Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

OT Kinesiology > Muscle Physiology I > Flashcards

Muscle Physiology I Flashcards

Exam 1

1
Q

What are the characteristics of muscle tissue?

A
  • irritabilility/exciltability: able to receive and respond to chemical, electrical, and mechanical stimulus
  • contractilicity: muscles change shape as a result of stimuli becoming shotere and thicker, and develops tension.
  • relaxation: the opposite of contractibility: the giving up of tension
  • extensibility: muscle can be stretched or lengthened by a force outside of the muscle itself
  • elasticity: muscle tissue readily returns to normal length when a stretching force is eliminated
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What is the purpose of skeletal muscles

A
  1. generate movement
  2. arrest movement
  3. modify movement

Muscles actively exert force by shortening and building up tension or passively exeriting force by resisting stretch

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What are rotary and translatory movements

A
  • rotary: plane that moves around an axis, (ex: add/abduction)
  • translatory: moves around the whole body not just a joint
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What is the structure of a skeletal muscle?

A
  • endomesium: coating around a muscle fiber (like plastic wrap), seperates one muscle fiber from the other
  • fasicle: group of endomesium bundled wiyh perimesium
  • perimysium: sheath that surround the muscle fasicles (bundles). [in long muscles it may be arranged chain-like and extends the length of the muscle]
  • epimysium: tough outermost layer, surrounds the entire muscle tissue/belly. Helps give muscle its shape and is very resistant to stretch (think of a corset)
  • tendon: receives contributions from all connective tissue layers, it develops tension when the muscle shortens or is on stretch
  • periosteum: highly vascularized CT that is the outer layer of the bone; tendons and ligaments be;lnds into it. It provides nourishment
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What is actin?

A

thin, light, 2 chain-like strings of actin molecules are wound around each other. They form the I band of the sarcomere

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What is myosin?

A

The thick, dark, large molecules. Has globular head groups that swivel and attch to binding sites on actin (crossbridge). The “H” zone is central protion of the myosin filament

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Describe the A band, I band, & H zone, and M band

A
  • A-band: overlapp of myosin and actin fillaments
  • I-band: thin actin
  • H zone: only myosin; this is the contractile region, no overlapping
  • M band: the part of the h-zone that contains myosin filaments that connect to one myosin filament
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Important details about actin-myosin crossbridging

A
  • during the shortening of the muscle, the actin is pulled towards the myosin–crossbridges are formed, broken, and reformed as greater overlapp occurs
  • During lengthening contractions, the actin pulls away from the myosin–crossbridges are broken, reformed, and broken as graduak reduction in overlapp occurs
  • The degree of overlapp is the only thing that changes, the actin/mysoin dont actually change in length
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What are the functions of connective tissue?

A
  • bind muscles together
  • harnesses the force of muscle contraction and transmits this force to the bony attachmnets via the tendons
  • provides structure and shape
  • a conduit for blood vessels and nerves
  • contributes to passive tension to the muscle fiber as the muscle contracts or stretches
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What are the passive contributors to muscle tension?

A
  • various tissues, just by being there, contributes **passive tension **
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What are the passive elastic components?

A

CT is associated with muscle tissue: endomysium, perimysium, epimysium, tendon; they are all interconnected
* they contribute to overall tension present in a muscle, Lengtyen or shorten when the muscle actively does these

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What are the non-connective tissue elastic components

A
  • the sarcolema, nerve, and blood vessels will also contribute to tension to the overall muscle contraction by lengething and shortening as the muscle contracts and relaxes
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What is the difference between fusiform and penniform fibers of muscles?

A
  • Fusiform: arranged in elongatyed/parallel fashion. Provide greatest degree of shortening, = quick muscle and good ROM
  • Penniform: shorter fibers, oblique arrangement, = greater force but smaller ROM
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Describe crossbridge formation?

A

Crossbridge formation occurs when a muscle is stimulated at its motor end plate and a chemical change occurs in the sarcomere.

  • an influx of Ca+ triggers the exposure of binding sites on actin
  • then head groups of the myosin swivel causing the actin to be pulled along the length of the myosin (this is called “power stroking”
  • As the actin slides past the myosin, a chemical reaction occurs which binds the actin to the myosin
  • As crossbridges form and old ones are rebuilt, the actin is moved closer to the H zone of the sacromere, until a maximum overlap occurs (no more increase in tension can develop in the fibers)
  • The fillaments do not change in length, however the sacromere (contracile unit) becomes shorter
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What is the sarcolemma, myofibril, sarcomeres, and Z-lines?

