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BIOL 3010K > Chapter 10 - Muscles > Flashcards

Chapter 10 - Muscles Flashcards

1
Q

Three Types of Muscles

A
  1. Skeletal
  2. Cardio
  3. Smooth
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2
Q

Muscular System

A

only skeletal muscles

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3
Q

Myology

A

study of the skeletal muscles

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4
Q

Skeletal Muscle

A
  • Voluntary
  • Striated
  • Attached to bone
  • Muscle cell = “muscle fiber” or “myofiber”
  • Mutinucleated
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5
Q

Cardiac Muscle

A
  • Involuntary
  • Striated
  • Cell = “cardiocyte” or “myocyte”
  • Short, branched cells
  • Intercalated discs w/ gap junctions
  • Typically mononucleated
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6
Q

Smooth Muscle

A
  • Involuntary
  • Non-striated
  • Fusiform cell shape
  • Mononucleated
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7
Q

Functions of Muscle

A
  1. Movement (body parts, communication)
  2. Stability
  3. Heat production
  4. Control of body openings & passages
  5. Store nutrients (amino acids, glycogen)
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8
Q

Properties of Skeletal Muscle

A
  1. Excitability (responsiveness)
  2. Conductivity (electrical impulse)
  3. Contractility (shorten)
  4. Extensibility (stretch)
  5. Elasticity (recoil)
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9
Q

Fascia

A

wraps muscle group

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10
Q

Epimysium

A

wraps muscle

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11
Q

Perimysium

A

wraps fascicle

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12
Q

Endomysium

A

wraps muscle cell

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13
Q

Skeletal Muscle Shapes

A
  1. Fusiform - tapered ends
  2. Parallel - uniform width
  3. Triangular (convergent) - tapered at one end
  4. Pennate - feather-shaped
  5. Circular - forms rings around body openings
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14
Q

Muscle Attachments

A
  1. Indirect - tendon, connects into periosteum and matrix
  2. Aponeurosis - broad sheet of tendon (e.g. scalp, wrist, abdomen)
  3. Direct - muscle to bone, w/ collagen fiber
  4. Other tissues, i.e. dermis
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15
Q

Origin

A

muscle attachment at relatively stationary end

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16
Q

Insertion

A

muscle attachment at more mobile end

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17
Q

Belly

A

muscle area between origin and insertion

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18
Q

Functional Groups of Muscles

A
  1. Prime Mover - produce main force of action
  2. Synergist - aids prime mover, may stabilize joint
  3. Antagonist - opposes prime mover (antagonistic pair act on opposite sides of joint)
  4. Fixator - prevents bone movement
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19
Q

Lever Model for Muscles

A

Lever = bone
Fulcrum = joint
Effort of Force = muscle
Resistance = object moved

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20
Q

First Class Lever

A
  • “Seesaw”
  • E.g. extension of neck
    • Fulcrum in middle (atlanto-occipital joint)
    • Resistance is weight of head
    • Effort by neck muscle to hold head erect
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21
Q

Second Class Lever

A
  • “Wheelbarrow”
  • E.g. bouncing child on thight
    • Fulcrum = hip
    • Resistance is weight of child in middle
    • Effort from quads
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22
Q

Third Class Lever

A
  • “Paddling Canoe”
  • Most common
  • E.g. Paddling
    • Fulcrum = elbow
    • Resistance is weight in hand
    • Effort from biceps & brachialis
23
Q

Sarcolemma

A

muscle fiber plasma membrane

24
Q

Transverse (T) Tubules

A

conduct impulses from the sarcolemma down into the cell

25
Q

Sarcoplasm

A

cytoplasm of skeletal muscle cell (fiber)

  • Myofibrils (contain myofilaments)
  • Glycogen (carbohydrate)
  • Myoglobin (red pigment)
26
Q

Sarcoplasmic Reticulum

A

endoplasmic reticulum of skeletal muscle cell (fiber)

  • terminal cisternae (enlarged areas of sarcoplasmic reticulum surrounding the T tubules)
  • Ca++ reservoir
27
Q

Types of Myofilaments

A
  1. Myosin

2. Actin

28
Q

Myosin

A
  • Myofilament
  • Thick, contractile
  • Heads project from bundled tails of hundreds of molecules
29
Q

