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Are a fusion of muscle cells.Contain many myofibrils, that are made of actin and myosin.Myofibrils are composed of many sarcomeres.

The cell needs lots of mitochondria to respiare. A nucleus to control the cell. The sarcoplasm is share cytoplama between the cells. The myofibrils are a sub unit and they contract to move the muscle.The sarcoplamic reticulum store calcium ions.The sarcolema is the cell membran.The t tuble have ions channels so that the impluse can travel far and fast.

Are the sub units that form a myofibril. They have alternate I/light(actin) and A(myosinand actin)dark band. The Z is line in the I bands and the space between is a sarcomere. H zone is a lighter and found in the A band (only myosin present)

They are weak but togueter they contract produce great amounts of force.They are made of lot of sarcomere.

Myosin are thicker filaments and with bulbous heads that project one side. Actin the thinner filament. It consist of two strans twisted around each other.

The H zone , sacomere and light band shorten.The a band remains the same.The z line and actin move to the centre.

The synapse between motor neurone and muscle fibres.The acetylcholine is the molecule that binds to the receptor of the sarcolema.One motor unit comprises all muscle fibres.

1- The sarcolema is polarise 2-The deploralisation spreads trough T-tubules to sacoplamic reticulum. 3- Calcium release from SR. 4- Calcium binds to troponin that is attached to actin. 5- The troponin changes shape and causes tropomyosin to be moved way from myosin biding site . 6- Myosin heads bind to the biding site on actin( cross bridges). 7- The myosin head tilt and move actin(stroke power), releasing ATP usewell. 8- ATP binds to myosin head causing it to detach from actin. 9- ATP is hydrolysed to ADP, causing the myosin head to resume to its original position and bind to actin again. 100 power strokes happens every second.

They are globular heads that serve to bind to both ATP and actin

They are both protein and are called troponin-tropomyosin complex. When troponin changes shape , the tropomyosin moves away from the actin bidding site.

A mulecule that binds to the post synaptic menbrame.

The aerobic respiration is used for exersice of low intensaty and produce the ATP for the contraction by glycolysis.

The anaerobic respiration is useful short period of high intensaty exercise. The anaerobic respiration works by producing ATP trough glycolysis,however, the pyruvate will be turn in lactic acid.

The creatine phosphate process converts ADP in ATP , adding a phosphate.The singular phosphate are storr in the muscle and are used up very quickly in this process. The craetine is used for short period of burst high intensaty.