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Physio Ch. 9

muscle breakdown tendon, muscle, CT and bloodvessels, muscle fiber, myofibril, sarcomere, actin and myosin
myofibrils have what three structures a band, i band, z lines
sarcomeres have z line, m line, h zone
thick filament is...thin filament is... myosin...actin
myofibril of muscle fiber is a collection of protein fibers in muscle cells
myofibril's sarcomere is the...unit containing... contracting...thin and thick filaments
myofiber/muscle fiber also has the... sarcolemma and the sarcoplasmic reticulum
neural control of skeletal muscle: ...division and more specifically... efferent...somatic motor
neural control of skeletal muscle has what kind of junction and also the... neuromuscular junction...motor end plate
skeletal muscle contraction: myofiber excitation neuromuscular junction stimulation and excitation of sarcolemma
skeletal muscle contraction: ...coupling: opening release... excitation-contraction...sarcoplasmic to cytosol
skeletal muscle contraction: cross bridge cycling: interaction between...and...use actin and myosin...atp
myofiber relaxation: stop...and.,.. excitation..return cell to 'normal'
contraction and relaxation depends on cross bridge action
accordig to the sliding filament mechanism what changes length? length of the sarcomere
motor unit motor neuron innervating each myofiber or multiple myofibers
...innervates each motor unit 1 somatic motor neuron
motor unit number of arrangement 1:10, 1:100, 1:1000
one AP in a motor unit -> one contraction of entire motor unit
consequences of motor unit arrangement: direct relationship with...indirect with... strength...control
the larger the motor unit the...and the smaller the unit the... less precision..more precision
neuromuscular junctions are also called neuroeffector junction
axon terminal of neuromuscular junction efferent division - somatic motor
the neurotransmitter for neuromuscular junctions is ach
motor end plate of neuromuscular junction contains ach receptors (nicotinic) and ache
end plate potential (EPP) is a...and is...only graded potential...excitatory (very easy to excite)
only one epp necessary for sarcolemma depolarization and AP
sarcolemma AP depolarization is bi-directional meaning an AP is happening in the middle of postsynaptic neuron so it can go out to the left or right, just not backwards
neuromuscular junctions end with a muscle action potential
events at the neuromuscular junction 1-8 1. neuron AP 2. ca enters voltage gated channels 3: ach is released 4. ach binds to receptors 5. the binding opens ligan gated na channels 6. EPP is caused by the opening of na channels 7. voltage gated na channels open 8. bidirectional propagation of ap
event at the neuromuscular junction step 9 ache and dimished stimulation
ache is always working - as long as you release more ach than is being destroyed, the voltage gated na channels will remain open
problems with skeletal muscle excitation curare, nerve gas, botulism, tetanus
curare binds to ach receptors but no epp because no channels are opened and it is not affected by ache because it is the wrong shape
curare leads to paralysis
nerve gas ache...ach remains at receptors and eventually the receptors become desensitized to ACh which leads to paralysis
botulism reduces..thus it effects... release of ach from axon terminals...presynaptic neurons
tetanus blocks neurotransmitter release to inhibitory neurons so it causes spasms
excitation-contraction coupling goes muscle fiber AP...muscle contraction
muscle fiber ap neuron stimulation - epp
latent period 3 things occur sarcoplasmic reticulum releases ca, ca goes into the cell, ca binds to troponin
muscle contraction cross-bridge cycling increases force = movement of actin/myosin
muscle relaxation ca sequestered (break cross bridge between actin and myosin)
transfer of muscle ap to sarcoplasmsic reticulum goes t tubules...lateral sacs of sarcoplasmic reticulum
t tubule: axon potential travels here to open right next to the SR
lateral sacs are also called the...and is where... terminal is stored
t tubules have...known as... junctional feet...dihydropyridine receptors (DHP)
dhp is...meaning it is a... voltage activated...voltage receptor
ap changes shape of dhp
dhp is physically connected to ryanodine receptors in SR
SR ryanodine receptor is...and lets...out of the sr via... mechanically
ca atpase pump puts ca back into the SR
release and uptake of ca by the SR during contraction and relaxation of a skeletal muscle fiber has 6 steps 1. muscle AP propogated into t tubule 2. junctional feet -DHP -ryanodine activation with ca release 3. ca and troponin interaction to remove blocking action of tropomyosin 4. cross bridge formation 5. ca uptake 6. ca removed from tropo/tropom blocks
cross bridge cycling structures myosin and actin
myosin is shaped like...and has two parts... golf club...tail and head
tail of myosin heavy chains
head/cross bridge are made of...which contains two sites heavy chain...actin binding site(what the head interacts with) and atp binding site/atpase
