Chapter 9 Exam 2

Front 1

Describe the properties of muscle

Back 1

•Contractility: ability of a muscle to shorten withforce

•Excitability: capacity of muscle to respond to astimulus

•Extensibility: muscle can be stretched to its normalresting length

•Elasticity: ability of muscle to recoil to originalresting length after stretched

Front 2

Describe the functions of muscle

Back 2

•Movement of the body

•Maintenance of posture

•Respiration

•Production of body heat

•Communication

•Constriction of organs and vessels

•Contraction of the heart

(Mark munched raspberries, Carl chowed candy)

Front 3

What are the three layers of connective tissue that are a part of each whole skeletal muscle

Back 3

Epimysium, perimysium, endomysium

Front 4

Describe epimysium

Back 4

denseirregular connective tissue layer that surround the entire muscle

Front 5

Describe perimysium

Back 5

dividesthe skeletal muscle into compartments, each containing a bundle of musclefibers (muscle cells) called a fascicle

Front 6

Describe endomysium

Back 6

–Withina fascicle each muscle is surrounded by sheath of connective tissue calledendomysium, thin sleeve of areolar connective tissue that allows capillaries and nerves to reach everymuscle fiber. Between the endomysium andmuscle fibers are satellite cells, stem cells that function in repair

Front 7

Describe tendons and aponeuroses

Back 7

–At each end of the muscle, thecollagen fibers of the epimysium, perimysium, and endomysium combine to form atendon or a broad sheet called an aponeurosis. Tendons and aponeuroses usually attach skeletal muscles to bones

Front 8

Describe deep fascia

Back 8

•sheetsof connective tissue that separate neighboring muscles from each other

Front 9

Describe the microanatomy of skeletal muscle

Back 9

•Skeletalmuscle contains hundreds of thousands of myofibrils arrangedparallel to the long axis of the cell and as long as the cell. Consist of bundles of myofilaments, proteinfilaments composed primarily of actin (thin) and myosin (thick) filaments

•SarcomereMyofibrilsconsist of repeating units called sarcomeres (functional unit of skeletalmuscle). The thin and thick filaments of myofibrils are arranged intosarcomeres of the myofibrils. The myofibril consists of thousands of sarcomeres end to end like boxcars in a train

Front 10

Describe the microanatomy of skeletal muscle

Back 10

•SarcoplasmicReticulum Transverse tubule encircles both sides of asacomere, T tubule is tightly bound on either side to membranes of thesarcoplasmic reticulum (a T tubule sandwich).

Sarcoplasmic reticulum (SR) is similar to the smooth endoplasmicreticulum. It forms a tubular networkaround each individual sarcomere. Oneither side of a T tubule, the tubules of the SR enlarge and form expandedchambers called terminalcisternae. The combination of a pair of terminalcisternae of the SR plus a transverse tubule is known as a triad. SR is a reservoir of calcium ions that canrelease a flood of Ca2+ into the cytosol

Front 11

Describe the microanatomy of skeletal muscle

Back 11

•Musclefibers have an abundance of mitochondria and smooth endoplasmic reticulum (ER)

•Thecytoplasm also contains an abundance of glycogen (energy-storagecarbohydrate) and some types of skeletal muscle contain a good deal ofmyoglobin(anoxygen-binding protein)

Front 12

Describe the components of the sarcomere (A band)

Back 12

•TheA Band–Thick filaments are located at thecenter of a sarcomere in the A band. TheA band consist of:

•The M line:central portion of each thick filament. Thick filaments attach to and extend outwards from either side of the Mline

•The H zone: In a resting sarcomere, the H zone is alighter region on either side of the M line. The H zone contains thick filaments but no thin filaments

•The zone of overlap: Thin filaments are situated between the thickfilaments

Front 13

Describe the components of the sarcomere (I band)

Back 13

–EachI band, contains thin filaments but not thick filaments, extends from the Aband of one sarcomere to the A band of the next adjacent sarcomere

–Zlinesmark the boundary between adjacent sarcomeres. The Z lines consist of proteins which interconnect thin filaments ofadjacent sarcomeres. From the Z lines ateither end of the sarcomere, thin filaments extend toward the M line and intothe zone of overlap

–Onetriad is located on each side of the M line at the overlap zone ,

Front 14

Describe the sliding mechanism

Back 14

•Slidingoccurs when the myosin heads bind to the active site on actin. When thecross-bridge is formed, the myosin head pivots towards the M-line. This action pulls the thin filaments towardsthe center of the sarcomere.