Actin

A
  • Myofilament
  • Thin, contractile
  • Fibrous (F) Actin = resembles necklace
  • Globular (G) Actin = resemble one head of necklace
  • Active site = myosin binding site area on G actin
30
Q

Skeletal Muscle Regulatory Proteins

A
  1. Tropomyosin (“gate”) - blocks active sites when muscle is relaxed
  2. Troponin (“lock”) - attaches to tropomyosin, binds calcium (“key”) when excited
31
Q

Muscle Striations

A

narrow stripes (light and dark) that run perpendicular to the length of the cell

32
Q

A Band

A

area of myosin and actin overlap

33
Q

H Band

A

central region of A band that is lighter due to lack of actin

34
Q

M Line

A

midline of A band (and H band) that anchors myosin filaments together

35
Q

I Band

A

area of actin filaments

36
Q

Z Disc

A

midline of I Band, protein that anchors actin filaments together, define boundaries of a sarcomere

37
Q

Sarcomere

A

basic unit of striated muscle tissue

38
Q

Motor neuron’s synaptic knob contains vesicles with _____________.

A

Acetylcholine (ACh)

39
Q

Junctional folds of muscle cell’s membrane contain _________ _________.

A

Acetylcholine (ACh) Receptors

40
Q

Motor Unit

A
  • Consists of one motor neuron and multiple muscle fibers
  • Behaves as a single, functional unit
  • Fibers from one unit are dispersed in muscle
41
Q

Phases of Contraction and Relaxation

A
  1. Excitation
  2. Excitation-Contraction Coupling
  3. Relaxation
42
Q

Excitation of a Muscle

A
  1. nerve signal arrives at knob
  2. knob releases ACh, which binds to muscle’s receptors, opening ion gates and exciting muscle
  3. excitation spreads down and through muscle cell
43
Q

Excitation-Contraction Coupling

A
  1. electrical impulse triggers calcium release from SR
  2. calcium binds troponin, which moves tropomyosin to expose actin
  3. myosin breaks down ATP and extends head
  4. myosin form cross-bridge with actin
  5. myosin pulls actin in power stroke, then detaches, reattaches, pulls again, etc.
44
Q

Relaxation of a Muscle

A
  1. nerve signal stops

2. SR reabsorbs calcium, tropomyosin blockade resumes, and tension subsides

45
Q

At rest, muscle receives about ___________ of heart’s output.

A

one-quarter

46
Q

During heavy exercise, muscular system receives more than _______________ of heart’s output.

A

three-quarters

47
Q

Muscle Growth and Atrophy

A
  • resistance exercise stimulates production of more myofilaments, thus more myofibrils
  • growth by hypertrophy
  • exercise also stimulates production of mitochondria, myoglobin, glycogen, and blood vessels
  • unused muscles atrophy
48
Q

Two Classes of Muscle Fibers

A

Type I = Slow Oxidative (SO)

Type II = Fast Glycolytic (FG)

49
Q

Slow Oxidative Muscle Fibers

A
  • slow-twitch, red, Type I
  • small diameter
  • aerobic ATP production
  • abundant: mitochondria, myoglobin, capillaries
  • resistant to fatigue
  • predominate in postural muscles (e.g. soleus, back muscles)
50
Q

Fast Glycolytic Muscle Fibers

A
  • fast-twitch, white, Type II
  • large diameter
  • anaerobic ATP production
  • abundant glycogen
  • fatigue quickly
  • predominate in quick response muscles (e.g. gastrocnemius, bicep)
51
Q

Myopathies

A

diseases of the muscle

52
Q

Muscular Dystrophy

A
  • several types of skeletal muscle degeneration
  • most common
    • Duchenne
    • Hereditary (sex-linked)
53
Q

Myasthenia gravis (MG)

A
  • autoimmune disease
  • affects women age 20-40
  • destruction of ACh receptors
54
Q

How Muscles are Named

A
  1. Size (e.g. brevis = short)
  2. Shape (e.g. teres = round)
  3. Location (e.g. brachii = of the arm)
  4. Number of heads (e.g. biceps = two heads)
  5. Orientation of the fibers (e.g. rectus = straight)
  6. Action (e.g. flexor = muscle that flexes joint)

BIOL 3010K (19 decks)

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