heads/cross bridges also have light chain (smooth muscle function)
actin is made of a...which is the site for... polymer helical chain...cross bridge binding
actin also has tropomyosin covering the myosin binding site and troponin that moves the tropomyosin out of the way
initiation of cross bridge cycling 3 steps ca enters cytosol, ca binds to troponin c, tropomyosin is shifted
myosin moves actin in to shorten the sarcomere
mechanism of cross bridge cycling 1: cross bridge formation which is the link between actin and myosin
mechanism of cross bridge cycling 2: power stroke and adp release on myosin head in order to bind to actin
mechanism of cross bridge cycling 3: ...which causes... atp binding ... myosin-actin dissociation
if there is no atp in cross bridging it leads to...or.. rigor mortis...cramps
mechanism of cross bridge cycling 4: cross bridge energized
cross bridge cycling goes as long as tropomyosin is out of the way which it is out of the way as long as ca is bound to troponin
skeletal muscle relaxation involves no...which means... neuron additional ACh release
no addition ach release in skeletal muscle relaxtion means...which means... ache epp
no epp means that there is..activity to put... ca backk into the longitudinal elements of the SR
final stages of muscle relaxation tropomyosin shifts back over the actin-myosin binding sites thus there is no cross bridge formation
tension muscle strength or tone
load = object force is exerted upon or the weight
tension developed by myofiber = force exerted
force exerted = load effect nothing
force exerted > load effect shorten muscle to lift the load
force exerted < load effect put load down
isometric muscle contraction = same length or tension = load
isometric holds...or...position load steady...constant
if tension is less than load then the load can't be moved bec enough force can't be developed
in isometric muscle contraction what is maintained sarcomere length
the sarcomere of an isometric muscle contraction may...but...and it...force to... shorten...elastic components of the myofibers extend to make overall change zero...passively transmit...ends of muscle
isotonic muscle contractions =...meaning that the muscle maintains...or the muscle may... same tension...same tension...shorten or lengthen
concentric muscle movement or contraction means the muscle is... actively shortened (stepping up) and the tension > load
the sarcomere length of a concentric muscle movement is decreased
eccentric muscle movement or contraction the muscle is actively...meaning...and the sarcomere length is... lengthened...tension < load to lower the load...increased
a twitch is...->... one epp
twitches affect one myofiber and not the whole muscle
isometric twitch contraction the tension...and there is a...which is when...occurs = load...latent period...excitation-contraction coupling
contraction time for an isometric twitch contractions is roughly...and to relax is you have to... 140 msec...release tension
after you've had can have a... isometric twitch...isotonic twitch
isotonic twitches occur when tension...and during the...a couple things occur such as... > load...latent period...exictation-contraction coupling and isometric contraction
contraction time of isotonic twich is roughly 50-70 msec
length represents force
relationship between isometric and isotonic twitches tension must = load before it can exceed it
isotonic twitches load v. latent period ^ > ^ (takes more time to shorten muscle)
isotonic twitches load v velocity ^ > \/ (heavy load = slower speed)
frequency v tension depends on stimulus duration, twitch duration, summation and tetanus
stimulus duration: 1 ap = 1 twich that lasts about 1-2 msec(myofiber ap)
twitch duration 10 msec to 100+ msec
summation applies additional stimulus while partial contraction is occuring
tetanus can be either fused (no relaxation) or unfused (some relaxation)
maximal fused tetanus leads to extended work, muscle cramps and fatigue
length v tension can either be passive or active
passive tension comes from...and there is no... tissue itself...cross-bridge cycling or atp
passive tension involves titin w/i sarcomeres and CT between myofibers and in muscles
passive tension: stretch of myofibril increases passive tension- no cross bridge cycling
tension increases stretch to develope force in passive tension
active tension involves actin myosin cross bridges and altered sarcomere length
sarcomere length alters active tension meaning length can be optimal (lo, right amoutn of actin/myosin overlap to develope force), length < 60% lo or > 175% lo
active tension muscle length is restricted by..which ranges approx... skeletal structure...70-130% lo...50%max tension
diameter v tension and velocity ^ diameter of myofiber > # of myofilaments (^ tension and ^ velocity)
atp is required to energize myosin head for power stroke, release cross bridges (rigor mortis) and for the ca atpase pump
