Musculoskeletal Flashcards
ability of a muscle to shorten, accompanied by mechanical force generation: role in movement
contractility
capacity of muscle to respond to a stimulus
excitability
muscle can be stretched to its normal resting length and beyond to a limited degree
extensibility
ability of muscle to recoil to original resting length after being stretched
elasticity
What are a few properties of skeletal cells
-attached to bones
-nuclei are multiple per cell and peripherally located
-striated
-under voluntary and involuntary control
Fibrous connective tissues that connects muscle fibers to bones and serve as elastic anchors
Tendons
Muscle end attached to more stationary of two bones
origin or head
muscle end attached to bone with greatest movement
insertion
largest portion of the muscle between origin and insertion
belly
separate muscles that work together to cause a movement around a joint
synergists
muscle causing a particular action when it contracts
agonist
muscle working in opposition to agonist; typically relaxes during contraction of agonist
antagonist
What is parallel fiber arrangement?
parallel to the longitudinal axis of the muscle
What is pennate fiber arrangement?
fibers are at an angle to the longitudinal axis of the muscle
-typically generate a greater force per mass of tissue compared to parallel fiber arrangement, but have shorter range on motion
What surrounds muscle fibers?
connective tissue
What organizes muscle fibers into multiple bundles parallel to each other and provides a parallel component of elasticity?
connective tissue
plasma membrane of muscle fibers
sarcolemma
product of fusion of multiple cells sharing internuclear content
multinucleated syncytium
the fundamental contractile structure (defined by z lines)
sarcomere
bundles of myofilaments packed within the muscle fiber and constitute the contractile machinery
myofibrils
prevents interaction between actin and myosin in absence of Ca2+
tropomyosin
promotes a change in tropomyosin allowing binding of actin and myosin with binding of Ca2+
troponin
at what point does ADP and Pi dissociate from the myosin head
power stroke
what allows for the release of myosin from actin
ATP binding to myosin head
rapid net redistribution of ions across the plasma membrane, driven by previously established concentration gradients (transmission of electrical signals)
action potential
specialized ca2+ reservoir within cells
sarcoplasmic reticulum
resides in the sarcolemma/t tubule, a voltage sensitive channel which opens in response to membrane depolarization, allows a slow influx of calcium
DHPR
resides in SR membrane, opened directly by activated DHPR, allows release of Ca2+ stores in SR into the sarcoplasm
RyR
ion pump protein principally responsible for moving Ca2+ from sarcoplasm into the SR and restoring the Ca2+ gradient to terminate contractile response
SERCA (SR Ca2+ ATPase)
a motor neuron plus all the muscle fibers to which it connects
motor unit
varying degrees of force produced by variations in number of motor units activated
graded contractions
fibers per neuron can vary based on functional requirements of muscle in question
innervation ratios
generates a contractile force of contraction that decays as fiber relaxes, stimulated by a single isolated electrical stimulus
twitch
more frequent stimuli each production units of contractile force, next stimulus arrives before relaxation from previous stimulus is complete
summation of twitches
frequency high enough to produce steady contraction (no relaxation) and maximal force development
tetanic contraction
the effect of the series elastic component of the actively stretched muscle
elastic recoil
in muscle stretched to an extreme via an autonomic nervous signal to contract and thus shorten, protecting the muscle
stretch relex
high myosin ATPase activity, thus more rapid cross bridge cycling and high shortening velocity, fatigue rapidly
fast fibers
low myosin ATPase activity and lower shortening velocity, fatigue more slowly
slow fibers
numerous mitochondria, high capacity of oxidative phosphorylation, ATP production dependent on blood borne oxygen and fuel, contain myoglobin which increase rate of oxygen capture in fiber
oxidative fibers
high concentration my glycolytic enzymes and glycogen, larger and have more thick and thin filaments and can develop more tension, fatigue rapidly
glycolytic fibers
low intensity exercise effects
oxidative fibers
high intensity exercise effects
glycolytic fibers
ability to adapt in size and composition to needs and activity
plasticity
