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The Normal Animal > Musculoskeletal > Flashcards

Musculoskeletal Flashcards

(69 cards)

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1
Q

Contractility

A

Ability of a muscle to shorten, accompanied by mechanical force generation, role in movement

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2
Q

Excitability

A

Capacity of muscle to respond to stimulus

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3
Q

Extensibility

A

Muscle can be stretched to its normal resting length and beyond to a limited degree

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4
Q

Elasticity

A

Ability of muscle to recoil to original resting length after being stretched

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5
Q

Skeletal muscle

A

Attached to bones
Multinucleated, peripherally located
Striated
Voluntary and involuntary (reflex) control

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6
Q

Cardiac

A

Heart
Single nucleus, centrally located
Striated
Involuntary, intercalated discs

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7
Q

Smooth

A

Walls of hollow organs, blood vessels, eye, glands, skin, etc
Single nucleus centrally located
Not striated
Involuntary, gap junctions in visceral smooth

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8
Q

Tendons

A

Fibrous connective tissue that connects muscle fibers to bones
Serve as elastic anchors

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9
Q

Origin/head

A

Muscle end attached to more stationary of two bones

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10
Q

Insertion

A

Muscle end attached to bone with greatest movement

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11
Q

Belly

A

Largest portion of the muscle between origin and insertion

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12
Q

Synergists

A

Separate muscles that work together to cause a movement around a joint
e.g. flexors and extensors

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13
Q

Agonist

A

Muscle causing a particular action (e.g. flexion) when it contracts

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14
Q

Antagonist

A

A muscle working in opposition to agonist, typically relaxes during contraction of agonist

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15
Q

Passive tension

A

Exerted by elastic components (tendons) lying in series and parallel to contractile (active) elements

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16
Q

Series-elastic component

A

In series with the force of muscle contraction

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17
Q

Parallel components of passive tension

A

Muscle cell membrane, extracellular matrix

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18
Q

Parallel fiber arrangement

A

Parallel to longitudinal axis of the muscle

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19
Q

Pinnate fiber arrangement

A

Fibers are at an angle to the longitudinal axis of muscle

Typically greater force but shorter range of motion

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20
Q

__________ tissues surround muscle fiber

A

Connective

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21
Q

Multinucleated syncytium

A

Developmental origin as a fused aggregate of progenitor cells

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22
Q

Sarcolemma

A

Muscle cell plasma membrane

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23
Q

Dimensions of muscle cell

A

0.1 mm in diameter, up to several centimeters in length

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24
Q

During development, ___________ fuse to become ___________

A

Myoblasts, myotubes

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25
Myofibrils
Bundles of myofilaments packed within the muscle fiber and constitute the contractile machinery
26
Z lines
Striations
27
Sarcomere
The fundamental contractile structure
28
Myoblasts
One nucleus each | Lack myofibrils
29
Myotubes
Develop myofibrils | Other specialized organelles for contraction (sarcoplasmic reticulum, transverse tubules)
30
Thin filaments
Actin
31
Thick filament
Myosin
32
Tropomyosin
Protein on actin that prevents interaction between actin and myosin filaments when calcium is absent
33
Troponin
Binds to calcium, promotes change in conformation of tropomyosin, allowing myosin head access to binding sites on actin
34
Which part of myosin contains ATPase?
Myosin head
35
What binds to myosin head to release from actin?
ATP
36
Relative force generation is dependent upon number of ________________ forming reversible attachments to actin filaments
Myosin heads
37
Magnesium role
Cofactor in ATP hydrolysis
38
Muscle fiber
Muscle cell
39
Action potential
A rapid net redistribution of ions across the plasma membrane, driven by previously established concentration gradients, which locally and sequentially depolarizes the membrane along length of cell
40
An electrochemical potential (energy gradient) dependent upon:
The relative concentrations of major ions across plasma membrane Permeability of membrane to each ion through pores Driven by the action of ion pumps (ATPases) that create gradients of Na+, K+, Ca2+, and other ions
41
Gating
Opening and closing of ion channel pore in response to an electrical or chemical signal
42
Selective permeability
Each class of ion channel is selective in its permeability, restricted to one or several types of ions
43
Resting potential
Governed by Na and K gradients and relatively high resting permeability to K, interior of cell relatively negative compared to outside
44
Depolarization
Above a threshold value, Na channels open, allowing an influx (inward flow) of Na, temporary overshoot into a reverse polarized state (interior positive)
45
Acetylcholine receptor
A ligand gated ion channel, allowing transit of Na and K ions, depolarizing the membrane
46
Activation of ACh receptor causes a ________ depolarization
Local
47
T tubules
Transverse tubules, in folding so of the sarcolemma Allow spreading AP to pass into depths of fiber; allow coordination of calcium mobilization from sarcoplasmic reticulum and contraction along length of muscle
48
Sarcoplasmic reticulum
A specialized Ca reservoir within cells
49
Dihydropyridine receptor
Resides sarcolemma/T tubule Voltage sensitive channel, opens in response to membrane depolarization Allows slow influx of calcium from extracellular space Physically interacts with and activates RyR
50
Ryanodine receptor
Resides in SR membrane Opened directly by activated DHPR Allows release of calcium stored in SR into sarcoplasmic where it can activate contractile machinery
51
Sarcoplasmic reticulum Ca2+ ATPase
Moves calcium from sarcoplasmic into SR to terminate contractile response
52
Motor unit
A motor neuron plus all the muscl fibers to which it connects
53
Graded contractions
Varying degrees of force generation are produced by variations in the number of motor unit activated
54
Innervation ratios
Fibers per neuron, can vary based on functional requirements of muscle in question
55
Twitch
Stimulated by a single isolated electrical stimulus | Generates a fractional force of contraction that decays as fiber relaxes
56
Summation of twitches
More frequent stimuli, each producing units of contractile force Next stimulus arrives before relaxation from previous stimulus is complete, allowing summation
57
Peak force generation
Occurs when there is maximum potential for overlap between thick and thin filaments,allowing the greatest number of myosin head/actin interactions to occur
58
Elastic recoil
The effect of the series elastic component of the actively stretched muscle
59
Stretch reflex
In muscle stretched to extreme: via an autonomic nervous signal to contract and thus shorten, protecting muscle tissue
60
Fast fibers
High myosin ATPase activity, thus more rapid cross bridge cycling and high shortening velocity. Fatigue rapidly.
61
Slow fibers
Low myosin ATPase activity and lower shortening velocity. Fatigue more slowly.
62
Oxidative fibers
Numerous mitochondria, high capacity of oxidative phosphorylation. ATP production dependent on blood borne oxygen and fuel, contain myoglobin
63
Myoglobin
Increases rate of oxygen capture in the fiber
64
Exercise increases _____of muscle fibers
size (hypertrophy), numbers of myofilaments, capacity for ATP production
65
Low intensity exercise affects ________ by increasing ________
Oxidative fibers, number of mitochondria and capillaries
66
Satellite cells
Donate new nuclei, proliferate in response to mechanical stress
67
Atrophy
Muscle wasting or loss | Results from inactivity, disease, aging
68
Glycolytic fibers
Have few mitochondria but a high concentration of glycolytic enzymes and glycogen Larger and have more thick and thin filaments and therefore can develop ,ore tension Fatigue rapidly
69
High intensity exercise affects __________ fibers by increasing _________
Glycolytic, diameter and production of Glycolytic enzymes

The Normal Animal (5 decks)

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