A
  • Sarcolemma: singe muscle cell surrounded by a cell membrane
  • Myofibril: threadlike structure runs through the muscle cell and allows the muscle to contract
  • Sacromeres: a series of units that makes up the myofibril, and extends between two Z-lines
  • Z-lines: located at regular intervals throughout the myofibril and act as boundaries for the sarcomere and a means of linking the actin fillaments together
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What are red (tonic fibers)?

A
  • Type I, slow oxidative, slow twitch
  • innervated by lower thresholds than pale fibers, so used more frequently
  • fibers designed for endurance
  • red, small diameter, high myogliobin (oxidative) capacity, small MU size and slow axon conduction
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

What are pale (phasic fibers)?

A
  • Type IIa/b, fast twitch, glycolic
  • for rapid contractions, less capable of sustained contractions
  • innervated by higher thresholds than red fibers
  • desinged for short term bursts of energy
  • white, large diameter, low myoglobin contenet (oxidative capacity), high glyocolic capacity, fast fatigue, large MU size and fast axon conduction
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

What is the muscle fiber’s response to a single brief stimulus?

A

a muscle twitch
- the muscle contracts quickly and relaxes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

What are the 3 types of sensory neurons?

A
  1. exteroceptors: conduct electrical impulses of sensation from outside the body (touch, smell, vision)
  2. Proprioceptors: located in muscles, tendons, and ear that bring info about postion in space (pressure, movement, equilibrium)
  3. Interoreceptors: located deep in viscera and detect stimuli from internal organs and blood vessels
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

What is a motor unit?

A

fibers of skeletal muscles that are organized into motor units, they vary in size. On average, there are 150 fibers in each motor unit

  • motor unit: the motor nerve fiber and all the muscle fibers it serves/innervates (via the axon)
  • motor units are not grouped together but are dispersed throughout the muscle
  • the more motor units stimulated, the greater the contraction
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

What are the 3 CNS recruitment strategies?

A
  1. Small cell bodies are recruited first, then if not suffciient (wants to have the smallest amount of energy expendature/conseve energy)
  2. Larger size MU are recruited next is needed (will generate more muscle tension and expend more energy)
  3. Otehr factors will be taken into consideration by the CNS are: habituation, magnitude of msucle force required, speed/timing of muscle output, type of muscle contraction recuired, type of muscle fiber needed to complete the task
22
Q

How do motor units vary in muscles that control small movements or large amounts of force vary?

A
  • Muscles with large size MU have smaller number of total MU
  • Muscles with smaller size MU have relatively large number of total MU

Muscles that control fine movements:
- have only a few muscle fibers in each motor unit or have a good proportion of small size motor units in their total number of motor units
- small size MU can fire *more rapidly *than large size (small size give the CNS time to modulate motor output)

Muscles which cause less refined movements but need lot of force will have *larger size *motor units
- large motor units fire with *greater force *than smaller size motor units

23
Q

Do mammals have only one one type of fiber or both in every muscle? Does heredity play a role, can can it be changed?

A
  • Mammals have a mixture of phasic and tonic in every muscles, although one may be more dominant
  • through heredity a person may have more of one type (those with more red have advanatge at endirance exercise, and those with pale have more explosiveness)
24
Q

Give examples of what situations FG fibers are good in and also what muscle groups typcially dominate?

A
  • good for mobility, non-postural and phasic activities (quick burst), produces large amount of tension such as in lifting
  • higher proprotion in shoulders and arms
  • gastroc
25
Q

Give examples of what situations SO fibers are good in and also what muscle groups typcially dominate?

A
  • used for stability, postural, or tonic activities
  • postural muscles of neck, back, and leg have higher proportion
  • soleus
26
Q

What is a muscle twitch?

A
  • muscle fibers response to a single stimulus
  • all or nothing response
  • depends on the size of a motor unit being stimulated, a twitch may be strong or weak
27
Q

What 3 periods occur duing a muscle twitch?

A
  1. latent period: no change in fiber length; time duing which impulse is traveling along the sarcolemma, calicum is being released
  2. Contraction period: tension increases (cross bridges sweiveling), shortening of fibers occurs
  3. Relaxation period: contractile force is no longer generated, muscle relxes and returns to origninal length
28
Q

What is the average number of fibers in a motor unit? And what does a motor unit consist of?

A

Average number of MU is 150
Consist of:
* the cell body of an alpha motor neuron
* the axon that conducts the impulses from the alpha motor neuron to the skeletal muscle fiber and its motor end plate
* the skeletal muscle fiber

29
Q

Are muscle fibers in a motor unit dispersed or grouped in a muscle?

A
  • they are dispersed throughot the muscle
  • activation of one a few motor units will = a weak muscle contraction, but activation of more motor units will = a stronger muscle contraction
30
Q

What are the variations between motor units?

