Muscular System Flashcards

1
Q

Describe the morphology of skeletal muscle cell

A
  • extremely long and cylindrical shape
  • Nuclei are peripherally located
  • Cells are multinucleate
  • Striated
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2
Q

Why skeletal muscle fiber is multinucleated?

A

B/c there’s embryonic mesoderm cells that divide and increase

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3
Q

What is the functional organelle of skeletal muscle fiber?

A

Myofibrils

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4
Q

What is the smallest functional unit of muscle fiber?

A

Sarcomeres

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5
Q

Do muscle cells divide? Describe cellular differences that are associated w/ muscular “hypertrophy” vs “atrophy”.

A

Muscle cells don’t divide

Increase in cell size (hypertrophy) vs decrease in cell size (atrophy)

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6
Q

Describe in detail the 5 major structural components of a sarcomere

A
  1. Z disk(c): Boundaries of each sarcomere
  2. Actin (thin) myofilament: Extend from Z disc towards center of sarcomere
  3. Myosin (thick) Myofilament: Located in center of sarcomere
  4. M-Line: Bisects the myosin myofilaments
  5. Titin: Springlike molecule that resists overstretching

ALL ARE PROTEINS

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7
Q

What is the source of skeletal muscle fibers being striated?

A

Source of striation is myosin and actin myofilament

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8
Q

What are the three regions of the myofibril?

A
  • I Band
  • H Zone
  • A Band
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9
Q

What happens in the A band?

A

More and thicker structures that allows for less light to pass through (More myosin)

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10
Q

What happens in the I band?

A

Less structure and allows more light to pass through (no myosin)

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11
Q

What happens in the H zone?

A

Occurs in less structured middle of the A band (no actin)

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12
Q

What structures can be found in the I band?

A

Z-Disc, Titin, and Actin

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13
Q

What structures can be found in the A band?

A

Myosin, actin, m line, and titin

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14
Q

What structures can be found in the H zone?

A

Myosin, M line, and titin.

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15
Q

What happens to the 3 regions during full contraction?

A

A band doesn’t change in size
H zone disappears
I band gets smaller

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16
Q

Describe conducting system of skeletal muscle to trigger muscle contraction

A
  1. Neurotransmitters are released from the ends of somatic motor neurons that stimulate sarcolemma
  2. Action potential spreads throughout the sarcolemma of muscle cells
  3. Action potential hits deeper and hits sarcoplasmic reticulum, which triggers it to release calcium inside the cell
  4. Once calcium is released; actin and myosin are triggered to slide and create contraction of sarcomere
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17
Q

What is rigor mortis?

A

Stiffness of skeletal muscle after death

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18
Q

What causes rigor mortis, and how muscle relaxes after RM?

A

Cause: Sarcoplasmic reticulum leaks calcium signaling myofibrils to contract (body stiffens)

Relaxation: As proteins denature, actin and myosin detach then the body relaxes

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19
Q

What is a bundle of muscle fibers called?

A

Fascicle or fasciculus

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20
Q

What are the 3 connective tissues of skeletal muscles?

A
  • epimysium
  • perimysium
  • endomysium
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21
Q

What is epimysium?

A

Fibrous covering of whole muscle

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22
Q

What is perimysium?

A

Fibrous covering of fascicle

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23
Q

What is endomysium?

A

Fibrous covering of a single cell (muscle fiber)

24
Q

Describe origin and insertion of a skeletal muscle

A

Origin: One end of muscle acts as an anchor (doesn’t move)

Insertion: Other end attaches to the bone that is moving (moves during contraction)

25
Q

What’s tendon?

A

Structure that connects muscle to bone; made of dense regular proper connective tissue

26
Q

What’s aponeruosis?

A

A flat tendon

27
Q

When you extended your cubital joint, what are the prime mover, and antagonist muscles?

A

Prime mover (agonist): Triceps

Antagonist: Biceps

28
Q

What are characteristics that muscles names are based on? (7)

A
  • location
  • size
  • shape
  • orientation of fasciculi
  • origin/insertion
  • # of heads
  • Function
29
Q

What are two muscles based on location?

A
  • Pectoral
  • Brachial
30
Q

What are 2 muscles that are based on size?

A
  • gluteus medius
  • gluteus maximus
31
Q

What are 2 muscles based on shape?

