Muscle Tissue, Case study 5 Flashcards

1
Q

duchenne’s muscular dystrophy

A

caused by a genetic mutation, resulting in the absence or insufficient amounts of the dystrophin protein to be present in the sarcomere
- X chromosome linked bc more common in males (ie if they have the gene, they have DMD bc they can’t pass it on unless they have it)

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2
Q

lordosis

A

excessive convex curvature of the lumbar vertebrae

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3
Q

kyphosis

A

excessive concave curvature in spine of cervical, thoracic and sacral regions

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4
Q

dystrophin

A

a protein that attaches onto actin filaments and connects them to the sarcolemma

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5
Q

how does muscular dystrophy cause muscle weakness?

A
  • tears in muscles from poor structure, then always trying to repair muscles and so they are weak when used bc not enough myosin and actin are present
    OR
  • muscle fibers are not connected all the way to the CT surrounding structures (tendons, bone) and so when H band shortens, there is no pull on surrounding tissues
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6
Q

skeletal muscles system functions

A
heat production
body movement
posture maintenance
communication
respiration
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7
Q

mnemonic for remembering functions of skeletal muscle

A
holy == heat prod.
billy's === body movement
puppy == posture
can === communication
run == respiration
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8
Q

properties of skeletal muscle

A

contractility
excitability
extensibility
elasticity

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9
Q

contractility

A

muscles can contract, generating force or tension

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10
Q

excitability

A

muscles can respond to a stimulus by producing action potentials
- they are electrically excitable

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11
Q

extensibility

A

muscle can be stretched beyond its resting length and still be able to contract bc of overlapping proteins

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12
Q

elasticity

A

muscles can recoil to their original resting length after it’s been stretched

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13
Q

skeletal muscle cells are (one word)

A

fibers

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14
Q

skeletal muscle cells

A
  • highly organized structure
  • long (run length of muscle)
  • multinucleated bc they come from myoblasts merged together during embryology
  • nuclei loc just below plasma membrane
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15
Q

order of layers of CT surrounding muscle tissue

A

fascia - muscle groups
epimysium - around whole muscle
perimysium - surrounds fascicle
endomysium - loose areolar/reticular CT b/w cells in a fascicle

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16
Q

tendon

A

dense regular CT

- layers of periosteum (dense irregular) become dense regular

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17
Q

fascia

A

surrounds groups of muscle

- dense irregular CT

18
Q

epimysium

A

dense irregular CT

- surrounds whole muscle

19
Q

fascicle

A

multiple muscle fibers grouped together

surrounded by perimysium

20
Q

perimysium

A

surrounds fascicle

21
Q

endomysium

A

loose areolar/reticular CT b/w muscle fibers

22
Q

myofibril

A

proteins bundled inside muscle fiber/cell

- run length of muscle fiber and create striped appearance of muscle

23
Q

sarcolemma

A

muscle cell membrane

24
Q

sarcoplasm

A

cytoplasm of muscle cell

25
myofilaments
muscle filaments: protein strands inside myofibril
26
each muscle fiber has its own _ and _.
- capillary beds | - branch of a somatic motor neuron
27
how are mitochondria dispersed around a muscle fiber?
they are everywhere bc they are where ATP is being generated | - can acquire more mitochondria through more endurance training
28
myofibrils are surrounded by what
triad | consists of 1 T-tubule with a terminal cistern on either side
29
T-tubule
transverse tubule - evaginations in the sarcolemma that run around each myofibril - how AP get to each part of muscle cell - 2 wrap around each sarcomere
30
sarcoplasmic reticulum
smooth endoplasmic reticulum, wrap around myofibrils to be kind of network like - store calcium
31
terminal cisterns
one found on either side of T-tubules, makes up a part of the triad
32
z-disk
runs across proteins and helps hold myofibrils together | - forms contractile unit called a sarcomere
33
dystrophin
connects actin filaments on "free" side of z-disk to sarcomere and can also extend to endomysium
34
myoglobin
makes muscles red | - picks up and carries oxygen
35
titin
large coiled protein, gives skeletal muscle its elastic ability attaches z-disk to m-line
36
what are the types of proteins present in an actin myofilament
actin proteins tropomyosin troponin
37
actin protein
ball shaped | lined up and twisted on 2 strands of tropomyosin to make a helix shape
38
tropomyosin
2 long strands of protein that wrap around and cover all myosin-binding sites
39
troponin
3 parts: - 1 attaches to actin - 1 attaches to tropomyosin - 1 binds to calcium when avail from SR; when binds causes troponin to change shape and tropomyosin moves away from binding sites
40
myosin myofilament
myosin protein is composed of 2 protein strands twisted together - a filament is composed of 300 molecules all stuck together, held at the m-line
41
myosin ATPase
located on myosin head | - ATP allows head to bend upward, grab actin and pull towards m-line