•Thecross-bridge detaches and returns to its original position. The pattern is “attach”, “pivot” and “detach”

•Eachcross bridge attaches and detaches several times during a contraction togenerate tension and pulling the thin filaments inward. This occurs simultaneously in sarcomeresthroughout the muscle cell causing shortening

•HZone & I bands get smaller

•Zoneof overlap larger

•Z-Linesmove closer together

•Withof the A band remains constant over contraction

Front 15

Describe a motor unit

Back 15

•Allof the muscle fibers that are controlled by a single motorneuron

–Largemuscles have motor units with many muscle fibers.

–Smallmuscles that make delicate movements contain motor units with few muscle fibers

Front 16

Describe the neuromuscular junction

Back 16

•The nerve and muscle fiber meet ata synapse called a neuromuscularjunction•Each tip of the nerve fiber ends ina dilated bulb, the synapticknob (Axon Terminal or Synaptic Terminal), nestledin a depression of the muscle fiber sarcolemma called the motorend plate

•A narrow gap, thesynaptic cleft,separatesthe synaptic knob from the sarcolemma

•The synaptic knob contains synapticvesiclesfilledwith the chemical acetylcholine(ACh)•The sarcolemma across from the knobhas ACh protein receptors

•An enzyme called acetylcholinesterase(AChE),foundin the synaptic cleft and sarcolemma breaks down ACh to terminate stimulationof the muscle fiber

Front 17

Describe muscle control

Back 17

•Skeletalmuscle contracts when its motor units are stimulated.

•Tensionproduced is dependent upon 2 factors –the frequency of stimulation

–the number of motor units involved

•Allor None Principle a muscle fiber contracts completely or does not contract atall

Front 18

Describe muscle tone

Back 18

•Atrest, some motor units are always active and creating a small amount oftension. This tension is not greatenough to cause movement, but does cause a “tensing” effect in the muscle

•Motorunits are randomly stimulated, so that there is a constant tension by somefibers •Specializedmuscle fibers called muscle spindles that sense tension and are monitored bysensory nerves that control muscle tone•Restingmuscle tone stabilizes the position of bones and joints (balance and posture)

Front 19

What are the different types of muscle fibers?

Back 19

Fast glycolytic, slow oxidative, intermediate

Front 20

Describe fast glycolytic muscle fibers

Back 20

•fibers (fast twitch, white, or typeII fibers) appear pale and are often called white muscles

–Supported by anaerobicglycolysis

–Contract quickly after stimulation

–Large in diameter

–Contraction are powerful & uselarge amt of energy (ATP)

–Fatigue quickly

–Large glycogen reserves

–Relatively few mitochondria

–Most skeletal muscle of body

Front 21

Describe slow oxidative muscle fibers

Back 21

•(slow-twitch,red, or type I fibers)

–Extensive vessels and myoglobin inslow fibers give these fibers a reddish color; muscles dominated by slowoxidative fibers are known as red muscle

·Contract slowly after stimulation

·Half the size of fast fibers

·Relatively fatigue-resistant,contract for extended periods of time, long after fast fiber fatigue

·Aerobic ATP production

Front 22

Describe intermediate fibers

Back 22

•a type of FG fibers that combinefast twitches with aerobic fatigue-These are relatively rare except in someendurance-trained athletes

•Although some muscles have apredominance of one fiber type, most body muscles contain a mixture of fibertypes, which gives them a range a contractile speeds and fatigue resistance

•All muscle fibers in a particularmotor unit are of the same type

•Characteristics of muscle fiberscan change with physical conditioning

Front 23

Describe fiber organization of whole muscle

Back 23

•Musclefibers in skeletal muscle form bundles called fascicles. Muscle fibers of each fascicle lie parallelto one another

•Thestrength of a muscle and the direction of its pull are determined partly by theorientation of its fascicles

•Differences in fascicle orientationis the basis for classifying muscles into five types•Fusiform musclesare thick in the middle and tapered at each end –Thebiceps brachii of the arm and gastrocnemius of the calf are examples of thistype

