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BPK 142 > 4. Skeletal Muscle > Flashcards

4. Skeletal Muscle Flashcards

1
Q

What is Myology?

A

Myology – the scientific study of muscle

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2
Q

What is special about Muscle Cells?

A

Muscle cells (fibres) are the only cells in the body that have the property of contractility, which allows them to shorten and develop tension.

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3
Q

Three Muscle Types

A
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4
Q

What is Skeletal Muscle? (3)

A
  • Attaches to and moves the skeleton.
  • The contractile molecules are very organized giving skeletal muscle a striated (striped) pattern - “striated muscle”.
  • It is under voluntary control.
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5
Q

Composition of Skeletal Muscles (4)

A

Skeletal muscle comprises about 36% of the total body weight in women and 42% in men.

  • 75% of skeletal muscle is water
  • 20% is protein
  • remainder consists of
    – inorganic salts (K+, Cl-),
    – pigments
    – fats
    – carbohydrates.
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6
Q

What is Smooth Muscle? (4)

A
  • Found in the walls of hollow organs and blood vessels.
  • Contractile molecules are not aligned, creating a smooth appearance
  • Smooth muscle is under involuntary control.
  • Connections between cells allow them to contract together – syncytium
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7
Q

What is Cardiac Muscle? (4)

A
  • The contractile tissue of the heart wall.
  • Has characteristics of both smooth muscle and skeletal muscle.
  • Like skeletal muscle.
    – contractile molecules are organized in striations
  • Like smooth muscle
    – under involuntary control
    – Connections between cells allow them to contract together.
    syncytium - facilitating ejection of
    blood.
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8
Q

What are some functions of Skeletal Muscle?
(10)

A

Functions of Skeletal Muscle
1. Produce skeletal movement
2. Maintain posture and body position
3. Breathing – the diaphragm is a skeletal muscle
4. Stabilize joints
5. Support soft tissues – e.g support the weight of organs
6. Generate heat to maintain body temperature
7. Guard entrances and exits within the body
8. Chewing food and talking
9. Provide nutrient reserves – muscle protein for energy
10. Skeletal muscle as an endocrine organ
- Signalling proteins (myokines) have hormone-like effects

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9
Q

What are Criteria Used To Name Muscles? (6)

A
  1. Shape
  2. Action
  3. Location
  4. Division
  5. Size relationships
  6. Directions of the fibers.
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10
Q

Criteria Used To Name Muscles - Shape

A
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11
Q

Criteria Used To Name Muscles - Action

A

Action - various muscle names include the terms flexor, extensor, adductor, or pronator.
e.g. - Adductor Magnus

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12
Q

Criteria Used To Name Muscles - Location

A
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13
Q

Criteria Used To Name Muscles - Divisions

A

biceps brachii (bi – two)
triceps brachii (tri–three)
quadriceps femoris (quad–four)

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14
Q

Criteria Used To Name Muscles- Size

A

. Size relationships - gluteus maximus, gluteus medius, gluteus minimus.
Several names include the terms
“brevis” (short), and “longus” (long).

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15
Q

Criteria Used To Name Muscles - Direction

A

The direction of fibers –
transverse (across)
rectus (straight)

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16
Q

Why do Men have more muscle mass than women?

A

testosterone, fast twitch muscle, different genes, its complicated!

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17
Q

How many times a day does your heart beat in a day?

A

around 100,000

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18
Q

What are bundles of Muscles called?

A

Fasciculi

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19
Q

How are Fasciculi organized? (2)

A

Fasciculi (bundle of muscle fibres) may:
1. Run PARALLEL to long axis of muscle
(greater range of motion, less strength)

  1. DIAGONALLY into a tendon running the length of the muscle
    (smaller range of motion, greater strength).
20
Q

What is Unipennate?

A

Unipennate -
all fasciculi insert on one side of a tendon
- semimembranosus

21
Q

What is Bipennate?

A

Bipennate -
fasciculi insert on both sides of tendon
- rectus femoris

22
Q

What is Multipennate?

A

Multipennate -
convergence of several tendons
– deltoid

23
Q

What is Longitudinal Muscle (strap)?

A

fasciculi run parallel to the long axis of the muscle -
sartorius, rectus abdominus

24
Q

What are Radiate Muscles (convergent)?

A

Radiate (convergent) - fibers fan out from a single attachment
- pectoralis major

25
Q
A
26
Q

What is the Antagonist?

A

Antagonist -
muscles that oppose one another upon contraction
- biceps brachii vs. triceps brachii;
- quadriceps vs. hamstrings
- antagonists are located on opposite sides of a joint.

27
Q

What is a Prime Mover?

A

Prime mover -
a muscle whose contraction is primarily responsible for a particular movement.

28
Q

Example of a Prime Mover and Antagonist?

A
29
Q

What are Fixators/Stabalizers?

A

muscles that immobilize a bone or joint near the origin of the prime mover so that the prime mover can act more efficiently.

More muscle stabilizers are required using free weights compared to using weight machines.

30
Q

What is the Origin?

A

Origin - less movable end of a
muscle, usually proximal.

31
Q

What is the Insertion?

A

Insertion - more movable end
of a muscle, usually distal.

32
Q

What is the “Belly”?

A

Belly - widest portion of a muscle, between its origin and insertion.

32
Q

What is Connective Tissue? (4)

A
  • Three layers of connective tissue surround;
  • serve in part to maintain intramuscular pressure
  • thereby augmenting force production.
  • whole muscle
33
Q

What is Epimysium?

A

bundles of muscle fibers
(fasciculi)

34
Q

What is Perimysium?

A

muscle fibers

35
Q

What is Endomysium?

A
36
Q

Functions of Tendons? (2)

A
  • Tendons are extensions of connective tissue membranes beyond the end of the muscle.
  • Tendons transmit the force of contractile tissue to bone.
37
Q

Muscles or Tendons, which is stronger?

A

Tendons are much stronger than muscle and as such can receive a force from a large number of muscle fibers (with a much larger total cross-sectional area than the tendon) and insert on to a small area of a bone such as a tuberosity*.

38
Q

What is Tuberosity?

A

Tuberosity is a bony prominence where muscles, tendons, or ligaments attach on a bone (e.g. deltoid tuberosity)

39
Q

What are Myofibrils?

A

Myofibrils are thread-like structures found within muscle cells (also known as muscle fibers) that are responsible for muscle contraction.

40
Q

What are Contractile Proteins?

A

Each myofibril consists of a large array of contractile proteins arranged repeatedly in series.

41
Q

What is a Sarcomere?

A

a repeated array of contractile
proteins

42
Q

What are the 2 major contractile proteins of the sarcomere?

A
  • actin (thin filament)
  • myosin (thick filament).
43
Q

Describe Myosin

A

Myosin has crossbridges extending from
its thick central core.

44
Q

Describe Actin

A

Actin has binding sites for myosin

44
Q

What is The Sliding Filament Theory?

A

This theory suggests that, when the muscle is activated, the protruding cross-bridges on myosin attach to actin and, with the aid of ATP, the cross-bridge microstructure can “rotate” thus causing the thin actin filament to “slide” over myosin. This causes the sarcomere to shorten.

45
Q

What are The three layers of connective tissue?

A

endomysium, perimysium, and epimysium,

BPK 142 (18 decks)

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