atp sources for skeletal muscle metabolism aerobic cell resp, anaerobic cell resp, creatine phosphate
atp replenished while... aerobic and anaerobic...muscles work
once creatine phosphate's atp is used no more can be created until the muscle stops working
aerobic and anaerobic cell resp get atp from food
creatine phosphate is located in...where it is... skeletal muscles...stored
aerobic respiration includes...and is..but has high... glycolysis and oxidative phosphorylation...slow...atp production
aerobic resp produces...and depends on... atp from food breakdown...amount of myoglobin, # of mito, o2 & nutrient availability, waste removal
anaerobic resp includes...and is..but... glycolysis and fermentation...faster...low atp production per glucose molecule
anaerobic produces..and can produce...and depends on... atp from food breakdown...large amounts of atp...nutrient availability and waste removal
creatine phosphateis a..system; it is the...and only takes... out of temporary storage
creatine phoshpate depends on cellular creatine phosphate concentraion
oxgyen debt is also called recovery
oxygen debt means that o2 consumption is elevated after exercise
oxygen debt results in...which can be used as an energy source in... lactic acid metabolism...kidneys, liver and heart
oxygen debt replenishes...and also results in the production of... muscle glycogen (storage of glucose)...creatine phosphate
muscle fatigue is a loss of..and involves and recovery
high frequency fatigue results from high intensity, short duration exercise (burst of activity like weight lifting)
low frequency fatigue results from low intensity, long duration exercise (cyclic contraction and relaxation)
factors associated with fatigue muscle AP conduction failure, lactic acid build up, inhibition of cross bridge cycling, low glycogen and blood sugar levels, dehydration
muscle AP conduction failure means excess...and constant... k in t tubules...depolarization and inactivation of voltage gated na channels
lactic acid build up changes...and reduces..and results in... pH of muscles...activity of ca pumps...poor relaxation of fatigued muscles
inhibition of cross bridge cycling ^ atp use and adp + Pi build up
inhibition of cross bridge cycling is an inhibition in step...but it protects against... 2...dramatic decline of ATP (rigor mortis)
low glycogen and blood sugar levels depends on nutrient availability
central command fatigue always involves cns
central command fatigue has no...which means that muscles... signals from the cns...are not necessarily fatigued
maximal velocities of shortening include two types of fibers fast twitch and slow
fast twitch fibers involve...which makes..happen... myosin w/ high atpase activity...cross bridge cycling...4x faster
slow twitch fibers involve...which makes the...occur... myosin w/ low atpase activity...cross bridge...slower
pathway of atp production occurs via oxidative fibers or glycolytic fibers
oxidative fibers use...have what kind of diameter...and many o2...small fiber diameter...mitochondria
oxidative fibers = ^ myoglobin and blood supply (red fibers)
glyolytic fibers have...with...and \/ large fiber diameter...fewer mitochondria...myglobin and blood supply to make white fibers
type 1 fibers are called...and they slow oxidative..resist fatigue
type 1 decrease size > decrease maximal tension
type 1 have slow atpase= oxygen can keep up and good endurance
type 2a are called....and have an...rate fast-oxidative-glycolytic..intermediate fatigue
type 2a: increase size > increase maximal tension
type 2b are called...and they... fast-glycolytic...fatigue quickly
type 2b: ^^ size > ^^maximal tension
motor unit increase... stimulate more motor units...tension and velocity
a motor unit is the motor neuron and all the myofibers it innervates
tension developed by each fiber depends on ap frequency, fiber length, diameter and fatigue
factors that determine muscle tension depend on the # of... active fibers (number of fiber per motor unit and number of active motor units)
atrophy decrease size of muscle bec of denervation or disuse
hypertrophy increase size bec of increased use
changes in muscle result from changes in... size of fibers not the number of myofibers
changes in muscle also result from metabolic activity of fibers
poliomyelitis is caused by neural damage to somatic motor neuron cell body in spinal cord
poliomyelitis causes a lack of...which impacts...and results in.. stimulation...individual motor units...flaccid paralysis
muscle cramps or muscle...result from tetani...ion imbalance and hypocalcemia
ion imalance for muscle tetani include which ions k, ca, s mg
muscular dystrophy is a...resulting from genetic disorder...lack of dystrophin
lack of dystrophin in muscular dystrophy means there is no pulling ability to cause tension
muscular dystrophy leads to degradation of muscle cells
myasthenia gravis is decrease in...which reduces... sensitivity to ach..EPP=no ap=no contraction
Created by: handrzej



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