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Anatomy > Chapter 9- Muscles > Flashcards

Chapter 9- Muscles Flashcards

1
Q

the scientific study of muscles is known as what?

A

myology

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2
Q

muscular tissue amount for approx. ___% of total body mass

A

45

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3
Q

What are 5 functions of muscles?

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

What are the 4 properties of muscle tissue? describe them briefly

A

Excitability: ability to receive and respond to electrical or chemical stimuli
Contractility: 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

Are muscles organs?

A

yes

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6
Q

what are some tissue types found in muscles?

A 
connective tissue
arteries/veins
nerves
lymphatics
contractile muscle cells
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7
Q

Where do skeletal muscles attached?

A

attach to bone, skin, or fascia

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8
Q

What are some characteristics of skeletal muscle? (6)

A
  • 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
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9
Q

1 muscle fiber is equal to______

A

1 muscle cell

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10
Q

What is the main portion of the muscle called?

A

Belly (Gaster)

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11
Q

what is the Belly of the muscle attached to?

Then what is this attached to?

A

tendons; tendons are attached to bone

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12
Q

What is the deep fascia made of and what does it do?

A

made up of dense irregular CT around the muscle

holds it in place and separates it from other muscle

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13
Q

What is the subcutaneous fascia made up of and where is it located?

A

Loose CT beneath skin, surrounds several muscles

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14
Q

many muscle fibers are bundled together into groups called______

A

fascicles

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15
Q

fascicles can have anywhere from _____-_____ muscle cells (fibers)

A

10-100

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16
Q

several _______ make up a muscle

A

fascicles

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17
Q

What are the three parts of skeletal muscle CT? briefly describe them

A

Epimysium: surrounds the whole muscle
Perimysium: surrounds fascicles
Endomysium: separates individual muscle fibers (cells)

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18
Q

All CT extend beyond the muscle belly to form the_____

A

tendon

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19
Q

tendons may form thick flattened sheets called what?

A

aponeuroses

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20
Q

what are myoblasts?

A

embryonic cells that fuse to form muscle fibers

*this is why they are so long and multinucleate

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21
Q

Myoblasts that do not fuse become__________ cells. what do these cells do?

A

myosatellite cells

they assist in the repair of damaged cells

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22
Q

for the fiber structure of skeletal muscle, what is the name for the fiber cytoplasm?

A

sarcoplasm

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23
Q

for the fiber structure of skeletal muscle, what is the name for the plasma membrane of a fiber?

A

sarcolemma

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24
Q

what are transverse (T) tubules?

A

extensions of the sarcolemma into the sarcoplasm

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25
Q

What are myofibrils?

what do they do?

A

contractile organelles

they extend the length of fiber

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26
Q

what surrounds myofibrils?

what does it contain?

A

sarcoplasmic reticulum
contains calcium ions
*similar to ER

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27
Q

the functional unit of a myofibril is a …..

A

sarcomere

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28
Q

Sarcomeres are made up of______ and _____ filaments

A

thick and thin

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29
Q

the thick filament of sarcomeres is made up of what? describe it

A

Myosin

  • twisted protein with globular heads
  • 1.6 mu m long
  • 500/thick filament
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30
Q

the thin filament of sarcomeres is made up of what? describe it

A 
Actin
-structural protein 
-coiled "beads" 
Regulatory Proteins
-allow/prohibit attachment between actin and myosin
-Tropomyosin
-Troponin
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31
Q

Describe sarcomere ‘bands’ and the different types

A

Sarcomere ‘bands’ cause the striated appearance

A: entire thick filament range
I: only thin filaments
H: only thick filaments
Zone of overlap: both filaments

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32
Q

Describe sarcomere ‘lines’ and the different types

A

Divide and flank the sarcomere

Z: 
-the end of the sarcomere
-made of actinin protein
-anchor thin filaments 
M: 
-middle of the sarcomere
-stabilize thick filaments
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33
Q

What are 3 structural proteins of sarcomeres? describe them

A

Titin: anchors a thick filament to a Z line; accounts for elasticity and extensibility
Nebulin: holds F actin together on thin filaments
Actinin: makes up Z line

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34
Q

Look at slide 24

A

:)

35
Q

describe the sliding filament theory

A

As the actin slides over the myosin…

  • zone of overlap enlarges
  • H band shrinks
  • I band shrinks
  • A band remains the same
  • The Z line moves closer to the A band
36
Q

What is the motor unit of the neuromuscular junction?

A

neuron + all muscle cells stimulated by the neuron

37
Q

What is the neuromuscular junction?

A

point of contact between the neuron and the muscle

38
Q

What is the synaptic terminal of the neuromuscular junction?

A

end of axon that contacts motor end plate

39
Q

What is the motor end plate of the neuromuscular junction?

A

point on muscle fiber that contacts synaptic terminal

40
Q

What is the synaptic cleft?

A

gap between two neurotransmitters

41
Q

What is a neurotransmitter?

A

chemical released into the synaptic cleft

in the case of the photo, Ach

42
Q

Describe muscle contraction

A

Ach stored in synaptic vesicles
Impulse reaches end of neuron Ach released
Ach crosses gap & binds to receptors
Impulse travels through motor end plate down T-tubules to SR
Ca2+ ions diffuse out of SR into sarcoplasm
Ca2+ exposes the active site
Myosin then binds to active site
ATP is used and contraction occurs
Contraction continues as long as Ca2+ concentration is high

43
Q

describe muscle relaxation

A 
Ach decomposed by acetylcholinesterase (AChE)
Ca ions transported back to SR
Actin & myosin links broken
Cross-bridges move back
Active site is blocked once again
44
Q

the tension produced by a muscle is determined by what 2 things?

