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Bmsc 207 > Muscle I > Flashcards

Muscle I Flashcards

1
Q

What is the primary function of all muscle

A

Generate force and/or movement in response to physiological stimulus

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2
Q

What are 7 functions of muscle

A
  • body movement
  • maintenance of posture
  • respiration
  • productions of body heat
  • communication
  • constrictions of organs and vessels
  • heart beat
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3
Q

What does all generation of force depend on

A

Conversion of chemical energy (ATP)

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4
Q

What are characteristics of skeletal muscle?

A
  • primarily voluntary by somatic motor neurons
  • striated and multinucleated
  • attached to bone or attached to other skeletal muscle that is attached to bone
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5
Q

What is another word for muscle cell

A

Muscle fiber

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6
Q

Why is muscle striated

A

Arrangement of thick and thin filaments

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7
Q

Characteristics of cardiac muscle

A
  • generates force to create pressure gradient that drives blood flow
  • primarily involuntary; spontaneous electrical activity (doesn’t need neuronal input)
  • can be altered by autonomic NS, hormones
  • striated and uninucleated
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8
Q

Characteristics of smooth muscle

A
  • primarily involuntary: autonomic control, spontaneous, hormones, paracrines or autocrines
  • non-striated and uninucleated
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9
Q

What does smooth muscle provide mechanical control of?

A
  • digestive tract
  • urinary tract
  • reproductive tract
  • blood vessels
  • airways
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10
Q

How is skeletal muscles attached to bone

A

Tendons

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11
Q

What is origin

A

Closest to trunk or to more stationary bone

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12
Q

What is insertion point

A

More distal or more mobile attachment

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13
Q

What are antagonistic muscle groups

A
  • when movement is around a joint
  • flexor-extensor pairs
  • flexor: brings bones together
  • extensor: moves bones away
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14
Q

How much of total body weight is skeletal muscle and how much of daily energy expenditure does it use

A

40%
Based on activity level 15-60%

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15
Q

What is a muscle cell membrane

A

Sarcolemma

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16
Q

What is a muscle cytoplasm

A

Sarcoplasm

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17
Q

What is a muscles modified endoplasmic reticulum

A

Sarcoplasmic reticulum

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18
Q

How long are muscle fibers

A

Can extend entire length of muscle
- sartorius ~30cm

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19
Q

What is components of skeletal muscle from largest to smallest?

A

Muscles fascicles and connective issue and nerve and blood vessels -> muscle fibers -> sarcolemma (t-tubules) and sarcoplasm and nuclei -> SR and myofibrils and mitochondria and glycogen -> troponin, actin, tropomyosin, myosin, titin, nebulin

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20
Q

How many muscle fibers in a muscle fascicle

A

20-60

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21
Q

How many myofibrils in a single muscle fiber

A

1000+

22
Q

What are myofibrils composed of

A

Sarcomeres stacked end to end

23
Q

What is a sarcomere

A

Basic functional unit of skeletal muscle
Made of long myofibrils

24
Q

Where is force generated

A

At level of individual sarcomere

25
Q

What are the contractile proteins

A

Thick filament: myosin
Thin filament: actin

26
Q

What is dark on a sarcomere

A

Thick filament doesn’t let light through (myosin)
Z-disk is dense protein structure

27
Q

What is the model of a sarcomere

A

Z disk to z disk

28
Q

What are the thin filaments

A

F-actin, tropomyosin, troponin complex

29
Q

What is F-actin

A

Back bone of thin filaments
- double stranded alpha helical polymer of G-actin molecules
- contains binding site for myosin

30
Q

What is tropomyosin

A
  • two identical alpha helictites that coil around each other and sit in the two grooves formed by actin strands
  • regulated actin-myosin binding
  • when active sit over myosin binding sites
31
Q

What is the troponin complex

A

Heterotrimer (3 protein structures) consisting of:
1. Troponin T (TNT) : binds to a single tropomyosin
2. Troponin C (TnC): Ca2+ binding site
3. Troponin I (TnI): under resting conditions is bound to actin inhibiting contraction

32
Q

Where is troponin complex situated

A

~ every 7 actin molecules
- holds tropomyosin over myosin binding site

33
Q

What are the thick filaments

A

Bundle of myosin molecules
- two intertwined heavy chain
- each heavy chain contains two light chains
- regulatory light chain
- essential light chain

34
Q

What does the myosin head contain

A

Region for binding actin as well as site for binding and hydrolyzing ATP (ATPase)

35
Q

What does regulatory light chain regulate

A

ATPase activity of myosin
- controls speed and movement

36
Q

What does essential light chain stabilize

A

The myosin head

37
Q

What are the accessory proteins in the sarcomere

A

Titian and nebulin

38
Q

What is titin

A

Very large protein extending from m-line to z line
- appears to be involved in stabilization of thick filaments and elastic recoil of muscle (pulls sarcomere back to resting length)

39
Q

What is nebulin

A

Large protein that interacts with thin filaments
- believed to regulate length of thin filaments and contribute to structural integrity of myofibrils

40
Q

What are the 5 bands of the sarcomere

A

Z disk, I bands, A band, H zone, M line

41
Q

What is the z disk

A

Zigzag protein structure that is the attachment site for thin filaments

42
Q

What are I bands

A

Lightest band of sarcomere, occupied only by thin filaments
- considered 2 with z disk in middle

43
Q

What is A band

A

Darkest band, encompasses entire eight of thick filament, including area where thin and thick overlap

44
Q

What is H zone

A

Central region of A band, consists only of thick filaments

45
Q

What is M line

A

Proteins form attachment site for thick filaments, equivalent to z disk for thin filaments

46
Q

What are the transverse tubules

A

Continuation of sarcolemma into middle of muscle fiber

47
Q

What is a muscle triad

A

T-tubule with 2 adjacent terminal cisternae

48
Q

What is a terminal cisternae

A

Portion of SR that interacts with t-tubules (most of calcium storage)

49
Q

What is Sarcoplasmic reticulum

A

Modified endoplasmic reticulum that serves Ca2+ storage for contraction

50
Q

What is the sliding filament model

A
  • sarcomere shortens
  • actin and myosin do not change length but slide past one another
51
Q

What is muscle tension

A

Force generated by contracting skeletal muscle

52
Q

When muscle is contracted which band remains constant

A

A band doesn’t change while H zone and I band shorten

Bmsc 207 (35 decks)

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