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Anatomy Test 4 > histology 7- muscle > Flashcards

histology 7- muscle Flashcards

1
Q

3 types of muscle tissue

A

skeletal
cardiac
smooth

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2
Q

skeletal muscle

A
  • strong, quick discontinuous voluntary contractions

- long striated strings (muscle fibers)

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3
Q

cardiac muscle

A
  • strong, quick continuous involuntary action
  • only found in heart
  • presence of larger nuclei and intercalated discs distinguish it from skeletal
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4
Q

smooth muscle

A
  • weak, slow involuntary contraction

- non-striated, group of cells

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5
Q

special characteristics of muscle tissue

A
  1. excitability/ irritability
  2. contractility
  3. extensibility
  4. elasticity
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6
Q

excitability

A

can be excited by electrical potentials

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7
Q

contractility

A

fibers condense unilaterally to move bones without stretching cell

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8
Q

extensibility

A

fibers can be overextended without stretching/deforming cells

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9
Q

elasticity

A

fibers are elastic, can stretch and deform

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10
Q

function of muscle tissue

A
  • Production of movement
  • Maintaining posture
  • Stabilizing joints
  • Generate heat (thermogenesis)
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11
Q

list the different types of skeletal muscle

A

type 1
type 2a
type 2b

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12
Q

type 1 skeletal muscle fibers

A

Slow, red oxidative fibers

  • a.k.a. Slow twitch, fatigue resistant fibers
  • Many mitochondria and lots of myoglobin
  • Derive energy from aerobic oxidative phosphorylation of fatty acids
  • Adapted for slow, continuous contractions over time
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13
Q

type 2a skeletal muscle fibers

A

Fast, intermediate oxidative-glycolytic fibers

  • a.k.a. Fast twitch, fatigue resistant fibers
  • Many mitochondria, lots of myoglobin and glycogen (intermediate)
  • Derive energy from aerobic oxidative metabolism and anaerobic glycolysis
  • Adapted for rapid contractions and short bursts of activity
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14
Q

type 2b skeletal muscle fibers

A

Fast, white glycolytic fibers

  • a.k.a. Fast twitch, fatigable fibers
  • Fewer mitochondria and myglobin, but LOTS of glycogen (pale color)
  • Derive energy from anaerobic glycolysis
    • movement
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15
Q

Describe the organization of muscle tissue from the organ level down to the myofilaments.

A

Molecules → myofilaments → myofibril → muscle fiber → muscle fascicle → skeletal muscle

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16
Q

Sarcomeres

A
  • Interlocking rods of actin and myosin
  • Z line (Z disc) endpoints of sarcomere
  • M line: midpoint of sarcomere, myosin
  • A band: length of myosin fibers in sarcomere, actin & myosin
  • H band: (H zone) length of myosin fibers not surrounded by actin, shortens with contraction, myosin
  • I band: length from ends of myosin fibers on adjacent sarcomeres, shortens with contraction, actin & titin
17
Q

Describe the filament sliding hypothesis and changes in the appearance of the sarcomere during contraction. Filament sliding hypothesis in relaxed, partial contraction, and full contraction

A

relaxed muscle- sarcomere, I band, H zone all at relaxed length

partial contraction:

  • thick (myosin) and thin (actin) filaments slide past one another
  • I band and H zone almost nonexistent
  • thick fibers meet at M line (here, M line = H zone)

full contraction:

  • thick filaments overlap
  • adjacent I bands overlap, H zone nonexistent
  • shortest length of sarcomere
18
Q

thick and thin filaments don’t _________, just interlock and slide against each other

A

change length

19
Q

excitation-contraction coupling

A

1) Action potential generated along sarcolemma down t-tubules.
2) Action potential triggers Ca2+ release from terminal cisternae of sarcoplasmic reticulum
3) Ca2+ binds to troponin, cross-bridges form…contraction

20
Q

Sarcoplasmic reticulum

A

-endoplasmic reticulum of muscle cells, stores and pumps Ca2+ ions

21
Q

T-tubules

A

-invaginations of sarcolemma designed so action potentials can travel into cell

22
Q

Terminal cisternae

A

-enlarged areas of SR that surround t-tubules. Stores Ca2+ to release when action potential travels down t-tubule

23
Q

Triad

A

-structure (group) formed by T-tubule and 2 sarcoplasmic reticula/terminal cisterna

24
Q

Describe the process of cross-bridge formation, the power stroke, and cross-bridge detatchment. Describe how this relates to rigor mortis.

A

1) Head of myosin cross bridge attaches to actin myofilament
2) Working stroke – myosin head pivots and bends to pull actin filament toward M line
- ADP and Pi released
3) New ATP attaches to myosin head, head detaches from actin filament
4) ATP hydrolysis splits ATP on myosin head, cocking of myosin head occurs
- Repeat

25
Q

Rigor mortis-

A

caused by inability of ATP replenishment due to death. Muscles lock up.

26
Q

List and describe the CT layers associated with skeletal muscle.

A

Endomysium -encases muscle fibers
Perimysium -encases muscle fascicle (bundle of fibers)
Epimysium -encases entire muscle (bundle of fascicles)

27
Q

Describe how muscles attach to bones.

A

tendons

  • continuous with bone and muscle
  • extension of periosteum/epimysium
28
Q

morphological features of cardiac muscle

A
  • branched, uninucleated cells separated by permeable intercalated discs.
  • mitochondria make up 25-40% of cell volume
  • T-tubules: one per sarcomere at Z line
  • SR: simple, small terminal cisternae, forms diads with T-tubules
29
Q

morphological features of skeletal muslce

A
  • multinucleated independent cells
  • mitochondria only 2% of volume
  • T-tubules: two per sarcomere at A-I junctions
  • SR: complex, larger terminal cisternae, forms triads with T-tubules
30
Q

Describe the structure and function of intercalated discs.

A
  • fascia aderens (links actin filaments)
  • macula adherens (desmosomes) stop separations during contraction via linking intermediate filaments
  • gap junctions for intercellular communication (ion exchange)
31
Q

Describe the distinct morphological features of smooth muscle.

A
  • no striations

- relaxed: looks like pseudostratified columnar cells

32
Q

Describe the differences in myofilament organization in smooth muscle as compared to striated muscle.

A

Smooth muscle

  • individual cells shrivel up via intracellular criss-crossed actin/myosin filament contraction
  • contractile fibers (actin/myosin) connect to sarcolemma
  • intermediate fibers attach contractile fibers to corresponding contractile fibers at cytoplasmic dense bodies

Anatomy Test 4 (11 decks)

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