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A&P Chapter 10
A&P
86
Physiology
Undergraduate 2
09/27/2012

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Term
Muscle Function
Definition
Motion of skeleton, stabilizes body position, regulates organ volume to store and release materials, moves substances within the body, thermogenesis
Term
Muscle Properties
Definition
Electrical excitability-muscle action potentials
Contractibility
Extensibility
Elasticity
Term
Muscle Fiber
Definition
Individual muscle cell
Term
Fascia
Definition
sheet of fibrous C.T. that surrounds muscles and other body organs
Term
Superficial Fascia
Definition
separates muscle from skin and is composed of adipose and aerolar C.T.
Term
Deep Fascia
Definition
Dense irregular C.T. that lines the body wall and also holds muscles with similar functions together
Term
Epimysium
Definition
Outer most layer which surrounds muscle
Term
Perimysium
Definition
Surrounds each fascicle
Term
Endomysium
Definition
Thin sheath of aerolar C.T. around each muscle fiber
Term
Aponeurosis
Definition
Broad flat tendon
Term
Somatic motor neuron
Definition
stimulate skeletal muscle to contract
Term
Axon collaterals
Definition
axons branch inside muscle branch inside these and they extend to different muscle fibers
Term
Tendon
Definition
Cord of dense regular C.T. that attaches muscle to bone periosteum
Term
Synatpic End Bulbs
Definition
Axon terminals expand into these
Term
Neruomuscular Junction
Definition
Connection between the neuron and the muscle fiber
Term
Satellite Cells
Definition
cells in mature muscle that retain the capacity to regenerate muscle fibers
Term
Blood Supply
Definition
muscle is well supplied with blood so that each fiber is in close contact with blood capillaries
Term
Sarcolemma
Definition
Plasma membrane of a muscle fiber
Term
T Tubules (transverse)
Definition
tiny invagination of the sarcolemma that tunnel into each fiber and are filled with ECF- allow action potential to spread rapidly throughout cell (depolarizes membrane of t tubule)
Term
Sarcoplasm
Definition
Muscle fiber's cytoplasm - contains glycogen and myoglobin
Term
Sarcoplasmic Reticulum
Definition
Modified ER of muscle fibers that stores Ca2+ and ends in terminal cisterns near T Tubules
*depolarization causes SR to release calcium into muscle cells
Term
Myofibrils
Definition
Lengthwise threads inside and extend the entire length of the fiber-contain sarcomeres
Term
Sarcomeres
Definition
thin and thick filaments arranged in compartments
Term
Functional Units of a myofibril
Definition
sarcomeres connected end to end and are functional units of a myofibril
Term
Describe NMJ
Definition
NMJ is the site where signal to contract is passes from the neuron to the fiber.
on the neuron side of the synaptic cleft between the neuron and fiber is synaptic end bulb
muscle side=motor end plate
Term
How action potentials arise at NMJ
Definition
Nerve impulses-release of Ach-activation of Ach receptors-muscle action potential-termination of Ach activity
*Ach diffuses into the synaptic cleft to the motor end plate and binds to receptors on sarcolemma which opens ion channels which allow Na+ to rush in and generate muscle action potential
Term
Striations
Definition
Thick and thin filaments overlap eachother in a patter that creates this ___________
Term
I bands
Definition
Thin filaments
Term
A bands
Definition
Thick filaments
Term
Z Discs
Definition
Separate sarcomeres
Term
Myosin
Definition
Thick filaments and serves as motor proteins to move thin filaments - bind to myosin heads that will bind to thin filaments to move them
Term
Actin
Definition
Thin filaments and contains myosin binding sites that will bond to the myosin heads to move actins during contraction
Term
Tropomyosin
Definition
covers myosin binding sites on actin to prevent contraction in resting muscle
Term
Troponin
Definition
Holds tropomyosin in place
Term
Titin
Definition
gives elasticity and extensibility to myofibrils by stretching and then springing back
Term
Dystrophin
Definition
Links thin filaments to sarcolemma to strengthen it and help transmit force to tendons
Term
Muscle fiber cell simplified
Definition
sarcomeres-dystrophin- t tubules-terminal cisterns-SR-sarcoplasm
Term
Sliding filament mechanism of muscle contraction
Definition
1. muscle action potential reaches terminal cisterns and stimulates Ca2+ channels to open and release calcium into surround sarcoplasm
2. calcium bonds to troponin on thin filaments and causes troponin-tropomyosin complex to shift and uncovers myosin binding sites on actin
3. energized myosin head bonds to actin to form cross bridge and pulls actin toward center
4. atp bonds to myosin head and it is broken down and its energy causes the head to detach, rotate, and reattach furth down filament
5. myosin head swivels and pulls further toward center
6. repeated as long as calcium is present
Term
Relaxation
Definition
Ach-esterase breaks down Ach transmitter at motor end plate so that muscle action potentials are no longer generated and calcium channels close
-calcium is pumped back into terminal cisterns so that Trop-tropom shifts back to cover the myosin and stops muscle contracting
Term
Length Tension Relationship
Definition
Muscle fiber develops its greatest tension when there is optimal zone of overlap between thick and thin filaments
Term
Creatine Phosphate
Definition
Provides enough energy for maximal contraction for about 15 seconds
*stored in muscles and then transfers its high energy phosphate group to ADP to make ATP
Term
Anaerobic Cellular Respiration 1
Definition
Provides energy for 30-40 seconds and it occurs when O2 is not available for aerobic cell respiration
Term
Anaerobic Cell Respiration 2
Definition
1.glucose is broken down into pyruvic acid (glycolysis) and produces 2 ATP per glucose