A
  • size of motor neruon cell body
  • diameter of cell body axon (larger it is the faster conduction speed)
  • # of muscle fibers the axon innervates as ut branches throughout the muscle
  • types of fibers (all MU will be made up of 1 type of fiber, so FG MU, FOG, or SO MU’s exist
31
Q

What are the 5 factors that the magnitude of active tension is determined by?

A
  1. size of motor units firing
  2. # of motor units firing
  3. frequency of motor units firing
  4. # of crossbridges occuring
  5. load on the muscle
32
Q

Describe muscle attachments

A
  • Origin- proximal attachment
  • Insertion- distal attachment
  • Line of pull: determines the type of motion produced (flex, extension, abd, and add)
  • direction of fibers
  • proximal and distal attachmnet
  • position of msucle relative to joint
33
Q

What is the action of a muscle?

A
  • general location of the muscle (ant, post, med, lat)
  • Muscles do not usually perform both actions that are antagonistic to each other. THEY HAVE 1 ROLE
34
Q

What is muscle action and functional muscle groups?

A
  • Muscle action: the development of tension/force by a muscle
  • Functional muscle group: a group of muscles that are capable of causing a speciifc joint action (wrist radial deviators)
35
Q

What is a motive VS a resistive force?

A
  • Motive force: force causing the observed movement (agonist)
  • Resistive force: force opposing the observed movement (antagonist)

You need both when performing a movement
- it is a combination of both

36
Q

Why is the angle of pull important?

A

idk

37
Q

What is an agonist or prime mover?

A

a muscle of group of muscles that produces teh desired motion

ex) anterior delt does shoulder flexion

38
Q

What is the purpose of accessory/assist muscles (emergency muscles)?

A
  • they assist the prime mover but is less effective at this motion
  • ex) bicep can help produce shoulder flexion but is not the prime mover
  • sometimes with stroke pt their accessory muscles take over the load from the prime mover who may be damaged
39
Q

What is the purpose of an antagonistic muscle

A
  • produces the opposite action of the prime mover
  • (in order for the agonist to successfully shorten as it contracts, the antagonist muscle must relax and passively lengthen
40
Q

What is a stabilizer/fixator muscle?

A
  • Muscle contracts isometrically to hold a body part stable against the pull of another contracting muscle
  • Not directly involved with moving the load but works to keep parts of the body stable so primary movers can do their job
41
Q

What is a neutralizer muscle?

A
  • a muscle that contracts to prevent unwanted movemnet component in another muscle (they cancel out unwanted movements)
42
Q

What are spurt muscles?

A

Muscles that have a large rotary component
- the proximal attachmnet is far from the joint axis, and the distal attahmnet is close to the joint axis
- it allows for more leveage

EX) biceps brachii and brachialis

43
Q

What are shunt muscles?

A
  • Muscles provide mainly joint stability by providing compression due to a translatory component
  • The proximal attachmnet is close to the joint, and the distal attachmnet is far from the joint (muscle belly is distal to the joint)

EX) brachioradialis

44
Q

What are spurt-shunt muscles?

A
  • multi-joint muscle may act as a spurt muscle in one joint and a shunt muscle on another joint
  • ex) a bicep is a spurt on the elbow but a shunt for the shoulder
45
Q

What are muscle contractions?

A
  • muscle fiber generates tension through the action of actin and myosin cross-bridge cysling
  • the development of tension is seen in the shortening of a muscle fiber
  • however, while under tension, the muscle may lengthen or shorten, or remain the same
  • motion at a joint can be produced by gravity or through muscle activity. If gravity will produce the desired movement, the msucles are not needed to contract.
  • Only muscle actiivty can control, modify, or regulate motion
46
Q

What is a concentric contraction?

A
  • the muscle is shortening, and develops enoigh tension to pvercome the resistance of body part, gravity, & other forces
  • decrease in joint angle (shortening)
47
Q

What is an isometric contraction?

A
  • the musle is held in a shortened posiion (partial or complete contraction) vs weight of body part and gravity (no motion) and possibly other external forces (resistance, weight, time)
  • MAINTAINS A FIXED POSITION, no change in joint position
48
Q

What is an eccentric contraction?

A
  • a lengtehning contraction
  • from a shortened position the muscle gradually returns to a resting length
  • esures smoothness of motion
  • may also occur when extrneal resistance overcomes muscle resistance, forcing return to normal length
49
Q

What is a co-contraction?

A

agonist and antagonist contract simultaneously to provide stability, maintain joint in a neutral position (wrist and forearm position duing hammering)

50
Q
A

OT Kinesiology (11 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions