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Definitions Test 4

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muscle fibers
skeletal and smooth muscle cells; elongated cells;
myo
muscle
sarco
flesh
voluntary
subject to conscious control
involuntary
no conscious control, automatic
striations
obvious stripes in muscles
"bundle-within-a-bundle" design
muscle, fasicle, muscle fiber, myofibril, sarcomere, myofilament
endomysium
surround muscle fibers; composed of areolar and reticular tissue fibers
perimysium
surround the fascicles; composed of fibrous connective tissue
epimysium
surrounds the whole muscle; composed of dense irregular tissue
insertion
muscle attachment to the movable bone
origin
muscle attachment at the immovable/less movable bone
direct muscle attachment
epimysium fused directly to the periosteum of obone
indirect muscle attachment
muscle is connected to a tendon
tendon
rope-like muscle attachment
aponeurosis
sheet-like muscle attachment
skeletal muscle fibers
long cylindrical cell with multiple oval nuclei arranged just beneath the sarcolemma
sarcolemma
plasma membrane of a muscle cell
sarcoplasm
cytoplasm of a muscle cell
myoglobin
red pigment similar to hemoglobin that stores oxygen
myofibrils
rod like fibers that run the length of the cell; contain contractile elements; 80% of cellular volume; made up of myofilaments
Sarcomere
region of a myofibril between two successive Z discs
thick filaments
composed of myosin
myosin
rod-like tail with two globular heads
cross bridges
globular heads of myosin line the thick and thin elements together; allows contraction
thin filaments
composed of actin; contain tropomyosin (to stiffen) and troponin
actin
bears active sites for myosin during contraction
Sarcoplasmic Reticulum
comparable to the smooth endoplasmic reticulum; regulates intracellular levels of ionic calcium; stores and releases calcium at the correct times
T tubules
elongated tube penetrating into the cell from the sarcolemma; the "telegraph system"; ensures every myofibril contracts at the same time
sliding filament model of muscle contractioin
thin filaments are pulled toward the sarcomere centers by cross bridge activity of the thick filament
action potential
electrical current/ nerve impulse.
neuromuscular junction
location where the terminal portion of a motor neuron axon meets a muscle cell membrane
synaptic cleft
the space between the nerve and muscle fiber
motor unit
one motor neuron and all the muscle cells it innervates
muscle twitch
response of a muscle to a single action potential of its motor neuron
latent phase
first few milliseconds after stimulation
contraction phase
cross bridge actively forms and muscle shortens
relaxation
calcium is reabsorbed into the sarcoplasmic reticulum; muscle tension decreases to zero
incomplete tetanus
more rapidly delivered; quivering contraction
complete tetanus
if stimuli are given quickly enough, smooth sustained contraction occurs (tetanus)
recruitment (staircase effect)
increased contraction in response to multiple stimuli of the same strength; increases availability of calcium in sarcoplasm; "warm-up" period for athletes
muscle tone
constant slightly contracted state of all muscles that does not produce movement; keeps the muscles firm, healthy and ready to respond
isotonic contraction
occur at a joint; decrease muscle length, moves the load
isometric contraction
increases muscle tension; load is not moved
roles of ATP
1. transfers energy to myosin cross bridge to energize the power stroke; 2. disconnects the myosin cross bridge from the actin binding site; 3. fuels the pump that actively transports calcium ions to the sarcoplasmic reticulum
regeneration of ATP
1. interaction of ADP with creatine phosphate; 2. stored glycogen via anaerobic pathways, aka glycolysis; 3. aerobic respiration
aerobic endurance
length of time a muscle can contract by glycolysis
anaerobic threshold
point that muscle metabolism converts to anaerobic glycolysis
muscle fatigue
physiological inability to contract due to shortage of ATP; results from ionic imbalance, lactic acid and lack of ATP
contractures
total lack of ATP; cramps
oxygen debt
the amount of oxygen required after physical exercise for restorative processes
optimal length for muscle fibers
80-120% of their normal resting length
muscle fiber types
1. slow oxidative; 2. fast oxidative; 3. fast glycolic
resistance exercise
lifting weights; isometric excercise; promotes strength not stamina
myoblasts
cell that nearly all muscle tissues develop from
muscle mass
36% of body for women; 42% of body for men; main difference is levels of testosterone
Muscular Dystrophy
muscle destroying disease
Duchenne Muscular Dystrophy
most common form of muscular dystrophy; inherited sex-linked disease carried by females and normally expressed in males; diagnosed between the ages of 2-10; victims become clumsy and fall frequently as their muscles fail; progresses from the extremeties upward and victims die of repiratory failure in their 20s; there is no cure
spasm
sudden, involuntary twitch; possibly due to chemical imbalances
Sprain
stretching or tearing of the ligaments
strain
commonly called a pulled muscle; excessive stretching and possible tear of muscle due to overuse/ abuse
tetanus (bacterial)
acute infectious disease resulting in painful spasms of skeletal muscles; eventually results in lock jaw and respiratory failure
myalgia
muscle pain resulting from any muscle disorder
myopathy
disease of the muscle
RICE
treatment of sprains and strains; stands for Rest Ice Compression and Elevation
myositis
inflammation of muscle tissue
rigor mortis
muscular stiffening that begins 2 to 4 hours after death and last for about 4 days
prime mover
provides major force in movement
agonist
also called prime mover; provides major force in movement
antagonist
oppose/reverse a particular movement; produce smooth, coordinated and precise movements with synegists
synergists
add extra force to the prime mover; reduce undesirable movements; also called fixators when they immobilize a bone or muscles origin
parallel fascicles
run parallel with bone; straplike
pennate fascicles
short, attach obliquely to a central tendon; look like a feather; ex. extensor digitorum
convergent fascicles
broad origin; fascicles converge toward a single tendon; triangular shape; pectoralis major
circular fascicles
concentric rings; body openings; sphincters and orbicularis oris
fusiform fascicles
spindle shaped with a "belly"; biceps brachii
sphincter
body openings controlled by contractions
lever
rigid bar that moves on a fixed point when force is applied; bones
fulcrum
fixed point in a lever system; joints
effort
applied force; muscle contraction
load
resistance; bone, tissue and everything else that needs to be moved
first-class lever
load-fulcrum-effort; raising head off of chest
second-class lever
fulcrum-load-effort; standing on tiptoe.
third-class lever
load-effort-fulcrum; flexion of the biceps brachii, doing a curl
Valsalva Maneuver
abdominals contract with the diaphragm and the glottis is closed to create internal pressure; promotes urination, defecation, childbirth, vomitting, screaming, sneezing, burping, and nose blowing