A
  • deltoid
  • trapezius
32
Q

What are 2 muscles based on orientation of fasciculi?

A
  • rectus
  • oblique
33
Q

What are 2 muscles based on origin/insertion?

A
  • digiti
  • carpi
34
Q

What are 2 muscles based on # of heads?

A
  • biceps
  • triceps
35
Q

What are 3 muscles based on function?

A
  • extensor
  • flexor
  • pronator
36
Q

What is a primer mover?

A

Primarily responsible for generating movement

37
Q

What is a antagonist?

A

Muscle that does the opposite of th agonist

38
Q

What is a synergist?

A

Muscle that helps out

39
Q

What does the fixator do?

A

Stabilize one part of the body during movement of another part

40
Q

When you flex your cubital joint, what are the prime mover, synergist, and antagonist?

A

Primer Mover - Biceps
Antagonist - Triceps
Synergist - Brachialis

41
Q

What are the 13 characteristics of skeletal muscles?

A
  1. cell size: extremely long
  2. nuclei? : multinucleated
  3. shape: cylindrical
  4. location: attached to the bone
  5. sarcomeres? Yes
  6. striated?: Yes
  7. Interconnected?: No
  8. Sarcoplasmic reticulum?: Yes
  9. Transverse Tubules?: Yes
  10. Source of calcium: Sarcoplasmic reticulum
  11. Speed of contraction: very rapid
  12. Nervous control: Voluntary
  13. Fatigue: Tires rapidly
42
Q

What are the 13 characteristics of cardiac muscles?

A
  1. cell size: normal cell size
  2. nuclei? : mononucleated
  3. shape: cylindrical branched
  4. location: heart
  5. sarcomeres? Yes
  6. striated?: Yes
  7. Interconnected?: Yes
  8. Sarcoplasmic reticulum?: Yes
  9. Transverse Tubules?: Yes
  10. Source of calcium: Sarcoplasmic reticulum & external (blood)
  11. Speed of contraction: rapid
  12. Nervous control: autorhythmic involuntary
  13. Fatigue: does not tire
43
Q

What are 13 characteristics of smooth muscles?

A
  1. cell size: slightly longer cell size
  2. nuclei? : mononucleated
  3. shape: spindle
  4. location: walls of hollow organs and tubes
  5. sarcomeres? no
  6. striated?: no
  7. Interconnected?: Yes (GI Tract) and No (Eye Iris)
  8. Sarcoplasmic reticulum?: no
  9. Transverse Tubules?: no
  10. Source of calcium: External blood
  11. Speed of contraction: Slow
  12. Nervous control: Involuntary
  13. Fatigue: Does not tires (Latches)
44
Q

Difference b/w multiunit and visceral smooth muscles?

A

Multiunit: are not interconnected, has precisely controlled movement, and example is the iris (eye)

Visceral: Interconnected like cardiac muscle and has rhythmic pulsating contractions

45
Q

What are the 5 functions of the muscular system?

A
  • Produce movement of skeleton
  • Maintain posture and body position
  • Supports soft tissue
  • Guard entrances and exits
  • Generate heat
46
Q

What are skeletal muscle cells also called?

A
  • Muscle fibers
47
Q

Where do muscle tissues develop from?

A
  • Myoblasts fuse together to form muscle fibers
48
Q

What are sarcomeres?

A

Long row of repeating segments that consists of the smallest functional unit of muscle cell

49
Q

What is the sliding filament theory?

A

Actin slides towards myosin during contraction

50
Q

What is the sarcolemma?

A

The muscle cell membrane

51
Q

What is transverse tubules?

A

Folded sarcolemma tubules that conduct electrical impulses

52
Q

What is the sarcoplasm?

A

Cytoplasm of the muscle cell/fiber

  • Contains sarcoplasmic reticulum
53
Q

What is the sarcoplasmic reticulum?

A

Network of membranous channels around each myofibril

  • stores calcium and is continuously pumping calcium in and out
54
Q

What is the triad?

A

Connecting point b/w surface signal of the T tubule and the two terminal cisterns of sarcoplasmic reticulum

55
Q

What is the neuromuscular junction?

A

The link b/w nervous system and muscular system in which the “synapse” or space where motor neurons meet muscle

56
Q

What neurons dictate the contraction of skeletal muscle fibers?

A

Somatic motor neurons