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Anatomy > Skeletal Muscles (Ch. 9) > Flashcards

Skeletal Muscles (Ch. 9) Flashcards

1
Q

Muscle tissue types

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

Muscle tissue properties

A
  1. Excitablility (respond to stimuli)
  2. Contractibility (shorten + exert pull/tension)
  3. Extensibility (continue to contract over range of resting lengths)
  4. Elasticity (rebound towards orignial length)
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3
Q

Skeletal Muscle Characteristics

A
  1. Stomatic structures – under voluntary control
  2. Innervated by: cranial/spinal nerves
  3. Contractile muscles – attach (in)directly to bones
  4. Produce motion
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4
Q

Skeletal Muscle Functions

A
  • Skeletal movement (pull tendons)
  • Maintain posture + body position
  • Support soft tissue
  • Regulates orifices (swallowing/defecating/etc.)
  • Maintain body temperature (shivering)
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5
Q

Epimysium

A

Dense tissue that surrounds entire muscle
- muscles are innervated by nerves penetrating epimysium

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6
Q

Perimysium

A

Dense tissue that divides muscle into parallel compartments called fascicles

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7
Q

Endomysium

A

Dense tissue that surrounds individual muscle fibres

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8
Q

Tendons

A

Epimysium, Perimysium, and endomysium converge to form tendons. Attach the muscle to bone

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9
Q

Aponeuroses

A

Thick, flattened sheets that connect muscle to muscle

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10
Q

Skeletal Muscle Fibre

A

(Muscle cell)
- multinucleated, larger, have transverse tubules

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11
Q

Sarcolemma

A

Membrane around the muscle cell

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12
Q

Sarcoplasm

A

The cytosol of the muscle cell
- contains myofibrils

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13
Q

Myoblast

A

Embryonic cells that form skeletal muscle cells

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14
Q

Myosatellite cells

A

Myoblasts that do not form skeletal muscle cells
- differentiate to assist in repair and regeneration of muscle cells

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15
Q

Transverse (T) tubules

A

Conduct electrical impulses for muscle fiber contraction

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16
Q

Myofibrils

A

Responsible for the contraction of muscles
- attached to the sarcolemma
- Made of myofilaments (Actin + Myosin)
- surrounded by sarcoplasmic reticulum (SR)

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17
Q

Sarcoplasmic reticulum

A

Surrounds myofibrils
- consists of terminal cisternae and triads

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18
Q

Sarcomere

A
  • organized repeating units of myofibrils (~10,000 per myofibril)
  • overlapping myofilaments (actin/myosin)
    SEE DIAGRAM
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19
Q

Z Line

A

Boundary between sarcomere units
- made of actinin
- titin connects myosin to z bands

20
Q

I band

A

Only actin

21
Q

A Band

A

Myosin and Actin
- Overlapping creates striations (zone of overlap)

22
Q

H Band

A

Only myosin

23
Q

M Line

A

Middle of H band

24
Q

Tropomyosin

A

Blocks connection between actin and myosin head
- otherwise the muscle would always be contracting

25
Thin Filaments
(aka. actin) Twisted filaments of: - F-actin strands - Nebulin hold F-actin strands together - G-actin globular molecules (active/binding sites) - Tropomyosin - Troponin holds tropomyosin in position
26
Thick Filaments
(aka. myosin) - Myosin head pivots towards M line to bring thin filaments towards M line (cross bridging) - attach to active site
27
Nerve stimulation + Muscle contraction
- All of none response of muscle contraction - Force is dependent on the number of motor units activated (recruitment)
28
Motor Unit
All muscle cells controlled by a single motor neuron - smaller the motor unit = finer the control of movement (ie. eye vs leg movemnet)
29
Types of Skeletal Muscle Fibers
1. Slow - red fibres, contain myoglobin, slow contractions, fatigue resistant 2. Fast - white fibres, fast contractions, gets fatigued faster
30
Slow Fibres
Red - abundant mitochondria Weak contractions Fatigue resistant Uses aerobic metabolism Smaller diameter Takes 3x longer to contract, but can contract for a longer period of time
31
Fast Fibres
White - few mitochondria Powerful contractions Fatigue rapidly Uses anaerobic metabolism (glycolysis) Larger diameter Features: densely packed myofibrils, large glycogen reserves, large amounts of ATP used
32
Hypertrophy
Enlargement of the muscle Exercise increases: - # of mitochondria - activity of muscle spindles - concentration of glycolytic enzymes - glycogen reserves
33
Atrophy
Discontinued use of muscle - decrease in muscle mass + tone - muscle becomes flaccid - muscle fibres become smaller + weaker
34
Origin
Point of muscle attachment that remains stationary (fixed, more proximal-- bone/"anchor")
35
Insertion
Point of muscle attachment that is moveable (joint)
36
Agonists
Primary movers - responsible for producing a particular movement - ie. Biceps femoris -- flexes the leg at the knee joint
37
Antagonists
Actions oppose the actions of the agonist - ie. Quadriceps femoris -- extends the leg at the knee joint
38
Synergists
Assists the primary mover in performing an action - ie. Semitendonosus -- also flexes the leg at the knee joint
39
Parallel Muscles
Most common - parallel to longitudinal axis - flat band or spindle shape (ie. abs) - when contracting: body of muscle becomes shorter and wider - produces great force bc all fascicles pull in the same direction
40
Pennate Muscles
Form an oblique angle to the tendon - Tendon begins deep in muscle and runs the body of muscles - contains more fibers than parallel = more tension - Unipennate, Bipennate, Multipennate
41
Unipennate Muscles
Muscle fibres on the same side of the tendon - ie. Extensor digitorum
42
Bipennate Muscles
Muscle fibres on both sides of the tendon - ie. Rectus femoris
43
Multipennate Muscles
Tenon branches within the muscles - ie. Deltoid
44
Convergent Muscles
Fan shaped (ie. pecs) - Originate from a broad area but come together at a common point (tendon or raphe) - less force than parallel - direction of pull can be varied depending on which fascicles are contracted
45
Circular Muscles
- concentric rings - aka sphincter muscles

Anatomy (16 decks)

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