Lab 6: EMG, Fatigue, & Muscle Microanatomy

Nuclei of muscle fiber

Striations

alternate dark and light bands found on skeletal and cardiac muscle

Sarcomere

I band

A band

H zone (band)

Z line

M line

Actin

thin filaments

Myosin

thick filament

T-tubules

Terminal cisternae

Sarcoplasmic reticulum

Myofibril

Motor unit

Isometric muscle contraction

develops tension without changing length

important in postural muscle function and antagonistic muscle joint stabilization

Isotonic muscle contraction

muscle changes in length with no change in tension

Agonist muscle

The muscle primarily responsible for movement of a bone.

Antagonist muscle

The muscle opposite the agonist, which must relax and lengthen during contraction of the agonist.

EMG

electromyogram

Muscle fatigue

Inability of muscle to maintain its strength of contraction or tension; may be related to insufficient oxygen, depletion of glycogen, and/or lactic acid buildup

Muscular contraction

the process in which a muscle becomes or is made shorter and tighter.