are the three energy (ATP) producing systems in the human body?

*there is a very small amount of atp reserve present before the following systems take place

1^st system - Creatine phosphate system

2^nd system – glycolysis and fermentation

3^rd system – citric acid cycle and e- transport chain

What is the first ATP producing process that occurs once muscular activity beyond rest begins?

Creatine phosphate system

Where do the anaerobic and aerobic phases of cellular respiration take place?

Glycolysis takes place in the cytosol, as does fermentation

Citric acid cycle and e- transport chain take place in the mitochondria – this is in the presence of oxygen

When is lactic acid produced, and how does the body flush out lactic acid under normal conditions?

Lactic acid is produced during fermentation. It is cleared by sending it to the liver where it is recycled and converted into glucose through gluconeogenesis

What happens if the sarcomere is too short?

Not enough space to create a forceful contraction

What happens if the sarcomere is stretched to far?

Not enough myosin heads forming cross-bridges to create a forceful contraction

What causes the summation of muscle fiber twitches into a smooth and sustained contraction?

The frequency of stimulation from a nerve will increases twitches into a sustained contraction, and fiber recruitment (motor unit recruitment) will increase the smoothness of contraction.

What is a motor unit?

One motor neuron and all the fibers it innervates

For larger, coarser movements, would one motor neuron stimulate a large or small amount of muscle fibers? Why?

One motor neuron would stimulate a large number of fibers that all move in a similar fashion.

For smaller, finer and more complex movements, would one motor neuron stimulate a larger or smaller amount of muscle fibers? Why?

One motor neuron would stimulate only a small amount of muscle fibers.

Type I

Slow-twitch; oxidative – uses oxygen; resistant to fatigue as long as oxygen is present; lots of mitochondria to produce continuous supply of ATP in the presence of all the oxygen; good blood supply ensuring continuous oxygen; can generate sustained contractions found in leg muscles and back postural muscles

Type IIb

Fast-twitch; glycolytic (anaerobic); poorer blood supply; less mitochondria since less oxygen requiring ATP production; more susceptible to fatigue; more force than slow twitch

Type IIa

Intermediate/fast twitch; fast oxidative; mix of type I and IIb; contract quickly, somewhat resistant to fatigue; between types I and IIb