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Anatomy > Chapter 9- Muscles > Flashcards

Chapter 9- Muscles Flashcards

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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
What are myofibrils? | what do they do?
contractile organelles | they extend the length of fiber
26
what surrounds myofibrils? | what does it contain?
sarcoplasmic reticulum contains calcium ions *similar to ER
27
the functional unit of a myofibril is a .....
sarcomere
28
Sarcomeres are made up of______ and _____ filaments
thick and thin
29
the thick filament of sarcomeres is made up of what? describe it
Myosin - twisted protein with globular heads - 1.6 mu m long - 500/thick filament
30
the thin filament of sarcomeres is made up of what? describe it
``` Actin -structural protein -coiled "beads" Regulatory Proteins -allow/prohibit attachment between actin and myosin -Tropomyosin -Troponin ```
31
Describe sarcomere 'bands' and the different types
Sarcomere 'bands' cause the striated appearance A: entire thick filament range I: only thin filaments H: only thick filaments Zone of overlap: both filaments
32
Describe sarcomere 'lines' and the different types
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 ```
33
What are 3 structural proteins of sarcomeres? describe them
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
34
Look at slide 24
:)
35
describe the sliding filament theory
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
What is the motor unit of the neuromuscular junction?
neuron + all muscle cells stimulated by the neuron
37
What is the neuromuscular junction?
point of contact between the neuron and the muscle
38
What is the synaptic terminal of the neuromuscular junction?
end of axon that contacts motor end plate
39
What is the motor end plate of the neuromuscular junction?
point on muscle fiber that contacts synaptic terminal
40
What is the synaptic cleft?
gap between two neurotransmitters
41
What is a neurotransmitter?
chemical released into the synaptic cleft | in the case of the photo, Ach
42
Describe muscle contraction
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
describe muscle relaxation
``` 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
the tension produced by a muscle is determined by what 2 things?
the frequency of stimulation and the number of motor units stimulated
45
what is the All-or-None Law?
all fibers in a motor unit fully contract if stimulated
46
what is Recruitment?
steady increase in tension by increasing the number of contracting motor units
47
what is it called if a muscle never begins to relax?
Tetanus
48
What is muscle tone? | Why is it important?
``` Motor units contract randomly . There is tension but no movement. It can: -stabilize joints -hold objects in place -maintain posture ```
49
What is hypertrophy?
Constant, exhaustive stimulation that increases the number of organelles/proteins in a fiber; Overall enlargement of the muscles
50
what does hypertrophy increase?
mitochondria glycolytic enzyme reserves myofibrils filaments within myofibrils
51
Do muscle fibers reproduce?
No
52
What is atrophy?
lack of constant motor neuron stimulation reduces organelles and proteins
53
What causes atrophy?
Age Hormones Lack of use Nerve damage
54
is atrophy reversible?
yes if the fiber is not dead
55
Describe origin, insertion and Force
Origin: attachment site that does not move Insertion: attachment site that moves Force: tension
56
describe parallel muscles and give an example
Fascicles parallel to long axis Unidirectional force ie: Biceps brachii
57
describe convergent muscles and give an example
Fan shaped: - multidirectional force - versatility - generates least amount of force ie: Pectoralis major
58
describe pennate muscles and give an example
Feather shaped: - fascicles oblique to long axis - tendon passes through muscle - greatest force ie: deltoid
59
describe circular muscles and give an example
- Concentric fascicles around an opening - Contraction decreases lumen diameter ie: orbicularis oculi
60
rotation around one axis called what? | what movements does this allow?
Uniaxial Rotation: atlantoaxial; pivot joints Angular: knee, IP joints
61
Movement occurring along 2 axes is called what? | what movements does this allow?
Biaxial Angular motions: -flexion/extension and abduction/adduction ie: ellipsoidal joint, radiocarpel, metacarpelphalange; caropmetacarpel (2-5)
62
describe multiaxial movement what movements does this allow? example?
- movement on all axes - angular motion: same as biaxial - rotation - circumduction ie: ball and socket
63
the main muscle causing directional force is called....
Agonist
64
The muscle that contracts to the main muscle causing directional force is called...
Antagonist
65
the muscle that assists/modifies movement is called....
Synergist
66
What is a fixator?
muscle that stabilizes elements associated with agonist | ie: deltoid stabilizes glenohumeral joint
67
What do lever systems do?
modify movements
68
Levers can change.... (4 things)
magnitude of force speed direction distance of limb movement
69
What are the components of lever system?
Lever (L) = skeletal element Effort (E) = applied force (AF) Fulcrum (F) = joint Resistance (R) = body part or object moved
70
What are the names of the three types of levers?
First, Second, and Third Class
71
Describe first class levers
``` teeter-totter/see-saw R opposite of E with central F Ex: neck extension E = neckextensors F = atlanto-occipital joint R = skull ```
72
Describe second class levers
``` wheel-barrow E opposite of F to move R Ex: plantar flexion E = calf F = MP joint R = weight of body ```
73
Describe third class levers
``` Shovel, broom E in between F and R Ex: elbow flexion E = biceps brachii F = elbow joint R = weight distal to joint ```
74
Describe fast fibers
- Fast acting; high energy requirements - anaerobic - large diameter - densely packed myofibrils - large glycogen reserves - few mitochondria - rapid, powerful brief contractions
75
Describe slow fibers
- More myoglobin; slower sustained contraction - aerobic - smaller diameter - longer to contract - contract for longer
76
describe Intermediate fibers
- Attributes of both fast and slow fibers - similar to fast fibers - greater resistance to fatigue
77
______ can change one muscle type to another
Exercise (or lack of)
78
What are 7 characteristics of smooth muscle?
``` 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
Do smooth muscles... 1. ) Contract Slowly or Quickly? 2. ) Resistant or Unresistant to fatigue?
Slowly | Resistant
80
What stimulates smooth muscles?
Nervous System Hormones Ions Stretching
81
Describe Single-Unit smooth muscle | Where is it found?
- Many gap junctions - Sheets of spindle-shaped cells - Contract together (syncytial contraction) ie: BV's, digestive tract, respiratory tract, urinary tract
82
Describe Multi-Unit smooth muscle | Where is it found?
- 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
What are 5 characteristics of cardiac muscle?
``` striated in appearance involuntary control autorhythmic network of fibers with intercalated disks at ends found only in heart ```

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