Front 24

Describe fiber organization of whole muscle

Back 24

•Parallelmusclesare long, straplike muscles of uniform width and parallel fascicles–Examples include the rectusabdominis of the abdomen, sartorius of the thigh

•Convergentmusclesare fan-shaped - broad at the origin and converging toward a narrower insertion–Pectoralis major in the chest is amuscle of this type

Front 25

Describe fiber organization of whole muscle

Back 25

•Pennatemusclesare feather-shaped

–Theirfascicles insert obliquely on a tendon that runs the length of the muscle, likethe shaft of a feather

–Threetypes:

–unipennate,all fascicles approach the tendon from one side semimembranosus of the thigh

–bipennate,fascicles approach the tendon from both sides (for example, the rectus femorisof the thigh)

–multipennate,shaped like a bunch of feathers with their quills converging on a single point(for example, the deltoid of the shoulder)

•Circular muscles (sphincters) formrings around body openings–Theseinclude the orbicularis oris of the lips and orbicularis oculi of the eyelids

Front 26

Describe muscle terminology

Back 26

•Origin: Ingeneral, the origin remains stationary, attached to a bone or other structurethat doesn’t move

•Insertion: the muscular point of attachment that ismoveable

•The movement produced by a muscleis called its action

Front 27

Describe muscle terminology

Back 27

•Muscles work in functional groupsthat act on a single joint with different effects

•In a given joint movement

–a primemoveroragonististhe muscle that produces most of the force

–an antagonistis amuscle that opposes the prime mover (such as an extensor that opposes a flexor)

–a synergistis amuscle that aids the prime mover by adding power, stabilizing a joint, ormodifying the direction of joint movement•and afixatoris amuscle that holds a bone still

Front 28

Describe muscle terminology

Back 28

•Alever is a rigid structure that moves on a fixed point a fulcrum. In the body the lever is bone and fulcrumjoint. Bone as a lever provides force to muscle contraction

•1stClass- leverhasthe effort at one end, resistance at the other end, and the fulcrum between theeffort and resistance, as in a crowbar or the atlanto-occipital joint

•2ndClass- leverhasthe fulcrum at one end, effort applied at the other end, and the load orresistance between the fulcrum and effort, as in a wheelbarrow or the action of the mandible as the mouth isopened

•3rdClassleverisone with the fulcrum at one end, the resistance at the other end, and theeffort applied between the fulcrum and resistance, as in a baseball bat or theaction of the biceps brachii muscle on the forearm

Front 29

Describe cardiac muscle

Back 29

•Cardiacmuscle is striated, involuntary, single nucleus usually, branched, cellsconnected by intercalated discs

•Cardiacmuscle can contract spontaneously without need of nervous stimulation, howeverthe nervous system usually controls heart rate and contraction strength

•Thecontractions of cardiac muscle are very prolonged compared to those of skeletalmuscle, allowing time for the heart to eject blood

•Cardiacmuscle has an abundance of myoglobin and glycogen, and has numerous largemitochondria; it is highly resistant to fatigue

Front 30

Describe smooth muscle

Back 30

•Smoothmuscle contains the same contractile proteins as skeletal and cardiac muscle,but there are no striations, short, fusiform, single nucleus, involuntary

•Withinwalls of organs such as the uterus, bladder, and blood vessels, &respiratory tract. Regulates movement.

•Smoothmuscle cells contain myosin and actin like skeletal and cardiac muscle, but themyofilaments of smooth muscle are not regularly aligned with each other

•Smooth muscle has no T tubules andhas very little sarcoplasmic reticulum; the calcium needed to activate itscontraction comes mainly from the extracellular fluid

Front 31

Describe the characteristics of smooth muscle

Back 31

•Smoothmuscle contains the same contractile proteins as skeletal and cardiac muscle,but there are no striations, short, fusiform, single nucleus, involuntary

•Withinwalls of organs such as the uterus, bladder, and blood vessels, &respiratory tract. Regulates movement.

•Smoothmuscle cells contain myosin and actin like skeletal and cardiac muscle, but themyofilaments of smooth muscle are not regularly aligned with each other

•Smooth muscle has no T tubules andhas very little sarcoplasmic reticulum; the calcium needed to activate itscontraction comes mainly from the extracellular fluid