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Anatomy and Physiology 1 > 3. Skeletal Muscles > Flashcards

3. Skeletal Muscles Flashcards

1
Q

What are the 4 characteristics of muscles?

A
  1. Excitability
  2. Contractility
  3. Extensibility
  4. Elasticity
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2
Q

Excitability

A

Ability to receive and respond to stimuli

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3
Q

Contractility

A

Ability to shorten and thicken (contract) when sufficient stimuli is received

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4
Q

Extensibility

A

Ability to be stretched

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5
Q

What is important to note about extensibility and skeletal muscles

A

Skeletal muscles are arranged in pairs so when one is contracting, the other is extending

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6
Q

Elasticity

A

Ability of muscles to return to original shape after contraction

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7
Q

Three Main Types of Muscle

A

Skeletal, Smooth, Cardiac

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8
Q
A

Skeletal muscle

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9
Q
A

Smooth muscle - the blobs are the nuclei

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10
Q
A

Cardiac muscle

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11
Q

Skeletal Muscle Percentage

A

~30-40% of total body mass

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12
Q

Smooth and Cardiac Muscle Percentage

A

~10% of total body mass

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13
Q

Skeletal Muscle Fiber Characteristics (4)

A
  1. Long and cylindrical
  2. multinucleated
  3. striated
  4. voluntary control
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14
Q

Cardiac Muscle Fiber Characteristics

A

Short, branching, single centrally located nucleus, striated, involuntary control

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15
Q

Smooth Muscle Fiber Characteristics

A

Spindle-shaped, single centrally located nucleus, nonstriated (makes it look smooth) , involuntary control,

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16
Q

Functions of Skeletal Muscle

A

Motion, maintenance of posture, heat production

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17
Q

What is the other name for skeletal muscles?

A

Voluntary striated muscle

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18
Q
A
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19
Q

Striations Definition

A

Band like structures visible when examined under a light microscope

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20
Q

Voluntary Muscle Control

A

Can be made to contract under conscious control

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21
Q
A
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22
Q

Skeletal Muscle Diameter vs Length

A

10 to 100 micrometers
Highly variable - not necessarily the whole length of the muscle

23
Q

Endomysium

A

Connective tissue sheath that individually wraps each muscle fiber

24
Q

Fascicles

A

Bundles of muscle fibers held together by perimysium

25
Q

Perimysium

A

Connective tissue sheath that holds together muscle fibers in fascicles

26
Q

Epimysium

A

Connective tissue sheath that bundles fascicles together, creating the whole skeletal muscle

27
Q

Connective Tissue Sheaths

A

these sheaths connect muscle to bones and other structures, helping them stay attached

28
Q

Muscle Fiber Innervation

A

Each fiber is innervated by only one nerve ending, located near the middle of the fiber (except for ~2% of fibers)

29
Q
A
30
Q

Myofibril

A

Muscle fiber

31
Q

Sarcolemma

A

Cell membrane of a myofibril

32
Q

Sarcolemma Composition

A

True cell membrane and an outer coat (thin layer of polysaccharide material that contains thin collagen fibrils)

33
Q

Sarcolemma Function

A

Fuses with tendon fibers that collect in bundles to form tendons

34
Q

Myosin vs Actin Filaments per Fiber

A

~1500
~3000

35
Q

Causes of Muscle Striation (dark and light bands)

A

Partial interdigitation of myosin and actin filaments

36
Q

I Bands

A

Light bands, contain only actin filaments

37
Q

A Bands

A

Dark bands, contain myosin filaments and the ends of actin filaments

38
Q

Cross Bridges

A

Located on myofibrils, act with actin to cause contraction

39
Q

Z Disc Proteins

A

Attach to the ends of actin filaments

40
Q

Sarcomere

A

The portion of the myofibril (or of the whole muscle fiber) that lies between two Z discs

41
Q

Sarcomere Length (Contracted)

A

~2 micrometers

42
Q

Actin-Myosin Overlap (Contracted)

A

Actin filaments completely overlap myosin filaments, and the tips of the actin filaments just begin to overlap one another

43
Q

A Band Arrangement

A

Each myosin is surrounded by 6 actin filaments, and each actin filament is surrounded by 3 myosin filaments

44
Q

H Band Composition

A

Lighter part of the A band

Contains only myosin filaments (unlike the rest of the A band, which contains both myosin and actin)

45
Q

M Line - location and function

A

Found in middle of H band

Contains enzymes needed to provide energy for muscle contraction

46
Q
A
47
Q

Titin - composition and function

A

C: Large, springy, filamentous protein

F: Acts as a framework to hold the myosin and actin filaments in place

48
Q
A
49
Q

Sarcoplasm - composition and contents

A
  • Intracellular fluid that fills the spaces between myofibrils
  • Large quantities of potassium, magnesium, phosphate, protein enzymes, and many mitochondria
50
Q

Sarcoplasmic Reticulum - location and function

A
  • Located in sarcoplasm
  • Controls muscle contractions, stores calcium ions
51
Q

Transverse Tubules (T Tubules) - composition and function

A

C: Inward extensions of the plasma membrane

F: communication links between the cell membrane and the myofibrils within each muscle cell

52
Q

Triad

A

Structural relationship between the T tubule and sarcoplasmic reticulum

53
Q

Mammalian T Tubule Location

A

Located at A band - I band junction

54
Q

Amphibian T Tubule Location

A

Located at the Z discs

Anatomy and Physiology 1 (17 decks)

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