A

the frequency of stimulation and the number of motor units stimulated

45
Q

what is the All-or-None Law?

A

all fibers in a motor unit fully contract if stimulated

46
Q

what is Recruitment?

A

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

47
Q

what is it called if a muscle never begins to relax?

A

Tetanus

48
Q

What is muscle tone?

Why is it important?

A 
Motor units contract randomly . There is tension but no movement.
It can:
-stabilize joints
-hold objects in place
-maintain posture
49
Q

What is hypertrophy?

A

Constant, exhaustive stimulation that increases the number of organelles/proteins in a fiber; Overall enlargement of the muscles

50
Q

what does hypertrophy increase?

A

mitochondria
glycolytic enzyme reserves
myofibrils
filaments within myofibrils

51
Q

Do muscle fibers reproduce?

A

No

52
Q

What is atrophy?

A

lack of constant motor neuron stimulation reduces organelles and proteins

53
Q

What causes atrophy?

A

Age
Hormones
Lack of use
Nerve damage

54
Q

is atrophy reversible?

A

yes if the fiber is not dead

55
Q

Describe origin, insertion and Force

A

Origin: attachment site that does not move
Insertion: attachment site that moves
Force: tension

56
Q

describe parallel muscles and give an example

A

Fascicles parallel to long axis
Unidirectional force
ie: Biceps brachii

57
Q

describe convergent muscles and give an example

A

Fan shaped:

  • multidirectional force
  • versatility
  • generates least amount of force
    ie: Pectoralis major
58
Q

describe pennate muscles and give an example

A

Feather shaped:

  • fascicles oblique to long axis
  • tendon passes through muscle
  • greatest force
    ie: deltoid
59
Q

describe circular muscles and give an example

A
  • Concentric fascicles around an opening
  • Contraction decreases lumen diameter
    ie: orbicularis oculi
60
Q

rotation around one axis called what?

what movements does this allow?

A

Uniaxial
Rotation: atlantoaxial; pivot joints
Angular: knee, IP joints

61
Q

Movement occurring along 2 axes is called what?

what movements does this allow?

A

Biaxial
Angular motions:
-flexion/extension and abduction/adduction
ie: ellipsoidal joint, radiocarpel, metacarpelphalange; caropmetacarpel (2-5)

62
Q

describe multiaxial movement
what movements does this allow?
example?

A
  • movement on all axes
  • angular motion: same as biaxial
  • rotation
  • circumduction
    ie: ball and socket
63
Q

the main muscle causing directional force is called….

A

Agonist

64
Q

The muscle that contracts to the main muscle causing directional force is called…

A

Antagonist

65
Q

the muscle that assists/modifies movement is called….

A

Synergist

66
Q

What is a fixator?

A

muscle that stabilizes elements associated with agonist

ie: deltoid stabilizes glenohumeral joint

67
Q

What do lever systems do?

A

modify movements

68
Q

Levers can change…. (4 things)

A

magnitude of force
speed
direction
distance of limb movement

69
Q

What are the components of lever system?

A

Lever (L) = skeletal element
Effort (E) = applied force (AF)
Fulcrum (F) = joint
Resistance (R) = body part or object moved

70
Q

What are the names of the three types of levers?

A

First, Second, and Third Class

71
Q

Describe first class levers

A 
teeter-totter/see-saw
R opposite of E with central F
Ex: neck extension
E = neckextensors
F  = atlanto-occipital joint
R = skull
72
Q

Describe second class levers

A 
wheel-barrow
E opposite of F to move R 
Ex: plantar flexion
E = calf
F = MP joint
R = weight of body
73
Q

Describe 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
74
Q

Describe fast fibers

A
  • Fast acting; high energy requirements
  • anaerobic
  • large diameter
  • densely packed myofibrils
  • large glycogen reserves
  • few mitochondria
  • rapid, powerful brief contractions
75
Q

Describe slow fibers

A
  • More myoglobin; slower sustained contraction
  • aerobic
  • smaller diameter
  • longer to contract
  • contract for longer
76
Q

describe Intermediate fibers

A
  • Attributes of both fast and slow fibers
  • similar to fast fibers
  • greater resistance to fatigue
77
Q

______ can change one muscle type to another

A

Exercise (or lack of)

78
Q

What are 7 characteristics of smooth muscle?

A 
attached to hair follicles in skin
in walls of hollow organs & blood vessels
nonstriated
involuntary control
contractions are slow and sustained
Spindle shaped
Very elastic
79
Q

Do smooth muscles…

  1. ) Contract Slowly or Quickly?
  2. ) Resistant or Unresistant to fatigue?
A

Slowly

Resistant

80
Q

What stimulates smooth muscles?

A

Nervous System
Hormones
Ions
Stretching

81
Q

Describe Single-Unit smooth muscle

Where is it found?

A
  • Many gap junctions
  • Sheets of spindle-shaped cells
  • Contract together (syncytial contraction)
    ie: BV’s, digestive tract, respiratory tract, urinary tract
82
Q

Describe Multi-Unit smooth muscle

Where is it found?

A
  • No or few gap junctions
  • Separate fibers; contract independently
  • Only contract when stimulated by motor nerves
    ie: walls of large BV’s, uterus, iris of eye
83
Q

What are 5 characteristics of cardiac muscle?

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

Anatomy (23 decks)

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