Muscle/ Nervous

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Skeletal muscle

striated, voluntary

Smooth muscle

non-striated, involuntary, single/ multiunit

Cardiac muscle

striated, involuntary, autorhythmicity

Basic functions of muscle

movement, maintain posture, heat generation

Characteristics of muscle

excitability, contract-ability, extensibility, elasticity

Sarcolemma

plasma membrane with t-tubules

Sarcoplasm

cytoplasm of muscle cell

Sarcoplasmic reticulum

smooth er, calcium ion storehouse

Myofibrils

organized proteins responsible for contraction

Myofilaments

cytoskeleton

I band

light band, thin filaments, myosin

A band

dark band, thick filaments, actin

Z line

middle

H band

center area

Myosin properties needed for contraction

-ATP site closely associated with actin binding site -Position of the myosin -release of ADP, so muscle can relax & new ATP can bind

Troponin- Tropomyosin complex

serve as a switch for muscle contraction and muscle relaxation tropomyosin must be moved for myosin cross bridges to attach actin- requires ca++

Motor unit

a lower motor neuron & all of the skeletal muscle fibers stimulated by branches of its axon, larger units= more force, smaller units= finer degree of neural control

Muscle twitch

occurs when muscle is stimulated with a single electric shock, a quick contraction then relaxation

Latent period

time stimulus is applied until contraction begins

Contraction

beginning of contraction to peak

Relaxation

peak to end of contraction

All or none

a given response will be produced to its maximum extent in response to any stimulus equal to or greater than threshold response ex- action potential to twitch

Temporal summation

asynchronous contraction, twitches alternate to produce a continuous maintenance of force

Spatial summation

recruitment, more cells = more force

Elastic components function

smooth out muscle behavior, absorbs some of the tension as a muscle contracts, elastic recoil help muscle return to resting length

slow twitch

small, rich in myoglobin (oxygen), sustain aerobic

fast twitch

larger, lots of thick & thin, low myoglobin (oxygen), less blood flow, fast to fatigue

Golgi tendon organs

can stop a muscle contraction, protective device, senses the tension muscle exerts on its tendons

Muscle spindles

senses muscle length, muscle that require the finest degree of control have the most extrafusal: insert into tendons on each side intrafusal: several thin muscle cells in connectrive tissue sheath

Final common pathway

motor pathway, consisting of the motor neurons by which nerve impulses from many central sources pass to a muscle

Smooth muscle cells

filaments in a spiraling pattern, no striations, can stretch greatly, big active range, gap junctions

single unit/ multiple unit

single: cells work as a collective group, lots of gap junctions multiple: each cell functions independently, few gap junctions ex- eye