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Anatomy > Chapter 10- Muscles > Flashcards

Chapter 10- Muscles Flashcards

1
Q

Myology

A

scientific study of muscles

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2
Q

how much mass do muscles account for

A

~45%

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3
Q

functions of muscles

A 
maintain posture and body position
movement
heat production
guard orifices
support visceral organs
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4
Q

properties of muscle tissue

A

Excitability
-the ability to receive and respond to electrical or chemical stimuli
Contractility
-the ability to shorten forcibly when stimulated
Extensibility
-ability to be stretched without damaging the tissue
Elasticity
-ability to return to original shape after being stretched

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5
Q

composition of mucles

A
  • muscles are organs
  • consist of many tissue types
  • connective tissue
  • arteries/veins
  • nerves
  • lymphatics
  • contractile muscle cells
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6
Q

skeletal muscle characteristics

A
  • attaches to bone, skin, or fascia
  • striated with light and dark bands
  • voluntary control
  • long, thin and multi-nucleated fibers
  • arranged into packages that attach to and cover the bony skeleton
  • contracts rapidly, but tire easily
  • may exert great force
  • fiber=1 muscle cells
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7
Q

muscle structure

A
  • belly: main portion of a muscle (thick part)
  • belly is attached to tendons
  • tendons are attached to bone
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8
Q

fascia

A
  • deep fascia
  • -dense irregular CT around muscle
  • -holds it in place and separates it form other muscles
  • subcutaneous fascia
  • -loose CT beneath skin, surrounds several muscles
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9
Q

skeletal muscle organization

A
  • many muscle fibers are bundled together into groups called fascicles
  • 10-100 muscle cells
  • several fascicles make up a muscle (so several hundred fibers(cells))
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10
Q

skeletal muscle CT

A
  • epimysium
  • perimysium
  • endomysium
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11
Q

epimysium

A

surrounds the whole muscle

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12
Q

perimysium

A

surrounds fascicles

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13
Q

endomysium

A

separates individual muscle fibers

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14
Q

tendon formed from what

A

all connective tissue extended beyond the muscle belly

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15
Q

aponeuroses

A

tendons that form thick flattened sheets

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16
Q

myoblasts

A

embryonic cells that fuse to form muscle fibers

-causes the length and multinucleation

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17
Q

myosatellite cells

A

myoblasts that do not fuse

-assist in repair of damaged cells

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18
Q

fiber structure

A
  • sarcoplasm: fiber cytoplasm
  • sarcolemma: plasma membrane of a fiber
  • transverse (T) tubule: extensions of the sarcolemma into the sarcoplasm
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19
Q

myofibrils

A

contractile organelles

-extend the length of fiber

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20
Q

sarcoplasmic reticulum

A

surrounds the myofibrils

  • similar to ER
  • contains calcium ions which tell muscle to contract
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21
Q

sarcomere

A

functional unit of the myofibril

-made of thick and thin filaments

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22
Q

thick filaments

A

myosin

-twisted protein with globular heads

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23
Q

thin filament

A 
actin
-structural protein
-coiled "beads"
regulatory proteins
-allow/prohibit attachment between actin and myosin
-tropomyosin
-troponin
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24
Q

sarcomere bands

A 
cause the striated appearance
bands
-A band: entire thick filament range
-I band: only thin filaments
-H band: only thick filaments
- Zone of overlap: both filaments
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25
Q

Sarcomere lines

A

divide and flank the sarcomere

  • Z line:
  • -end of sarcomere
  • -made of actin protein
  • -anchor thin filaments
  • M line:
  • -middle of the sarcomere
  • -stabilize thick filaments
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26
Q

structural proteins

A

titin: anchors a thick filament to a Z line
- accounts for elasticity and extensibility
nebulin: holds F actin together on thin filaments (runs through center)
actinin: makes up Z line

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27
Q

sliding filament theory

A

actin slides over myosin

  • zone of overlap enlarges
  • h band shrinks
  • I band shrinks
  • A band remains the same
  • Z line moves closer to A band
28
Q

Neuromuscular junction is made up of

A
  • motor unit
  • neuromuscular junction
  • synaptic termical
  • motor end plate
  • synaptic cleft
  • neurotransmitter
29
Q

motor unit

A

neuron and all the muscle cells stimulated by the neuron

30
Q

neuromuscular junction

A

point of contact between the neuron and the muscle

31
Q

synaptic cleft

A

end of axon that contacts motor end plate

32
Q

neurotransmitter

A

chemical released into synaptic cleft

-acetylcholine

33
Q

events of muscle contraction

A

Ach stored in synaptic vesicles

  • impulse reaches end of neuron-Ach released
  • Ach crosses gap and binds to receptors
  • impulse tracels through motor end plate down T-tubules to SR
  • Ca2+ ions diffuse out of SR into sarcoplasm
  • Ca2+ exposes the active site
  • myosin binds to active site
  • ATP is used and contraction occurs
  • contraction continues as long as Ca2+ concentration is high
  • Ach decomposed by acetylcholinesterase
  • Ca ions transported back to SR
  • actin and myosin links broken
  • cross bridges moved back
  • active site is blocked again
34
Q

acetylcholinesterase

A

breaks down acetylcholine

35
Q

tension produced by muscle

A

determined by
-frequency of stimulation
-number of motor units stimulated
brain tells muscle how much tension to apply

