mechanics of muscle learning objectives

functions of muscle tissue

generate heat, stabilize and support joints, produce movement, open and close passageways

properties of muscle tissue

contractility, extensibility, excitability, elasticity

types of muscle tissue

smooth, cardiac, skeletal

skeletal muscle tissue

found throughout body (majority of muscle tissue)

smooth muscle tissue

found in the lining of organs

cardiac muscle tissue

found in the heart

types of tissue in skeletal muscle

connective tissue: epimysium - around whole muscle

perimysium - around each fascicle

endomysium - around each muscle cell/ fiber (aka sarcolemma)

direct attachment

short CT fibers

indirect attachment

long CT fibers

how do muscles pull

muscle pull insertion towards origin

microscopic anatomy of skeletal muscle

wrapped in endomysium, fibers are long and cylindrical, formed by embryonic cells, multinucleate and peripherally located

thin filaments

actin, gets pulled toward myosin

thick filaments

myosin, stabilizing, actin pulls towards myosin

m-line

in center of h-zone, tiny rods that hold myosin together

h-zone

zone of only thick filaments (myosin), no thin filaments

i band

only thing filaments

a-band

full length of thick filaments including heads of thin filaments

z-disc

boundaries of each sacromere

process of excitability

motor neuron recieved signal, sent to axon where is reaches the terminal bouton. goes through the synaptic cleft, then to the sacrolemma, to t-tubules, to sacroplasmic reticulum, then releases calcium to start contraction

types of myofibrils

oxidative fibers, glycolytic fibers

slow oxidative fibers

contract slowly, resistant to fatigue (not that strong)

fast oxidative fibers

more stronger, somewhat resistant to fatigue

fast glycolytic fibers

contracts fast, fast to fatigue, most strong

types of muscle contraction

concentric contraction, eccentric contraction

concentric contraction

muscles shorten to do work (ex. squatting up)

eccentric contraction

muscle generates force as it lengthens (ex. squatting down)

what are the different types of fascicle arrangements?

circular, parallel, fusiform, bipennate, unipennate, mulitpennate, convergent

fascicle arrangement that converges at one point

convergent

fascicle arrangement that goes in a circular pattern

circular

fascicle arrangement that runs parallel to the long axis of muscle

parallel

fascicle arrangement that runs parallel to the axis of the muscle but is greater in width in the middle than either side

fusiform

fascicle arrangement that inserts into one side of tendon

unipennate

fascicle arrangement that insert into tendon from both sides

bipennate

fascicle arrangement that insert from multiple sides

mulitpennate

what class lever is this

first class lever

what class lever is this

second class lever

what class lever is this

third class lever