The Muscular System

Thick Filaments

arranged in a bundle with heads directed outward in a spiral array around the bundled tails.

Antagonist

opposes the prime mover, prevents excessive movement and injury.

Dystonia

a movement disorder that causes the muscles to contract involuntarily.

Tetanus

or lockjaw- spastic paralysis caused by toxin of Clostridium bacteria, blocks glycine release in the spinal cord and causes overstimulation of the muscles.

Plantar fasciitis

heel pain cause by straining the ligament that supports the arch.

Rigor Mortis

Stiffening of the body beginning 3 to 4 hours after death caused by deteriorating sarcoplasmic reticulum releases calcium, Calcium activates myosin- actin cross- bridging and muscle contracts but can not relax, Muscle relaxation requires ATP and ATP production is no longer produced after death.

Collagen

extensible and elastic, stretches slightly under tension and recoils when released, protects muscle from injury, returns muscle to its resting length.

Junctional folds

region of sarcolemma, increases surface area for ACh receptors, contains acetylcholinesterase that breaks down ACh and causes relaxation.

Geniohyoid

widens pharynx during swallowing.

Twitch

a single brief stimulus at that voltage produces a quick cycle of contraction and relaxation (lasting less than 1 /10 second)

Synaptic knob

swollen end of nerve fiber (contains ACh)

Elasticity

returns to its original resting length after being stretched.

Fixator

during Elbow Flexion= muscle that holds scapula firmly in place.

Extensibility

capable of being stretched.

Tennis elbow

inflammation of lateral epicondyle.

Endurance

Ability to maintain high- intensity exercise for> 5 minutes determined by maximum oxygen uptake.

Hiatal hernia

occurs when the stomach protrudes through diaphragm into thorax.