36
Q

all or none law

A

all fibers in a motor unit full contract if stimulated

37
Q

recruitment

A

steady increase in tension by increasing the number of contracting motor units

38
Q

tetanus

A

muscle never begins to relax, continuous fused contraction

39
Q

muscle tone

A
  • motor units contract randomly
  • tension, but no movement
  • can stabilize joints, hold objects in place, maintain posture
40
Q

hypertrophy

A 
-constant, exhaustive stimulation increases the number of organelles/proteins in a fiber
increases:
-mitochondria
-glycolytic enzyme reserves
-myofibrils (more and thicker)
-filaments within myofibrils
Muscle fibers DO NOT reproduce
41
Q

atrophy

A

-lack of constant motor neuron stimulation reduces organelles and proteins
-due to:
age
hormones
lack of use
nerve damage
-reversible if fiber is not dead

42
Q

muscle attachments

A
  • origin: attachment site that does not move
  • insertion: attachment site that moves
  • force= tension
  • fascicle arrangement varies based on position of muscle
43
Q

parallel muscles

A

-fascicles parallel to long axis
-unidirectional force
ex= biceps brachii

44
Q

convergent muscles

A
  • fan shaped
  • multi-directional force
  • versatility
  • generates least amount of force
  • not all parts pulling in same direction at same time
    ex. pectoralis major
45
Q

pennate muscles

A 
feather shaped
-fascicles oblique to long axis
-tendon passes THROUGH the muscle
-greatest force
ex=deltoid, quadricep
con=distance. cannot pull as far because of angle
46
Q

circular muscles

A

-concentric fascicles around opening
-contraction decreases lumen diameter
ex= orbicularis oculi (eye)
mouth

47
Q

articulations and muscle actions: uniaxial

A

rotation around one axis
movements: rotation (atlantoaxial); pivot joints
Angular: knee, IP joints

48
Q

articulations and muscle actions: biaxial

A 
movement occurs along 2 axes
angular motions:
-flexion/extension
-abduction/adduction
-ex: ellipsoidal joint, radiocarpal, metacarpal phelange, carpometacarpal (2-5)
49
Q

articulations and muscle actions: multiaxial

A

-movement on all axes
-angular motion: same as biaxial
-rotation
-circumduction
ex=ball-and-socket

50
Q

Actions: agonist

A

main muscle causing directional force

-this can be any muscle of interest

51
Q

actions: antagonist

A

muscle that contracts to oppose the agonist

ex=bicep brachii vs tricep brachii

52
Q

actions: synergist

A

muscle that assits/modifies movement

ex=brachialis and pronator teres

53
Q

actions: fixator

A

muscle that stabilizes elements associated with agonists

-deltoid stabilizes glenohumeral joint

54
Q

levers

A

lever systems modify movements

  • can change:
  • magnitude of force
  • speed
  • direction
  • distance of limb movement
55
Q

components of lever system

A
  • lever(L): skeletal element
  • effort (E): applied force (muscle pulling)
  • fulcrum (F): joint
  • resistance (R): body part or object moved
56
Q

types of levers: first class

A 
teeter totter/see saw
-R opposite of E with central F
ex= neck extension
-E=neck extensors
F=atlanto-occipital joint
-R=skull
57
Q

Second class levers

A

-wheel barrow
-E opposite of R to move R
Ex=plantar flexion
-E=calf
-F=MP joint
-R=weight of body

58
Q

Third class levers

A

-shovel, broom
-E in between F and R
Ex= elbow flexion
-E= biceps brachii
-F=elbow joint
-R=weight distal to joint

59
Q

types of skeletal muscle fibers: fast fibers

A

-fast acting; high energy requirements
-anaerobic
-large diameter
-densely packed myofibrils
-large glycogen reserves
-few mitochondria
-rapid, powerful, brief contractions
LIGHTER, less myoglobin

60
Q

types of skeletal muscle fibers: slow fibers

A

-more myoglbin; slower sustained contraction
-aerobic
-smaller diameter
-longer to contract
-contract for longer time
DARKER b/c myoglobin

61
Q

types of skeletal muscle fibers: intermediate fibers

A
  • attributes of both
  • similar to fast fibers
  • greater resistance to fatigue
  • exercise (or lack of) can change one muscle type to another
62
Q

smooth muscle characteristics

A

-attached to hair follicles in skin
-in walls of hollow organs and blood vessels
-nonstriated
-involuntary control
-contractions are slow and sustained
-spindle shaped
-very elastic
do not fuse like muscle cells do

63
Q

smooth muscles

A

characteristics:
- contract slowly
- resistant to fatigue
- stimulated by:
- nervous system
- hormones
- ions
- stretching

64
Q

smooth muscle types: single unit

A
  • many gap junctions
  • sheets of spindle shaped cells
  • contract together
    ex: BV’s, digestive tract, resp. tract, urinary tract.
  • either closed or open, no precision
65
Q

smooth muscle types: multi-unit

A
  • no or few gap junctions
  • separate fibers; contract independently
  • only contract when stimulated by motor nerve
  • ex: walls of large BV’s, uterus, iris of the eye
  • lots of precision, degree of refinement/contraction
66
Q

cardiac muscle characteristics

A

-striated in appearance
-involuntary control
-autorhythmic
network of fibers with intercalated disks at ends
-found only in heart

Anatomy (19 decks)

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