2. if O2 isnt available, most of py-acid is broken down into lactic acid and most of this diffuses back into blood to be converted back to glucose in liver
3. anaerobic process because it does not require O2
Term
Aerobic Cell Respiration 1
Definition
Provides ATP in muscle activity that lasts longer than 30 seconds
Term
Aerobic Cell Respiration 2
Definition
1. Presence of O2, py-acid is not broken down into lactic acid, but it is broken down into CO2 and water in mitochondria-36 ATP produced
2. also fatty acids and amino acids can be broken down
Term
Motor Unit Structure
Definition
consists of one somatic motor neuron and all of the muscle fibers it stimulates
Term
Motor Unit Function
Definition
all of the fibers of one motor unit contract and relax together--can control the strength of a contraction by the number and size of motor units stimulated
Term
Twitch Contractions
Definition
Brief contraction all of muscles fibers in motor unit in response to one action potential from somatic motor neuron-4 phases
1.latent period
2.contraction period
3.relaxation period
4.refractory period
Term
Latent Period
Definition
time between application of stimulus and begining of a contraction-calcium is being released from SR and filaments start to exert tension as slack is removed from elastic components
Term
Contraction Period
Definition
fibers shorten
Term
Relaxation Period
Definition
calcium is actively pumped into SR
Term
Refractory Period
Definition
time when fiber cannot respond to another stimulus-toliet flush
Term
Frequency of stimulation
Definition
number of nerve impulses arriving at NMJ per second and is the main factor that determines a muscle fibers tension
Term
Wave Summation
Definition
if subsequent stimuli arrive before a muscle fiber has finished relaxing, then they will produce a stronger contraction
Term
Tetanus
Definition
sustained contraction
Term
Fused tetanus
Definition
shows no discernible twitches
Term
Unfused tetanus
Definition
shows discernible twitches
Term
Motor unit recruitment
Definition
process in which number of motor unit activated increases - helps produce smooth fine movements
Term
Size of motor units activated
Definition
larger-stronger
smaller-more precise
Term
Muscle tone
Definition
Small amount of tension in muscle due to weak involuntary contractions
*muscle becomes flaccid
Term
Isometric
Definition
muscle does not shorten, develops tension
Term
Isotonic
Definition
tensions stays almost constant while muscle shortens to move a load
Term
Slow oxidative fibers
Definition
contain many mitochondria and a lot of myoglobin and have many blood capillaries
*very resistant to fatigue (neck muscles)
Term
Fast oxidative fibers
Definition
contain many mitochondria, blood capillaries and myoglobin *split ATP rapidly and are moderately resistant to fatigue
(leg muscles of sprinters)
Term
Fast glycolytic fibers
Definition
Term
Fast glycolytic Fibers
Definition
Generate ATP by glycolysis
Relative few mitochondria, blood capillaries, and have relatively low amounts of myoglobin.
Split ATP rapidly but have the lowest resistance to fatigue. E.g. in arm muscles
Term
Effects of exercise on skeletal muscle fibers
Definition
endurance exercise causes some fast glycolytic fibers to transform into fast oxidative glycolytic
strength exercise increases size and strength of fast glycolytic fibers and thus the size of the muscles
Term
Single unit smooth muscle tissue
Definition
visceral smooth muscle tissue- occurs in walls of small arteries, veins, and hollow organs
Term
Multiunit smooth muscle tissue
Definition
occurs in airways, large artery wall, arrector pilli muscles, and eye muscles- fine precise smooth muscle motor control
Term
Sarcoplasm of smooth muscle
Definition
contains both thick and thin filaments which are not organized into sarcomeres
Term
Characteristics of smooth muscle fibers
Definition
-contractions start more slowly than in other muscle
-last longer-smooth muscle tone
-contract in response to autonomic nervous system
-can stretch and still maintain contractile function
Term
Regeneration of skeletal muscle
Definition
-limited due to replacement of damaged muscle fibers by fibrous scar tissue (fibrosis)
satellite cells help in regeneration
Term
Regeneration of cardiac muscle
Definition
-lacks satellite cells and has low regeneration capabillity
-stem cells may migrate from blood to form new muscle fibers
Term
Regeneration of smooth muscle
Definition
-greatest power of regeneration
-retains capacity to divide
-pericytes can form new smooth muscle
Term
Development of muscles
Definition
-muscle fibers in iris and arrector pilli---ectoderm
-all other muscles ---mesoderm
Term
Aging effects on skeletal muscle tissue
Definition
loss of muscle mass
decrease in maximal strength
muscle reflexes slow down
loss of flexibility
slow oxidative fibers increase
Term
Muscular dystrophy
Definition
inherited disease-degeneration of muscle fibers
Term
Myasthenia gravis
Definition
weakness of skeletal muscles by blockage of impulse transmission at neurotransmitter junction
Term
fibromyalgia
Definition
affects fibrous c.t. of muscles, tendons and ligaments
Term
Fasciculation
Definition
involuntary brief twitch of motor unit visible under skin
Term
Fibrillation
Definition
involuntary twitches of s single muscle fiber but is not visible under skin
Term
Myalgia
Definition
pain associated with muscles
Term
Myomalacia
Definition
pathological softening of muscle tissue
Term
Myostitis
Definition
inflammation of muscle fibers
Term
Myotonia
Definition
muscular excitability and contractibility with decrease power of relaxation
Term
Volkmann's contracture
Definition
permanent shortening and lack of extensibility due to replacement of destroyed muscle fibers by fibrous connective tissue
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