Sarcomere, Nerves, contraction/relaxation, twitches, skeletal muscle fibers

Module 9: Muscle Tissue

Sarcomere

Organization of Filament (segment from Z line to Z line)

H band

Thick (myosin) filaments only

M line

Thick filaments are linked by filaments of the

I band

Thin (actin)

Z line (disc)

Thin filaments attach at either end of the sarcomere

Zone of overlap

Both thin and thick overlapping

A band

M line, H band, and zone of overlap

Synaptic knob

Swollen end of nerve fiber (contains ACh)

Acetylcholine

Neurotransmitter released from nerve fiber (cell) stimulates muscle cell

Pesticides

Bind to acetylcholinesterase and prevent it from degrading ACh

Tetanus (lockjaw)

Form of spastic paralysis caused by toxin of Clostridium tetani bacteria

Respiratory arrest

Flaccid paralysis (limp muscles) due to curare that competes with ACh

-90mV cell

Resting membrane potential

Excitation

Nerve action potentials lead to muscle action potentials

Excitation-contraction coupling

Prepares them to contract

Contraction

Muscle fiber develops tension

Relaxation

Stimulation ends, returns to resting length

Myogram

Chart of the timing and strength of a muscle’s contraction

Twitch

Contraction and relaxation, low frequency

Treppe

Muscle stimulated for a 2nd time immediately after relaxation phase

Incomplete Tetanus

muscle producing peak tension

Complete Tetanus

relaxation phase is completely eliminated

rigor mortis

Hardening of muscles and stiffening of body beginning 3 to 4 hours after death

Anaerobic fermentation

Enables cells to produce ATP in the absence of oxygen

Aerobic respiration

More ATP produced, requires continuous oxygen supply

Fast fibers

Contract very quickly, large size, few mitochondria, fatigue quickly

Slow fibers

Longer endurance, slow contraction, fatigue slowly, small, high oxygen supply, contain myoglobin

White muscles

Mostly fast fibers, pale

Red muscles

Mostly slow fibers, dark

Most human muscles

Mixed fibers, pink

Muscle Hypertrophy

Muscle growth from heavy training

Muscle Atrophy

Lack of muscle activity

Cardiac Muscle

Involuntary, single nuclei, branched cells

Smooth Muscle

Fusiform cells with one nucleus

Muscular Dystrophy

Group of hereditary diseases which skeletal muscles degenerate and weaken and are replaced with adipose (fat) and fibrous scar tissue

Facioscapulohumeral MD

Autosomal dominant trait affecting both sexes equally